RV Battery Overcharging

I tow a 22-foot travel trailer and we do most of our camping in provincial parks here in Ontario. Most of the time we are hooked up to electricity full time. Does it hurt the RV batteries if you are always hooked up to electricity and the batteries are always being charged? What about during those times we store the trailer? It almost seems after I have the batteries for about a year they don't last as long as when I first got them. Every once in a while we go to parks which don't have electrical hook-ups. I do carry two batteries.
Reinhardt, (Windsor, ONT)

Reinhardt, I’m not a fan of leaving the RV plugged in non-stop unless you are close by to monitor the batteries. Overcharging is a common malady caused primarily by mediocre charging converters. There are exceptions of course; those sophisticated chargers which employ a three or four-step charging process, for example. Boiled batteries are far too common when RVs are left plugged in during non-use, unless you take the time to check the electrolyte level quite often.

It’s actually better to fully charge and then remove the batteries from the RV during any long period of non-use, especially over a harsh winter where temperatures may dip below freezing. Constant overcharging causes batteries to sulfate at a quicker rate, thereby reducing effective performance. This sounds like what you are experiencing. Decent deep cycle batteries should certainly last longer than one year.

I recommend the Xantrex Truecharge line of RV battery chargers. Most battery makers heartily favor the application of a definitive, three-stage charging process to fully and quickly charge battery systems on modern RVs. Outfitted with a sophisticated microprocessor, the charging amperages and charge voltages produced by the Truecharge2 unit, for example, are accurately regulated to provide the correct charging cycle without the risk of overcharging. This means RVs can be stored over long periods while plugged into shore power without worry. Additionally, the Truecharge2 is applicable to wet cell, gel and AGM batteries.

No DC in RV

I recently upgraded from our 1987 pop-up and purchased a 2003 Starcraft Travel Star. I used an adapter to power the camper at the house. When I first plugged it in, it appeared that everything was fine. After approximately 15 minutes, all of the lights went out.  I purchased the unit from my brother and I camped in this unit last fall so I know that there were no previous issues. A few details to mention. We had a storm a day or two before I picked it up and the wind blew the refrigerator vent cover off of the roof, so it is possible that water got down in behind the fridge. 

Further investigation revealed that there is power to all of the outlets, so the microwave also works, as well does the fan for the air conditioning unit. The refrigerator, radio and lights do not work. I checked all fuses and breakers and all are fine. The battery was disconnected at the time, I connected it and still didn't have power, however, I'm confident that the battery is no good and I don't believe that the battery should need to be connected for the lights to work anyway. The last detail that I will mention, is that when I pulled to check the 30 amp fuses, I did notice some "browning" on the circuit board on the panel. (A few pictures attached). Any ideas? Mark W. 

Mark, unfortunately your photos are way too small for me to discern anything conclusive from them, but keep in mind, all the lamps, radio, controls for the refrigerator, etc., are all powered by 12-volts DC. The receptacles, the converter, air conditioner, microwave, etc., are all 120-volt AC loads. Without a battery in the system, some converters do not operate. The battery acts as a sort of filter and must be connected into the system even when connected to shore power.

The discoloration you mention on the circuit board leads me to believe the converter has failed, either the board itself or the switching mechanism that is energized when shore power is available. It’s doubtful any rain water entering behind the refrigerator caused the damage. More likely a voltage surge or spike from the storm burned out components inside the converter. To be sure the 12-volt DC system is still operating, install the battery and see if everything works without the coach being plugged into shore power; just being powered by the battery. If all works off the battery, the problem is central to the converter (either the relay or the board). But before buying a new converter/charger, I’d have a certified technician perform some measurements and tests to declare the existing unit faulty.

What's that Receptacle?

Dear Doctor, I just bought my first RV. It is a Winnebago Minnie Winnie 25B. I didn't receive any manuals so I am learning as I go. What is the service receptacle in the electric cord compartment? It says close when not hooked to outside power. I have left it open since I got it 6 weeks ago. I am also unclear if the house battery disconnect switch should be left on all the time, even when hooked up to outside power. Is this connected to my engine battery and if it is left on will it drain the engine battery? I have heard many different viewpoints. Thank you! Cathy R.

Cathy, if what you are seeing looks similar to this photo, that is the RV's generator output receptacle. In order for the generator to power the coach, the shore cord must be plugged into that receptacle. Some larger motorhomes come equipped with an automatic transfer switch that makes the connection automatically soon after the generator is started. But on some of the smaller coaches, in order to power the coach with 120-volts AC electricity, the shore power cord must be plugged somewhere; either into the pedestal at the campground, or into that receptacle inside the compartment.

When activated, the house battery disconnect solenoid removes the battery from the system during a period of storage or non-use. The house and engine batteries remain separated so it will have no effect on the engine start battery. Also, if the solenoid is activated while the coach is plugged in to shore power, the battery charger will not be able to charge the house batteries since they are now “disconnected” from the system. So typically you’d activate the disconnect switch during storage so the battery won’t be drained. But when using the coach, leave it off.

Battery Ratings

Dear RV Doc, your article on batteries was informative but gave information that is in conflict with information in two other articles I've read. You say the Amp-Hour (AH) rating is a 20-hour rating that indicates the number of amps a battery can deliver for 20 hours. From this one would expect a 100 AH battery to deliver 5 amps for 20 hours. The other articles I've read stated that the AH rating is based on a 20-amp drain. That at 80 degrees F., a 100 AH battery can deliver 20 amps for five hours before the voltage (12-volt battery) drops to 10.5 volts. The results may seem to be the same but one article went on to say that the length of time is not a direct inverse proportion to the amp drain. In other words, a 100 AH battery cannot be expected to last 10 hours at a 10-amp drain or 20 hours at a five-amp drain. What is correct? Keith L., (Swansea, IL)

 
Keith, I think it may be a matter of semantics mostly, but the 20-hour mention is the common time frame usually referenced for rating batteries, according to the Battery Council. Peukert’s Law notwithstanding! The 20-hour time frame is simply the usual benchmark. 


Here's how one major battery manufacturer states it:


"The amp-hr rating for an automotive battery is usually based on a 20hr discharge at 80° F, at a particular rate (determined by the amount of active material within the battery), until a minimum voltage of 1.75V/cell (10.5 volts for a 12 volt battery) is reached. For example, if a 12-volt battery at 80° F delivers 4 amps for 20 hours before its voltage drops below 10.5 volts, its amp-hr capacity will be 4 amperes x 20 hours = 80 ampere-hours." 

Scientific measurements/data will be different. Obviously, to be 100% correct, the Peukert formula would have to be factored in. But to explain that would simply further confuse most readers not holding a degree in engineering.

 

Voltage Monitor Gone Awry

I have an issue with my Xantrex panel. When I plugged in the motorhome, all the panel lights for the charging sequence strobe and still strobe.  I have attached a movie to show you what I'm talking about. I also saw that the house batteries were showing 6 volts at the time. I really do think my batteries, four 6-volt batteries are bad as they do not hold a charge long at all. Could this strobing be from the batteries being shot and needing replacing? Doug K., (Redmond, WA)

Doug, Xantrex is aware of this problem and has released new software in the remote control unit. The problem happens with the older remote panels when the DC voltage dips momentarily, causing the processor to try to quickly track which LEDs should be illuminated on the display. Evidently it was searching too quickly and it basically confused itself! The newer remote re-tracks every three seconds which enables it to lock onto the correct sequence better. Replace the remote with a new device and it should be rectified. It might run through that rapid sequence once or so, but it will eventually fix itself rather quickly. Your local dealer can probably order one for you or you can also contact Xantrex directly.

RV Battery Charging at Home

Hey Doc, I have bought two six volt batteries. My problem is that I have to store the trailer in a lot with no access to electricity. So I bring the batteries home to be charged. My question is what battery charger should I purchase to recharge at home. Also what amp should I use to recharge. Thanks and I always enjoy your presentations in Seattle. Mike A.

Mike, it’s probably better actually, to bring those batteries home to charge. That way you can monitor the charging process and keep a watchful eye on the electrolyte much easier. Simply connect the two batteries in series (one cable running from the positive post of one battery to the negative post on the other battery, and simply use any applicable battery charger to the other two posts. In this diagram, the battery charger would be connected to the same terminal posts as the two loose cables.

To fully charge both batteries, I recommend a multi-stage battery charger (such as the Xantrex TrueCharge2) and remember to never overcharge them beyond the gassing point. A computer-controlled battery charger will accomplish that automatically. The charger should be sized C/5; meaning, divide the total amp-hours of the battery bank and divide it by 5. That would be the recommended minimal charging unit required. As an example, two six-volt batteries in series would yield approximately 225-amp-hours. Divided by 5 = a 45-amp battery charger would suffice. I would recommend a 50-amp charger in case your batteries can store a little more than that.

 

RV Battery Capacity Question

Hey Doc, will two, T-105, 6-volt batteries be able to crank over and start a generator on a toy hauler? Frank C., (no city/state) 

Indeed and with plenty to spare Frank! But I assume you mean two, charged batteries, right? Two dead batteries of any make would have trouble. But Trojan T-105s are often used to provide DC power to a whole RV. That’s almost 450-plus amp-hours of storage capacity when configured into a 4-battery, series/parallel set-up and around 220-250 amp-hours when two are simply connected in series. If that generator won't crank, there's something else amiss. 

Smoke Gets in Your Eyes

I'm trying to find out what I have to do in order to fix this power issue. When I last parked my trailer I plugged it into a 50 amp shore power source. Then while trying to raise the power jacks in order to unhook the truck, the switch wouldn't work. It was like there was no power at the switch. So I clicked the battery power switch on in order to use the battery power. It worked fine but after raising the trailer I noticed and smelled smoke. It was like a burning electrical smell. I opened the door for the garage and it was full of smoke. After the smoke cleared I'm pretty sure the smoke was coming from the electric motor that raises and lowers the power jacks. After this I started looking into the problem further and noticed one of the electric breakers that controls the power converter was tripped off and it would not stay reset. Then I unplugged from the 50 amp and with the plugin adapter plugged into 30 amp shore power. That seemed to fix everything and I've been running it that way since (about 3 weeks). I have the trailer for sale and don't want to sell it without fixing this issue. Please point me in the right direction. I don't want to call an RV repair dealer because I've been ripped off by them before. Thanking you in advance... Gary S., (Lisbon, OH)

Gary, with all the accoutrements that come with a coach that large, the 12-volt power demand is huge. Some manufacturers fail to let their customers know about the vital importance of having enough battery power to operate all things 12-volt. Plus that battery disconnect switch must be off in order to have 12-volts distributed throughout the coach. I’m not sure how many batteries are in your bank, but it’s doubtful the full load of those landing jacks lifting that much weight can be adequately provided by the converter/charger alone. There may be something internal to the converter that is not allowing it to fully charge the battery bank, but the symptom suggests a low amount of voltage in the batteries. When connected to 30-amp shore power, is the converter still in operation? With less power available, it’s possible the converter/charger is not being powered by 120-volts AC from the shore line at 30-amps service. If you send me the brand and model of the converter, I can delve deeper into that device.

Another thing some RV makers fail to understand is the negative side of the DC system. Be sure the negative cables are greater than or equal to the size/amperage rating of the positive cables. The high current demand of the landing jacks under load could have overheated the motor by a lack of proper grounding. If possible, fully charge the battery bank independently of the converter/charger and see if the jacks operate normally. If so, we can focus attention to the converter itself.

With 50-amp service and the converter operational, is there a voltage increase, as measured at the battery bank? It’s possible the converter is undersized for the 12-volt demands of the entire coach. Adding the high current demand of those landing jacks possibly overheated the motor causing it to smoke. Typically they are protected by an internal breaker so hopefully no internal damage exists. Have you noticed other 12-volt devices with problems? Dim lighting, slow fan speed on the furnace, low water pressure from the pump, etc.? If other devices exhibit problems, I’d focus on the ground cables and all connections, plus the state of charge of the batteries.

Loose connecting points can also cause overheating and smoke. If the problem is dedicated to only the powered landing jacks, then it could be a problem with the jack motor or possibly the converter. Another question; do you have a power management load center? One that sheds loads if power consumption is exceeded? When operating on 30-amp service, some devices cannot operate unless the management load center can make that decision based on load requirements. Sounds confusing, I know. But until we have some specifics about the individual components, we're just guessing.

Send me the specs on the converter/charger and the landing jacks, and how many and what type of batteries are in the battery bank and I’ll dig further. There’s a logical explanation in there somewhere.

Dog Bones & RV Batteries

Thanks for your information at the RV show last weekend. Your seminars were very informative and those tire pressure requirements were new to me. Also you mentioned the dog bone adapter is a not a good idea. I’ve used them for years with no problem. How can I plug my 50-amp trailer to the 30-amp post at the campground without one? What do you know that I don’t?

What do you think about solid state batteries? We live full time in our 5th wheel and currently have two lead acid 12-volt deep cycle batteries. Weight seems to be a good thing with the solid state and they are available in a higher amp-hour rating, (but for a price!). Or shall I upgrade to four, 6-volt batteries in a parallel/series configuration? Thomas S., (Seattle, WA)

Thanks for coming to the seminars Thomas! Glad to hear you liked them! About those dog bone adapters....only use them if you absolutely have to. The biggest concern is that one or more safety devices are bypassed when using them. Plus more connections in the chain gives moisture intrusion and electrical corrosion a leg up. But if all you have available is a 30-amp receptacle, unfortunately you’ve got to use one. But try to always plug in to the correct receptacle so you can have full operation of all your components and circuit protection. Here's an industry expert's similar remarks about those dog bone, reducing electrical adapters. Check out this short video. 

I’m not quite sure what you mean by a solid state battery. Do you mean a sealed battery like an AGM? Do you have a specific brand in mind? Upgrading your battery bank to four, 6-volt batteries would be a huge advantage! You would more than double the amp-hour capacity, in most applications. Just remember, you’ll then be required to have the capacity to charge that new configuration also! 

##rvt749--dog bones
 

Electric Brakes - Unintended Break-away Switch Activation

After we set up our 5th wheel at the RV park, the breakaway switch cable got snagged in the truck box and I pulled the plug out of the breakaway switch. I noticed it laying in the box three days later. I immediately put the plug back in. The trailer is plugged into 50 amp service so the batteries are continuously being charged. Would there be any damage to the break magnets or the switch itself? Also when would the magnets release? When I reinserted the plugs, or would I need to jack up the trailer and spin the wheels? Your assistance would be appreciated. Garry F., (Mill Bay BC, Canada) 

The good news, Garry, is that it’s unlikely anything was damaged by the constant, three-day amp draw. I’m sure the magnets got pretty warm, but nothing was spinning so there would be no extra wear on the magnets or the armature plate inside the wheel assembly. As soon as you re-inserted the pin, the current flow was terminated. As long as the batteries held their charge by being plugged into shore power the whole time, chances are the batteries are fine too. Unless the trailer was also plugged into the truck during this time, there’s nothing to worry about from the dash controller end of the circuit. If the truck WAS plugged into the trailer, I’d replace its 12-volt circuit breaker, which may have been rendered weaker due to the constant current flowing through it. That component may have overheated, but typically it would not be involved in activating the brakes under normal break-away circumstances anyway. You should be good to go! 

##RVT782
 

Cooking My RV Batteries

Can you give me some important tips on storing my RV? I park my RV behind my garage and plug in to a 30-amp shore power cord. I have discovered that my battery bank of two, Group 27 batteries are "cooking" and I don't know why. Sure would appreciate any input. Dee S. (Seal Beach, CA)

Dee, aggressive overcharging by the on-board converter/charger would likely be the reason the batteries appear to be “cooking.” Many RV converter chargers are equipped with, what I call, mediocre technology concerning the battery charge function. They serve as outstanding converters (converting AC electricity to DC electricity), but lack the complexity of a processor-controlled battery charger. Many common converters force the maximum amount of current into the battery bank at too high of a voltage rate. Some may taper the amount of amp-hours (current), but it takes special and specific charging algorithms to push the correct amount of current at the correct amount of voltage at a rate that is advantageous to that type of battery, all the while considering its state of charge at that moment in time. 

As a battery charges (accepts and stores amp-hours), the voltage and current rate must constantly be evaluated and modified to ensure that any given battery will not be overcharged or undercharged, yet charged fully. A sophisticated, processor-controlled, three-step charger is needed to accomplish this. I’m a fan of employing the stock converter as a converter only, but to add an aftermarket, multi-step battery charger to be solely in charge of keeping the battery bank(s) fully charged while connected to shore power. The newer technology allows for an RV to be kept plugged in all the time, without the risk of overcharging or “cooking” the batteries in the system. Some are applicable to the various types of RV batteries; wet cell, AGM, gel, etc. I would suggest you upgrade at some point. Until then, if you opt to leave the coach plugged in all the time, be sure to inspect the condition of the batteries every couple of days. Unplug the coach or disable the converter, (simply turn the circuit breaker off), if overcharging or gassing at the batteries is discovered. 

Some RVers have used a timer placed in the AC circuit of the converter to only allow it to operate at certain times. But I’d rather see the stock converter convert and a separate battery charger charge. 

Boiling Batteries

I just bought a used coach equipped with dual auxiliary batteries. I used my voltmeter to test them and only got a reading of 8.5-volts. When I checked the cells I found they all were almost dry. I refilled them all with distilled water and plugged in my outside power cord to allow a trickle charge. I checked the battery readings every day for three days and the readings were still routinely 8.5-volts. Today when I pressed the AUX button on my panel, all five indicator lights came on to the 'Full Charge' indicator. I tested the batteries again and they all registered 8.5- volts. I flipped the auxiliary battery switch to "On" with the outside power still connected and immediately heard a humming sound coming from the battery compartment. When I leaned down over the battery storage compartment I also heard a sound like boiling water and there was a strong nauseating odor. I tested the batteries again while this was occurring and they tested at 13-volts. I turned the auxiliary battery switch' to "Off" and again tested the batteries which were back at 8.5-volts. I turned the switch to "On" again and it hummed, sounded like boiling water with the same odor and tested at 13-volts. Yet when turned off, they tested at 8.5-volts again. The two utility batteries are Group 24 Marine/RV batteries. Is this normal or do I have a problem? Are there specific procedures for checking and recharging utility batteries? Ken V. (Tyrone, NM)

Ken, first of all, in order for the onboard converter/charger to actually charge the battery bank, that auxiliary battery switch must always remain on or “Connected.” It is apparently a battery disconnect switch; typically used during periods of non-use. It basically takes the battery out of the system altogether, including the charge current coming in as well as the battery current going out. But it is quite possible you have more than one problem; a battery charger problem, a miswired battery bank or, since we don’t know their true condition, simply faulty batteries. 

A process of elimination will determine the culprit, but it’s obvious the batteries probably suffered some damage just by being boiled dry. The first thing pro RV service techs do is eliminate the battery bank as the cause of the problem. It may be time to have a tech fully test them by using a carbon pile battery tester. Not usually found in the DIYers tool kit, a carbon pile battery tester will reveal internal battery problems not normally detected by simple voltage measurements. 

But here’s what’s probably happening. The batteries are definitely dead and may be sulfated and damaged beyond rescue. But since the battery bank is removed from the circuitry by virtue of the battery disconnect switch being off, you are actually measuring the converter/charger voltage at the monitor panel while the motorhome is plugged into shore power, not the actually battery voltage. When you turn on the disconnect switch (bringing the batteries back into the system), the converter/charger is suddenly tasked with trying to charge two completely dead batteries. Since you added water to the electrolyte, the sulfuric acid content is very low in each cell and the charger is trying to pump as much current at the highest voltage it can into those dead batteries. The off-gassing (bubbling and odor) are the result. The first step would be to fully charge them prior to having a carbon-pile test performed. If possible, disconnect the batteries from the RV charging system and charge them both independently using a shop battery charger. Of course, if during the off-line battery charging process, it's discovered that both batteries simply will not take a charge, than we can probably assume they are internally sulfated beyond resuscitation and it may simply be time for a new battery bank. But if they indeed begin to accept a charge (meaning the open circuit voltage and the specific gravity gradually increases), under a low charge rate, they may still be salvageable. 

Completely dead Group 24 batteries, though not huge in terms of battery capacity, may still take a few days under a slow/low charge rate to fully charge. Here's how to determine when any given battery is fully charged. While charging, monitor the specific gravity in each cell using a temperature compensated hydrometer. As the battery continues to accept a charge, the specific gravity will continue to rise. At some point the specific gravity simply will stop increasing. When it refuses to keep escalating in all cells after a two or three-hour period, that battery is indeed fully charged. It simply will not store any more amp-hours. By the way, if there is a difference of .050 points between any two cells on the same battery when using the hydrometer, that battery is indeed faulty and should be replaced. Test over! 

Once the batteries are each fully charged, have them tested on a carbon-pile load test. Some RV shops may not be equipped with a carbon-pile tester (though they indeed should), but you can also have this service performed by any independent battery retailer. If the batteries indeed become fully charged and they pass the carbon-pile test, next, be sure they are reinstalled and wired correctly. Two 12-volt batteries are wired in parallel to double the storage capacity yet still remain at 12-volts output. Be sure the "hot" wire from the RV charging system is wired to the positive post of one of the batteries and that the negative ground wire is connected to the negative post of the other battery and to a good, clean and dry connection on the coach frame. 

I wouldn't put too much faith in the onboard battery meter on the monitor panel. Rely on a good volt-ohmmeter (VOM) for more accurate measurements. I recommend every RVer carry a decent digital VOM anyway. This leads me to the third possibility; the condition of that onboard battery charger. Depending on the brand and model, some less expensive converter/chargers have a propensity to overcharge batteries, hence the condition you found the battery bank in originally. There are much better chargers available that may be a better choice. And you always have the option to upgrade. But with shore power connected, the battery switch activated and the charger operating, you should measure an increase in the voltage at the batteries, above what the batteries measure in an open circuit situation. All this said, I'd wager the charger is probably okay, simply typical and mediocre and that the batteries will fail one of the tests mentioned above. If I'm right, new batteries and an investment in a sophisticated, chip-controlled RV battery charger will probably eliminate your issue forever. If you opt to keep the current charger, be sure to monitor the electrolyte level in the batteries often while the coach is connected to shore power.

##RVT871

Maintenance Free Batteries

How do I know if I have maintenance-free batteries in my motorhome or if I have to periodically check the water levels? Kirk P., (St. Louis, MO)

Kirk, I'm guessing you're referring to the automotive start battery in your motorhome. Those so-called maintenance-free batteries will have non-removable cell caps or no caps at all. Personally, I believe the moniker, "maintenance free," is really a misnomer in that even if a battery has no access to measure the specific gravity of each cell using a hydrometer, still the battery and its terminals must be kept clean and free from oxidation and corrosion. In other words, there is still maintenance to be performed if you want to get optimum performance out of those batteries. 

Rather than specific gravity readings, voltage measurements can suffice for checking the state of charge of batteries without access to each cell; (I’ve included a chart below).

Open Circuit Voltage vs. State-of-Charge for 12-volt Batteries of Various Types

                                        Battery Electrolyte Type

State of Charge       Flooded            AGM             Gel

100%                           12.6                 12.9             12.8

75%                             12.4                 12.7             12.6

50%                             12.2                 12.4             12.3

25%                             12.0                 12.0             12.0

0%                               11.8                 11.8             11.8

But if you do not see removable caps on the top of the batteries, chances are they are probably considered the maintenance-free type. Keep in mind, some batteries by certain makers may have only two caps that cover three cells each; they may not have six individual cell caps. Hope this helps!

##RVT851

Inverter Questions

Where can I find the wiring diagram for a 1989 Citation RV? I have one in NJ. I bought it used and it is having some electrical problems. I don't know what the inverter is used for. I was told that my lights are low voltage (12-volts), therefore I need the inverter. I don't believe it for a minute, but I would like to get a copy of the diagram in order to troubleshoot the problem. Can you help? Gerzan A., (N. Bergen, NJ)

Gerzan, it’s doubtful you’ll ever find an accurate schematic or wiring diagram for a coach that old, even if one existed. But typically, all lighting in an RV is 12-volts DC (direct current). An inverter is the electrical opposite of a converter. It takes 12-volt battery power and inverts it to 120-volts AC (alternating current). By the way, some of today’s sophisticated inverters are also very good battery chargers. When the coach is plugged into 120-volts AC shore power, (or operating on generator power), the inverter becomes a multi-step battery charger. I'm wondering if you're confusing a pre-existing CONverter with a non-existent INverter?

If you have a battery bank, you do not need an inverter to power the interior lamps. The inverter would be used to produce AC voltage so you can power 120-volt AC devices/circuits when shore power is not available. What is the brand and model number of the inverter you have in your coach? Inverters come very sophisticated (true sine wave output) while some lesser expensive models output a modified square wave. If you indeed have an inverter, it’s possible it did not come stock from the factory. Unfortunately, I’ll need a little more information to help any further.

Two Fuses on RV Battery Post

I was wondering why there are two fuses on the hot wire of my battery on my travel trailer and if they are needed. Andy, (Lignum, VA)




Simply put, it’s quite possible that an existing circuit somewhere in the trailer is wired directly to the positive battery post instead of to a fuse panel inside, Andy. Chances are you need them both. A quick test would be to pull the fuses, one at a time, and see what doesn’t work inside the RV. Be sure to label each fuse so you’ll know exactly which circuit(s) they are protecting.  

Constant LED for RV Dump Valves

I have a 2011 Carriage Carri-Lite. Both the grey water and black water electric dump valve switch lights are illuminated indicating the valves are in the open positions. They have been working fine but seem to be "stuck" in the open position. This happened once before and I cannot remember what the fix was. I checked the fuses and breakers and they seem to be fine. The actual valves are not immediately accessible and I'm not sure where they are. I believe it's an electrical issue. HELP! Thanks, J. W., (Three Rivers, TX)

J. W., it is unusual for both lights on the those switches to stay lit. Usually the black indicator LED stays on even while the valve is working properly. The indicator stays on when the magnet on the gate does not line up under the magnetic switch, which is mounted on the body of the valve itself. The switch is a “normally closed” switched and it takes the magnet to hold the contacts “open.”

Unfortunately you will have to gain access to the valves at some point in order to troubleshoot that magnetic switch. It will be necessary to remove the belly pan or at least part of it to get to the valves. Some of the Carriage models have a molded plastic piece on the street or driver’s side of the coach that looks different than the other underbelly pans. This is where the valves are located.

Remember the light is simply an indicator and not part of the actual valve operation, so if you are on a trip, you do not need to address this issue until you return home. You can verify that the gray valve is indeed closed even though the LED is illuminated by emptying the tank, then close the valve and run water in the sinks and see if it continues to drain out of the tank and through the sewer hose. Chances are, however, the valve is still closed, even with the LED illuminated.

I’ve attached some additional troubleshooting information for you regarding this issue. You can also call Drain Master 877 787 8833 Toll free and the good folks there will be happy to assist you further if necessary. (Any interested reader can also download the same troubleshooting information from this link).

Trailer Break-Away Switch Operation

Gary, I have several questions about the break away switch on a travel trailer. First, thank you so much for all of your time at the Hershey Show. You went way beyond what was expected to answer questions. My wife, Jayme, and I have attended several of your sessions over the years. I have always learned something from each session, even when I attended the same session two days in a row! 

Now for the questions concerning a break away switch on a travel trailer. Is the power to the brakes directly from the battery or is it routed through the converter distribution box? Should a travel trailer be stored with the pin in or out of the break away switch? With the break away pin out, do the switch and the brakes consume much power from the battery? If you have the ability to keep the batteries charged during storage, should you remove the break away pin? Is it best for the trailer brakes to be set (pin out) or open (pin in) during a month or more of storage? 

Also, I had an inverter installed with an automatic transfer switch so that all the 120V outlets and systems will work in the trailer. It is not powerful enough to run the microwave or air conditioner, but can power anything else in the trailer. Besides using the TV while boon docking, my main use is so I can run the absorption refrigerator using electric during travel. I have to engage the battery disconnect switch before I turn on the inverter and keep it disconnected while the inverter is on. If I have the inverter on and the battery disconnect switch engaged during travel, will this effect the operation of my break away switch? 

Thanks for you help in understanding the break away switch and the impact on the batteries and brakes. Graham & Jayme M., (Jeffersonton, VA)

It was good to have you at the seminars in Hershey, Graham and Jayme! The break-away switch on a towable RV is always powered by the battery bank on the trailer. That way, if the tow vehicle and trailer ever part company, the brakes will be activated and remain fully applied. It should not be connected through the converter since the converter is only activated with the application of 120-volt AC power.

Always leave the pin in the switch. Once a year, jack up one or two tires on each axle, spin the tires and pull the pin to be sure the brakes are fully activated. The tire/wheel assembly should immediately stop with the pin pulled. (This is also a good time to determine if the brakes need adjusting. To read about trailer brake maintenance, check out this article).

While the pin is out, spray electrical contact cleaner inside the switch housing to keep those contacts fresh. Then fully reinsert the pin. When the pin is out or not fully inserted, the brake magnets will continue to draw power and eventually drain the battery bank. The brakes can draw a lot of current; upwards of 3-amps or so for each magnet, depending on the size of the brakes. So the bottom line is never remove the pin except once a year for cleaning and testing.

While driving, you’ll want the alternator of the tow vehicle engine to keep charging the battery bank on the trailer. If you disconnect the battery, it won’t be able to accept that charge. I’m not sure why you need to disconnect the battery to activate the inverter while traveling. You should be able charge the battery while driving AND operate the inverter to power the AC side of the refrigerator. In this manner, nothing will affect the break-away switch. Even with the disconnect activated, the break-away switch should still be able to power the brakes in an emergency. Easy to test....activate the disconnect switch, spin the tires and pull the pin. You might need to have your tow wiring evaluated.

Besides using the inverter, you could also run the refrigerator to get it cold overnight, and turn the whole refrigerator off while driving. Without opening the door often, the contents will typically still stay cold enough as you drive. Once you stop, light it on propane, turn on the inverter, or plug into shore power. A couple different options to consider.... 

##RVT842;##RVT931

RV Batteries Leaking Electrolyte

First time RVer here. I have a 2002, 31-foot Jayco. Why is my battery bank leaking acid? I have two batteries and two solar panels with a PWM charge controller. When we bought it, it was hooked up to power, now we keep it stored. One battery was leaking in the first two months so we replaced both batteries. Now a month later, it's leaking again. The only power we see on the fifth-wheel is a clock on an entertainment center which we can't power off, and a green light on the LP gas detector. We also found a horizontal crack on the side of the wall half way up above the hitch about 8-inches long and 1/8-inch or less wide. Can this cause internal water damage? Should I patch it? Lisa, (Naples, FL)

Lisa, I’m assuming the batteries have been inspected for physical cracks in their casings. It is entirely possible the battery bank is not receiving the proper charge rate and is being subjected to overcharging, thereby boiling the electrolyte. It will be necessary to perform some diagnostic measurements before, during and after charging the bank, I’m afraid. It is crucial that the PWM (pulse-width modulated), charge controller be configured to an algorithm that is beneficial to the specific batteries in your battery bank; one that will fully charge them, yet not exceed the gassing voltage during the charge cycle. I’m guessing the charging voltage might be set too high and a continued overcharge by the solar system is taking place. Or it may be set for AGM batteries rather than wet cell batteries. I wish I could be of more help, but to ascertain exactly what is transpiring, some specific measurements must be taken. I’d suggest a pro (certified) RV service technician take a look to see what’s going on.

And yes, any opening into the roof, sidewalls, front or rear of any RV is an open invitation for water intrusion. Water intrusion is the number one cause of RV damage and can lead to very expensive restorative repairs if not addressed soon. So, indeed have that crack repaired as soon as possible! Even a temporary fiberglass patch is better than leaving it open until a professional repair can be made. And welcome to the RVing lifestyle!

##RVT841 

RV Solar Panels and Shoreline Electrical Quandary

Earlier this year, I asked if I had to isolate my solar panels if I am connected to shore power. I do have a charging unit installed with these solar panels. I check the RV Doctor newsletter and website often and have not read anything on this subject. Maybe it is that I live in Canada and we don't count? Larry G., (Alberta, Canada) 

Larry, I live fairly close to Canada and know more than one Canadian personally, so I’m sure it’s not your country of origin, (check out the question just below yours)! Hey, I even root for the Canucks since they're the closest NHL team to me! Bottom-line, I wish I could respond to everyone immediately, but the volume of emails I receive is simply overwhelming. But on to your question...

Usually, solar battery charging systems are equipped with a charge controller which is a very sophisticated device that monitors the voltage and amperage produced by the array of panels. It has built-in protection to keep from overcharging. The ones I recommend actually provide pulse-width modulation and multi-stage battery charging algorhythms that enable a full charge without the possibility of an overcharge. Here's an interesting article you might find interesting. 

A new charge controller can be retrofitted to any solar charging system. Even if the system was originally equipped with a less-than-stellar blocking diode, shunt-type controller, etc. Even if your inverter/charger or converter/charger is activated while connected to shore power, the batteries will only accept the voltage from the source with the highest potential. Meaning, the charge controller output can be wired in parallel with the converter or inverter charger. Solar, however, works best with a sophisticated inverter/charger rather than one of the mediocre converter/chargers.

So if your system is not equipped with a three or four stage solar charge controller, it’s perfectly okay to upgrade and install one. It just depends on what came with your system. I recommend the charge controllers offered by AM Solar. 

It is important to “size” the controller properly for the voltage and amperage output of the solar array, so you have some choices to make.

RV Batteries - Redux

Is it better to have two, 6-volt batteries or one, 12-volt battery in our 5th wheel? I have heard stories about both. What do you think is better? Larry W., (OKC, OK)

Larry, if you go to the DC Electrical section in the RV Doc archives, (scroll down, on the right-hand side), you’ll find a bunch of similar questions; some with cool diagrams. But two, 6-volt batteries will provide almost double the current storage capacity of a single, 12-volt battery. I often recommend using 6-volt batteries in place of TWO, 12 volt batteries. Here’s why; using simple math, two 6-volt batteries wired in series will typically hold more amp-hours than two 12-volt batteries connected in parallel, utilizing the same foot print (taking up the same real estate space). Two Group 27, 12-volt batteries have the capability to store approximately 105 amp-hours. Double that for two batteries wired in parallel; 210 amps approximately. Two Trojan T-105 6-volt batteries wired in series have the capability to hold about 225 amp hours. In series, the voltage doubles, but the amperage remains the same.

Though minimal, the storage capacity leans in the favor of the twin 6-volt batteries. And with the 6-volt batteries you also get true, deep cycle, commercial grade storage. They’re designed to be cycled over and over.

So from a clinical, purely mathematical, point of view, I give the edge to the 6-volt configuration. That said, there are many outstanding 12-volt batteries (think AGM), that can be just as effective, so in reality, it’s probably a wash when compared to two, 12-volt batteries, but you’d certainly gain storage capacity when replacing just a single, 12-volt battery. And if you are prone to dry camp, those extra few amp-hours may just come in handy.