No Voltage Output from RV Generator

We own an older (1990's) motorhome with an Onan generator (gas). We are ready to go away in a couple weeks, so I started to check everything. The generator is running fine but is not putting out power. There is a junction box right next to the generator where I opened it while it was running and no power was present there. Is there anything else I can check? The nearest Onan repair shop is 50 miles away! Bill D. (Williamstown, NJ)

Bill, if you cannot measure the generator voltage at that first junction box, chances are the output voltage is not even leaving the generator itself. Basically, everything on the coach is now isolated. Depending on the year of the generator, you might see two small, pop-out circuit breakers (see photo), on the side of the control box.  Chances are they are in the popped out, or tripped, position. Try pushing them both in and see if you then have any voltage to the RV. Be sure all loads inside the coach are turned off prior to resetting the breakers on the generator. If the integral generator breakers are not the issue, then there could be an internal problem in the generator. If you still have no output power whatsoever, send me the model number and spec number from the data plate on the generator and I'll dig a little deeper, but I'd wager, it's the circuit breakers. 

One caution! In the future, do not open any junction box or electrical panel while the generator is running or the shoreline cord is connected to shore power! Always disconnect or disable all 120-volt AC producing components before gaining access to any electrical connection.

##RVT810

RV Holding Tank Removal

I need to remove my black holding tank off of a 29-foot Class C motorhome with a slideout. How do you remove the RV plumping from tank? One RV person tried telling me you have to bust it out and replace it with a new tank. This make no sense to me. What can be done and how do you do it? Crawford O. (Dandridge, TN)

Crawford, I'm thinking your RV person is not familiar with the NFPA 1192, Standard for Recreation Vehicles. According to the code, all holding tanks must be removable. That alone, does not mean it’s an easy job. It simply requires manufacturers to make it possible for the tanks to be removed even if it means removing other components first. I go into detail about the procedures in my RV Owner’s Handbook. Unfortunately, it’s too much information to include in an email response, but be assured, it does not have to be busted out piece by piece. 

First verify that the tank actually requires a total replacement. Plastic holding tanks can be successfully welded if cracked. Only when completely destroyed or damaged beyond repair does it actually need to be replaced. I'd "remove and replace" only as a last resort. Here's the bottom line if it does have to come out...

The tank vent and toilet drain enter the holding tank from the top and the drain outlet exits at the lowest portion of the tank. In some cases, the vent can be cut with a hacksaw or disconnected from inside the cabinetry. The toilet simply unbolts from the floor flange, then the flange (which may be connected to the tank in a variety of ways), is simply removed from the top of the tank. The same for the drain outlet on the holding tank itself. It will ultimately terminate and connect with the other holding tank at a location near the left rear side of the coach. All termination valves are removable so you simply remove that pipe and valve associated with the tank in question and reverse the process for installation.

Wish I could provide more clear-cut instructions, but without seeing the actual installation it’s nigh impossible to respond fully. But I hope this little bit will help! 

Unintentional Keyless RV Entry

I bought an older, 1978 Coachman travel trailer which had no keys available for the compartments or entry door.  How do I pop out the plastic key bolt mechanism without damaging the bolt or the RV?And what about the entry door? How can I break in to my own RV? Nikki N. (Breck, TX)

Nikki, you could always call a local locksmith to open the entry door lock to at least gain access to the interior, but this may come with a hefty fee for a mobile service call. Back in the 70s, I know for a fact that just about all entry door lock assemblies and compartment locks had master keys that literally opened all of them. At that time, there were only two or three different compartment lock manufacturers and each brand only had a few key combinations for all locks; supposedly to keep the honest people out! But most created a master key for use by dealers. My suggestion would be to try to find an RV dealer who was around back then. Chances are one of the service technicians will have a set of master keys for that vintage. Once opened, replacement locks are readily available in the aftermarket. 

Also, some the lesser expensive, plastic compartment locks can simply be twisted open with a pair of channel-locs or pliers, though this tactic does risk some damage to the compartment door. I'd check first with a dealer and see if he has a set of master keys.

Water Pump Installation Down Under - Literally!

When installing an RV pump, can it it be fitted upside down under the floor of an off-road caravan? The caravan can be subjected to water and dirt so will have some degree of exposure. Mark B. (Dandenong, Victoria Australia)

Mark, though the typical RV water pump can be installed in a number of configurations, upside-down and exposed to the elements are, unfortunately, not included among them. Now it might be possible to mount it upside-down if the pump can be protected from dirt, moisture and debris; especially on an off-road vehicle. It would most certainly have to be bolted rather than attached by screws. But I believe I’d do my best to locate the pump inside the caravan, especially if colder temperatures are expected. Perhaps a storage box of some sort can be installed through a sidewall under a cabinet? But exposure to dirt, moisture and freezing temperatures should be avoided.

 

Improper Installation of RV Roof

I recently had my rubber roof replaced on my Class C, 22-foot motorhome. The rubber was still good but getting old. But because the old plywood was bonded to foam insulation, they put plywood over it and installed the new rubber roof. Within four months the plywood under the rubber warped really bad. They say they will fix it under warranty but I was curious as to how they do this as it seems the plywood didn't hold the first time around. It's been in the shop over two weeks now and I cannot find anything out yet. How will they attempt to solve this problem? BMCM, (FL)

It’s difficult to ascertain just how they installed that new substrate plywood to the older roof. Hopefully, they removed the rubber membrane, inspected the older substrate plywood for damage, then glued and screwed the new plywood directly to the old plywood after properly preparing it. The condition of the old plywood is crucial. If they attached the new wood to a deteriorated or moisture-damaged substrate, it’s possible the new plywood would buckle in places. It sounds like this may be the case.

They will have to remove the new membrane and the new plywood and thoroughly inspect the old substrate to determine the best course of action before continuing. It is salvageable for sure, but to avoid future issues, it must be done correctly this time. I would also insist on a new membrane. Once they remove the rubber from the new plywood, it will have stretched and been rendered unusable.

Let me know how it turns out. It’s great that they will at least honor their warranty! But they must prepare the old roof properly prior to installing the new roof substrate and EPDM membrane.

RV Holding Tank Evacuations Optimized!

When you are at a campground that has a sewer hook up and you are only going to be there over the weekend, should you leave your tank closed and dump when you get ready to leave or can you leave it open and just clean up? Pam S. (Waco, TX)

Pam, in order to practice optimum waste management, it is always best to keep both holding tank valves fully closed until the tanks are as full as possible. Most experts recommend at least 3/4 full. If you do not fill it to that level during the course of a weekend, it’s still best to fill them with fresh water to at least the 3/4 mark (completely full is best), before evacuating. There’s a couple of reasons for this. The fuller the tank, the more velocity you’ll have during the evacuation which helps to completely flush all the contents; especially for the solid waste tank. Plus it gives the through-the-wall monitor probes a better chance of staying cleaner. The sludge/tissue/residue on the sides of the tank are less likely to dry out and become rigidly stuck when you fill each tank almost full prior to evacuating.

Another reason for closing the valves, specifically the liquid tank valve, is to avoid your RV becoming a virtual vent for the septic system of the campground itself. See my explanation under number 3 below. If you happen to have an internal venting problem or dried out P-traps within your RV, odors can further proliferate.

Here’s a proper dumping procedure that was recently featured in an article I wrote for FMC Magazine.

Correct Waste System Evacuation Procedures
1. Always wear disposable protective gloves when handling any waste system component and be sure to wash your hands thoroughly afterward.

2. Connect the sewer hose. Begin by inserting the nozzle end of the hose into the campground sewer inlet or dump site, and open the valve on the nozzle. Walk back towards the termination assembly on the coach extending the hose only the distance required. Always avoid snaking a full-length hose back and forth on the ground. If more hose is needed to reach the coach, simply attach an extension hose when necessary. All quality hose makers will have extension hoses and connectors. To complete the connection, remove the protective cap or plug on the motorhome end and attach it to the termination outlet. Be sure to maintain the proper slope of the drain hose from the termination outlet to the sewer inlet.

Known as the “first in - last out” rule, inserting the sewer end first and removing it last will guarantee no release of waster water and avoid further contamination on the ground. Note: this is only applicable if the hose has a positive shut-off valve on the sewer end and a cap or plug on the coach end.

3. Only evacuate a holding tank (black or gray) when it is over 3/4 full. Yes, contrary to what some veteran RVers may tell you, this means leaving the gray valve fully closed while in the campground. Filling each tank to a level above the 3/4 mark before evacuating will ensure you’ll have enough volume (and velocity), to thoroughly drain the tank and flush the hose.

Here’s another reason for keeping the gray holding tank valve completely closed except during evacuation. Ever walk through a beautiful, scenic campground and catch a whiff of sewer odor wafting through the park? Kinda ruins the moment, right? All coaches with the gray tank valve in the open position (sewer hoses obviously connected), are simply acting as a direct conduit to the park’s sewer system. Each coach becomes a mini-vent of sorts, in parallel with the septic system of that campground. No wonder sewer odors still abound in the nicest of destination sites.

Follow the logic; a large septic system in a campground will have fundamental venting designed into it, but with numerous RVs connected to that system with their gray tank valves open, odors can rise up through the park’s septic system, through the sewer hoses of those coaches, through their empty gray holding tanks and up the vents of those holding tanks. Remember, it may be your gray tank, but it’s the campground’s black and gray odors coming up and through it. The only problem with this scenario is that the gray tank vents on the RVs are a lot closer to the ground and more prominently located than the park sewer stack so odors are more noticeable. By keeping the gray tank valve closed until the tank is almost full, you will eliminate the localized venting of the campground sewer gasses at your particular site. The more RVers who follow this precept, the less likely we’ll have to endure septic odors in and around the campsite.

4. Evacuate the black tank first. This is pretty much standard procedure and something most all coach owners are aware of, but it’s worthy to mention it again.

After the black tank empties flush it out with a large amount of fresh water when connected to city water. Simply keep flushing the toilet while the termination valve remains open. If you opt for the Polychute or Drainmaster hose, monitor the cleanliness of the water through the integral Clear-Vu fitting as it drains. There are other clear fittings available for the bayonet-type hose adapters as well. When the draining water is relatively clear, stop flushing, close the gate valve and cover the bottom of the black tank completely with fresh water.

Permanently installed holding tank spray kits are available in the aftermarket that attach to each holding tank thereby allowing fresh water to be directly induced into the tank after dumping, but I’m hesitant to drill mounting holes into holding tanks. Plus I like to flush all components of the waste system including the toilet, sink drains, etc., so I prefer to simply flush the toilet and run water through the sinks.

5. Evacuate the gray tank last. After the black tank has completely emptied and its termination valve properly closed, open the gray tank valve and empty that holding tank. Be sure to rinse this tank as well. Dumping the gray tank last utilizes its liquid contents, as well as the fresh water induced after dumping, to help wash away any solid waste that may remain in the sewer hose.

6. Drain the sewer hose. After both tanks have been emptied for the last time at that location, take the time to thoroughly rinse the sewer hose with fresh water until clear water is viewed through the Clear-Vu fitting on the sewer hose. After closing the gray termination valve, remove the sewer hose from the termination outlet on the motorhome and, if so equipped, secure the plug to the hose and the termination outlet. Then begin “milking the hose.” In other words, raise the hose at the coach end and walk it towards the sewer inlet. Keep raising the hose as you walk, thereby “milking” the hose and emptying it completely of water. Even a properly sloped flexible sewer hose may have residual water and waste particles left inside. These particles will become an odor generator over time, so it is imperative to completely remove as much moisture as possible.

7. After milking the hose and as you reach the campground sewer inlet connection, close the positive shut-off valve on the sewer nozzle and disconnect it from the campground sewer inlet. Remember the “first in - last out” rule! With the cap on the coach end and the nozzle valve turned off on the sewer end, all remaining odors stay inside the hose. Cap the sewer inlet and then stow the hose and add an enzyme-based additive to all holding tanks.

8. Check the P-traps. Unless you upgrade to HepvO waterless sanitary valves, every month or so, look down each sink drain and the tub/shower drain to ensure the water seal is still there. In some waste system configurations, a quickly draining tank can actually cause the water lock to be siphoned out of the trap. You’ll probably have to use a flashlight, but it is essential that a water lock remain at all times. Remember, this is the primary method of preventing gray holding tank odors from entering the interior of the coach. Bottom line; a dry P-trap is nothing more than a shortcut for odors to gain entry into the motorhome.

9. Be sure the toilet bowl contains water at all times. If water eventually seeps past the seal and the toilet bowl empties, it’s time to make an appointment at your local service center. An empty toilet bowl will permit black tank odors into the coach. If water can leak past the seal, odors can also!

##RVT789 

Product Spotlight: Xantrex Truecharge2 Battery Charger

By Gary Bunzer

One of the most popular seminars that I present at RV shows, conventions and rallies is entitled, “Optimizing the 12-volt Battery System.” It’s been a topic that undergoes frequent updating as new technology comes to the fore or as new problems arise within the DC systems found on today’s recreation vehicles. Clearly 80-90% of the questions sent to the RV Doctor Column are electrical in nature, so it’s no surprise one of the biggest challenges facing RVers today is maintaining a healthy battery system; what I call, battery optimization.

In my “Optimizing….” Seminar, I advocate having the ability to carry as much current-carrying capacity that space permits and that your wallet can endure. One can never have too much battery current on hand to power the DC components found in the modern RV. And there are many! Typically, all lamps, fans, slideouts, water pump, leveling jacks and electronic ignition appliances, among other devices, rely heavily on a hefty 12-volt battery system in order to operate at their optimum. A healthy battery system is a mandate in most applications, so having as many batteries as possible should be a good thing, right? 

What some RVers often forget, is that adding more batteries to become more self-sufficient (especially when dry camping), is only half of the equation. Yeah, it’s great to be able to have lots of amps at your beck and call, but it’s just as important, if not more so, to be able to properly replenish that battery bank in order to take advantage of having those extra amps available. And that’s the rub.

Along with simply adding batteries to the bank, one must also consider how to be able to fully charge that larger depository without risking damage to the batteries. The more current you store, the more important it becomes having the proper charging methodology on hand to safely charge any battery bank. One way is to replace the stock engine alternator with one of a higher output capability to help charge the house batteries while driving down the road. The other is to ensure the inverter or converter is sized appropriately and designed properly to fully charge the battery system without an inherent danger of overcharging when connected to shore power.

But the typical converter/charger installed by the coach manufacturer will not likely be able to properly charge the complete system in a timely fashion. Because of the proliferation of 12-volt DC accoutrements, many converter/chargers are undersized for the task as they leave the factory, even before adding additional batteries to the equation. And that’s when I start seeing an increase in emails to the RV Doctor Column. Dear Gary, my furnace will not ignite but the fan comes on; my generator will crank, but not start; my slideout moves very slowly and stops before retracting all the way; my water pressure is too low at the lavatory faucets; my hydraulic jacks will not level the coach. These and a few hundred other symptoms can be caused by a faulty battery system; specifically, low voltage at the batteries.

Many converter/chargers installed in some RVs seemingly are designed to never overcharge the batteries since that condition leads to a plethora of issues. That’s the good news. The bad news is that many of these same converter/chargers are not designed to be able to fully charge the batteries either; at least in a timely manner and some are simply not capable of fully charging a large battery bank efficiently at all. Some even have the predilection to overcharge the batteries.

That said, most modern RV converter/chargers are typically great converters, simply poor battery chargers. Their main job is to convert 120-volt AC electricity into 12-volt DC electricity since most every convenience on a contemporary coach is powered or controlled by DC. And most do that gallantly depending on the type of converter. Their shortfall is clearly with the battery charging capability. It’s my opinion the committed RVer truly requires a dedicated battery charger; one designed with the health of the batteries in mind.

Since no two RV battery systems are identical; varying loads, different types and number of batteries, length of conductors, etc., how can one be sure the batteries will be charged completely and effectively in the shortest amount of time? As I’ve often stated in my seminars, thank goodness for the aftermarket! Read on.

The term “smart charger” has been around for a few years now, but what does that really mean? Do they embody some type of intelligence? Well, in a manner of speaking they do. A true smart charger is controlled by an internal microprocessor, it has multiple stages of charging procedures, it can operate under varying AC input voltages, it employs temperature compensation and has safeguards against overcharging as an inherent characteristic. All this and more can be found in the serious RVer’s newest best friend, the Xantrex Truecharge2 battery charger.

The Truecharge2 is the newest version in the Truecharge line. Available in 20, 40 and 60-amp outputs, the Truecharge2 just might be the answer to quite of few of those RV Doc questions. In fact, I know that to be true in many cases. Not only is the Truecharge2 processor-controlled and features either two or three-stage charging, it also contains battery charging algorhythms (customized charging procedures) for multiple battery types. Here’s the key difference between a mediocre charging/converter and a thoughtfully designed smart charger; the typical charging/converter has only one type of charging sequence (based on voltage and current flow), regardless of the “type” of battery it is charging. And please realize not all 12-volt batteries are created equal.

I won’t bore you with all the specifications regarding the various types, (you’ll have to attend my seminar for that much detail), but suffice it to say there are many different types of batteries designed with different technologies and chemical make-up found in recreation vehicles:

·       Flooded, wet cell (lead-acid) batteries

·       AGM (absorbed glass mat) batteries

·       GEL batteries

·       RV/Marine batteries (considered a hybrid type)

·       Automotive cranking batteries

·       True deep cycle industrial/commercial batteries

·       Sealed, maintenance-free batteries (lead-calcium)

In order to become optimized, the different types of batteries require varying levels of voltage and amperage delivered over specific time frames. In other words, a one-size-fits-all battery charger will result in a less-than-optimized DC power source. Thankfully, the Truecharge2 battery charger allows the user to choose the type of battery bank being charged. It is compatible with flooded, GEL, AGM and lead-calcium batteries. (There is also a “custom setting” for specially designed algorhythms programmed by Xantrex for specific applications).

This assures the optimum amount of current, pushed by the correct amount of voltage over the proper amount of time (based on that battery’s current state of charge and temperature), is delivered to that bank. Bingo! Battery optimization! The charging sequence is designed specifically for that battery type. The fear of over-charging the battery bank is eliminated altogether.

Another key to proper battery optimization is multi-stage charging. The three charging stages produced by the Truecharge2 are:

·       Bulk stage

·       Absorption stage

·       Float stage

A fourth available process, Equalization, is applicable to liquid-filled batteries only (flooded lead-acid and lead-calcium). Another nice function of the Truecharge2 is the ability of the user to choose between three-stage charging and two-stage charging (eliminating the Float stage).

During the Bulk stage, the charger delivers its maximum current output in a constant fashion; full amps flowing into the battery bank. All batteries store current, measured in amps. Once the battery voltage reaches a pre-set point (remember, it’s a different requirement for each of the battery types), it switches to the Absorption stage.

In the Absorption stage, the Truecharge2 holds the voltage steady at a set rate as the current flow lessens. Once the battery reaches its gassing threshold, (again, a different voltage level for each type of battery), the charger switches to the Float stage.

During the Float stage, the Truecharge2 delivers a lesser amount of voltage to maintain the battery bank in a charged condition until the bank voltage drops below 12.5 volts for about fifteen minutes. Then it awakens and enters the Bulk stage and the process continues.

I’m often asked if it’s permissible to leave the RV plugged into shore power during lengthy periods of non-use. I usually warn against such a practice primarily because it’s likely the battery bank will be over-charged by a typically mediocre converter/charger at some point and literally boil the electrolyte out of the batteries. Over-charging a flooded, wet cell battery (lead-acid and lead-calcium) produces dangerous gasses containing hydrogen and oxygen. I’ve personally witnessed exploding batteries in the shop during an improper charging cycle; it ain’t pretty (see my sidebar note below).

With the Truecharge2, the over-charging concern mentioned above is totally eliminated. Under normal circumstance (the absence of 12-volt DC anomalies), it is now possible to leave the RV plugged into shore power continuously, even without adult supervision. Here’s why, once the battery bank enters the Float stage and no 12-volt device is energized, it will stay in float for seven days or until the voltage falls below 12.5 volts for fifteen minutes. Assuming nothing is draining amperage out of the battery bank, after the seventh day, the Truecharge2 again begins its charging algorhythm anew, just to keep the batteries refreshed. Because of the integral design principles, the proper charging sequence remains in effect for as long as the Truecharge2 is powered by the 120-volt AC electrical supply.

One of the advanced features of the Truecharge2 is the inclusion of proper charging sequences based on the temperature of the battery. Though it is offered as an option, I highly recommend the installation of the Xantrex Battery Temperature Sensor (BTS). The importance of battery temperature is reinforced by virtually all battery experts even when measuring the Specific Gravity of each cell in a flooded battery. That’s why it is advisable to always use a temperature compensated hydrometer. So it is when charging a battery bank.

The Truecharge2 employs manual temperature settings if a BTS is not installed. And its importance cannot be overstated. A manually chosen incorrect temperature setting may cause the battery bank to be overcharged. The addition of the BTS, as part of the installation, will eliminate that concern. Temperature compensation is applied according to the following ranges:

·       Cold - battery temperature below 41-degress F.

·       Warm - battery temperature between 41 and 86-degrees F.

·       Hot - battery temperature above 86-degrees F.

With multiple batteries in a single bank, always install the BTS to the battery that is typically the warmest. All batteries in the same bank will be charged according to the temperature of the warmest battery.

Long considered a design fault with the typical converter/charger is the fact that it can only charge one battery bank. Usually only the house batteries receive a positive charge when connected to shore power in the typical RV. In a motorhome application, the engine battery only receives a charge via the engine alternator when driving down the highway. Taking into consideration the normal current draw on batteries in a static situation (parasitic drains), the motorhome engine battery often goes dead during lengthy stays in one location. Not so with the Truecharge2. In fact, it is designed with three separate charging outputs. (The third output may be utilized for a dedicated generator-starting battery). Now, both (or all three) battery banks can be safely charged whenever 120-volts AC electricity is available.

This eliminates the necessity of those dreaded “Emergency Start” solenoid switches found on some motorized RVs. I’ve been railing against them for decades. It is simply detrimental when two individually designed (drastically different) and totally separated battery banks are, all of a sudden, linked in parallel. With the push of a momentary switch, the two battery banks instantaneously become one big battery bank. The massive transfer of energy from the charged bank into the dead battery can damage internal plates, create excessive heat and cause accelerated sulfation in some batteries; none of which is a good thing (remember…the key word is optimization; that which is best!).

Whenever energized, the Truecharge2 charges all battery banks at the same time, but the most-drained battery bank receives the biggest charge first. This is determined by the unit’s built-in battery qualification sequence. Whenever 120-volts AC first powers the Truecharge2, it goes through a complete battery evaluation to determine which of the batteries is most in need of replenishment. So, if an RVer stays in one campground for a long time, he can be assured the engine starting battery will be up to snuff and should never have to be interconnected with the house battery ever again. The battery qualification sequence can be manually induced at any time, by the way, by simply removing the Truecharge2 from the AC source until all the indicators on the unit have gone dark. Then simply plug it back in. Each charging circuit is protected by a separate 30-amp fuse inside the Truecharge2.

Every RVer who has ever experienced less-than-stellar performances from the stock converter/charger should seriously consider adding the Truecharge2 to the 12-volt DC battery systems. This will help optimize the systems by allowing the converter to simply convert and the Truecharge2 to be the dedicated battery charger for all the batteries on the RV.

In order to function properly, the Truecharge2 must be “sized” appropriately for the task at hand. The user will have to determine how large all the battery banks are combined and then choose the correct DC output model to properly charge that bank. The minimum requirements are:

Truecharge2 (12-volt Models)                        Minimum Battery Bank Size

            20-amp (TC2012)                                                40 amps

            40-amp (TC4012)                                                80 amps

            60-amp (TC6012)                                                120 amps

I’ve installed the Truecharge2, complete with its comprehensive remote panel, in a motorhome and will be evaluating its performance over the course of a full RVing season. I’ll be posting updates as well as installation photos in the coming weeks and months as a follow-up to this RV Doctor Product Spotlight, so stay tuned! And remember, RVing is more than a hobby, it’s a lifestyle!

Sidebar Note:

The danger of battery explosions is very real concerning flooded lead-acid batteries. I tell this true story to my RV students to drive home the importance of practicing correct safety precautions while working on or charging RV batteries.

I was a working as a flat rate service technician at a large dealership that sold a very nice, elegant motorhome line. One of my shopmates was in the process of (incorrectly) charging a big 8D battery located in a side compartment of the motorhome. The compartment door was hinged on top. He had it flipped up and latched with two latches. The 8D battery was in a convenient slideout tray. Larry had the tray halfway slid out, battery caps off the cells and a healthy dose of current being pumped into it. Actually too much current as the battery was definitely gassing as it charged. Unfortunately, he had only latched one of the two latches and when he accidentally bumped that compartment door…you see it coming right? The aluminum-bottomed door fell across the two terminals on the battery and that big 8D battery literally exploded, spraying Larry and everything nearby with sulphuric acid. Thankfully he did not get acid in his eyes, but we never did find the majority of his right thumb. Safety is paramount when working on or near RV batteries! Never compromise the safety factor! ‘Nuff said!