By Mike Sokol
Dear Readers,
These pictures came in from one of my Facebook Group members. Yes, it is indeed as bad as it looks.
A battery explosion
It appears that the multi-stage charger might have failed and kept pumping significant current into the batteries, after it should have gone into “float” mode. The poster noted that he only had to add water every 6 months, so he consequently only checked water level every 6 months.
This was compounded by how far he was away from the RV, so it would often sit for 6 months by itself while plugged into power to keep the batteries fully topped off.
Batteries are potential bombs
So, all was well until apparently something happened with the multi-stage charger that caused the water to boil out the batteries, one of which exploded. When the water boils out of a lead-acid battery and exposes the plates, there can be serious outgassing of hydrogen and oxygen gases in the perfect ratio for an explosion.
If these gases accumulate in the top of the battery due to a void from a lack of water, then it only takes a spark from one of the overheated plates to make a small bomb. And it’s powerful enough to blow up the casing of the battery and spray sulfuric acid over everything in the area. Then you have some serious cleanup to do in addition to replacing the batteries.
What to do?
First of all, never leave your battery plugged into a standard trickle charger or old-school RV charger. That’s just asking for overcharging trouble. Also, I highly recommend monthly checks of the electrolyte level in your FLA (Flooded Lead Acid) batteries. While it may not be convenient to do this in some RVs where the batteries are located in a hard-to-reach location (like under the steps), nonetheless, checking the electrolyte level monthly is very important. Don’t become my next poster child for battery explosions.
Making it easier with Flow-Rite
I haven’t completed my review of the Flow-Rite battery watering system just yet, but I’ve had a number of unsolicited testimonials from readers who have used the Flow-Rite system for years with great success. They note that it only takes two minutes to check the electrolyte level on up to four batteries at the same time, and fill them with distilled water. Best of all, you don’t even have to touch the batteries to check the level. There’s just one place to fill and you’re done. Seems like the real deal to me – which is why I asked for a review sample from Flow-Rite Controls™, Ltd. As soon as it warms up a bit I can complete my review. Brrrrrrr!!!!!
Charging options
If I needed to leave an RV unattended for 6 months at a time, I would consider shutting off all shore power to the RV and hooking up a Battery Tender instead of the on-board multi-stage battery charger.
Battery Tender has a great reputation for making a product that floats your FLA or AGM batteries perfectly. And you can even get solar versions in case you need to store your RV in a spot without electric power, but that does have sunlight. Just remember that Lithium batteries don’t need (or want) to be float charged in most cases. But check with your battery manufacturer just to be sure.
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
This column was originally posted on RVtravel.com in June, 2021.
Mike Sokol is an electrical and professional sound expert. His excellent book RV Electrical Safety is available at Amazon.com.
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Another excellent article Mike! Could you also speak to the temperature range a wet cell battery can endure? For example, at what point do we need to worry about a fully charged wet cell battery, maintained by a Tender, freezing? We’ve had some record cold temperatures here lately.
My understanding is that fully charged batteries won’t freeze. Not sure about 30-40 below zero, but I’ve had my six volt batteries sit outside when it was a few degrees below zero (fully charged with my multi-stage converter) with no ill effects.
More to study and write about. Yippie!!!
I found this on Battery University. It appears that a fully charged flooded lead acid battery is safe down to -67 degrees F. Baby, that’s cold…
Freezing a lead acid battery leads to permanent damage. Always keep the batteries fully charged because in the discharged state the electrolyte becomes more water-like and freezes earlier than when fully charged. According to BCI, a specific gravity of 1.15 has a freezing temperature of –15°C (5°F). This compares to –55°C (–67°F) for a specific gravity of 1.265 with a fully charged starter battery. Flooded lead acid batteries tend to crack the case and cause leakage if frozen; sealed lead acid packs lose potency and only deliver a few cycles before they fade and need replacement.
Hi Mike,
Love your articles and lessons. Regarding the Flow-Rite system, there have been similar systems for filling multiple batteries in golf carts. There have also been several reports of multiple batteries exploding due to the hydrogen being shared through the filling tubes.
Thanks, Rick
When returning to my winter home in AZ I checked my golf car batteries and found them dry. I had purchased an expensive battery maintainer to prevent a thing like that happening. I added 4& a 1/2 gallons of distilled water and charged it back uo. All seems to be good and specific gravity is pretty good considering.
I called the company that made the maintainer and was told ” if any of the cells are bad or weak the maintainer will try to bring them uo to full charge and could boil out the other cells.”They said ” buy a timer and charge just an hour a day”. My cart is 48 volts with 6- 8 volt batteries. 24 cells.
Greetings Mike, your article today was very informative but scary to say the least! I do have a question in regard to gases accumulation in a void at the top of the battery & it would only take a spark from one of the overheated plates to make it explode! So how would a spark happen in the battery, I could understand a possible spark happening with a solenoid or relay or maybe a loose connection, or even worse if the owner opened the access door & a light came on causing a spark!
Just to let you know you have SPARKED my curiosity!!
Snoopy
Plates can warp when they overheat. If the insulation breaks down they can make contact and creaet a spark. Then it’s boom boom time…
I keep saying some people are just too ignorant to own RV/BOAT/Car. They are used to batteries which need no maintenance. All RV’s come with the cheapest batteries possible, UNLESS you upgrade to AGM/Lithium-Iron type, Those are sealed, and DO not need checking. I check my lead acid ones about every two to three weeks, sometimes one or two cells need water. But give me a break, every 5 months is just stupid.
Flooded Lead-Acid batteries in an RV lead a sad life. Most people don’t think about them at all until something goes wrong.
(novice here) So if I upgrade my (2) 6-volt wet cell batteries to LiFePo, then do I need to also upgrade my 13 yr old converter/charger to a multi stage converter/charger that supports LiFePo? Does the charging voltage from the alternator on my MH flow thru the converter/charger as it charges the house batteries?
Did you watch my “Ask the Expert” webcast a few weeks ago with Dennis from Progressive Dynamics? I believe we answered your question in depth. Here it is in case you missed it: https://youtu.be/NPGw9vI5jDI
Can I use one battery tender for more than one battery?
Yes, just connect it across the main negative and positive terminals. So it works with a pair if 12-volt batteries in parallel, or two 6-volt batteries in series, or even four 6-volt batteries in series/parallel.
When I store our camper in a location without AC power, I disconnect the AGM deep cycle battery from the camper (switch on ground side) and plug in my POWOXI Solar Panel, 12V 10W Magnetic Solar Battery Charger Maintainer. I modified my battery box to include a SAE Quick Connect, so setup is really fast. I have a solid year’s (over a couple years) use and it works like a champ, even when not directly aimed at the sun.
Note: that quick connect is fully bidirectional. I can use it to power a macerator/pump for black tank emptying and I have a quick connect to 12v automotive jack adapter to run a 12v compressor (camper tires are only 60 psi). Make sure you are properly fused. No the solar panel isn’t going to quickly recharge the battery after using these high-demand devices, but when I use them I am typically I’m either hitched to a tow vehicle or on shore power to handle that.