🟦 🆘 RV Battery Safety: It’s more important than you think…

Please read this before disconnecting or reconnecting your RV batteries!

I know that many of you disconnect your RV batteries and bring them inside your garage or house for safekeeping or charging over the winter. While Lithium batteries are perfectly happy to be charged anywhere from 50% to 100% SoC (Stage of Charge) depending on the Manufacturer, and simply disconnected from any parasitic loads like your smoke and LP detectors, the idea of leaving your expensive Lithium batteries in an unsecured area is a bit worry some. And FLA (Flooded Lead Acid) batteries can self-discharge at rates up to 10% per month (or more) and could be dead by the spring.. So bringing them in and hooking them up to a Float Charger is still a good idea.

But whatever you do, make sure you mark all wiring and take pictures of the battery hookup BEFORE you start disconnecting anything. And take all safety practices around batteries, which I detail below. By the time spring comes around I’ll get dozens of emails from readers asking how to reconnect the Series/Parallel battery bank, and there’s no easy way to figure it out. So Read and Head!

Dear Mike,

My husband is getting ready to put the golf cart batteries back in our trailer, and I told him to be careful. Do you have a checklist of how to do this safely? What about things to avoid? —Evelyn

Dear Evelyn,

Great question and very timely. Here’s a list of things to keep in mind when reinstalling batteries from storage, and what you need to do next winter.

1)  Always wear safety glasses!

I know what it’s like to be nearly blind. All I have to do is take off my glasses and look around. Since I have 20/800 vision I literally can’t recognize a face just a few feet in front of me without glasses. 👓

Splashing battery acid or an arc flash in your eyes is a sure way to create permanent vision loss, so always wear safety glasses around any battery work.

2) Remove all jewelry before you proceed…

Metal jewelry and battery power don’t mix. If you accidentally get your wedding ring or bracelet in a short circuit, there will be hundreds of amperes of current flow that will turn your jewelry red or yellow hot in seconds.

And yes, it will burn like holy heck and can create muscle or nerve damage rapidly. So remove everything metallic from yourself BEFORE you touch an RV battery connection. How hot will it get, you ask?

Take a look at this temperature chart and think about how much that would burn.

3) Get an insulated ratchet wrench

Here’s a simple solution that will increase your safety around battery terminals and connections. I found an affordable composite-insulated ratchet wrench at Harbor Freight which works great for battery terminals. An insulated ratchet wrench for only $12 to $15 is quite a deal.

This composite-covered wrench is available in 1/4”, 3/8” and 1/2” drive sizes, and the 1/4” size seems perfect for working around batteries since you really don’t want a long wrench with a lot of leverage that can easily break off a battery terminal. You can find these composite ratchet wrenches at Harbor Freight HERE. Get one before the spring thaw when you de-winterize your RV and need to hook up the batteries.

4) Take a picture, it will last longer

I will get dozens of emails in the spring asking me how to reconnect RV batteries. Note that if you get them wired backwards, for even a second, it will blow the inverter fuses (at the very least) and possibly do all sorts of other damage to any of your DC appliances like your refrigerator.

So, you should have marked all cables with white electrical tape and a Sharpie marker BEFORE you took anything apart. If not, now is a good time to start. Plus you should take a few close-up pictures of how they’re connected. It will save a ton of grief later, I guarantee you.

5) Reconnect the negative battery terminal LAST!

When disconnecting the wiring of any vehicle 12-volt battery system, it’s important to disconnect the negative terminal from the battery first, then you can disconnect the positive terminal safely. When installing the wiring you’ll reverse the sequence—so you’ll reconnect the positive battery terminal first, then connect the negative battery connection LAST.

If you don’t do it in that order, then it’s possible to have the wrench that’s on the positive battery terminal make contact with the metal frame of the RV. This will weld the wrench in place, and if you get your metal bracelet or ring in the middle, it will cause things to heat up quickly. This is why I also recommend using an insulated wrench for battery connections.

Note that some early Magnum Hybrid Inverters with a remote monitor require that you disconnect the positive battery terminal first since their remote monitor box has a secondary ground wire that can burn if the main battery negative terminal is disconnected. but that’s the only case I know of.

6) Holy Pants, Mike! What did you do???

Finally, make sure to wash your hands carefully, and never touch your clothing when working with lead-acid batteries. It only takes a tiny bit of sulfuric acid on your clothes to rot out the fabric in a few days.

Yes, these are my own “acid-washed” jeans that suffered this fate while I was working with some 6-volt FLA batteries. I don’t think it’s stylish at all, but at least I relearned my lesson, which is why I’m passing this on to you, as well.

That’s all, folks…

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there…. Mike