Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. Today I discuss flooded lead acid battery safety.
Dear Mike,
My husband is getting ready to pull out the golf cart batteries 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 most of the things to keep in mind when removing batteries for storage and maintenance charging over the 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 I have 20/800 vision and literally can’t recognize a face just a few feet in front of me.
Splashing battery acid 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.
3) Take a picture, it will last longer
I will get dozens of emails in the spring asking me how to reconnect the 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, mark all cables with white electrical tape and a Sharpie marker BEFORE you take anything apart. Then take a few close-up pictures of how they were connected. It will save a ton of grief later, I guarantee you.
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4) Disconnect the negative battery terminal FIRST!
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 the negative battery connection.
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.
How hot, you ask. Take a look at this temperature chart and think about how much that would burn.
5) 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 pants 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.
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….
Send your questions to me at my new RVelectricity forum here.
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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After pulling all wires off the terminals I like to put some plastic tape around the positive terminal.
Remind people that golf cart batteries use a special strap for lifting. You can see in the photo 2 small holes in the green tabs in the photo of the batteries on top. The batteries come with straps but they never give them out. Ask for one. Costco and sams have them and i didn’t get charged .wear old clothes and rubber gloves AND eye protection
Good reminders. I’ve always followed these, except for removing my wedding ring. You’ve convinced me to start doing that.
Hi, Warren. Thanks for your comment. This earlier article from Mike will further reinforce your plan to remove your wedding ring, and other jewelry, etc., before working around batteries: https://www.rvtravel.com/rv-electricity-12-volt-battery-dangers/ Stay safe! And have a great day. 😀 –Diane
Mike I love your comments (and your book which I have), however my Magnum inverter manual states to disconnect the positive cable first and reconnect the positive last. I have a 2018 Tiffin Open Road motorhome.
I’m not sure why they wrote that, but if you switch off your battery connect switch before touching the converter wiring, that should kill all DC power going to it keep you safe from a short circuit to the chassis.