Battery safety tips
Bring a big truck when you visit and work safe when you get home.I write this stuff for fun and to be helpful. I’m not an employee of Sun Electronics, I’m a customer. In my role as customer, I set out the other afternoon for my third visit to Sun’s Miami headquarters and my first visit to the Miami Lakes facility. This place is a lot nicer than the Miami Gardens warehouse, though it lacks the artistic touch left at the old place by some tag artists.
It is a round trip of 1482 miles for me, so I like to make a good haul of it. I brought my big trailer. We stacked panels until the fenders rested on the tires and I made the decision to leave two pallets behind. 14kw will keep me busy for a while, anyway. I also didn’t get as many batteries as I wanted. Upon calculation back home, I figure I brought home close to 6000 lbs. I could have carried that extra stuff, after all! We just needed to pry the fenders up a little further off the tires.
Live and learn.
Well, back home, I had some ideas how I was going to treat the batteries on my new 48v system a little differently. I like to improve safety and efficiency as I go. I know ways of doing it wrong, both from investigation and from practical experience. One of the easiest ways of blowing up some batteries is to hook them up backwards. The things are marked plus and minus and we all know not to mess up the connections, but you get tired, the area may not be well lit and the batteries may have some dust or baking soda on them to obscure the markings molded into the cases. Furthermore, those pesky cables get in the way! Believe me, you CAN hook them up wrong and I HAVE done it and didn’t like how it worked out.
First thing I did before taking them off the tailgate was to hit the POSITIVE corners with a dash of white paint. I thought about red but Trojan batteries are sort of red, so I think the white will stand out better, even in poor light. White on the black Sun batteries will not be confused.
After the paint dried, I used a felt marker to put the date, 11-18, on the white patch. Time gets by, you know. If you don’t date them, 8 years from now you’ll be wondering why those batteries you JUST BOUGHT aren’t holding a charge like they used to. My Dad dated every tool and appliance he bought and I have decided it is a good idea.
Next step is to get out a little tub of grease, or maybe get into the grease gun you use for the pickup. The area where the lead terminal pokes through the plastic case should be sealed, but you will always find one or two that eventually leak acid fumes and make green stuff corrode your nice battery cables. Take the grease and smear it around that transition from lead to plastic. Then save some to coat the terminals when you get your cables connected.
And speaking of terminals, why not make new battery cables for your new batteries? I checked and found I have a good supply of double-ought (2/0) cable and around 30 big, tinned terminals for 5/32″ studs. That’s probably overkill, but I am good to go. I need to order a bit of marine shrink tube.
Some people crimp with a tool that looks like a bolt cutter with dull jaws. I have a couple of tools that look like little presses. You put the terminal on the wire, poke it between the jaws and beat the heck out of it with a big hammer. For even less resistance, I then heat the terminal with a torch and slip some solder inside. I finish by covering the transition from wire to terminal with marine shrink tubing. This is available in red or black, coding + and -, and it has an inner lining of melty glue like you get from a glue gun. You shrink that stuff down with a heat gun or torch (if you are careful) and nothing is getting in. AND the color gives you a surefire coding for polarity.
Why is polarity so important? If you try to connect two banks of batteries in parallel and do it backward you will blow yourself up. Usually the cases don’t blow apart, but everything gets sprayed with acid and your battery caps get ruined if they are the push-and-twist variety. If you blow up a set of the expensive water saver caps you will be especially displeased with yourself. If you aren’t wearing your safety glasses you can be blinded. Your hearing might be damaged. Your clothes will need to be replaced, even if you wear a protective apron. Don’t blow up your batteries.
That’s hooking batteries up backwards. What if you get the battery banks right and then connect backwards to your charge controller or inverter? If you bought hardware with “reverse polarity protection” then nothing will happen. NOTHING. If not, there will be a spark, a puff of smoke and you just trashed a $500 charge controller or a $5000 inverter!
The synopsis of all this is that it is best to hook the batteries up right and any trick you can come up with to help you avoid a mistake is smart procedure. So, wear your safety gear (goggles, gloves, apron), color code your batteries and cables and check your work with a meter before making the connection.
Something else to consider is that some things will give you a spark, even when you do connect it right. Charge controllers and inverters have big capacitors that will draw a huge quick current as they charge when you connect. If you connect to a battery post the pop may ruin the threads and I don’t think you will have a lot of luck rethreading that stainless stud. Make a quick jab at a place that is not threaded on a battery or equipment connection. Let it get the pop out of its system and then slip on the terminal and the nut. Oh, and making that pop on the battery ends of things is making a spark near a source of hydrogen gas, so best to do your sparking elsewhere. I have a big knife switch that lets me disconnect all the charge controllers when connecting the battery bank and I just slip the fuse out of the inverter.
And, hey, next time you see some of those nice LED shop lights on sale, get one to put over the batteries to make it easier and safer to hook up, tighten up and water up when installing or doing maintenance. More battery ideas next time.
By: Neal Collier