Sometimes you get what you pay for! An attempt to bring back SLA batteries

If you’re reading this, perhaps you’ve run across the endless forums of magic battery revival modules, advice for adding acid, water, salts.. whatever? I spent a solid day reading/surfing.. maybe there are a few magic ways to save your batteries? I don’t know lets see… but before I start let me say one thing: Have a ten year old car battery you’re trying to make last another two? Well, sit down, this may sting… you’re cheap.. buy a new damn battery! 🙂 I scored four *free* 12V 20Ah SLA batteries.. they were installed 2 years ago.. only lasted in some biomed equipment for about 18 months… why? Who knows.. they aren’t used much.. probably a crappy charging system in a 20,000$ piece of equipment. Worse case I drive a mile down the road to drop off the batteries for recycling (also free).

I refuse to chuck these.. even though they are really in a bad way. Status of batteries: 4-6 Volts… DEAD. Below dead.. and they’ve been sitting that way for weeks. So lets see how these goes! All batteries are close to the same age, came out of the same equipment and are roughly the same voltage. Also of note, these aren’t gel cells.

Battery 1: I put battery 1 on a Powersonic SLA battery charger (12V 4A..) PSC-124000A for 24 hours. the battery charger sat in float the whole time.. didn’t get warm.. didn’t draw much more than 10mA — not looking great.

Battery 2. This battery went through the same 24 hour ineffective charge as above…. I popped off the top. The cells were lacking water, I don’t know what is normal but it looked considerably low. I put about 150mL of water into the six cells which brought it up to just under the vent ports. I also put in two drops of sulfuric acid into each cell (why not!?). I threw it on my current limited power supply 15VDC and I put the current trip at 250mA just in case something gets away while I don’t have my eyes on it. I’ll adjust this later on if needed. It started off at 10mA, but I’m in about 4 hours and i’m up to 50mA… lets see what a day or two does?! Many of these sites mention this process taking a week or two. I’ll put the battery on the powersonic charger once my current gets up to 100mA or so.

Battery 3 & 4… To be continued!


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