I'm tinkering with a winter project for which I could use a little medium voltage DC, but not much current nor many amp-hours.
I thought of some weary old 8v golf car batteries I've had sitting untouched and unloved in the garage for several years. They were pretty well clapped out, down to maybe 20-25 usable amp hours when I parked them there. I wondered if they might still have 5 or 10 amp hours in them even after sitting all this time. The electrolyte level was WAY low, below the tops of the plates. It took almost a gallon of water for 8 batteries, just to barely bring the level up above the plates. (Not a good sign already.) I connected them in series. The whole 64v nominal string read a little over 9 volts! But I connected a Fair Radio charger (mil-surplus charger, really just an unregulated adjustable voltage DC supply) with a 60 watt incandescent light bulb in series and cranked up the charger as high as it would go, 120 vdc. No indication on the ammeter. The bulb didn't light. I left it overnight. Lo and behold, the next morning, the bulb was lit, though not very brightly. I measured a bit more than 25 volts across the bulb on my cheapo Harbor Fright garage DMM. (Across battery and bulb I was seeing more like 160 volts.) The charger's ammeter still hadn't budged. Twenty-four hours more and the bulb had brightened. I now read 34 volts across it. So I thought I'd see what happened if I took the bulb out of the circuit. I cranked up the charger until its ammeter read about 1.5 amps. After a few minutes I heard a sizzling noise. So I shut down the charger and started popping cell caps. Found a cell that was steaming. Yep, that's the one. Bypassed its battery and tried again. This time, after a couple of minutes, I heard a distinct POP. Shut down the charger and checked cells again. Didn't see anything strange this time. Reduced the voltage and current. POP again. My worry is that I'm hearing little hydrogen explosions, possibly from a cell that's generating hydrogen and internal cell sparking from a partial short circuit. Is that possible? I'm not feeling brave enough to want to try charging with all the call caps off. I really don't want to lose my garage and/or my eyes. Any conjecture as to what caused the hissy-steamy cell? As to what's making that unnerving POP? Does the hydrogen/spark scenario make sense? What's to blame for this? Could it be months - or more likely, years - of sitting with lead (sulfate) plates exposed to the air? Does anyone really think there's any hope for these batteries? My inclination at the moment is to just haul them all to the recycling center, except that you never know when you might need a dead battery so you can avoid paying a core charge. So what do y'all think? Any hope? Or are they suitable just as dead weight and cores? David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
