Just wondering if you can get a rough idea of battery capacity from how long it takes to re-charge a completely discharged battery. For instance if you are using a 6 amp charger and it takes 30 hours to charge a completely discharged 12 volt Lead acid battery, does that mean you have a 180 ah battery? I bought an old Lansing Bagnall platform cart a few years ago and the batteries were dead when I got it. So I took them out and left them in my field ready to go to tha scrap man one day, but never got around to taking them. Anyway, to cut a long story short, after these batteries were sat in the field, in the open, with no lids on, for well over 12 months, I decided to try to get some of them up and running. So I chose 6 cells which happened to be sitting upright and full of rain water. I emptied them and sluiced them out with tap water and EDTA, left them sitting for a couple of days with EDTA and tap water, jammed a hose pipe into the opening and forced water in so hard the plastic cases bulged out like a balloon. I then drained them and filled 3 of them with battery acid (with more EDTA), and plugged a 6 volt charger to them. Wouldnt take a charge so I wired up a good 6 volt battery to them and tried again. Amazingly they stared to charge. So I did the same with the other 3 cells, and then hooked the 6 cells up to a 12 volt charger. They were on charge for days and amazingly got up to 12.7 volts. I was still sceptical of how good they would be so I hooked up a 50 watt 12 volt light to them last friday afternoon, and then promptly forgot all about this project until monday morning. When I went down there again I noticed the extremely dim light still on, turned it off and checked the voltage which was reading 4 volts! They would not take a charge again as the voltage was so low, so I hooked up a full 12 volt battery to them to fool the charger, and am now charging them again with the 6 amp charger which has now been going for about 20 hours. My question is (if you are still reading!) if I check on the cells every hour and can note how long it takes for the battery to achieve a full charge, would this be a good indication of the Ah of the battery how it is now. Originally there were 24 x 2 volt cells, and the battery bank was 480 AH, so each cell would have been 2 volts at 480AH, and the 6 hooked together would be 12v at 480 ah. If the battery started charging from 4 volts, to get the charge up to 12.7 again would be another 9 volts almost, which should be approx 60 hours on a 6 amp charger. (if I am right in my thinking!) If it achieves full charge at say 30 hours, then this would mean the battery is only around 50% efficient and not up to much. Which brings me to my next question. If I have a 480 AH battery that is only achieving say 180 ah at full charge, would this then still be a better battery than a 100 ah brand new battery? it seems to me the more I read up on this stuff the more confusing it is.
Thanks for any help anyway,
Stuart
