Although I charged up the batteries several times so that the dash voltmeter reads between 26 and 27 volts, the next day, the voltmeter is down to 24 volts or even less. I suspected some pernicious load somewhere, but my amperage draw goes from 2.6 amps with the main switch on to .001 amps with it off (hardly enough to cause a problem). Both batteries had recently been load tested and passed. I decided to charge and check the batteries separately and found that when I connect the charger to one of the batteries that just read 12.5 volts, the charge rate jumps to over 15 volts and the battery starts bubbling. The other battery just charges to 13.5 volts and the charger shuts down. Does this mean that there is some sort of short in the first battery?
Also, since someone offered me a couple of 4D batteries at a good price, what are opinions on using those instead of 8D's?
Lin, you don't give up much in the 8D vs the 4D's go for the 4D's
I know with Lifeline AGM batteries, the 8D are 255 amp/hrs, and the 4D are 210. So with two you're giving up 90 amp/hrs-also, they're a bit lighter in weight. Good Luck, TomC
I do like AGM batteries. These are Deka blems and would be $200/ea. The only nuisance is they are 2 hours away. Anyway, this is the first time I have noticed a 12 volt charger (two separate ones actually) putting out 15+ volts. Am I right in assuming that battery is bad?
I would charge both up then separate them and let them sit for a couple of days. If one battery has a shorted cell, it will be down noticeably. Good Luck, TomC
Just wanted to pass on some info on this situation since I have not had this kind of experience before. I spoke to a tech guy at Interstate Battery. He said that it could be a sulfate issue and the battery might not be bad. He advised me to just let it sit on the charger and see if something changed. So, it has now been on the charger for two days. The charger is still pumping out over 16 volts, and the battery is still sizzling. The specific gravity is fair or good in 4 cells, but higher than the hydrometer can read in two cells. I am beginning to doubt the battery will just decide to act normal, but will continue charging it in the interest of science.
Please be sure that you are working in a well ventilated place with no ignition source. If batteries are sizzling, they may be pumping out a lot of hydrogen. Be careful when you disconnect the charger not to create a spark.
Thanks Len. It is just on the battery slide pulled out in the open enjoying the desert air.