Determining AH rating of aging batteries
My Trojan 125's are almost 5 years old now, when they were new they were rated at 240 Ah. Now my trimetric is showing 70% at 12.1 volts which I know is wrong. So how can I determine the true Ah rati...
Forum Discussion
Fisherguy wrote:
Mex, none of the old transformer type chargers I had had any way to crank up charging voltage to 15 volts.
Barry, do I measure the weakest cell till it's at the half SG? It's almost there after drawing 102 amps for 9 hours, voltage on the trimetric is still showing 11.9 volts (with the load on). Maybe equalizing it before starting the test bumped things up to where they should be?
I'm really not feeling like this test is doing me much good. (probly cuz I'm not really sure what I'm doing.) I might just try setting the trimeteric to show I'm starting at 200 Ah and see how that goes our next trip.
Trojan spec for 50% is 12.1v and 1.172 SG
I haven't done it with a weak cell in the bunch. IMO ignore that one and go with the rest for their SG and that loaded voltage should be lower before you are near 50%.
What you are trying to find out is what is the capacity of the bank in spite of the weak cell, to see if that weak cell matters very much.
There is a guy here all summer with a pair of older 6s where one has all three cells in the green (just barely) and the other has the middle cell like that but the outer two cells are deep in the red. Looks bad. But he is getting by ok, even runs a 3000w inverter and his MW on that pair. He does have 130w solar on them which is what is saving him. He plans to get new batts next year, doesn't camp till then after this summer.
Just goes to show you don't have to rush out and do anything this minute if your bank still does the job.
