We have a John Deere 310 that currently has a pair of 12-year-old John Deere TY21737 batteries (Interstate equivalent 3EH-VHD). Each battery is 6v, 850cca, reserve of 270 mins. They are in series for 12v. My dad never maintained the batteries and it started cranking weakly in the last couple years, then not at all. He refilled the cells earlier this year and charged the batteries, but they didn't come back.
I tried charging them in series with a 12v Battery Minder 1500 (1.5 amps) but it kept saying the batteries timed out -- probably too much battery for it. I figured the desulfation would be a benefit. Then I took the weaker battery (6.15v; stronger one was 6.25v) and put it on the big charger, which only has a 40 amp setting for 6v. I charged it for 45 minutes or so and it didn't seem to hold a charge. I might have done it for another half hour at some point, still no more charge. So I charged it for 2 hours this morning. Now, it's measuring 4.1 volts... I think I fried a cell, unless I was hallucinating and it was saying 4.1 volts all along. Could the 40 amps at 6v have killed it? That seems like a reasonable current to me, since it's 6v and they're such large batteries, but some of you would probably know better!
Assuming I'll have to replace them (they're definitely old enough), what's the best way to do so? Same setup, about $270? Or perhaps similarly-sized dual 12v batteries such as Interstate 3ET-VHD in parallel, about the same price? Or, one large 12v battery, such as a 4DLT-VHD ($180)?
I'm leaning towards one large battery. Much cheaper, and simpler less terminals to corrode and connect. Just even bigger of a pain to drop way down in that little battery box.... Either that or two 12v in parallel, which would be easier to handle and maintain, since each battery could be charged individually. My understanding is that it would be less stress (amperage) on individual batteries in parallel rather than in series which would theoretically give them an easier life. I know that equalization is an issue with series, perhaps not with parallel? I can't see the benefit in another 6v series set up. Perhaps, in the 70's, that was the most economical setup for the machine?
Thanks for your words of wisdom!
I tried charging them in series with a 12v Battery Minder 1500 (1.5 amps) but it kept saying the batteries timed out -- probably too much battery for it. I figured the desulfation would be a benefit. Then I took the weaker battery (6.15v; stronger one was 6.25v) and put it on the big charger, which only has a 40 amp setting for 6v. I charged it for 45 minutes or so and it didn't seem to hold a charge. I might have done it for another half hour at some point, still no more charge. So I charged it for 2 hours this morning. Now, it's measuring 4.1 volts... I think I fried a cell, unless I was hallucinating and it was saying 4.1 volts all along. Could the 40 amps at 6v have killed it? That seems like a reasonable current to me, since it's 6v and they're such large batteries, but some of you would probably know better!
Assuming I'll have to replace them (they're definitely old enough), what's the best way to do so? Same setup, about $270? Or perhaps similarly-sized dual 12v batteries such as Interstate 3ET-VHD in parallel, about the same price? Or, one large 12v battery, such as a 4DLT-VHD ($180)?
I'm leaning towards one large battery. Much cheaper, and simpler less terminals to corrode and connect. Just even bigger of a pain to drop way down in that little battery box.... Either that or two 12v in parallel, which would be easier to handle and maintain, since each battery could be charged individually. My understanding is that it would be less stress (amperage) on individual batteries in parallel rather than in series which would theoretically give them an easier life. I know that equalization is an issue with series, perhaps not with parallel? I can't see the benefit in another 6v series set up. Perhaps, in the 70's, that was the most economical setup for the machine?
Thanks for your words of wisdom!
