I have 2 Trojan T106 golf cart batteries in my boat wired in series. My battery charger is a 12 volt deep cycle charger. Is it possible/safe to charge the 2 6v batteries in series or should I disconnect them and buy a 6v charger? Tim
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joe phibbs
if they are charge-able
IF the two are charge-able, then connect a good size (#2 or #4) wire in series and put it on a slow charge. But for <$20, you can get a switchable 6 & 12 volt charger. If you use a 10' jumper cable, you will have so much line loss that neither will charge. Joe
IF the two are charge-able, then connect a good size (#2 or #4) wire in series and put it on a slow charge. But for <$20, you can get a switchable 6 & 12 volt charger. If you use a 10' jumper cable, you will have so much line loss that neither will charge. Joe
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John Visser
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Don Berger
No problem
Connected in series as you have them, it wouldn't be possible to charge them individually regardless of the fact that you wouldn't want/need to anyway. A good 3 stage 12v charger is the only way to go Don
Connected in series as you have them, it wouldn't be possible to charge them individually regardless of the fact that you wouldn't want/need to anyway. A good 3 stage 12v charger is the only way to go Don
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Debra B
count the cells
A 6 volt battery is 3 2-volt cells. A 12 volt battery is 6 2-volt cells. The charger doesn't know the difference between a 12-volt and 2 6-volts.
A 6 volt battery is 3 2-volt cells. A 12 volt battery is 6 2-volt cells. The charger doesn't know the difference between a 12-volt and 2 6-volts.
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Tim
That's what I thought
Thanks everyone. I will charge them with the 12v deep cycle charger while connected in series. After all, the 12v alternator charges them. Tim
Thanks everyone. I will charge them with the 12v deep cycle charger while connected in series. After all, the 12v alternator charges them. Tim
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Dan McGuire
Not Neccesarily
I am a retired engineer with experience with batteries, although mostly other chemistries. All of what the previous replies have said is true except: The two batteries should be well matched. As long as the two batteries are about the same age and have the same history, they should be OK. If however, they are not matched, the difference in impedance will cause a different voltage across the batteries and they will likely have different capacities. As a result one battery can be overcharged and the other undercharged.
I am a retired engineer with experience with batteries, although mostly other chemistries. All of what the previous replies have said is true except: The two batteries should be well matched. As long as the two batteries are about the same age and have the same history, they should be OK. If however, they are not matched, the difference in impedance will cause a different voltage across the batteries and they will likely have different capacities. As a result one battery can be overcharged and the other undercharged.
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Tim
Thanks Dan
The batteries were both new this past spring and have been operating in tandem since. Tim
The batteries were both new this past spring and have been operating in tandem since. Tim
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Rich Stidger
One last caveat....
If your charger is a multi-stage device that is supposed to switch to a "float" mode after it senses the current is below a certain value, you have one more consideration. Be sure that the charger actually will switch to its float mode. If the T-105's (225AH) fully charged draw more current than the float trip point of the charger, then the charger will never go into float mode. It will keep a higher charge voltage on the batteries and eventually boil them dry. This happened to me with (4) T-105's (450AH total) and a Guest 30A charger. The Guest would switch to float below 4A, but fully charged the T-105 bank would draw 5+ amps. Hence, the charger was always in the bulk charging mode. Very bad for the batteries. The solution is to get a charger that is properly matched for your battery bank. Or you can watch it like a hawk and NEVER leave your boat with the battery charger running. Rich
If your charger is a multi-stage device that is supposed to switch to a "float" mode after it senses the current is below a certain value, you have one more consideration. Be sure that the charger actually will switch to its float mode. If the T-105's (225AH) fully charged draw more current than the float trip point of the charger, then the charger will never go into float mode. It will keep a higher charge voltage on the batteries and eventually boil them dry. This happened to me with (4) T-105's (450AH total) and a Guest 30A charger. The Guest would switch to float below 4A, but fully charged the T-105 bank would draw 5+ amps. Hence, the charger was always in the bulk charging mode. Very bad for the batteries. The solution is to get a charger that is properly matched for your battery bank. Or you can watch it like a hawk and NEVER leave your boat with the battery charger running. Rich
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