I have 3 deep cycle marine batteries hooked up in series so that they are still putting out 12 volts but last much longer. Can i charge them without breaking up the series. if so do i connect the charger to the positive terminal on battery one and negative on battery 3. i want to charge them with a portable generator and deep cycle charger. they are being used way out in the swamp to run scientific equpment and it would be nice to just pack the gas out there and charge them on sight instead of lugging them through the mud at swap out. if we have to charge them individually it might take too long and not be worth the investment in a generator and the time spent tending the charger. thanks for sharing your experience and expertise.
hutch
“I have 3 deep cycle marine batteries hooked up in series so that they are still putting out 12 volts but last much longer.”
According to that description, you actually have them rigged in parallel, not series. Series combines the voltage. Parallel combines the amp hours. When connecting a charger to batteries rigged in series, you just use a mutli-bank charger and hook one bank to each battery (separate + and - cables going to each battery’s + and - terminals). You don’t have to break the series to do this. However, per your description, this is not your case. I think it will still be the right way to charge them, or, since what you really have is one combined 12V battery, a single high-amp charger hooked to any of the + and - terminals would probably work, too; HOWEVER, I’ve never rigged a charger on a parallel setup (only on serial setups), so I’d call the charger manufacturer and ask them about this before doing anything.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance Agency, Inc.
https://stricklandmarine.net
843-795-1000 / 800-446-1862
you can charge them with it all hooked together like its one big 12 volt battery, but you will not get the full peak voltage on them, you best to charge them one at a time. Have you looked at solar chargers to keep them up? Would be lighter than a generator or gas.
quote:
Originally posted by sparepartsyou can charge them with it all hooked together like its one big 12 volt battery, but you will not get the full peak voltage on them, you best to charge them one at a time. Have you looked at solar chargers to keep them up? Would be lighter than a generator or gas.
Agree with everything except the comment about not getting the peak voltage. Pretty sure you’ll be fine charging them as you would one single battery. The way you have it wired, it’s basically one battery with more amp life capacity. Hook to any of the + and - terminals.
spareparts, why do you think the batteries won’t reach full (peak) voltage?
It is indeed a parallel set up, a series set up would result in a 36 Volt output.
It should act as one big battery, but I think Spare Parts may be right about auto-chargers stopping short of a full charge on a parallel setup because of the way they monitor the battery. Not sure.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance Agency, Inc.
https://stricklandmarine.net
843-795-1000 / 800-446-1862
A manual charger might be the answer, but you’d have to monitor it.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance Agency, Inc.
https://stricklandmarine.net
843-795-1000 / 800-446-1862
If all three batteries are of the same type, you can just connect your charger to ANY positive and ANY negative terminal, as they are each a common connection. Electricity doesn’t care where it lives inside a single wire, and if your terminals are all tight, you essentially have your positive terminals all shorted together with each other. Same for your negative terminals.
As your batteries age, they will charge at different rates. This can be a problem, as you can overcharge and undercharge different batteries in the circuit. You can add diodes or FETs that will keep the batteries from destroying each other. The biggest problem is having a bad cell in one of the batteries. It never reaches peak, so your charger doesn’t shut down. This overcharges the good batteries, which is the most damaging thing you can do to a battery. If you don’t mind monitoring the voltage, you can probably safely do this for a long time, making sure you don’t overcharge any of the batteries. Also, if they are relatively new, you could get several years out of the batteries, since they should be relatively closely matched.
If I were doing this (charging in parallel), at the minimum I would add battery switches and actually run each battery individually, switching as necessary. That way you don’t have one battery trying to charge the other when they are running your equipment.
Tidewater 196DC
Yamaha F115
Pungo 120Thank you all for your advice. they are indeed paralell not in series. boy i wish solar would do it(we tried) but we are studying sap flow rates on 10 trees at max leaf cover with each unit. They have to heat the sap and measure how long it takes the heat pulse to travel a fixed distance. Therefore everything is in deep shade way out in deep mud. too many cypress knees for any vehicle, so i am the beast of burden trying to think of a mobettah way. The idea of switches is interesting but it is easier to correct for a nice smooth voltage decay. one channel monitors voltage and it usually drops 3 large deep cycle batteries to the edge of consistency in about 7 days. i can test the decay rates of the batteries before we deploy to match them up in groups with similar age. we have some good chargers and i will try this at the lab before i count on it in the field. we may be deploying five sets this summer and i am as lazy as i can afford to be when it comes to this stuff. now i need to match a generator to the charger so i wont blow anything up.
Thanks again for your excellent help.
stop by the shade tree with the wires hanging out if you see me.
to answer the peak voltage point, its whats already been said, with an automatic charger, one of the batteries is going to peak before the others, that one will be at peak, the others may not be up to full voltage, charging with a manual charger will bring them all up, but may over charge one or more, it may also overload the charger. Like whats been said, wiring battery switches in line to separate the batteries, use three different charging outputs. I’ve had good luck with the Schumaker 1/10/50 chargers, they don’t cost too much, are light and easy to transport
Get a 3 bank charger and use the generator to run the charger
you may need to disconnect 2 leads to isolate them, but that solves all problems