Wiring 12V Parallel

[Guest]

Hey All-
Great board you have going here!! Maybe someone out there can offer some advice. I'm wiring up a 12V 55# MinnKota this weekend on our boat. I purchased two new Trojan Batts, and plan on running them in parallel to remain at 12V but add some run time. My question is about the on-board charger. We're running a 2 bank, 10 amp model from BPS. What is the most logical way to hook it up to my setup?? We're currently running one bank to the TM batt and the other to the starting batt. Can I hook up both banks to the TM batts in parallel without disconnecting the jumpers between them?? I assume that by hooking one bank up to a TM batt, it will "see" the parallel batts as one big 12V, but may take a long time to recharge both at 5amps??

Opinions/suggestions please!!

Thanks

chico

[Guest]

You will need to disconnect the jumper between the batteries. You could leave it on when you charge but that is only if your batteries discharge at the same rate, if they don't then on will be overcharged prior to the second coming to full charge. You might want to put a QD between the batteries, use the charger on the two trollers. And buy a 11/2amp for the starting batt.

Rob

[JIM PAYNE]

Like Rob said with ac chargers they will not charge the batteries correctly more then one battery at a time. you should wire both banks to trolling motor. do you really need to charge running battery?

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JIM PAYNE

[Grabs]

Batteries can be viewed as buckets of water. If you have two buckets of water tied together, the may discharge at different rates. But you can charge them in parallel, because the lower battery or bucket will fill until matches the level of the other. After they have leveled off they charge at the same rate until completed.

[wastewaterguru]

I currently use 2 12V batteries for my trolling motor setup and I use a single 2amp auto charger connected to one of the batteries. It takes about 24 to 30 hours to get to full charge. I would think that a 5 amp should drop this time substantially and how often are your batteries going to be fully discharged?

Do you really need to charge them faster than 15 to 20 hours??

Grabs is right about the water thing......both batteries will discharge and charge at the same rate. Because they are connected, if one discharges a little faster, the other will put energy back into it until they are at equal charge. They will always, by definition, have the same measured amp draw when connected in parallel.

[Guest]

Ok guys-
I'm going to try running one bank thru the TM batts. The charger is supposed to have full power transfer- meaning it will put the amps to the batt that is less charged. If the engine batt is full, it will maintain it, but turn the rest of the power to the less-charged one: more than likely the TM's. Hopefully it works as advertised! The time thing really only becomes a factor when we're fishing somewhere for all week. I would think that 8 hours of charge time should be OK with 10 amps total- most of which will be going to the TM batts. Would it be wise to charge thru the end batt of the parallel or the one the TM is hooked to?

Sorry for all the questions guys- just want my investment to last a little while, you know?

Thanks again for your time...

chico

[wastewaterguru]

It makes no difference which of the two batteries you connect the charger to. Pick the one that is most convenient.