wiring onboard battery chargers

[Larry H.]

Help me out guys:

I have two twelve volt batteries wired in a series to power a 24 volt Minn Kota motor. I want to install a two bank (4 leads) onboard charger and need to know how to hook it up. Do you install one set of leads to the -/+ of each separate battery? Or do you install one set with one lead to + of batt 1 and the other lead to - of batt two and ditto with the other set?
This is hard to describe but I hope you can see what I am getting at.

Another question, once you have wired two batteries in a series (24V) how do you wire something so that it only draws 12V-like an accessory light etc?

Thanks!

[Jim]

I just installed a three bank guest charge pro charger in my boat. I'm not sure about every charger but if it says it will work with 12 or 24 volt systems you should just connect each positive lead to each positive battery post and each negative lead to each negative battery post. Do this regardless of the fact that the bateries are in series(I know its against your better judgment, mine too, but it works). The charger has two independent chargers inside so the series thing is no problem.
As for powering 12 volt devices from these batteries. You can connect the negative from the device to the absolute negative of the battery series and the positive of the device to the positive on the same battery. This may cause this one battery to drain its charge faster than the other. This should just mean you may have slightly less time trolling.

Good Luck!

[Boatnut]

I put a quick disconnect on the "jumper wire" and simply disconnect that prior to charging. I've got a three bank charger and i use two pairs of the leads from the charger to charge my 2 -12v batteries as seperate batteries. The 3rd pair of leads charges the starting battery. I dont run any other accessories of my trolling batteries.
Mike(boatnut)

[Delgue]

just finished deinstalling my 3 bank Dual Pro charger, had a dealer install it originally cause i was too wary of my own electical abilitys--well, its like paintin by the numbers-each lead to each of the three batteries has a + and - terminal-separate- the dual pro system has a green light indicators for each of the three individual batteries, letting you know the status of each battery. if they were hooked up in series, the light indicators would not work.
---in other words, i think each lead from the charger to the separate batteries will have its own +and- terminal connections.

[PRO]

For proper 24 volt operation , jumper your trolling motor at the pluggin to the receptacle. This allows the batteries to be independent when charging. Unplug all those accessories when charging. Or set up a jumper for 24 volt if all you have is 2 prong plugs. It takes longer to charge in series 2 batt. than 2 batteries on independent banks. There are those that will disagree but I have 2 dual banks on mine and all batteries are identical in size. Plug it in at night,full charge on all batteries by morning plus on board charging while running at 40amps from alternator

[PRO]

You can leave your connections also as is but to hook up the charger it must be hooked up in a loop. This means both red charger wires to the postive terminal in the loop and the 2 black wires to the last negative terminal in the loop. That way you will charge if a 10 amp per bank 20 amps thru both batteries at once. Bad side is the led monitors will charge as a whole instead of independent. Guest chargers are good in your application. This should answer your original question.

[John in MN]

Jim's recommendation of which battery to run 12-volt accessories from is correct. I received the same information from a MinKota technician when I changed from a 12-volt to a 24-volt trolling motor. In my case I was getting a little interference on my locator because I had it hooked up to the other battery (the one with the absoloute positive for the 24-volt trolling motor). The tech also said to ground the battery with the absolute negative for the 24-volt trolling motor to the hull with the ground wire supplied with the motor.