Thread: Wiring batteries and charger

Originally Posted by CUZZIN

I just bought a boat that has a 12 volt trolling motor but has two batteries hooked to it, positive to positive and neg to neg. Is it wired this way so the batteries will last longer and when I hook my charger up do I need to hook to just one of the batteries and will it charge both at the same time? Thanks

Yes, as long as both batteries are the same type and capacity and in good condition, they will look like one big battery to the charger..., and you will get twice the run time as one battery. As the batteries are hooked up in parallel, both will charge at the same time.

Dave

Thanks Dave for the quick response this is the most helpful forum there is.

WOW! Great and helpful thread! I have one more question for you that I didn't see answered. I have my 2, 12 volt trolling batteries hooked in series to give me 24 volts to run my trolling motor. I currently charge these seperately, with my Sears battery charger, using the "Automatic, Deep Cycle" setting. I charge my single, 12 volt cranking/depthfinder battery using the "Automatic, Conventional low Maintainance" setting. Now, there is one more setting on the charger per a seperate switch for "12 volt" or "24 volt".
My question is, is there a way to leave my two deep cycles connected together with the positive to neg jumper, and charge them both at once? Or should I just continue onhooking the jumper and charge them seperately? Would I hook the pos/neg from the charger to the pos of one and the neg of the other (the ones not in use by the jumper?) Would I set the battery charger switch to the "24volt" side or the "12volt" side? I'm assuming I would still charge as "automatic, Deep Cycle, Maintainance free".

Thanks for your help!

I have a little tip for some of you who want good batteries, for little or no cost and much less weight.

I'm an aircraft mechanic and many of the aircraft I work on now use sealed, gel cell batteries. They come in 12v, 24v and 28v. These batteries are required to have a "capacitance check" every year and usually fail because the parameter is so stringent for aircraft (rightly so), but they will still "live" a nice long life in a boat (or tractor or whatever). The "footprint" on these batteries are usually smaller and they are lighter than auto/boat batteries. Also they are a deep cycle battery. I have used them in boats for years now. I run my 12/24 volt TM off of just one 24v battery only and just don't use the 12v side of it. I also have one for my cranking battery.

Now here is the kicker...

These batteries are not serviceable, so when they fail the "cap check", most all aircraft maintenance facilities just throw them away, unless there is someone there like me who uses them. These batteries cost $2,000 to $3,000 new, and they are throwing them away by PAYING someone to haul them off. My suggestion? Drop by your local airport and visit a maintenance facility and ask them if they have any old batteries they want to get ride of. Just make sure they don't give you a Nickel Cadmium, they weigh a TON.

Originally Posted by slydog1227

WOW! Great and helpful thread! I have one more question for you that I didn't see answered. I have my 2, 12 volt trolling batteries hooked in series to give me 24 volts to run my trolling motor. I currently charge these seperately, with my Sears battery charger, using the "Automatic, Deep Cycle" setting. I charge my single, 12 volt cranking/depthfinder battery using the "Automatic, Conventional low Maintainance" setting. Now, there is one more setting on the charger per a seperate switch for "12 volt" or "24 volt".
My question is, is there a way to leave my two deep cycles connected together with the positive to neg jumper, and charge them both at once? Or should I just continue onhooking the jumper and charge them seperately? Would I hook the pos/neg from the charger to the pos of one and the neg of the other (the ones not in use by the jumper?) Would I set the battery charger switch to the "24volt" side or the "12volt" side? I'm assuming I would still charge as "automatic, Deep Cycle, Maintainance free".

Thanks for your help!

i was wondering the same thing only i dont have a 24v selection on my charger. i think i should charge them seperatly without the 24v selection just not sure.

Slydog, yes you can charge both T/M batteries at once. Connect the charger just like you connect the T/M and set the charger for 24VDC.

Originally Posted by DEX

i was wondering the same thing only i dont have a 24v selection on my charger. i think i should charge them seperatly without the 24v selection just not sure.

Without the 24V selector you MUST charge each battery seperately if they are wired in series for 24V. It is not necessary to disconnect them. Just make very sure the connections from the charger only go to one battery at a time.

here is a question for you. I have three optima blue top marine battery's. The label says starting. Can I use two of them for my 24v trolling motor or do I need two that say starting/deep cycle? Also, what is the best onboard and portable charger to use for them? Thanks in advance for your response.

still having peoblems i have battires in series in the back i have a 4wire connector plug on back side the trolling motor plug has 4 males plugs. i read at the back of plug had 24v on one side i go to plug trolling plug in without trolling motor hook to hit it blew fuse do not under new motor can,t hook it up ,help

still having peoblems i have battires in series in the back i have a 4wire connector plug on back side the trolling motor plug has 4 males plugs. i used volt meter at the back of plug had 24v on one side i go to plug trolling plug in without trolling motor hook to hit it blew fuse ,do not under stand new motor can,t hook it up ,help