Battery Wireing

[tbot10]

I have been told that you can run all your 12 volt extras (lights,stereo,fishfinders,etc) off of one battery even while it is connected to another battery to supply 24 volts to a trolling motor. If this is correct can you also run the batteries in parallel so the 12 volt system will drain the batteries evenly? (Series for 24v and parallel for 12v at the same time)? ( hope I have my terms correct Series/Parallel?) If not I guess I could put a battery selector switch in to choose which battery I get my 12v from. Thank You!

 

[JB]

Re: Battery Wireing

Moving to Boats

 

[18rabbit]

Re: Battery Wireing

Tbot – you can do what you asked but it is not recommended. The reason is a pair of 12v batteries wired in series to provide 24v’s benefits from being the same size, make, and model to create an even load on all 12 cells.<br /><br />You are correct about ‘series’ and ‘parallel’. Batteries in series increase voltage, batteries in parallel increase amp.<br /><br />Think of a 12v battery not as a box that can store 12v’s, but rather as a collection of six boxes, each storing 2v’s. Those six boxes are wired in series to provide 12v’s. When you wire a second 12v battery in series, you now have twelve 2v boxes in series.<br /><br />Your battery system is only as good as its weakest 2v cell. With twelve 2v cells in series, placing a 12v load somewhere in the mix puts an uneven wear-n-tear on six of those cells. In this situation you can never realize the full useful potential of all twelve 2v cells.<br /><br />Personally, I would not worry about a minor 12v load on a 24v battery system. I would not consider doing so with lights that pull any significant amps or are lit for a significant amount of time.<br /><br />When you do need a bunch of 12v amps, either toss a third, independent battery into the mix (it has it’s own issues…like charging and stuff like that) or use something called a step-down converter. It is a box with 24v input and 12v output. They are made just for the application you mention. The disadvantage of converters is 1) price, and 2) inefficiency. They typically output 90% of the energy input. So if you need 10amps of 12v energy for your application, the converter will pull the equivalent of 11amps worth of energy from the 24v system (actually 5.5amps at 24v).<br /><br />I hope that helps. If you would like to post back here with your specific application there are lots of knowledgeable, experienced people here that can offer suggestions on how to properly wire your application.

 

[18rabbit]

Re: Battery Wireing

Here's the same thing but maybe easier to see:<br /><br />Don’t think of your 12v battery as this:<br /><br />[12v]<br /><br />Instead, think of your 12v battery as this:<br /><br />[2v] + [2v] + [2v] + [2v] + [2v] + [2v] = 12v<br /><br />When two 12v batteries are in series, you have this:<br /><br />[2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] + [2v] = 24v<br /><br />You want an even load across all those [2v] cells for the maximum useful life or your battery(s).

 

[Bass Runner]

Re: Battery Wireing

All you have to do is hook the batterys in series and then hook all you ground leads to neg on one batt and all the positive leads to pos on the other battery and you motor will recharge both batterys.

 

[tbot10]

Re: Battery Wireing

Thanks for the help! I already have three batteries but am trying to keep the cranking battery isolated to aviod depleting it. Normally I wont be out more than a day or two but there will be a few week long stays on the water. I thought about a phase charger to charge the batt. I have the 12v hooked to from the engine when it is running. Bass Runner, are you saying I could run 12v systems from two batteries hook up in series by putting all my POS leads and NEG leads together???. With my current set up I only have 24v when my trolling motor is pluged in. The 24v jumper is in the male plug and there are 4 wires from the two batteries to the trolling motor receptical.

 

[kd6nem]

Re: Battery Wireing

Not sure I understand Bass Runner's answer. A series wired system that has all the +'s, and/or -'s, hooked together WHILE STILL CONNECTED IN SERIES will create much unwanted excitement! That may well not have been the thought intended- just not enough details to tell. BR, please clarify! By trying to do both at once directly (not across a load) will result in one or both batteries having a direct short and will result in certain damage. I doubt that is what BR is saying, just how I read it. BR what do you mean by this? -

hook all you ground leads to neg on one batt and all the positive leads to pos on the other battery