connecting cranking and deep cycle batteries

[jjbuoni]

I have a mercury 25hp El and it is connected to a cranking battery. So the motor charges that battery. I also have a deep cycle battery which is connected to my trolling motor but not to my other battery. Hence, I musy recharge this with a deep cycle battery charger. The dealer set it up this way despite the fact I asked for one cranking/deep cycle battery. So the question is can I connect my deep cycle to my cranking with th expectation that my motor will charge both? Anyone doing that.<br /><br />Also if I did connect them, can I charge them both with my deep cycle charger?<br /><br /><br />Thanks

 

[Barnacle_Bill]

Re: connecting cranking and deep cycle batteries

You would be better off to get a 2 bank on board charger. When you get home, you plug it in and forget about it until your are ready to go out again. This way you are always sure both batteries are fully charged. Your 25 does not have enough current to keep both charged. Charging both of them with your charger will work. However, when it senses one of the batteries fully charged, it goes into a maintence mode. You could wind up with one of them not fully charged.

 

[steelespike]

Re: connecting cranking and deep cycle batteries

Just to elaborate you can't charge dissimilar batteries on one charger as either one could end up either over or under charged.You also can't charge identical batteries of different age together.If you want to save some dough just get a second good charger and charge each by them selves.Keep in mind rule of thumb 2 hours charge time for each hour of troller use.

 

[Dunaruna]

Re: connecting cranking and deep cycle batteries

Originally posted by steelespike:<br /> Just to elaborate you can't charge dissimilar batteries on one charger as either one could end up either over or under charged.

Not true.<br /><br />A VSR would isolate the batts. I use one to charge 1 (one) main cranking battery, and 6 (six) deeps. No problem.<br /><br />The alternator output is the main problem here. You ain't got enough.

 

[WillyBWright]

Re: connecting cranking and deep cycle batteries

The output from the alternator on any 25 is pretty small. Unless you run that motor 24 hours, it isn't going to do much charging. Stick to a plug-in charger. You'd be wasting time and money trying to make that little thing charge two batteries.