Running 12 volt batteries in series

[Papa Dawg]

I have a 12 volt set up and I tied two 12 volt batteries parallel in order to get more trolling time between charges. It works very well. I have both batteries wired to an on board charger. With the parallel set up I don't know that that it necessary but it works. With a trickle charge I guess you can't go wrong.

Another similar topic. How can you tell when your batteries are getting weak? Comments?

[yankee doodler]

An even better option than (2) 12v in parallel would be (2) 6v golf cart batteries in series. Gives you more amp hours.

[kkrueger]

I started to set mine up like this for the electric only lakes that I fish, but if they die I don't have the option of cranking up the big motor. So I'm still running them individually and when one dies I know I have a good one.

If I was really smart I'd buy a third battery and always have 1 as a spare.

[Hattiesburger]

Both Batts Should Match In Age And Amp Ratings

The reason for this is that if you wire 2 batteries in parallel and use a regulated charger to charge them together at the same time, the battery charger will only push current to the level of the most responsive battery. Most modern battery chargers have a regulated current loop. In essence the battery charger will seek a minimum current after the hotter battery is charged leaving the older or poorer battery still receptive to increasing charge. I'm using older or poorer battery to describe the effect of having 2 batteries strapped in parallel where one is obviously more competent than the other. This same condition will prevail if the 2 batteries are new but not rated for the same amperage or capacity (i.e. the same number of CCA's). If you're using an unregulated charger the hotter battery will be pushed beyond its charge capacity and will boil out water and possibly damage the internal plates in the battery before the weaker battery reaches saturation or becomes fully charged.

I hope this is clearer than mud.

[blairarnold]

IBNFSHN is the man on batteries.

[oldbigun]

I run two Delco 29 series parallel with an on board charger and have had no trouble for four years now.