Onboard Charger Wiring Question...

I know I will make a few cringe with this, but in my bass boat I only run two batteries. I have a 12/24v 56lb thrust trolling motor and my 115hp Mariner. I use battery 1 to start the motor and run all 12v accessories (as well as run my TM on 12v if I like which I never do). Battery 2 of course is wired 24v with a jumper from battery 1 strictly for the TM. I have ran my batteries for two days straight with no charge (except for the big motor charging on battery 1 when running from spot to spot) on Lake Cumberland and never had a problem firing the big motor back up, but on big trips I occasionally take a small jump pack just in case so I don't leave myself stranded. My boat is light for a fiberglass boat and only 17ft so it doesn't take a lot of thrust to move her. Getting to the point though, I have no onboard charger and have never wired one. Can a 2 bank 20amp charger that is capable of 12v or 24v wiring be wired for 24v in my boat without hindering my big motor wiring, accessories on battery 1, or the charger itself? OR, option 2, can I wire it one bank to each battery and be fine? I figured if I tried option 2 that I would have to disconnect my jumper every time I charge and possibly have to disconnect the charger from battery 2 every time I use the TM... True or False??? Also, I know my setup is not optimal by far. I don't really want to debate that. I know a third battery would be best but I don't want the added weight or space it would take. I just want to know what will and will not work. Thank you all. Any help is appreciated greatly.

Re: Onboard Charger Wiring Question...

You need a two bank 12V charger for the current wiring. No need to disconnect the link. Easy to hook-up. You are just adding a set of ring terminals to each battery.

Battery #1 is getting a work out. If you are considering going to seperate starter battery and two 12V in series for trolling motor, buy a 3 bank charger. You can tape off the third set of wires until you decide to add the battery.

Re: Onboard Charger Wiring Question...

Thanks for the info! I will consider that. I had hoped what you said would be the case. Makes it easier on me.

Re: Onboard Charger Wiring Question...

your biggest problem is that you are running no 2 down and not charging it whilst charging no 1 from the engine so you are getting them unballanced...you need to use your on board charger staraight after each trip and remember no 2 will take longer to charge ... good ideas to swop them over every few months to even out the wear

Re: Onboard Charger Wiring Question...

Some current dual and three bank chargers have a load sharing feature. When one of the outputs senses the battery it is responsible for is fully charged, that output is switched internally to one of the other batteries to help out. Not all chargers work that way so shop carefully. That type of system is what you need however because of the imbalance you are creating.

Re: Onboard Charger Wiring Question...

you dont need the output switching ( extra $$$ ) as long as you leave the charger on long enough to get all the "charged " lights on

Re: Onboard Charger Wiring Question...

Assuming each bank has 10A in that 20A charger, there will be no need for load balancer type. 10A should have each battery fully charged for AM fishing. I do recommend getting one that has seperate battery indicators, vs combined.

Read your charger manual. Many will go "green" once they are within the "good" range. Leave the charger on for a while longer to get fully chargered. Check with volt meter.