Dead boat batteries?

[KsRancher]

Can't figure out my issues. Need some help. Bought a boat this spring. Bought a new 24v trolling motor and 2 new 12v batteries. I have them wired in series. The boat had a new looking 12v charger with 2 wire banks on it. The place I bought the batteries told me wire them in series for 24v, but hook the 12v charger leads up just like I would if the batteries were separate.


I used to boat for a month in the spring and worked great. Life got in the way so the boat set in the shed for a little over 4 months without being touched. Drug it out and batteries are DEAD. As in ZERO reading on the voltmeter. Currently have them separated and charging using the 2 bank charger. They were so dead that I had to hook them up to my truck and get a little juice to them before the charger would begin to charge them.

Wondering where the juice went with only the trolling motor and charger hooked up. Bad charger maybe? Any thoughts? Thanks.

 

[RMac5]

My battery guy tells me to always disconnect the negative on everything that might sit for any length of time. He said everything has some sort of drain, disconnecting the negative stops all of that.

 

[Djacker]

There is a parasitic draw somewhere in your trolling motor. Is your heading sensor hooked to those batteries?

 

[KsRancher]

There is a parasitic draw somewhere in your trolling motor. Is your heading sensor hooked to those batteries?

It's a Minn Kota powerdrive with i-pilot

 

[49ereric]

Battery tender
My previous wood truck had a dead short so lived with disconnecting the battery.

 

[isItFallYet]

Get a battery disconnect for the ground. Also, when charging in series, connect positive of one battery and negative of other. Your guy told you wrong.

 

[Marbles]

Install a battery disconnect. Most everything has some level of parasitic draw. A battery tender would also work, but a disconnect will protect your charge when not at home as well.

Blue Sea makes quality marine electrical components.

 

[KsRancher]

Here is how I have it hooked up

 

[Binz17]

Install a perko switch to cut off. I do it even on my newer boat, seems like there is always something that has a short in a boat and slowly drains the batteries.

 

[Jeffro]

The charger as you have it drawn is a single bank charger with 2 batteries hooked up. A true 2 bank battery charger will have 2 separate pairs of output wires coming out of it. 1 pair for each battery. If you want to charge them as 2 separate batteries, they need to be completely isolated from each other. Your picture has them tied together at the charger.

 

[KsRancher]

The charger as you have it drawn is a single bank charger with 2 batteries hooked up. A true 2 bank battery charger will have 2 separate pairs of output wires coming out of it. 1 pair for each battery. If you want to charge them as 2 separate batteries, they need to be completely isolated from each other. Your picture has them tied together at the charger

Yep. My drawing is not exactly right. It has two different sets of wires coming out of the charger to charge separately. Its a 2 bank charger

 

[KsRancher]

Thinking about just getting a 24v charger

 

[Jeffro]

Thinking about just getting a 24v charger

That would certainly help. If you do that you would attach them where you have the 24v and ground notations on your picture.

 

[TSAMP]

Where do you have a ground in a boat?

 

[KsRancher]

Where do you have a ground in a boat?

No ground to boat. Ground and hot just go to the trolling motor

 

[Wellsdw]

Sell your boat. Second Happiest day of your life…….

 

[Mike Islander]

Here is how I have it hooked up

That's right. 12 volt charger charging multiple 12 volt batteries in parallel. No other way to do that.

 

[Keith Stone]

Did you have them charging while it was parked in the shed?

I was roasting batteries for several years but I would always charge them to full and only plug it in when needed. The past 3-4 years I have my boat plugged in any time it isn’t in the water and my battery problem went away.

 

[Mike Islander]

Did you have them charging while it was parked in the shed?

I was roasting batteries for several years but I would always charge them to full and only plug it in when needed. The past 3-4 years I have my boat plugged in any time it isn’t in the water and my battery problem went away.

Trickle charge works. Disconnect switch also works.

 

[Keith Stone]

Trickle charge works. Disconnect switch also works.

Yeah mine has a disconnect that kills power to everything besides my power poles which are on my cranking battery so I’m not sure what the problem was all I know is it is fixed by leaving them plugged in.