Batteries discharge while not using boat

[osur914]

What could cause my batteries to discharge while my boat is not being used. Like in less than a week. I have an onboard charger that I installed for all 3 batteries last summer and have the problem ever since. Coincidence?

 

[ohm116]

Re: Batteries discharge while not using boat

Are the batteries still connected to the boat, you might have a parasitic drain somewhere, my Dad's old boat was the same way so he would always just disconnect the battery when not in use and have it on a little solar maintainer. You can get battery disconnects from an auto parts store so it is just a flip of a switch.

 

[osur914]

Re: Batteries discharge while not using boat

I disconnected the onboard charger form the batteries today and I'm gonna charge them and check and see how they do. That will let me know if it's the onboard charger or not.

 

[5150abf]

Re: Batteries discharge while not using boat

I have battery disconnect on mine, when I am done with the boat you throw the switch and it can't drain.

You can still use an onboard charger you just have to wire it right.

 

[osur914]

Re: Batteries discharge while not using boat

Unless I'm mistaken, there's 2 wires coming off each bank of the onboard charger, positive and negative. You hook one set off each bank to the positive and negative terminals on each battery. As far as the battery disconnect , I'll have to look for one of those.

 

[Chris1956]

Re: Batteries discharge while not using boat

If three fully charged batteries discharged in less than a week, you have a significant drain on them. Get a 30 Amp ammeter, and connect it in series with the + terminal of a battery and the charger, and see if you get a reading. If so, one of the diodes in the charger is bad. If not continue to connect wires to the ammeter until you find the short.
Figure each battery is 75AH, and to discharge them in a week is a 2-3Amp constant drain, minimum. Find it and fix it.

 

[osur914]

Re: Batteries discharge while not using boat

Let me ask a question. I bought this 1997 Javelin last year. There are 4 cables coming in the passenger side of the boat at the back, 2 red, 2 black. 1 red is hooked up to one trolling motor battery and 1 black is hooked up to the other trolling motor battery. Then there's a cable running between the two batteries, positive to negative. Creating the 24 volt series, I guess. But the other 2 cables, black, and red, aren't hooked up to anything. Is it supposed to be that way?

 

[Silvertip]

Re: Batteries discharge while not using boat

What purpose are all three batteries? One is the starting battery. Are the other two for a trolling motor? If so, I'd suspect you have a bad on-board charger since the troller batteries are not electrically connected to other circuits on the boat (or at least they shouldn't be). Since the on-board charger outputs are likely 5 amps or more each, the batteries should not discharge since the output is greater than the draw. I suspect you have a wiring issue or bad charger since the problem surfaced after installation of the charger. You can do a basic test on the charger as follows:

Fully disconnect the charger from the batteries and AC power.

Using an ohm meter, measure resistance between each pair of leads with the red lead on the positive output and and black test lead on the black (ground) output lead. Note the reading. Now reverse the test leads and take a reading. If both readings are nearly the same the charger has a problem. Repeat for the other outputs.

 

[scipper77]

Re: Batteries discharge while not using boat

Sounds like the charger to me as well.
If the batteries are on separate circuits, i.e. one for boat and two for trolling motor I'd think it is highly unlikely that the something else could drain all 3. They are on separate circuits correct??

Are you using a 12v charger to charge the 24 volt pair??

 

[osur914]

Re: Batteries discharge while not using boat

I'm using a Promariner ProSport20 Plus, with 3 banks, charging all 3 at once. Or at least that is what I was doing until yesterday. I unhooked the onboard charger from the batteries. I replaced one trolling battery that was 20 months old and am probably going to have to replace the AutoZone Duralast battery that is less than a year old. I have a quick charger that I bought from walmart, 5/10/15 and am charging individually now. I had the worst luck with the Promariner onboard. The first 2 were bad and this is the third one.

 

[Silvertip]

Re: Batteries discharge while not using boat

The two pairs of red and black wires running to the back of the boat from the trolling motor area where intended for use in boats that had a 12/24 selector switch on the motor or on a separate switch panel. If you run 24V ONLY, there is no need to use the second pair. The jumper between the two batteries would not be needed in a 12/24 setup.