Battery discharging without any apparent draw?

[btravlin2]

My starting battery is the only battery on my boat at this time. With no key and all switches off, and no explanation that I can come up with, it discharges over 2-3 days. Where would you begin troubleshooting?

BTW: it's a new battery and this happens after fully charging it with a battery charger.

Thanks......

 

[Don S]

Re: Battery discharging without any apparent draw?

It could very well be nothing more than a bad battery. New ones fail too. Charge it up and let it set without anything connected to it and see if it discharges.

With everything turned off, remove the ground from the battery. Do you get any arching at all? That would indicate current draw. If you don't see sparks, use an ammeter to check for current draw.

 

[foodfisher]

Re: Battery discharging without any apparent draw?

New could be bad. Have it load tested. Disconnect it and see if it still drains. Edit: Slow typer

 

[sccatfish]

Re: Battery discharging without any apparent draw?

This is where a battery switch comes in handy. Disconnect everything with the main switch and you know nothing can draw power. Unless you wired it yourself or you have traced every single wire you do not know that there is nothing that is constantly drawing power. Plus there could be a bad switch that won't disconnect or there could be a bilge pump, radio, or something else that isn't wired through a switch.

 

[btravlin2]

Re: Battery discharging without any apparent draw?

Thanks......I'll disconnect, charge, and see what happens. I was thinking it could be a bad, new battery as well.

 

[bruceb58]

Re: Battery discharging without any apparent draw?

Pull of one of the battery cables and put a multimeter in between cable and battery and see what is being drawn.

 

[Wind dog]

Re: Battery discharging without any apparent draw?

Quick and dirty way, disconnect battery's negative cable, take test light & connect between negative cable & negative post. If test light lights, start pulling fuses until test light goes out. This will indicate what circuit the draw is on. If test light does not light you do not have a draw & the battery is no good.
Let us no how it goes.

 

[bruceb58]

Re: Battery discharging without any apparent draw?

If test light does not light you do not have a draw & the battery is no good.

You can have a pretty low draw that will discharge a battery in 3 days and you might not see it with a test light.

Agree with pulling each fuse to isolate.

 

[Grub54891]

Re: Battery discharging without any apparent draw?

A bad alternator will draw em down also.It'll charge when running but if a diode went out it'll drain the battery when sitting.
Grub