Trolling motor battery voltage ??

johninmo

Petty Officer 3rd Class
Joined
Apr 1, 2009
Messages
80
I bought a new trolling motor battery last year now when I charge it I cant get it past 12.3 volts mostly about 12.1 volts is that the normal? because I thought 12.8 was about normal Is this battery bad?

Thanks
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Trolling motor battery voltage ??

Are you sure your charger is working properly? If so have the battery load tested.
 

johninmo

Petty Officer 3rd Class
Joined
Apr 1, 2009
Messages
80
Re: Trolling motor battery voltage ??

No not 100% sure charger is working it always has in the past but it is several years old I tested the leads it shows 8 volts on a 2 amp charge and 12 volts on a 40 amp charge I have it on 2 amp now would it hurt my battery to put it on 40 amp?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Trolling motor battery voltage ??

Batteries can be safely charged at up to 20% of their Amp/Hr rating. If you are getting only 8 volts on the 2 amp setting the charger is not functioning properly. A 12 volt battery is a battery of six 2.1 volt cells. 6 x 2.1 = 12.6. Whether you charge at 2 amps or 40 amps, the output voltage should be 12.6 or even slightly higher. If you measure the voltage with the charger NOT connected to the battery you will not get an accurate reading.
 

johninmo

Petty Officer 3rd Class
Joined
Apr 1, 2009
Messages
80
Re: Trolling motor battery voltage ??

ok that makes more sense now I thought things wasnt acting right it is rated at 115 amp/hour so 40 Amps would be a little high then right?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Trolling motor battery voltage ??

Depends on how discharged the battery is. If it is dead or nearly dead 40 is ok for an hour or so. Also depends on how old the charger is and whether it is an automatic type.
 
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