battery/on board charger

[lilwalter]

On board charger is not charging one of my trolling motor batteries, and I am not getting power to my trolling motors. I have cleaned up the connections with no effect. I have never liked the connections from the 50amp breaker on the positive side of the battery and am thinking of replacing. Has to be bad connection, right? Even if battery was bad, the charger would show it charging right? Thanks

[harvey lee]

I have had batteries in my boat that the on board charger showed they were being charged and they were but would not hold a charge.

I would charge the battery up with a know good chrger and then have the battery's load tested. If that works, then your charger may not be putting out the amps it should be.

[Kyhl]

Or swap the charger leads between batteries to see if the the charging problem moves with it.

If the problem moves with the swapped leads then it is either the charger or the wiring. If the same battery has an issue then it is the battery.

[TSchultz]

Many on board chargers will not charge a battery if the voltage is too low. Say 6 volts, annoying if you left something on and drained them totally dead, but its a safety issue I guess.

[Whoaru99]

Right. Most "smart" chargers won't try to charge a battery if it thinks there's a problem with the battery or the circuit...for safety and or self-preservation.

Also, most(?) charger installations have an in-line fuse somewhere between the charger and the batteries. Is there one in your system and, if so, have you checked that?

[rocstar]

I have been having the same problem. I am hoping it is the battery. As said, if the charger senses something bad, it automatically stops charging giving you the impression the battery is fully charged. I charged the battery with another charger and took it to an AutoZone to be load tested. The guy told me it was OK. I took it to another place the that guy told me it was shot. He then used another testing unit and then said it was OK. I just bought a new battery!

Sounds like I might have to buy my own load testing at Harbor Freight and study up a little more. I have heard that if a battery really goes bad, the polarity can change, which would definately cut the charger out.

[Whoaru99]

Mine does not give an indication the battery is charged if it is not. I don't recall the detail, but the LED indicators on the charger show if there is a problem detected.