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Dead battery - Got jumped - Drove for 40 minutes - Stopped boat to restart it, battery dead again

tommy1005

New member
First time here, because I'm a little confused and need some help or advice on what happened.

I pulled my boat out of winter storage yesterday, I have a dual battery system (Add-a-battery by Blue Sea). Anyway, I go to turn on the boat, nothing. Completely dead. Tried changing the switch from On to Both, stlil nothing. Both batteries 100% dead. Now I've read that the ACR system for the Dual Battery system pulls a small charge even when the boat is turned off and after a few months could completely drain the battery...

Anyway, I got a jump start and the boat started up fine and everything was good. Drove for 40 minutes around 40 mph thinking that was enough to juice up the battery, I stopped the boat, tried to restart it, and it was completely dead. How? The boat is not that old, and I just got the 100 hour maintenance package at the marina, it should be tip top shape. Is 40 minutes really not enough to charge the boat battery?

I took both boat batteries off the boat and brought them home and charged them with a 6amp charger. They both charged in about 45 minutes and now are reading 12.86 and 12.50 on the multi meter. That means they are pretty charged up, close to 100%.


That seems way too quick, I've read online it should take 7 hours to charge up the battery from 0% using 6amp, not 45 minutes... I'm skeptical.

Does anyone have any thoughts before I haul these batteries back to the boat and see if the boat starts up?
 
You are correct about the charging times. I suspect that you may have a connector problem - i.e. a bad/corroded/loose connection that has too much resistance and impedes the flow of electricity to your starter.

First thing I would do is pull all the ground wires and thoroughly clean all ground connections, then put it back together. Test. Repeat for the positive connections.

As you inspect each wire, bend it back and forth several times If you hear crackling noise, it has corroded internally under the covering. If crackling, replace it.
 
time to charge will be driven by the battery capacity....I never saw where you stated their age(s)….so I'd be inclined to charge them and then subject them to a load test....If the batteries are good, proceed with checking the charging system. As noted by CHawk, the interconnecting wires must be in good shape or the batteries will never charge...
 
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