Charging

[ericcarr2000]

I have a 1990 7.4 motor. I've had the boat for just over a year now. One question I have is am I supposed to switch the battery selector switch to both batteries in order to charge them, or is it ok if I turn the switch to off while away from the boat? It seems that lately when we go up and take her out that while on battery 1 it turns over slow but when I put the switch to both it turns over normally....
I even used a different battery in battery 1's place and it still turns slow...

 

[RCAnderson]

You should be able to crank the engine on one battery. Check your connections. My own practice is to switch the battery selector to the starting battery to start the engine, run that way for 1\2 hour or so, then switch the battery selector to the deep cycle for down riggers and other drains during the day. This makes me all happy inside because I know that I always have a fully charged cranking battery. I always have the batteries off whenever I am not on the boat. My bilge pump is the only thing wired directly off the batteries that does not go through the battery selector.

 

[MarkSee]

Is the boat slipped in the water or on a trailer?
That's important that if slipped the bilge pump have a constant, good 12 volt power input and wired properly; especially when you are away from the boat.

The other thing is to not turn the battery switch through the 'off' position while the engines are running or you can do damage to the electrical system. I heard that back in the mid-80's when I was first round of boating and assume that is still true today.

Is the battery that seems slow labeled as a 'deep cycle' type battery or is it labeled like the other battery that I'm guessing is a 'starting' or 'dual purpose' battery.

Normally, each battery should be able to start the engine separately so if indeed they are both the same type, it seem like you have have 1 that needs some attention or replacing.

Mark

 

[Grub54891]

Even swapping the battery for a new one don't help, I would go through and clean all connections completely.

 

[gm280]

Sounds like corroded terminals on battery one position. Check both the batteries AND the terminal connections at the battery selector switch as well. They too can get corroded. And don't simply look at the terminals and think they look okay. Corrosion usually occurs between the terminal and wire connector and can look perfect... JMHO!

 

[Bt Doctur]

and also check to see if there is a second ground cable going to the motor. batt1 neg cable may be corroded and batt 2 neg cable is not.

 

[alldodge]

Agree with MarkSee question, is it on a trailer or sitting in the water?

 

[ericcarr2000]

The boats been in the slip all season now. The bilge pump does work while hooked up to shore power and while battery selector switch is turned off. I guess what I can do is hook up a multimeter to the battery and check it while switch is off then turn the switch on to that battery and see if there's any fluctuation in readings. I'll do that with both batteries. I'm assuming I should get around 14 volts while selector switch is turned on??

 

[alldodge]

The boats been in the slip all season now. The bilge pump does work while hooked up to shore power and while battery selector switch is turned off. I guess what I can do is hook up a multimeter to the battery and check it while switch is off then turn the switch on to that battery and see if there's any fluctuation in readings. I'll do that with both batteries. I'm assuming I should get around 14 volts while selector switch is turned on??

Boat being in the slip and not on a battery charger will cause an issue. The boat has a mercathode system on it and this will drain the battery trying to protect your outdrive.

You should get 12.7V for a fully charged battery

 

[ericcarr2000]

It's on a onboard battery charger, converter.

 

[alldodge]

It's on a onboard battery charger, converter.

In that case and if it is working correctly, then I would suggest start cleaning cable connections. Turns over slowly either is a weak battery which may need to be replaced or bad connections

 

[ericcarr2000]

Wouldn't you think if there was something going on in the battery selector switch that it wouldn't even turn over at all at that battery?

 

[alldodge]

Wouldn't you think if there was something going on in the battery selector switch that it wouldn't even turn over at all at that battery?

Not unless it makes no contact or very little, bad contacts on the selector switch will also cause the same issue as corrosion

 

[ericcarr2000]

Ok I guess what I'll do is head up there this weekend and clean some terminals...