Fortrex Speed Issue

[187famous187]

I bought a used boat and just recently took it out for the first time. It has a 60A breaker and 6ga wiring ran to a Minnkota Fortrex 112lb motor. The batteries (31's) appear to be new according to the last owner and date stamps. The motor does not spin on speeds lower than about 30. Between 30-45ish it spins but intermittently and its very jerky. At 50 and above it seems to be operating normally. I took the prop off and checked for line and didn't find any. Any ideas of where to start to find the issue?

Thanks

[Bradrodfish]

Pull the prop off again and loosen ont of the bolts that hold everything together. See if water comes out or if the bolt itself looks cruddy. If all that looks good then do a load test on yhe batteries. AutoZone or any car place should be able to do it. Make sure the batteries are fully charged have time to rest before you test them.

[187famous187]

Ok I’ll check that tonight.

a little more info- once I got home I tried it in the driveway and it started working at lower speeds but was kind of intermittent still. I didn’t have a lot of time to mess with it.

[187famous187]

I took the bolts out behind the prop. I didn’t see any water, but it was about 24hr since it’s been in the water. I don’t think it’s a battery/voltage issue since it seems to work fine on high speeds, right?

[Bradrodfish]

Probably not Batteries. Hard to say without seeing it. Take a peek at the commutator. See id you have black spots on it. May be a brush or commutator issue. Would have to look to see.