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Fish'n John · 06-04-2010, 12:12 PM

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Originally Posted by Mee-n-Mac

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To that end disconnect the trolling motor from the system, leaving the charger and batts as shown in the diagram (minus the jumper btw the batts, remove that per the instructions). That should give you 4 wires from the charger to the batts. With the charger off, measure the voltage (seems you know how to do this) between the neg on "batt 2" and the pos on the other batt. It should be 24V if my thinking above is correct. Turn the charger on and see if it's now 12V. Indeed a measurement from the neg of any batt to the pos of any batt should be 12V (again assuming I'm correct above). If the above works then the charger would seem to be doing it's job. My concern is that it might not be coming out of the "charge configuration".

With the trolling motor disconnected, jumper off (which indeed leaves 4 wires from the charger to the batteries) I measure no voltage measured either at the 24v terminals on the charger or between the batteries (from the positive on Bat 1 to the negative on Bat 2). If I turn the ignition switch to the "Accessory" position, I measure 12v at both locations. (I have noticed that at times I can keep the trolling motor running at 12v if I turn the ignition switch to this position???). I did not yet try turning the charger on, but it seems the internal series to parallel swith in the charger is not working.

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I assume you measured as above, from the neg of batt 1 (in the pic) to the pos of batt1 and then also to the pos of batt2 (from the neg of batt 1) ? I'm a little unsure of where to where you measured.

Actually, I was measuring the voltage at the output terminals on the charger. I didn't think to measure it right on the batteries.

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I'm a little confused as to what you did. Did you remove the charger completely and have the batts connected to each other (re-install the jumper btw the batts) and the trolling motor (controller) as shown in the pic (solid lines = wires you had, no wires coresponding to the dashed lines) ?

Yes, this is exactly how I wired it. Initially I used the wires that were initially hooked up from the charger to the motor. They were #12 or #14 wires and smoked like hell when I first put 24v to them. I also blew the 30A fuse they had in line.

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This certainly should have given your motor 24V, assuming the batts are good and the connections are good and the wires big enough for the current. On this latter point ... what wires were in the system when you got it ? Was this all working at some point in time ? The #8 wires should be OK, assuming they're not overly long as I'd expect your motor to draw less than 30A. Which leads me to suspect something isn't right in your motor/controller. It shouldn't have popped the 30A fuse nor melted anything (I'm assuming the motor plug/socket is really clean). I have a suspicion that your motor is somehow setup for 12V, not 24V, operation. Not to be too stupid but how sure are you that it's a 24V motor ? Is there any chance that the motor has a 12V option (ie - can it be wired to use 12V or 24V) ?

I checked the Minn Kota book that came with the 64lb thrust motor. It will work at either 12 or 24v. They recommend #8 wires and 60A fuses at 24v. I installed new wires and fuses but used the existing plugin connection on the front boat panel. When I wired the motor directly to 24v, it worked fine but stopped after awhile. I found I had melted the plugin connection. I don't think the motor was ever set up for 24V. I bought the boat new with a 12v Minn Kota installed by the dealer. It was too weak so I bought a new 24V motor and took it into the dealer (Expo North, Rt 16). They supposedly rewired it for me, but I think now that they just hooked it up with the old wiring. I guess the new motor at 12v was better than the first one and I never noticed that I wasn't getting full performance.

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I don't blame you. I'd be a little concerned about popping 30A fuses and melting wires !

Still it's best the divide and conquer these type of problems. First make sure the batts are both good and not just at no load conditions. Make sure the connections are all clean and tight. Try to see if it's the charger or the motor that's the problem. It appears you've already thought along these lines ! If there's no other way to connect or configure the motor/controller (12 vs 24 V) then it's time to pay the pro.

The batteries are both good. I had them checked under load and replaced one late last year. The connections are all clean and tight. I think it is clear that the charger is not working at 24v but the one question that keeps nagging at me is why it didn't output 24v as it first came back from Expo North. Could they have rewired the charger for 12v at each set of terminals?? Certainly if it had worked right in 1998 they would have burned up the existing wiring if they had run it the way it "appears" to be hooked up. I think I have to pull that battery charger for a look inside before I take it anywhere. What do you think?