What does a fault signify?

You can buy a (Battery Switch) that controls all your batteries. Where ever you turn the dial is what bank you will be using.
As far as The trolling motor go get a three prong plug, female male ground and stand by. The wiring is so simple it you do this.

Walld"

Do you remove the trolling motor wires before charging..? ...If not.. try that......mine started taking a LONG time to charge.. after I remove the trolling motor cables.. it take less time and charges better!!!

F03 means 1 of 2 things:
INTERNAL OPEN CELL - Bad battery. Battery needs to be replaced or
SULFATED CONDITION - Battery needs to be reconditioned for 24 to 48 hours. See owner's manual.

1. Short in the trolling motor itself
2. TOO SMALL a ground wire. ..need at least 8 gauge wire!!!!
3. Bad/dirty/corroded battery connections
..Make sure your battery/trolling motor is not accidentally touching the metal boat.. DO NOT CONNECT ANY WIRES TO THE BOAT!!! - PERIOD!!.

you can use most trolling motors in salt water, just make sure that if you do, you attach a self sacrificing anonde to the housing to prevent corosion.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/matthew_d24b835e574ef6ca

you can use an invertor to power a battery charger to charge the boat battery but you could not use the invertor to charge the battery it was running from as the invertor will use power faster then the battery could be charged

What your seeing there is indicating fully charged.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/sean_54c3a3dc48a7773c

not enough info. I went the the min kota website, they show four maxxum 80's at different voltages.is it a 12v 24v or larger? without a year model I'll have no reference to what wiring schematic Is the fuse connected inline with the trolling motor? what size amp fuse are you burning up? well I can give you some troubleshooting tips. tools to buy (1) amp gauge. if you are unfamilier with amp gauges make sure you get instruction book with gauge or you could burn yourself. Toubleshooting(1) Remove cover off minn kota trolling motor. black cover ontop of unit were the foot control wires go into.turn over foot control remove cover (2) check for corrosion. any exposed terminals should be cleaned.(3) go to your batteries and clean all connections. make sure the batteries are fully charged.(4) take amp gauge and test positive wire for amp draw as you tun on trollling motor and run it through all speeds. if batteries are in the rear away from trolling motor get a 2nd person to control trolling motor. if the trolling motor is more than a 12v system you will have more than one positive lead to test.GOAL. What your trying to find out is how many amps the trolling motor is really pulling. and at what speeds. under a load in the water and out of the water.how many more amps than the fuse raiting? newer trolling motors come with inline breakers not fuses so I'm guessing your using 30 amp fuses. again without more info i can only guess.

I won't leave them on constantly. How about a timer for the onboard charger. Set it for 30 minutes a day. You get 3 1/2 hours a week and the batteries won't heat up.

To get 36 volts, number batteries 1 thru 3. connect pos 2 to neg 1, connect pos 3 to neg 2, connect pos 1 to trolling motor controller and neg 3 to ground on trolling motor.
This is only a solution for 3 battery system.
For 4 battery system, connect 4 to 3 pos to pos and neg to neg.
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