A Trolling motors should be connected with 6 gauge wire.
The charging line gauge depends on the lenght of run from the starting battery to the trolling batteries. For runs up to 10 feet 10 gauge is sufficient. For 10 to 20 feet 8 gauge will do and longer than 20 feet should use 6 gauge. Using lighter gauges can extend charging time a few minutes but will work OK.
FAQ
What gauge wire should I use?
How come the Trollbridge24 only has 10 gauge wire? Why does shortening the leads on the Trollbridge24 void the warranty?
A 6 gauge wire is used to minimize voltage drop along the run to the motor. There is insufficient room on the Trollbridge24 for 6 gauge wires however the voltage drop under normal operating conditions on these short leads is not significant.
If I have a long wire run to the batteries or motor, is it OK to shorten the combiner leads?
A In general the answer is no, the small resistance of the 10 gauge wires protects the Trollbridge24 from overloading battery to battery current when they are put in parallel. 6 gauge or heavier wire would not protect the Trollbridge24. The short 10 gauge wires do not have any significant effect at normal operating currents.
Do the trolling batteries have to be the same size?
A Normally Yes but since the Trollbridge24 keeps the batteries in parallel when the motor is not running, their voltage gets equallized so the answer is No. If they are different sizes it is preferable to put the larger capacity battery as the bottom of the two in the 24 volt stack so it can also support house loads.
Can I mix new batteries with old ones? Can I mix one brand with one from a different manufacturer?
A Yes. Preferably the best battery (larger size or newer) should be the bottom of the two in the 24 volt stack so it can also support house loads.
Do batteries in parallel have to be "matched"?
A Although the standard recommendations are not to mix old and new, good and bad, big and small, etc., you should understand the reasons and make up your own mind. The truth is that you can parallel just about anything. The downside is, if they are not matched, one battery (the newer) will tend to carry most of the load and the total capacity will be slightly less than the sum of the individual capacities. The one with the lower internal impedance will tend to take more of the load. If your new battery has a capacity of 100AH and the old one still had 45AH, then in parallel you will get something a little less than 145AH, but it will help and it will work.
When the old one eventually dies, it will drag the new one down but this always happens whenever two batteries are in parallel and one dies, the only difference here is it is going to happen sooner than it would had they both been brand new. So big deal, you gained some residual use out of the old one and the new one will not be permanently damaged – just charge it up again. If you used a Combiner100 for charging your starting batter will not be run down.
The bottom line is the batteries in parallel provide more power – never less – than either one on its own – it just may not be the “ideal” way to do it.