Topic: Size of battery

[Sigler]

I called Motorguide to find out were that fuse would be in my TM because I was having interference on my graph, he said there wasn't one. He told me to clean all my grounds and I did that and I still have the TM interference. He also told me I may need a bigger battery which I probably do what size cranking amp should I get?

[benamen]

Check your manual to see what size circuit breaker they recommend for your unit. (Manuals for current models available online).


Maybe if you state what model TM you have and the size of the battery you currently have, someone may be able to help you.

[Moose1am]

Also need to know how long the wire is between the battery location and the trolling motor.  And the size of the wiring makes a difference in the amount of current that can flow though the wires.  Larger wiring will carry more current longer distances.  There is a voltage drop as well with a longer run that has greater resisntance. 

If you are getting interference with the trolling motor try putting just the trolling motor on the new battery and then hook up the depth finder to the other starting battery of your boat.

Use the new trolling motor battery (Optima Blue TOP is what I recommend) to power only the trolling motor and nothing else.

I use a 50 amp circuit breaker on the wiring for my trolling motor.  I have the AT 55 # Minkota Trolling motor.

Check you

r manual to see what size circuit breaker they recommend for your unit. (Manuals for current models available online).


Maybe if you state what model TM you have and the size of the battery you currently have, someone may be able to help you.

[Sigler]

My graphs are on the cranking battery, and the TM is ran of its own batteries there are breakers on those batteries but I don't what size they are. This is a Triton 186 boat. Motorguide said I need at least a 1000 cranking amp battery to run those graphs without interference the battery that is in there now isn't that big its( 625 Marine cranking and 700 cold cranking).

[Doc Stressor]

That's very strange advice from Motorguide. Very few deep cycle trolling motor batteries will put out 1000 cranking amps. Cranking amps are not relevant for trolling motor operation. The amp hr rating of the battery is what determines how long that you can run your motor. The higher the better. 

Outboards usually have specific minimum cranking amperage requirement for their starting batteries. They often specify a minimum reserve capacity for the starting battery as well. That because the electronic components of computer controlled fuel injected engines often exceed the alternator output at lower rpm. So the engine runs at least partly off of the battery until you get above a certain rpm.

You should certainly have a circuit breaker or fuse in the wiring going to your trolling motor. Corrosion can increase the Resistance of you trolling motor wiring. That can result in elevated levels of RF interference when the motor is operated. But I can't see how the size of the battery would make any difference.

A weak or too small cranking battery can result in problem with your fishfinder if it is running of the same battery as the engine.  But usually what happens is that the fishfinder will just turn off or try to restart itself if engine draws off the battery and the voltage gets too low.  I don't understand how a weak or inadequate battery would cause interference.