Can one of the trolling motor batteries be used as backup to the starter battery via a battery switch without disconnecting one of the trolling motor batteries? TM is 24V?
Off the top of my head, I’d say NO! Unless you have a switch between the 2 trolling motor batteries! You would need to isolate 1 of the battries or you would have 24 volts going into your 12 volt starter motor.
Are the trolling motor batteries 24v? Or, do you have two 12v in series to get 24v? If the battery is 24v, then don’t even try. If the battery is 12v, then you must isolate it from the other TM battery. Otherwise, the connections at the battery ARE 24v = bad mojo for your starting circuits.
17’ Henry O Hornet
26’ Palmer Scott
It’s not hard to do this as long as you are using two 12V batteries to power your 24V trolling motor. Remember that you can have your two 12-volt trolling motor batteries in series making 24 volts and still pull 12 volts off one of the batteries.
HOW TO DO THIS
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Connect one of your trolling motor battery grounds to your main ground (same as your starting battery). Alternatively, you could just put a T on your starter battery and connect it there.
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Instead of a “Main Battery” switch, use a “Battery Selector Switch” and connect the positive leads from your trolling motor and starter battery to that switch, with the other end going to positive cable that normally leads from the starter battery. This goes to your starter, voltage regulator, mains, etc.
NOTE!!! You have to use the positive and negative terminals off the SAME trolling motor battery for this to work. Either trolling motor battery will work, and you don’t have to disconnect the other trolling motor battery.
The selector switch enables you to isolate a bad starter battery from the circuit. Your trolling motor battery then becomes your starter/main battery.
I like Blue Sea Systems switches, because they are waterproof, and they allow you to switch from one battery to the other without ever having both batteries connected at the same time, something you can’t do with Perko switches.
EDIT: Found a nice graphic here:
And for some real reassurance, you could get one of these cool little devices (shown with an ATV battery, but you can use a full size battery):
http://www.charlesindustries.com/main/startnow.html (I am not affiliated in any way with this company)
One of the nicest things about this rig is that you can charge it with a charger without needing to disconnect anything. It will charge the starter battery first, then automatically switch to cha
Three Oaks - great explanation and nice find on a great (Scout) diagram!
Not a bad idea to have setup in case your cranking battery runs low (stereo?)!
and yes - Blue Seas are very nice switches!
Thanks, Captain Ross
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Thanks for the info and effort.
You are welcome.