Rigging question

This may sound dumb but I had a question about rigging that someone probably knows. I bought a new boat two years ago, and stored it outside this winter, so I pulled my 3 trolling motor batteries, and my starting battery before winter. I hooked everything back up and it worked fine, until I went to start my big motor and battery was dead. The only thing I can think is the dealer wired in spare connectors by my starting battery in case trolling motor ever died. I had them hooked up and was using my trolling motor and electronics all morning, which would have drained it. Plus whenever I started big motor my units would shutoff, which isn’t normal. My question is Is this standard practice for wiring? It makes sense, but being this is my first boat I’m curious

Are you saying you ran your trolling motor off of the spare connectors by the starting battery?

I’m thinking that’s what happened. I don’t remember if they were connected last fall and was curious if that’s normal to run spare connections

I haven’t seen it before. Have owned several boats.

Could the spare connectors be for your on board charger?

Do you have a tm plug at the back of the boat? Could it be run to connect the rear TM to the tm batteries in the bow?

You say you have 3 trolling motor batteries, which means you have a 36-volt trolling motor. If you were somehow running your trolling motor off the main battery (12 volts), it’s not surprising that you drained the battery.

Right. Just trying to figure out why

I would say you had some batteries go bad or not get charged.

I only have a 3 bank charger hooked up to TM batteries. Would it make sense the fact I was on a smaller lake for two days spot locked and vertical jigging with both units on constantly? I really only ran big motor to get to and from the spot so really not enough time to charge the starting battery back up? I’m not sure how much juice a helix 9 and 10 draw, but I’m thinking its either that, or starting battery is bad. It’s only 2 years old. How long does it take for big motor to charge starting battery when it’s running? Sorry for so many questions, just trying to make sure it doesn’t happen 5 miles out in Mille lacs

That two graphs would definitely drain a battery after two days of constant use and no recharge. Get a onboard charger for the starting batteries. I added a 2nd starting battery to extend the run time. Small lakes rarely have the big motor running long enough to recharge the power drawn from starting the motor

I would add a single charger for your starting battery so that you’re starting fresh every morning.

I would also set a low voltage alarm on your Humminbirds so that if you are getting low on the water you can take a little cruise to charge up the starter.

I’ve been close to not having enough juice to crank my motor a few times.

Thanks guys, sounds like that’s my problem. I appreciate all the info!

Carry jumper cables and charge your batteries.

What do you have for a starting battery? Size? Cranking only?

My money is that either your graphs drained it or bad starting battery.

Jumper cables are cheap insurance. My starting battery went bad without any warning. grabbed the cables and jumped off one of my TM batteries. Right back to fishing and later to get home. Made the difference from fiasco to minor nuisance.

I also have a charger bank for my starting batter so I know it’s 100% topped off.

It’s a group 24 cranking only. I did the math with the amp hours and came to about 15 hours before it was dead. Seemed about right to me. I put my jumper cables in the boat now…

Couple options for you:

Upgrade size and type for starter. I upgraded to a 27 dual purpose agm when my 24 cranking only died.

Second option is to add yet one more deep cycle as a house battery for accessories like graphs, livewells, radio, etc. Way overkill in my situation but others here have had success.