Uuuuh...Where's the cranking battery?

[bighe]

I just picked up a 2002 1900cc.  I have just read a thread on here about battery relocation.  Thank goodness this has already been done on her. I have two batteries under the console with an onboard charger.  Forgive me, everything I know will be in relation to my bass boat.  There is a 24v trolling motor on the bow, so I am confident that the batteries/dual bank charger under the console are for the tolling motor, BUT there are several wires hooked to the batteries.  If it were just the trolling motor, there should only be the one set motor leads and the one wire connecting the batteries in series.  I'll have to investigate what the other wires are.  

Where is the cranking battery?  I looked in rear hatch and see nothing.  The boat starts.  The main problem is I am a big guy and space is limited.  Surely its not in the bilge more forward towards the swingback? 

There are 3 batteries at minimum correct?

[freezerfiller]

Not necessarily. 3 batteries would be the best setup so if you use up all your batteries with the trolling motor, you can still start up and go home. The PO may have used one of the trolling motor batteries as the cranking battery. Hard to say until you start chasing things down. Start with the thick wires coming from the motor, they will lead to the cranking battery. Hopefully they will look different than the trolling motor wires.

[bighe]

Ok Thanks.  I'll have to look.  The thought crossed my mind that the outboard could be started by one of the batteries under the console, but none of the wires seemed heavy enough. 

[bighe]

Third battery was down in bilge. Whew! didn't want to deal with that.  Its sideway and a little forward so it was hard to see at night when I looked.  Cant see it standing behind the boat either, gotta drop my head in the hatch.

I got to thinking, after hearing that some people only run 2 batteries, that I could run everything to the trolling motor batteries since I only use trolling motor when I'm fishing shorter runs.  That way if I'm out a few miles nothing is drawing from cranking battery and I should be able to start up with no battery issues.  I've run my depthfinder/chartplotter for hours before without cranking big motor.  When it was time to fire up ther were no issues.  I wouldn't want to have an issue 3 miles offshore.

Would this work?

[bighe]

Wait...If that works. I could always jump big motor off one battery. I have done that in the past when I had a bad battery. I always disconnected the two batteries first though. If the above works, I could just jump off one battery without disconnecting right?

[gnrphil]

OK so assuming the battery in the bilge is the cranking battery and the two in the console runs the trolling motor and the house electronics I don't see why that wouldn't work, I would run heavy gauge wires from the cranking battery up to a couple of posts in the console so you could easily jump the cranking battery if required (like jumper points under a car hood that has the battery in the trunk). Waiting on Yolo to jump in on this one.

[freezerfiller]

It really is best to have deep cycle batteries for trolling and cranking for cranking. What you are showing would only work if those 2 12v systems never came near each other. In other words, you could only crank the engine and charge one battery with the motor. I've seen it done, but I wouldn't do it. If someone made me, I would only pull 12v off of one battery so there would be no way I could accidently hook a wrong wire up later.

[bighe]

Thanks for all the info.  It was always my intent to keep the cranking battery separate.  I wanted to run the sonar and VHF off of one of the 12v batteries within the 24v system to avoid prolonged draw of depthfinder/gps from the cranking battery. 

I also wanted to know if in the event I needed to jump the cranking battery could I do it off 1 of the batteries within the 24v system withouth separating them.  Just curious because in the past I always disconnected them before jumping the cranking battery. 

Still would like to know, but I think since longer runs are my only concern, I am going to carry a fully charged fourth battery when offshore.

Originally, I was thinking:


But now thinking:

[gnrphil]

Or just carry one of those small jump packs, about the same price as a marine battery anyway

[bighe]

True.  I need to get a better one. I have the big Schumacher one and it has failed me on two occasions when I needed it.  It indicated full charge each time.  That makes the most sense.

[freezerfiller]

Apr 24, 2015 7:47:33 GMT -6 bighe said:

But now thinking:

That is pretty close to my setup. I have the TM batteries that are dedicated to the trolling motor, and then I have two batteries in the bilge, one dedicated to cranking, and the other has all my accessories on it. I have those connected, but with a battery isolator, so if the voltage drops below 12.5 I always have cranking power, but if the engine is running and the cranking battery is charged, both batteries will charge from the engine, or charger.