Thread: cranking battery wont stay charged!

My 40hp motor requires a 1000 CA and 750+ CCA. I believe that interstate and tohatsu were in cahoots when developing the motor. If it does not have this it will do funny things like trip codes, go into limp mode or worse not start. I do not run anything extra on my cranking battery. Just a little draw over the day will cause me to have to troll back to the bank.

Originally Posted by BigRiverMarine

Get something with 1000+ CA, and 850+ CCA. A 31 series has more reserve than a 24 or 27 series.

Go BIG or go home!!!!

My guess is you have something drawing your battery's Greg, but too cover your bases I would do both things recommended here. I would also disconnect my cranking battery when I get home and put it on charge. This way I know nothing has drawn on the charge I put on them before I go fishing. This may not fix the problem but it can only help your cause, also helps if you accidently left something on draining your battery. Only takes a Minute to disconnect and reconnect a battery. Good Luck buddy.

Originally Posted by mdperson

My 40hp motor requires a 1000 CA and 750+ CCA. I believe that interstate and tohatsu were in cahoots when developing the motor. If it does not have this it will do funny things like trip codes, go into limp mode or worse not start. I do not run anything extra on my cranking battery. Just a little draw over the day will cause me to have to troll back to the bank.

Tohatsu recommends a minimum of 850 CCA for their TLDI's.

Originally Posted by CrappiePro

My guess is you have something drawing your battery's Greg, but too cover your bases I would do both things recommended here. I would also disconnect my cranking battery when I get home and put it on charge. This way I know nothing has drawn on the charge I put on them before I go fishing. This may not fix the problem but it can only help your cause, also helps if you accidently left something on draining your battery. Only takes a Minute to disconnect and reconnect a battery. Good Luck buddy.

We have put a battery disconnect switch on one of our work boats with the same problem. No more dead batteries.

Yeah its alot for a 40.

Greg I run a 12v leg off of one my trolling battery for my electronics and livewell. It does drain one of the trolling batts alittle more, but the motor fires up.

If a disconnect switch is helping the problem, something is drawing current...
But we don't know if that is the problem.

I don't know what all that boat has, relays and what not....
A relay could be stuck closed.
A tiny short could discharge the battery over a period of time, but typically something would get hot.

It takes about 1 min to stick a meter inline and check.
Greg, I can loan you a meter if you do not have one and wind up needing one.

I'm in total agreement with JPJ!!! Regardless of the fix, You Need To Find The Problem!!!!! It could possibly turn into a fire hazard if there a direct short somewhere causing the current draw. A chaffed hot wire can send current throughout an aluminum boat.

Disconnect the dash wires from the battery and see if a relay on the engine is causing the draw. If not, disconnect the battery cables from the engine and reinstall the dash wiring to see if that is the draw. A meter will tell you quicker.

I've seen batteries that checked good but had one bad cell that caused a faster discharge with a average load on them. I had just replaced the cranking battery in my blue demo for that very reason. Checked good, but went down to quick while running my live wells, electronics, and other stuff. Had to jump it 4-5 times before I replaced it. No problems after I did.

And I am assuming after this battery discharged, you fully charged it to only discharge again?

Just making sure something wasn't left on causing it to discharge and you never recharged it..