My cranking battery isnt holding its charge. I have a 3 bank 15a charger with a 24v trolling motor. Electronics are hooked up to cranking battery. I charges up fine but once i turn on electronics and use the power trim, the voltage , per the helm humminbird, drops to 12.0- 12.2 sometimes 11.9. No issues starting the motor but, like today, i was on the TM for a couple hours and the gps keep reading "low voltage" and i had to jump the cranking battery froma TM battery. It charges when i give it gas on the hot foot to 13.9-14.2 but will drop at idle to 12.6 and then if i shut it off, below that. First tile i've had to jump it i knew this was coming . Motor is a johnson fast strike 175.

Any recommendations? Id like somethibg worry free.

Sears Platinum Diehard PM-1 size 31.

Sears Platinum Diehard PM-1 size 31.

I was looking at these. Gotta find a sears ad ours closed. I, until 5 min ago before i took it out and plugged in the 2 TM batteries, had an everstart 12v 24ms 625 crank power in it. Worked when it was charged....

Sears Platinum Diehard PM-1 size 31.

I'm looking at a couple now. EverStart Maxx29dc. I know it's labeled a deep cycle but I hear a lot of good things about this battery used for cranking/electronics. 

 

 

What about these?

 

http://www.farmandfleet.com/products/661626-duration-agm-blue-marine-battery.html

 

size 31 specs-

Application: Marine, RVs - Deep Cycle / Starting

Cold Cranking Amps (CCA): 800

Reserve Capacity (RC): 200

Group Size: 31 DC

Height: 9-3/8"

Width: 6-3/4"

Length: 12-15/16"

Weight: 69 lb

Size 27 specs- 

Application: Marine, RVs - Deep Cycle / Starting

Cold Cranking Amps (CCA): 580

Reserve Capacity (RC): 175Marine

RVs - Deep Cycle / Starting

Group Size: 27 DC

Height: 9-7/8"

Width: 6-3/4"

Length: 12-3/4"

Weight: 63 lb

I have the Sears battery.  It is 4 years old and keeps all my stuff going and starts my hard cranking Optimax.  If you go for one of those listed get the 800 CCA and hope it is enough.