Cranking Batteries Uses

[HotDirk01]

Do cranking Batteries serve any purpose other than starting the engines and generator on my 360SRV? i.e. do they supply power to any dc equipment after engines are up and running.

 

[Skip Boyer]

Not 100 % sure on your boat but I would think that they would supply power to gauges, running lights, any trim/tilt motors, radio possibly, and most likely somewhere in her life someone has added or rewired something else into those particular batteries. Only way to find out for sure is to disconnect the start batteries and see what no longer powers up.

 

[HotDirk01]

Actually, in addition to the two cranking Batteries, i have a monster "house battery" that i believe powers all of the equipment you mention. The reason for the question is that the last time i took the boat out, i gassed up and on restart one engine would not turn over. Did emergency and started engine but quickly died and again wouldn't turn over. I attached a portable power station to the cranking battery associated with the failed engine fired up and got back to my slip. I asked the question trying to understand what might have drained the cranking battery so completely in such a short period of time.

 

[hottoddie]

RU sure your battery is dead. You may have just a bad battery or ground connection. Have you checked the battery voltage with and without a load. How old are the batteries?

 

[HotDirk01]

Sure seemed dead.
Cold 12.98
Engine running - no load 13.61
Engine running - with load 12.48
Batteries are 18 months old, but allowed electrolyte to go low. Just added 1 gal distilled water to five batteries.
Lastly, house battery 12.14
I think I am looking at toasted batteries due to neglect on my part.