Battery Type

[weephee]

Can someone help me understand what type of battery I am supposed to have in my boat. I have room for two batteries and at present I have two deep cell batteries hooked up in parallel. The inboard atomic has an alternator. Should deep cell batteries be totally discharged before being recharged. If so then do I need a car battery for the boat engine which is constantly being charged while the engine is running or will the deep cell batteries work for both the engine starter as well as the boat lights etc. Confusing for me. Any help appreciated

[SVPrairieRose]

Well the only thing more confusing than the question is all all the different answers. I would suggest that two banks are a good idea depending on how you are using the boat. If you are starting the boat and leaving the dock and sailing right away and rarely using lights, or running electronics then one bank should be sufficient. If there are electronics on board and you stay aboard and drain your batteries you could find yourself without a way of starting up. As for your other question, deep cycle batteries should never be brought down below half charge. I would suggest two things. One is to have two banks, deep cycle for electronics and a start battery for starting. Two is having a charge combiner. This creates two seperit circuits and charges both together but only allows discharge of your house bank for house loads and uses only your start battery for starting. Both are always fresh and you never forget to flip the swtch and find yourself with a dead house bank after a day of motoring. Hope this helps.

[JimsCAL]

The deep cycles are fine for both starting and house use. You say they are in parallel. No Off-1-2-Both switch? If not, consider putting one in so you can run house loads off one and keep the other fully charged when not running the engine. Adding a combiner as SV suggests even better as it will avoid you having to remember to switch from both the 1 or 2 when you shut down the engine.

[donlofland]

Can't hardly own a sailboat without also owning Nigel Calder's:
Boatowner's Mechanical And Electrical Manual: How To Maintain, Repair, And Improve Your Boat's Essential Systems

He details all the ins and outs of options for setting up your boats electrical system, and before I make any changes to mine, I'll read the chapter a couple more times.

[tap]

Originally Posted by weephee

Should deep cell batteries be totally discharged before being recharged.

No! Deeply discharging your batteries is not good for them. It's pretty standard to connect deep cycle batteries like your to an alternator.