What is the right type and 'size' of battery?

[NakedDog]

The more I read, sometimes the more confused I get....

I'm looking to get 3 new batteries this spring: 1 starter battery, and 2 batteries for a 24v setup for trolling. I think I've finally been educated regarding what kind of batteries to get, however now I need to know what size.

Starter: From what I understand, for the starter battery cranking amps are the important factor. However, is it possible to get a battery with too much power? For example, is a group 27 with 900 amps too large for my motor which is a 1996 Johnson 115 V4? Is larger always better? Is a marine battery required for a starting battery, or any (i.e. automotive) battery with suitable cranking amps ok? Are there specs listed for my motor somewhere? Is the group size an important factor, or only the cranking amps?

Accessory/ Trolling: Similarily, I have been advised to get deep cycle trolling batteries with a large reserve capacity of 190-200. Does size/ group matter? Do cranking amps matter for a trolling/ accessory battery?


Any advice or direction to a previous forum thread or website would be greatly appreciated.

 

[seabob4]

Re: What is the right type and 'size' of battery?

For your starting batt, the more CCA or MCA amps, the better. I use a group 24 Interstate 1000 MCA.

For trolling motors, you want reserve capacity. Group 27 deep-cycles are great for that setup, either wired in parallel for 12V, or series for 24V.

 

[Silvertip]

Re: What is the right type and 'size' of battery?

To answer your starting battery question regarding can you go too large the answer is no. You can go too small however. Electrical devices draw current from the battery. Every electrical device has a limit as what it is capable of drawing from a battery. Motors for example draw maximum electrical power when they are stalled. Every starter has a limit as to what that current draw is. So only if a battery is not capable of delivering that "maximum" would you have a starting issue. So on a boat, larger capacity (cranking power for starting, and reserve capacity for trollers) is better. Yes - group size is one of the factors that determines capacity. To deliver higher capacities battery cases must be larger to house the larger and heavier plates.