3 8v vs 2 12v batteries

[Vincentc]

I putting together a 24v battery bank of Golf Cart Batteries for a trolling motor. Any thoughts regarding the use in series of (3) 8volt batteries vs (2) 12 volt batteries. I have sufficient space for either option.

 

[cww]

The more individual batteries you use, the less susceptible to failure the bank will be as a whole. Obviously there's a cost/benefit curve here to consider. This is why Hatteras originally used a bunch of little batteries to make 32v banks, and why they last for a decade or more without much trouble vs. a year or two or three in most boats. Just depends on what you want.

 

[Boatsb]

Each wet lead acid cell is 2.2 volts. Lithium is different.

Having 2 or 3 cases is not the issue. If it were 6 volt batteries would be best. Its the quality of the cells. Not the number in a case that matters.i

I'd not use 8 volts for this at all as the 12 and 24 and 48 volt battery options are far better technology .

I do many 24 and 48 volt banks and never use 8 volt batteries.

 

[Vincentc]

Thanks for the comments

This project involves trying electric power as kicker for my infrequently used 1975 25 foot sailboat kept on a mooring. I've grown tired of replacing gasoline outboards and want to try electric.
Rather than spend 3000+ for an electric outboard I'm going to see how a trolling motor with a solar charged battery bank will work.. Lithium batteries are probably the best technology, but for this use, I suspect lead acid provides the best cost/benefit.

After comparing 6, 8 and 12 volt batteries it looks like 6 volt is best based upon cost and weight compared to amp hour capacity.

Using Duracell golf cart batteries:
(4) 6v Cost $440 provide 215 Amp Hr. cost $2.04 / AH and weight 1.13# / AH
(3) 8v Cost $390 provide 165 Amp Hr. cost $2.36 / AH and weight 1.24# / AH
(2) 12v Cost $708 provide 228 Amp Hr. cost $3.11 / AH and weight 1.11# / AH

 

[Boatsb]

Thanks for the comments

This project involves trying electric power as kicker for my infrequently used 1975 25 foot sailboat kept on a mooring. I've grown tired of replacing gasoline outboards and want to try electric.
Rather than spend 3000+ for an electric outboard I'm going to see how a trolling motor with a solar charged battery bank will work.. Lithium batteries are probably the best technology, but for this use, I suspect lead acid provides the best cost/benefit.

After comparing 6, 8 and 12 volt batteries it looks like 6 volt is best based upon cost and weight compared to amp hour capacity.

Using Duracell golf cart batteries:
(4) 6v Cost $440 provide 215 Amp Hr. cost $2.04 / AH and weight 1.13# / AH
(3) 8v Cost $390 provide 165 Amp Hr. cost $2.36 / AH and weight 1.24# / AH
(2) 12v Cost $708 provide 228 Amp Hr. cost $3.11 / AH and weight 1.11# / AH

I don't think the ah math is correct at 24 volts

 

[Vincentc]

What am I missing?
It is my understanding that the Amp Hour rating remains the same for batteries connected in series, only the voltage increases.