Why not?

I'm considering replacing my house bank 6v golf cart batteries (T105) with four 12v deep cycle car batteries.

Pros: long days on the hook without using gens.
Cons: long charging times.


Any other downsides you guys see?

Juliet 15 said:

I'm considering replacing my house bank 6v golf cart batteries (T105) with four 12v deep cycle car batteries.
Pros: long days on the hook without using gens.
Cons: long charging times.
Any other downsides you guys see?

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I don't believe the car batteries have the DOC or discharge that golf cart batteries have. Golf cart batteries are the only true deep cycle FLA batteries of which I am aware.

You didn’t say how many 6v batteries you are replacing. Also four?

I can only relay that in previous research years ago whenever 6v and 12v were compared that 6v bank was preferred comparing apples to apples as in 3-12v compared to 6-6v or 4-12v compared to 8-6v. The 6v bank was overall better.
With battery tech evolving things may change.

Juliet 15 said:

I'm considering replacing my house bank 6v golf cart batteries (T105) with four 12v deep cycle car batteries.

Click to expand...

How many T105s in your bank now?

What "deep cycle car batteries"? What voltage, 12V? Most 12V "deep cycle" batteries I've seen advertised are really dual-purpose...

-Chris

As usual, there are reasons things are the way they are.



Turns out 12v vehicle batteries are low amp hours, generally down in the 100 to 160-ish range. They're also wider and don't fit as well. For the amp hours you get, golf cart batteries can't be beat.



So I bought 4 new 230ah golf cart batteries.



Now onto the next project.

Juliet 15 said:

As usual, there are reasons things are the way they are.



Turns out 12v vehicle batteries are low amp hours, generally down in the 100 to 160-ish range. They're also wider and don't fit as well. For the amp hours you get, golf cart batteries can't be beat.



So I bought 4 new 230ah golf cart batteries.



Now onto the next project.

Click to expand...

I would like to suggest get 2 more. 4 can/will work most of the time, the extra 2 will ensure it and chances are they will not get depleted to 50% as a result. After having 6 in previous boats I tried 4-6v and ran out and had to start engine before I planned on moving.

ranger42c said:

Most 12V "deep cycle" batteries I've seen advertised are really dual-purpose...

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This ^^^^


Except that I would change "most" to "all." I am not aware of ANY automotive "deep cycle" battery that is not actually a dual-purpose battery.

Soo-Valley said:

I would like to suggest get 2 more. 4 can/will work most of the time, the extra 2 will ensure it and chances are they will not get depleted to 50% as a result. After having 6 in previous boats I tried 4-6v and ran out and had to start engine before I planned on moving.

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UNLESS
If you have some solar panels, your 4 will be enough. So no need to redesign your battery location.

koliver said:

UNLESS
If you have some solar panels, your 4 will be enough. So no need to redesign your battery location.

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You mean if I install solar I have to sell two batteries........


Good deal.

6V batts have fewer spacers between the usually more robust plates, so there heavier , more lead = more amps.

Stay with 6V if you can.

Another FLa true deep cycle option if you have sufficient height allowance (18”) is L16 scrubber batteries. Same width, slightly longer than GC 2’s mainly taller & very heavy, 370 Ahrs per pair

Here is the best explanation why FLA GCs are absolutely the way to go
https://marinehowto.com/what-is-a-deep-cycle-battery/

denverd0n said:

This ^^^^


Except that I would change "most" to "all." I am not aware of ANY automotive "deep cycle" battery that is not actually a dual-purpose battery.

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Above us true for FLA. If you consider AGM the answer changes significantly.
Both Trojan and East Penn when questioned confirmed that their GC and GP 31 AGMs perform equally well in deep cycle and starting applications. My understanding is no need to change / tailor plate designs as they are well supported by the glass mat and unlike FLA AGM plates aren't "submerged" where the space and depth of acid below & above plates is an important design difference.
You will notice AGM batty mfgrs spec both CCA and AH for AGMs.
It also turns out a pair of 6V GCs are roughly equal to (not exactly) a pair of GP 31s for AH and CCA and close to one 8D.

Juliet 15 said:

Turns out 12v vehicle batteries are low amp hours, generally down in the 100 to 160-ish range. For the amp hours you get, golf cart batteries can't be beat

So I bought 4 new 230ah golf cart batteries.

Click to expand...

While I too recommend GCs, the statement above needs clarification. A 6-volt battery may have 200-amps, but to get 200-amps at 12-volts you need two 6v batteries in series. Using rough math, four 12v batteries (all parallel) is 400-AH (@12v). Four 6v batteries (2x2 series-parallel) is also 400-AH @12v.

BTW - in my opinion, the Costco Interstate GC2 batteries are no bargain even at $93/ea. The true T105s really are a better battery and better value despite the signicant price difference.

Peter