6V Golf Cart Bank. How big can I go?

[Simi 60]

My understanding us a 100 A NRBF fuse will fail/open under a load of say 150A but if a batty bank is shorted and 20,000 A present the fuse may weld shut instead of opening and protecting the circuit. Likely a rare occurrence but that's my understanding of the whole topic / area if ABYC dealing with AIC. A type T fuse will still open and protect in the extreme cases where even NRBF exceed their ratings.

.

I know the theory behind it and spent a bit of time looking into it
As did the marine electrician who did the final install

But how does a battery bank get shorted?
If you don't let that happen is it needed?

I'm pretty sure in most of the world ABYC is not a thing.

 

[luna]

DDW

In your Post #19 you stated that there was "four 4DL's in series." A GPL-4DL is a 12V AGM battery that has a Short Circuit Current of 6105 amps. Four of these in series produces 48V. The MRBF series of fuses in not rated at 48V, but at 58V the AIC is 2000 amps and at 32V the AIC is 5000 amps. At 48V it would be someplace in between, say 3000 amps. Both are a fail as you need a fuse rated at 6105 amps or greater.

Now in Post #29 you have clarified that the batteries are a "4 series string of 4CTs." A GPL-4CT is a 6V AGM with a Short Circuit Current of 3621 amps. Four of these in series produce 24V and as you state, will have a Short Circuit Current of 3621 amps.
A MRBF at 24V will have an AIC greater than 5000 amps and as a result, as far as AIC is concerned, you're golden.

 

[Bacchus]

I know the theory behind it and spent a bit of time looking into it
As did the marine electrician who did the final install

But how does a battery bank get shorted?
If you don't let that happen is it needed?

I'm pretty sure in most of the world ABYC is not a thing.

Fair enough.
ABYC has been debated more than enough so don't mean to go there.
My point was/is only to raise the ABYC " recommendation" and try to educate others that AIC fusing is different that OCP fusing. You have confirmed you understand, have considered it and decided to make a conscious decision to not worry about ABYC. I have no familiarity nor interest in other international "standards" so no idea if others recognize a need for AIC.

 

[DDW]

DDW

In your Post #19 you stated that there was "four 4DL's in series." ....

Now in Post #29 you have clarified that the batteries are a "4 series string of 4CTs."

Yeah, I echoed some prior posts referencing 4DL without thinking/checking. Not sure how those got into the discussion. The OP's question was on 6V golf cart batteries organized as 4S4P, or 24V banks. So what I said was true for a 24V bank of 6V golf cart batteries - 4CT in Lifeline parlance - and the OP's battery banks.

 

[tiltrider1]

I know the theory behind it and spent a bit of time looking into it
As did the marine electrician who did the final install

But how does a battery bank get shorted?
If you don't let that happen is it needed?

I'm pretty sure in most of the world ABYC is not a thing.

ABYC comes from the point of view “if can happen, it will happen”. I believe that a lot of their rules are over reaching. I have no problem with ignoring ABYC if you are educated and have evaluated your situation.

In this particular thread it has been pointed out the risks of increasing the size of battery banks and the important safety considerations.

 

[Simi 60]

MRBF on 400ah of LFP handling a short.
Fluke meter overloaded at 1000 amps

I have one of these on each battery

https://youtu.be/y3gzhep8w4A

 

[Simi 60]

ABYC comes from the point of view “if can happen, it will happen”. I believe that a lot of their rules are over reaching
.

And that's why $100,000 boats are now $1million boats
Organisations protecting people from every eventuality
IMHO it breeds complacency and stupidity, no need for critical thinking or common sense anymore.
And Darwinism gets cheated

I have no problem with ignoring ABYC if you are educated and have evaluated your situation.

Agreed

 

[SeaMaster101]

I have a lucky situation. I have some extra area around the house bank, and I could use some extra weight on that side of the boat.

Boat has 12 x GC2 (6V -235 ah golf carts) = 3 banks of 24v. All batteries are due for replacement.

Anyone running 16 x GC2s (4 banks of 24v)?

I know of a large Tolly with this same setup, and they seem happy. The extra reserve capacity would be nice. I'm committed to the GC2 footprint and height.

Thanks,
-Morgan

I had 18 golf cart batteries on my boat same capacity as yours. I had them configured as a single bank - 2 grouped in series and 9 of these in parallel.
They lasted about 5 years cruising but what usually was negative ware the long layovers without me being on the boat.
I replaced them with 4x 300AHr lithium just before COVID lockdown. The lithium were fine after 26 months of being disconnected with no supervision

 

[Lostsailor13]

I have 4 of the 6v Duracell 370 ah batteries,after 3 years they are still like the day I bought them