our boat came with 2 huge 8Ds that took 2 hearty men to lift out and put in. when time came to replace them i just went with 2 smaller AGM lifelines, then decks at 135 aH each. those batteries are now ready for replacement and i am considering a conversion to 4 6 v 'golf carts'. ( i've read the wiring literature.) has anyone who's done one of these conversions give any advice ? it seems to me that having custom cables made up between the 4 new golf carts is only option. the downside of this project is that my OEM fancy house battery display for amp-hours remaining and chasing rates and the like won't work any more...
Converting 12v house to 'golf cart' 6v s..
- Thread starter MitchM
- Start date
Not all "golf cart" batteries are 6 volt. I am very happy with my Trojan T-1275 12 volt 'golf cart' batteries. They have the same footprint but are taller. 150a/h each.
A couple of years ago I replaced a poorly designed battery system with 4 GCs at 230 ah each for a total of 460 ah. It was not a particularly difficult job.
The first consideration is space for the battery box. I used this one: https://shop.sailboatowners.com/prod.php?1898
Making the cables is not that difficult. It is necessary to get a decent crimper. I used 2/0 marine grade battery cable.
It may be possible to recalibrate your amp hour meter. Take a look at this article Making Your Battery Monitor More Accurate – Marine How To if you haven't perused Maine Sail's site, this would be a good time.
The first consideration is space for the battery box. I used this one: https://shop.sailboatowners.com/prod.php?1898
Making the cables is not that difficult. It is necessary to get a decent crimper. I used 2/0 marine grade battery cable.
It may be possible to recalibrate your amp hour meter. Take a look at this article Making Your Battery Monitor More Accurate – Marine How To if you haven't perused Maine Sail's site, this would be a good time.
Here is a place that I purchased custom cable for the conversion that I performed
http://www.genuinedealz.com/custom-cables/custom-battery-cable-assembly
They did some nice work for me at a reasonable cost.
http://www.genuinedealz.com/custom-cables/custom-battery-cable-assembly
They did some nice work for me at a reasonable cost.
If you have room for 4 batteries using 6V batteries has the benefit of bigger cells (3 vs. 6) in the same footprint. More lead, more electrolyte. Any decent modern battery monitor should be configurable to the change in battery type, but if it isn’t now would be a good time to update your technology. Use covered battery boxes.
Mitch, could you please explain why?
Gunni, he's changing from 12V to 6V batteries for a 12V BOAT SYSTEM, so nothing should change.
That's why I asked.
@Stu Jackson thanks for clearing that up, I wasn't certain so I did not say anything, but if I am not mistaken all one would have to do is program the total amp hours for the new batteries into the existing system.
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A 12V bank is a 12V bank regardless of the number of 2V cells it is made from. Moving from 8D's to GC2's has no effect on your battery monitor. You'll just need to re-program it...
Your dual 8D bank, and current bank, had/has 12 2V cells, and wired in parallel, is a 12V Bank
Your four GC2's will have 12 2V cells, and wired in series/parallel, is a 12V Bank
This isn't very difficult. On Fraulein II, I wired two 6v Trojans in series then wired that to number 1 post on a selector switch. Did the same with the other two Trojans but wired that to number two on the same selector switch. Now, I can parallel the two house banks or isolate a house bank using that selector switch. Wired the hot side of that switch to the number 1 post on the main switch at the breaker panel. Wired my 12v starting batt to the number two post on the main switch. Am I even making any sense?
How many switches do you have?
If you have 4 GC batteries it is better to wire the 4 of them together as one large bank than 2 separate smaller banks. The larger bank the bank the more efficient the bank will be and the more usable amp hours you will have. There is a formula for calculating all of this, the Peukert equation and factors. Think of it this simple, mostly correct, way. With a battery bank of 460 ah, if you draw 46 ah out of the battery it will be at 90% State of Charge, or you have only drawn the bank down 10%. If you split that bank in to 2 banks of 230 ah and then draw 46ah out of one bank, the bank has been drawn down 20%. The smaller percentage that a bank is drawn down, the better it is for the battery bank.
The big question is what do you do have and use on the boat. Example on ours we have 4 6 volt golf cart that replaced 2 12 volt in doing so we doubled our amp hour as we anchor more than dock. We did install 2 65 watt solar panels last year that made it so we don't need power to recharge the system. What we run is a GPS, AP,Radios and lights so far we have not needed extra charging even on a 2 weeks at anchor. If you don't need the extra amp hour stay with the 12 volt batt and as for wiring you could do it your self. The biggest problem is containment and securing them in place.
please, many of you...buy and read nigel calders book; boat owners mechanical and electrical manual. it is full of the right way to deal with this stuff in a pretty easy read. LOTS of misinformed stuff going round lately on several electrical threads.
Just to note, I have not seen any reference to the use of fuses as close as possible to the batteries as possible, this will help protect against fire should there be a unexpected issue with any conductor between the distribution panel and the batteries.
This is an important point. The key with your drawing is that you've correctly fused the positive wire that runs, what appears to be, across the boat. One point however that is missed is that both ends of that + wire running across the boat, or between the separated batteries, should ideally be fused.
The fuse is protecting the length of wire extending from the battery bank. If the short were to occur on the port side of that wire (assuming port as drawn) it is still unprotected from the port bank. A protective conduit could also be used for that wire if it is short enough to not require a fuse..
What the drawing also shows nicely is your pos & neg takes offs are on opposite ends of the bank not just one side/end. This helps to keel the parallel pairs in better balance over their life. The charger however needs a fuse at the bank.
Two selector switches. One dedicated to the two house banks so I can parallel them giving me one bank at 460 Ah or choose one bank at a time for 230Ah if a batt in one bank goes dead. This SS feeds the main SS at the breaker panel number one position. The 12v starting batt goes to the number two position on that breaker panel SS. I can then parallel all banks or choose any combination.
Thanks, that makes a lot more sense.
When you parallel the 2 house banks, does the charging source(s) feed the banks properly? That is does the charge source go all the way through all 4 batteries, similar to the schematic DayDreamer posted above?
I have a three bank charger. All banks wired independently.Thanks, that makes a lot more sense.
When you parallel the 2 house banks, does the charging source(s) feed the banks properly? That is does the charge source go all the way through all 4 batteries, similar to the schematic DayDreamer posted above?