Converting from 12v to 6v battery system

[BobC]

Originally Posted by Leevormelker

There is a relatively small advantage by using 6 v vs 12 v batteries. You will gane more by just adding more battery ah capacity. It's a challenge keeping up with a compressor refer. Lee

There's more to this than AH. True, deep cycle batteries like 6v golf cart batteries have heavier, more robust plates and are more resistant to damage than your typical 12v "marine" batteries. They also tend to be somewhat less expensive than true deep cycle 12v batteries.

[Kayak73]

Originally Posted by BobC

There's more to this than AH. True, deep cycle batteries like 6v golf cart batteries have heavier, more robust plates and are more resistant to damage than your typical 12v "marine" batteries. They also tend to be somewhat less expensive than true deep cycle 12v batteries.

Yes, there is a 12VDC compressor refrigerator to operate. No one would seriously consider MARINE batteries in this application. The T-1275 is certifiably a true deep cycle battery and prior poster is correct, there is zero gain in this application in going to 6VDC batteries in series - you want all those AmpHours. Now if you have the ridiculous 18View with the battery tray made for only group 24 batteries and you must chop it anyway, cut it out and put in the big Trojans. It is not the complete answer but you can make it three nights maybe four without shore power or a very long generator run. So, where did MARINE batteries come into the discussion? If you are comparing marine batteries compare apples to apples, not grapes to pears. Check it out, those T-1275 batteries are true deep cycle batteries. I'll take those any day in this application compared to 6V in series but only because even with the tray chopped you can not put in giant Lifeline AGM with the same AmpHours capacity. In this application 6VDC is a loser compared to the big Trojans. Got to understand.


In this application those golf cart batteries from Costco won't do much more than the OEM trash. Even T-125 won't help a lot. You must get AH.

[BobC]

Originally Posted by Kayak73

Yes, there is a 12VDC compressor refrigerator to operate. No one would seriously consider MARINE batteries in this application. The T-1275 is certifiably a true deep cycle battery and prior poster is correct, there is zero gain in this application in going to 6VDC batteries in series - you want all those AmpHours. Now if you have the ridiculous 18View with the battery tray made for only group 24 batteries and you must chop it anyway, cut it out and put in the big Trojans. It is not the complete answer but you can make it three nights maybe four without shore power or a very long generator run. So, where did MARINE batteries come into the discussion? If you are comparing marine batteries compare apples to apples, not grapes to pears. Check it out, those T-1275 batteries are true deep cycle batteries. I'll take those any day in this application compared to 6V in series but only because even with the tray chopped you can not put in giant Lifeline AGM with the same AmpHours capacity. In this application 6VDC is a loser compared to the big Trojans. Got to understand.


In this application those golf cart batteries from Costco won't do much more than the OEM trash. Even T-125 won't help a lot. You must get AH.

I stand corrected, I didn't research the T-1275 model number but was reacting to the common misconception that the so-called marine batteries and the typical OEM batteries aren't true deep cycle batteries. However, it hasn't been my experience that the Costco golf cart batteries won't do much more than the "OEM trash". I do agree that the T-1275s would be a better, albeit more expensive, option.

[creativepart]

Folks, even though you might be frustrated because the RV you purchased doesn’t exactly fit your specific needs there is no need to get upset at others with differing opinions.

Keep it civil or do not post.

[Kayak73]

Bob,


Just so we are communicating, which I frequently do directly but with no ill will or intent to be offensive... I have used the Costco 6VDC GC2 batteries in the past with excellent results, in the right application a good bang for the buck. Those situations the RV had an LP or three way fridge and the load was easy on the batteries normally.


This situation is a bit different because the fridge is always running, 70-72% of the time, drawing 2.5-3.2 amps. For example today we have clear skies and good sun. The solar has kept the batteries FULL all day so far and simply respond to the fridge in operation. There is excess energy being discarded and I have the converter turned off.



I have acknowledged many times that the rig works fine for plug-to-plug camping. There is no identifiable problem at all with the refrigerator, doubt there ever was. The problem is simply keeping it powered up off-grid.


I'm almost there. With the remote pendant for the PD9245 I can force the converter into BULK charge mode when running the generator. Before I could not get the converter out of FLOAT because it saw the voltage from the solar controller - even on a cloudy, rainy day - and dropped immediately into FLOAT when the generator is started and converter comes on, regardless of how depleted the batteries were. That's about 90% of the fight won.

[Journey39n]

For my 2 cents to add, I went from two NAPA 12v group 31 batteries that died way too suddenly, to two Costco GC2 6v batteries. Slightly heavier, slightly taller, fit into the space easily, and provided similar 220 amp hours. Big advantage, the batteries were better suited to my discharge/charge cycles, and were much cheaper to buy.

After one year, I decided my wife's old CPAP running all night was draining the batteries more than I liked, especially if we needed to run the furnace at night too. So I added two more 6v batteries, configured in series creating two banks of 12v, delivering 440 amp hours.

Very happy with that setup for the next 6 years until they all needed replacing. Bought a new set of Costco batteries, price had increased about $10 per batteries, so still a terrific deal. Very happy the last two years with them again.

In my opinion, yes, AGM or Lithium Ion batteries would be better. But for the money spent, the job gets done for our needs. You have to balance your 'actual' need versus wishful thinking needs, and the cost for your whole system.

[Touchdown2]

Any idea how much noticeable difference between them or compared to the 6v

[Kayak73]

Weight. Hugh difference and in a small rig like the V/N a big deal, not so much in a big A class.


Recharge time is far less with lithium - extremely low internal resistance to charge. It will take what you throw at it up to 1C, most literature recommends .2C - .5C normally.



AmpHours are amphours. You still need what you need either way but you can occasionally discharge LiFeP04 lower than 50% although there is some literature suggesting staying above 50% SOC is better for life cycles.


Money. My FLA Trojans cost $1.00 per AH, LiFeP04 is running around $10.00/AH and you should consider a few mods, up to you.


Life expectancy. Much longer with properly operated and maintained LiFeP04 than either AGM or FLA.


Satisfaction and extended dry camping - up to the individual but LiFeP04 and a good solar installation would make me very happy right now. It would indeed make my check book sad. Life is short, we all must do what we consider is appropriate in our individual circumstance. I'm pretty close to having my dry camping issues solved without the lithium - that's money I can use for something else.