Two 6 volt batteries or two 12 volt batteries ??

Atlee wrote:
At the same time, the idea of an unexpected GC2 battery failure is also blown out proportion.

x2. By that logic, a single 12v battery camper should always carry a spare battery.

lawrosa wrote:

otrfun wrote:

ktmrfs wrote:
. . . if the pair of GC drops below about 75-80% SOC, you can hit the inverter shutoff limit pretty easy with loads of 800-1000 W. Some may depend on the specific inverter and what it's lower limit is.

Now if the batteriesa are above 80% or so, you in good shape. but that means keeping them near full charge when you want the inverter. So.... run the furnace at night then get up and turn on the toaster.... likely be a nope! low temps= higher internal resistance, lower capacity, coupled with partial discharge.

IMHO if your happy with your current 12V setup, don't mess with it. Or, get GC for most of the stuff and run the inverter off 1 or 2 12V AGM's or similar.

We had a situation where we had to run 35 ft. of 2/0 cable from a 1000 PSW watt inverter to two GC2 batteries. On a number of occasions we placed a 65 amp load on the batteries with the inverter (~700 watt a/c load) and regularly ran the two GC2 batteries down to 50% SOC with no inverter alarms or shutdowns. Output from the inverter was always stable at 117 vac. DC voltage drop (due to 35 ft. 2/0 cable) with the 65 amp load was approx. .35v (3%). This particular inverter was supposed to alarm at approx. 10.6v and shutdown at approx. 10.0v. It never alarmed or shutdown.

Thats what I would like real world scenarios on. The voltage drop with 6 volters. There are a lot of variables im sure. But is this a real concern?

Scenarios meaning what size cable and how many feet did others have that had issues?

Like I said I thought 6 volts were a no brainer until I read about said voltage drop.

BFL and someone else said they had issues @ 80%soc.

I guess I can test with my 3 batts all paralleled and see what I get with my new set up..

Im able to monitor voltage from in the camper now.

My last test was flawed as I had the solar hooked up..

My theory also was even if I ran a high current draw, my new set up with two panels and 40 amp mppt will offset the draw.. ( And voltage drop?)

Anyway and if I think about it more, I would only use the high draw appliances in full sun. I can easily use the RV oven and the perculator I have to make the pizza and coffee.

My next two items that are a muct is a c pap machine and a box fan in summer. Furnace in colder months.

C pap without heater and humidifier is about 6 watts. With humidifier and tube heater its only 50 watts.

Furnace 7 amps

Box fan on low is maybe 25 watts. ( I know on high its 100 watts).

Fan and c pap will run through the night and probably a TV ( 30 watts until 1-2am)

So my thinking is if I can eliminate the coffee maker and toaster oven 6 volts may be the better way to go???

IDK just talking out loud here.. As I have no experience with 6 volters.

I do 90 % boondocking. Back in the day I got by with a smaller inverters of 120 watts each x2. TV and fan only. Charged batts with 6 gauge jumper from alternator of truck to rv batts and one solar panel doing 15 amps in on sunny days.

Ditch the coffee maker and heat water on the stove and use a french press or areopress, use the oven on the generator if needed or get a pizza stone and use the gas oven if you have one.

Your other uses, and lot's of boondocking point towards GC. And with decent GC you can get 500+ charge discharge cycles even going down to 25% SOC (75%DOD) a big advantage over 12V cycle life. And how many years will it take to put that many deep discharges on the GC? I barely did it in 10 years on my last set and the batteries were still acceptable. I think age had as big effect as the cycles. They lasted our daughters in-laws another 2 years of abuse before it was time to toss them.

At the same time, the idea of an unexpected GC2 battery failure is also blown out proportion.

I understand that different situations call for different solutions. I just know I can get a lot more amps per dollar with 2 GC2 batteries rather than with two real true deep cycle 12V batteries.

SoundGuy wrote:

FrankShore wrote:
One 6v goes out and you're in trouble.

Atlee wrote:
And if you get rear ended at a stop light, you're in trouble.

I bet the latter is more likely to happen than a 6V die unexpectedly.

Every time this point is mentioned in these types of discussions it gets blown way out of proportion :S when if fact it's merely one point to consider, not intended to be the be the only reason to not choose 6 volt jugs, and doesn't diminish FrankShore's point in any way. Lose one of two 6 volts and you will be be out of business until you come up with an alternate solution, lose one of two 12 volts and you can continue on. Dual 12 volts also allow if you prefer to take one out of service for charging while the other continues to power the trailer, and in fact some prefer running their dual 12 volts this way rather than together all the time. Personal preference.

otrfun wrote:

ktmrfs wrote:
. . . if the pair of GC drops below about 75-80% SOC, you can hit the inverter shutoff limit pretty easy with loads of 800-1000 W. Some may depend on the specific inverter and what it's lower limit is.

Now if the batteriesa are above 80% or so, you in good shape. but that means keeping them near full charge when you want the inverter. So.... run the furnace at night then get up and turn on the toaster.... likely be a nope! low temps= higher internal resistance, lower capacity, coupled with partial discharge.

IMHO if your happy with your current 12V setup, don't mess with it. Or, get GC for most of the stuff and run the inverter off 1 or 2 12V AGM's or similar.

We had a situation where we had to run 35 ft. of 2/0 cable from a 1000 PSW watt inverter to two GC2 batteries. On a number of occasions we placed a 65 amp load on the batteries with the inverter (~700 watt a/c load) and regularly ran the two GC2 batteries down to 50% SOC with no inverter alarms or shutdowns. Output from the inverter was always stable at 117 vac. DC voltage drop (due to 35 ft. 2/0 cable) with the 65 amp load was approx. .35v (3%). This particular inverter was supposed to alarm at approx. 10.6v and shutdown at approx. 10.0v. It never alarmed or shutdown.

your inverter has a much lower threshold than mine does. mine alarms at 11.5V ad shuts down not much below that. From what BFL experienced I suspect his was similar to mine. You've got about another 1V margin, which would make a big difference. So, the GC work well with your combo. Another story with mine. So, yes sucess (or failure) is highly dependent on both the batteries and inverter.

Yes, your solar charging will offset voltage drop and current draw but only to the shared amount of battery charging that is taking place. I like to think of this relationship as the solar charging being a continuous stream of water into a container and any current drawn as taking the water out of the container (although, technically, it isn't that simple).

FWIW, I maintained a fleet of golf carts at one time, over 300 6V's. Said fleet was influenced by cart jockeys that ran carts down to inoperable (even caught one doofus trying to make his record jump into a sand trap). I have a lot of respect for the Trojan 6V. Similar respect is growing for the Sam's Club 6V. I think we are into year 6 with the Sam's Club batteries.

I'd suggest that you try a pair of 6V's. It is less than a $200 experiment and some of that is recoverable, should you later decide to go back to 12V jars. With constant solar charging and a good charge controller, the 6V batteries will last a long time, probably +10 years. If you run a hybrid 12V set down very low more than a few times, at the least, you'll have a loss of capacity. At the worst, you'll have inoperable batteries.

Your inverter mfg should have pertinent info on cable size and distances. I use a 1000W inverter and use 4 AWG, distance to nearest bus box--18". When my 120V fridge is running, the TV screen is being used, my 120V stereo receiver is on, and am powering a laptop, voltage drop is very, very rarely even close to the inverter shutdown point. I typically see voltage drop to 11.75V-> 12V, depending on SOC at the time everything is powered. If I disconnect the 120V devices, battery voltage immediately rebounds above 12.2V -> 12.5V.

Voltage drop happens no matter what type of battery you have. As long as there is available current above acceptable voltages, you're good to go.

otrfun wrote:

ktmrfs wrote:
. . . if the pair of GC drops below about 75-80% SOC, you can hit the inverter shutoff limit pretty easy with loads of 800-1000 W. Some may depend on the specific inverter and what it's lower limit is.

Now if the batteriesa are above 80% or so, you in good shape. but that means keeping them near full charge when you want the inverter. So.... run the furnace at night then get up and turn on the toaster.... likely be a nope! low temps= higher internal resistance, lower capacity, coupled with partial discharge.

IMHO if your happy with your current 12V setup, don't mess with it. Or, get GC for most of the stuff and run the inverter off 1 or 2 12V AGM's or similar.

We had a situation where we had to run 35 ft. of 2/0 cable from a 1000 PSW watt inverter to two GC2 batteries. On a number of occasions we placed a 65 amp load on the batteries with the inverter (~700 watt a/c load) and regularly ran the two GC2 batteries down to 50% SOC with no inverter alarms or shutdowns. Output from the inverter was always stable at 117 vac. DC voltage drop (due to 35 ft. 2/0 cable) with the 65 amp load was approx. .35v (3%). This particular inverter was supposed to alarm at approx. 10.6v and shutdown at approx. 10.0v. It never alarmed or shutdown.

Thats what I would like real world scenarios on. The voltage drop with 6 volters. There are a lot of variables im sure. But is this a real concern?

Scenarios meaning what size cable and how many feet did others have that had issues?

Like I said I thought 6 volts were a no brainer until I read about said voltage drop.

BFL and someone else said they had issues @ 80%soc.

I guess I can test with my 3 batts all paralleled and see what I get with my new set up..

Im able to monitor voltage from in the camper now.

My last test was flawed as I had the solar hooked up..

My theory also was even if I ran a high current draw, my new set up with two panels and 40 amp mppt will offset the draw.. ( And voltage drop?)

Anyway and if I think about it more, I would only use the high draw appliances in full sun. I can easily use the RV oven and the perculator I have to make the pizza and coffee.

My next two items that are a muct is a c pap machine and a box fan in summer. Furnace in colder months.

C pap without heater and humidifier is about 6 watts. With humidifier and tube heater its only 50 watts.

Furnace 7 amps

Box fan on low is maybe 25 watts. ( I know on high its 100 watts).

Fan and c pap will run through the night and probably a TV ( 30 watts until 1-2am)

So my thinking is if I can eliminate the coffee maker and toaster oven 6 volts may be the better way to go???

IDK just talking out loud here.. As I have no experience with 6 volters.

I do 90 % boondocking. Back in the day I got by with a smaller inverters of 120 watts each x2. TV and fan only. Charged batts with 6 gauge jumper from alternator of truck to rv batts and one solar panel doing 15 amps in on sunny days.

ktmrfs wrote:
. . . if the pair of GC drops below about 75-80% SOC, you can hit the inverter shutoff limit pretty easy with loads of 800-1000 W. Some may depend on the specific inverter and what it's lower limit is.

Now if the batteriesa are above 80% or so, you in good shape. but that means keeping them near full charge when you want the inverter. So.... run the furnace at night then get up and turn on the toaster.... likely be a nope! low temps= higher internal resistance, lower capacity, coupled with partial discharge.

IMHO if your happy with your current 12V setup, don't mess with it. Or, get GC for most of the stuff and run the inverter off 1 or 2 12V AGM's or similar.

We had a situation where we had to run 35 ft. of 2/0 cable from a 1000 PSW watt inverter to two GC2 batteries. On a number of occasions we placed a 65 amp load on the batteries with the inverter (~700 watt a/c load) and regularly ran the two GC2 batteries down to 50% SOC with no inverter alarms or shutdowns. Output from the inverter was always stable at 117 vac. DC voltage drop (due to 35 ft. 2/0 cable) with the 65 amp load was approx. .35v (3%). This particular inverter was supposed to alarm at approx. 10.6v and shutdown at approx. 10.0v. It never alarmed or shutdown.

FrankShore wrote:
One 6v goes out and you're in trouble.

Atlee wrote:
And if you get rear ended at a stop light, you're in trouble.

I bet the latter is more likely to happen than a 6V die unexpectedly.

Every time this point is mentioned in these types of discussions it gets blown way out of proportion :S when if fact it's merely one point to consider, not intended to be the be the only reason to not choose 6 volt jugs, and doesn't diminish FrankShore's point in any way. Lose one of two 6 volts and you will be be out of business until you come up with an alternate solution, lose one of two 12 volts and you can continue on. Dual 12 volts also allow if you prefer to take one out of service for charging while the other continues to power the trailer, and in fact some prefer running their dual 12 volts this way rather than together all the time. Personal preference.

Atlee wrote:
And if you get rear ended at a stop light, you're in trouble.I bet the latter is more likely to happen than a 6V die unexpectedly.

FrankShore wrote:
One 6v goes out and you're in trouble.

I think this notion comes from the idea that if you like to run your batteries until their last breath, then one will fail before the other.

A catastrophic battery failure is extremely unlikely, and certainly not something to base your battery choice on.

marcsbigfoot20b27 wrote:
I had the single OEM battery config grp 24. Upgraded to grp 31. Added 2 GC2 golf cart batteries that had to be set on the ground with cables run to the single.

Re-engineered the entire setup.
3 true deep cycle grp 31 AGM batteries (East Penn/Dekka) with 2/0 welding cable, able to mount the extra 2 batteries in a compartment since there is no outgsssing.

Original setup....pros- inexpensive batteries, can be found anywhere.
Cons - out gassing, slow rate of charge, always needed water, high self discharge, one dies both worthless, corrosion on terminals, must be in pairs, voltage drop when using 2000 psw inverter at 1300 watts.

New setup....
Cons- more expensive, only sams club has them in stock.
Pros- no outgassing, higher rate of charge/ less gen time with decent converter, never need water, one dies just remove it, no corrosion, lower self discharge, less voltage drop when pulling high amps with inverter, vibration resistant, mount it anywhere, add them in ones.

If you can afford double the price of GC2 then all the pros outweigh the cons imho. Plus you can go odd number of batteries or whatever suits your needs, not just pairs.

applications like yours with high inverter draw is another example where IMHO 12V wins. 6V vs. 12V really depends on YOUR application and needs to determine which is appropriate. each has noticeable advantages or disadvantages, depending on the application. Pick which works best for YOU.