6 volt vs 12 volt batteries for boondocking

[placergold]

Hi all, While waiting for our new 28' Stealth toy hauler we're trying to figure out the best batteries to get for when we're back in the hills camped off the grid.

We ordered the optional 200 watt solar panel & regulator with Power Boost. And a 1,500 watt Go Power Inverter.

I've been told the golf cart type 6 volt batteries will last much longer than the 12 volt deep cycle batteries available. Mainly because of the constant discharge/charge cycle that occurs.

But, I really have no experience in this area, so any and all input from those familiar with this subject would be greatly appreciated!

Thank you.

[OldSmokey]

All 3 of my batteries were bought in the same month....just adding them to the trailer permanently with some 1/0 cable.

not going to make much difference, 2-3 years max and you will be replacing them anyway..

[ktmrfs]

MEXICOWANDERER wrote:
ktmrfs

"A pair of GC batteries will drive a 1000W inverter untill the battery is down to around 80 percent SOC, then the inverter will alarm and shut down due to low input voltage. Now that means unless a pair is well charged, you may be out of luck even at 1000W"

Cannot this trait be deemed and treated as a "STUPID PREVENTER"?

Very very few RVs have the battery capacity to run a thousand watts long-term. And usually if high wattage is desired for an extended time I have a very hard time arriving at a justifiable reason. That's right up generator use alley.

long term I agree. However it is nice with our setup of 4GC to be able to run the microwave at 900VA setting (50ish percent power setting) for a few minutes to warm up coffee or tea, heat veggies for dinner, etc. etc. without going out to start the generator.

If we need the full microwave power, or for any length of time, then it's fire up the generator time.

[ktmrfs]

mike-s wrote:

ktmrfs wrote:
Even true deep discharge 12V like Trojan 12V renewable energy 12V have about 1/2 the cycle life of a similar 6V configuration.

Where did you get that from?

Trojan says otherwise. In their spec sheet, they show the 6V T-105 right next to the 12V J185H (which has the same capacity as 2 T-105s). Both are listed in the same 1200 cycles @ 50% discharge section, and they share the same cycle life curve. It's the Group 24/27 batteries which have shorter lives (and smaller capacities), because the case size restricts how large the plates can be (a 185 weighs over twice as much as a 27) and how much electrolyte they can hold (the 185 is twice the volume).


The reason to buy 6V GC2s is because they tend to be cheaper and easier to find locally due to the numbers used in golf carts, not because 6 V batteries are necessarily better than 12 V ones.

the chart I saw didn't show the 12V you referenced, only the 24/27 deep discharge. sounds like the other 12V you referenced is close to the 8D size, which is like 2 GC.

so there are 12V deep discharge with similar life cycles to a GC

[MEXICOWANDERER]

ktmrfs

"A pair of GC batteries will drive a 1000W inverter untill the battery is down to around 80 percent SOC, then the inverter will alarm and shut down due to low input voltage. Now that means unless a pair is well charged, you may be out of luck even at 1000W"

Cannot this trait be deemed and treated as a "STUPID PREVENTER"?

Very very few RVs have the battery capacity to run a thousand watts long-term. And usually if high wattage is desired for an extended time I have a very hard time arriving at a justifiable reason. That's right up generator use alley.

[MEXICOWANDERER]

flat screen TV, sound system, lights............................................


Where's my DEPENDS horsee?

Personally I use .000000000000001 kWh per decade for a TV

But then there are RV'ers who cannot eat dinner without a DVD shouting on a screen. The prize-winners have a 2nd TV going for the kids.

Some RV'ers are home and their outfit is near blacked out at 9:00PM

While others try to mimic Times Square for 6 hours after sundown.

Only the owner can rationally quantify total battery usage.

[RDMueller]

placergold wrote:

Off the batteries, we will occasionally be using the power tongue jack, power awning, and power stabilizer jacks. And daily, low draw items like flat screen TV, sound system, water pump, lights, stove top & bathroom pull fans, etc.

A couple folks have brought up the subject of the size of the 1,500 watt inverter, as relates to using just 2ea 6v golf cart type batteries.

Bottom line, now that you know our intended power usage, will this be a problem???

No problem at all. In fact, based on your planned usage, 2 6v golf cart batteries will serve you very well. Plus you'll have more amp hours available for the money spent than with any other type of battery.

[RJsfishin]

3 12v batteries in parallel works just fine. I haven't done it, but I know several that have.

Sure is a lot of battery BS here !

[marcsbigfoot20b]

OldSmokey wrote:

marcsbigfoot20b27 wrote:
Anyone have any feelings towards using say 3 of these batteries in parallel for boondocking?

Duracell AGM group 31 31DTMAGM

I have 1 as house batt and adding 2 more in parallel. Just installed 360 watts of solar. Converter is a WFCO 9855 3 stage.
Have a 2000 PSW inverter for microwave, Kurig, etc.

I do, firstly you want to get away from 12V batteries. the reason ?
LEAD.. not enough.. there are too many cells in a small space, so leave 12V for starting and the like.

Never parallel more than 1 set, you have no way to balance the currents and you will compromise lifespan.

Recommended best practices is to use 6,4 or 2V cells.
reason is that you can achieve better performance at lower cost
and have longer lifespan.


here is a table many won't like, but it's based on real world
recommendations that PE's like me use to size systems.

This is based on Panel Wattage and load ratings

0 to 600 watts = 12 Volts or higher
601 to 2000 watts = 24 volts or higher
2001 to 5000 watts = 48 volts or higher

so if you want to power a 4000W inverter, it's not going to be on 12 Volts. that's asking for a whole crock of trouble. voltage drop due to high current is your worst enemy here. and you don't have many volts to begin with.


looking at your apparent requirement of 300 Ah at 12V
you have 3 at $180 = $540 and probably 2 to 3 years max on one battery, you won't know which one until you disconnect the set and test them individually. PM me if you want a more technical explanation of why parallel is bad.

using 6V cells you will get much longer service and both cells will age at the same rate.

All 3 of my batteries were bought in the same month....just adding them to the trailer permanently with some 1/0 cable.

[OldSmokey]

marcsbigfoot20b27 wrote:
Anyone have any feelings towards using say 3 of these batteries in parallel for boondocking?

Duracell AGM group 31 31DTMAGM

I have 1 as house batt and adding 2 more in parallel. Just installed 360 watts of solar. Converter is a WFCO 9855 3 stage.
Have a 2000 PSW inverter for microwave, Kurig, etc.

I do, firstly you want to get away from 12V batteries. the reason ?
LEAD.. not enough.. there are too many cells in a small space, so leave 12V for starting and the like.

Never parallel more than 1 set, you have no way to balance the currents and you will compromise lifespan.

Recommended best practices is to use 6,4 or 2V cells.
reason is that you can achieve better performance at lower cost
and have longer lifespan.


here is a table many won't like, but it's based on real world
recommendations that PE's like me use to size systems.

This is based on Panel Wattage and load ratings

0 to 600 watts = 12 Volts or higher
601 to 2000 watts = 24 volts or higher
2001 to 5000 watts = 48 volts or higher

so if you want to power a 4000W inverter, it's not going to be on 12 Volts. that's asking for a whole crock of trouble. voltage drop due to high current is your worst enemy here. and you don't have many volts to begin with.


looking at your apparent requirement of 300 Ah at 12V
you have 3 at $180 = $540 and probably 2 to 3 years max on one battery, you won't know which one until you disconnect the set and test them individually. PM me if you want a more technical explanation of why parallel is bad.

using 6V cells you will get much longer service and both cells will age at the same rate.

[BFL13]

MEXICOWANDERER wrote:
Would not this discussion be more relevant if comparing the 3-cell vs a 24, 27, or 29? Scrubber batteries in RVs is presently "uncommon".

I have done it with various 6v, 12v, 12v AGMs, 12v scrubber T-1275s (which came from golf car usage in their former lives, so they are also "golf car batts"), and various combos of.

Yes, you get less voltage drop with 12s than with 6s, but the biggest diff to reduce voltage drop was to improve the wiring in my case. (Fatter, shorter wire and tighten those connections.)

My current set -up is two 6s and two T-1275s banked as two big 12s in parallel. Voltage drop with a 120 amp draw (microwave on MSW inverter) is 0.6 volts, which is way better than I ever got before I improved the wiring no matter if using 6s or 12s. Even when I had four 6s and the two T-1275s banked as three big 12s I got 0.7 volt drop doing that.

So wiring is almost everything in this game. You can't compare other folks' results with what you could get without also knowing their wiring set-ups.

[camperguy99]

I have 3 series pairs of GC2 (yep, 6 batteries & 690 AHrs) and my induction stove top draws 80-90 amps from the setup. By the time wife has tea water the batteries read around 11.5 volts. I've checked and each series pair runs about 30 amps discharge. Charging them from my Magnum 100 amp converter puts an almost equal 30 amp back into each pair. Takes forever to regain +90% charge. Oh, the other 10 amps (actually 15 since it puts out 105A) is used on the normal coach load. Ditto the uW oven.

[MEXICOWANDERER]

Would not this discussion be more relevant if comparing the 3-cell vs a 24, 27, or 29? Scrubber batteries in RVs is presently "uncommon".

[mike-s]

ktmrfs wrote:
Even true deep discharge 12V like Trojan 12V renewable energy 12V have about 1/2 the cycle life of a similar 6V configuration.

Where did you get that from?

Trojan says otherwise. In their spec sheet, they show the 6V T-105 right next to the 12V J185H (which has the same capacity as 2 T-105s). Both are listed in the same 1200 cycles @ 50% discharge section, and they share the same cycle life curve. It's the Group 24/27 batteries which have shorter lives (and smaller capacities), because the case size restricts how large the plates can be (a 185 weighs over twice as much as a 27) and how much electrolyte they can hold (the 185 is twice the volume).

The reason to buy 6V GC2s is because they tend to be cheaper and easier to find locally due to the numbers used in golf carts, not because 6 V batteries are necessarily better than 12 V ones.

[TurnThePage]

Nope

[placergold]

Thank you all for these very informative posts!

To clarify, and help narrow this down. We will not be using the AC, microwave, fridge, coffee maker, or any heavy draw appliances just off the batteries. We will use the 4K Onan generator, or shore power when available for that.

Off the batteries, we will occasionally be using the power tongue jack, power awning, and power stabilizer jacks. And daily, low draw items like flat screen TV, sound system, water pump, lights, stove top & bathroom pull fans, etc.

A couple folks have brought up the subject of the size of the 1,500 watt inverter, as relates to using just 2ea 6v golf cart type batteries.

Bottom line, now that you know our intended power usage, will this be a problem???