6 volt batteries and an inverter

If your 2000w inverter's low voltage shutdown spec is 11.0v or less AND you use inverter to battery cables that have less than a 2% voltage drop at your maximum anticipated load, this should significantly reduce your chance of having a problem powering your inverter with 2 GC2 batteries if they're discharged as low as 12.2v (50%).

We power our 2000w Xantrex PSW inverter with 2 GC2 batteries. FWIW, we can power a small 1,500w space heater on high (~140 amps) with 2 GC2 batteries already discharged to 12.2v. Inverter input voltage under this load is approx. 11.2 to 11.1v--just barely above the Xantrex's 11.0v low voltage shutdown voltage. Yes, the low voltage alarm activates, but the inverter does not shutdown. We use 4/0 cable for the 13 ft. battery to inverter cable run which limits our voltage drop at 140a to .15v (~1.4%).

I might add we can power our 1,100w microwave for up to 40 min. with our 2 GC2 batteries before they drop to 12.2v.

jdcellarmod wrote:
I'm planning on having 2-6 volt batteries with a 300 amp hour rating. ... I do not have room for 4-6 volt batteries...I'm not opposed to using 12 volt batteries.

Your 6v batteries are rated *each* at 300ah? Most I've ever seen is around 220.

Some here believe that 12v batteries are better for high-amp inverter applications. Perhaps some big 12s would be better.

2-6v batteries will be a struggle with a microwave.

Low voltage alarm is not killing the inverter yet.
I had 1500W toaster on my boat with single (and small) battery and 30 amp alternator.
The 1200W inverter would work for about 2 minutes before low battery alarm would come (I used it with engine running, so 30 amp alternator was charging) and after about additional 7 minutes, the inverter would shut off, but most of the time the food was hot by then, so this did not bother me much.
On boat cooling was good, so it will be different in camper, but I think my set was quite extreme?
The 6V golf-cart batteries proved themselves to be the best bang for a dollar, so I would go for it.
From listed items - hairdryer will be the biggest power draw. Once you do small test with it, you know where you stand.

2oldman wrote:

jdcellarmod wrote:
I'm planning on having 2-6 volt batteries with a 300 amp hour rating. ... I do not have room for 4-6 volt batteries...I'm not opposed to using 12 volt batteries.

Your 6v batteries are rated *each* at 300ah? Most I've ever seen is around 220.

6V L16 is even larger at 445.

For the OP... some get by on 200/300 amp hours and run a microwave but it will be marginal. Might get an alarm if the batteries are cold in the morning and a bit low from running the furnace all night.
Give it a go if that is all that fit. Worst case get a Panasonic inverter microwave where it actually heats at a lower power setting as selected instead of just cycling the megatron on and off.

I have 4 GC2s at 450 aH total and a 2000 watt MSW inverter and the microwave is iffy. I don't even try the hair dryer at 13 amps (AC) continuous.

2oldman wrote:

jdcellarmod wrote:
I'm planning on having 2-6 volt batteries with a 300 amp hour rating. ... I do not have room for 4-6 volt batteries...I'm not opposed to using 12 volt batteries.

Your 6v batteries are rated *each* at 300ah? Most I've ever seen is around 220.

Some here believe that 12v batteries are better for high-amp inverter applications. Perhaps some big 12s would be better.

2-6v batteries will be a struggle with a microwave.

For a 300ah rating each would have be 300ah. Connected in series the amperage doesn't double just the voltage.

If a 6v battery was rated at 300ah, 2 in series would make a 12v 300 ah battery. Conventional wisdom is to discharge only to 50% for better cycle life so in the end you would have a 12v 150ah usable amp hour capacity

Discharging at a .3C rate would be about 1200 watts which should be ok with a battery bank that size.

jplante4 wrote:
I have 4 GC2s at 450 aH total and a 2000 watt MSW inverter and the microwave is iffy. I don't even try the hair dryer at 13 amps (AC) continuous.

Are you sure you aren't adding the Ah capacities to arrive at that? Std. Trojan T-105 batteries are 225Ah each. Connecting them in series would give you a 12v 225Ah battery. Or do you have an L16 sized battery?

If you are new to RVing then consider an alternate power source. If you only camp once per year then no biggie, batteries will die of old age before you can consume them, but using batteries to power up heaters, hair driers, ovens or other high power appliances will cost you a lot in batteries eventually.

btw, discharge to 50% is not going from 12 volts down to 6 or 7, check the charts. Down to 11 volts is a dead dead battery and past 50% discharge.

Inverters are dangerous in that they will run down your batteries quick. Batteries only have so many cycles of charge/discharge before they are no longer able to be charged back. GC batteries are superior to Marine Rv batteries and can take more cycles, but all will succumb to cycling to death.


From more of a full-timer or part-timer RVer standpoint:
A small 2,000 watt generator is little less than double the price of the two batteries, but should last forever. You just put gas into it.
By comparison, If you charge your batteries off your alternator then you are still putting gas into having available power it just goes un-noticed.

Solar can keep the batteries topped off, but will not provide enough power to run 2,000 watts (unless you have 2,000 watts of panels up there pointed directly into the sun). Solar recharges batteries, and assuming you use a little power here and a little there then 200 watts (not 2,000) solar can keep up, but if you use more than the panel is supplying (maybe 150 watts from a 200 watt panel) then u are still cycling the battery from charge to some level of discharge so using up the battery lifespan.

jplante4 wrote:
I have 4 GC2s . . . and a 2000 watt MSW inverter and the microwave is iffy. I don't even try the hair dryer at 13 amps (AC) continuous.

Something's wrong. A couple of voltage/current checks should quickly narrow the problem down to bad/discharged batteries, a bad connection, use of too small of cables from batteries to inverter, and/or a defective inverter.

FWIW, I've seen 4 GC2's power an HE Coleman-Mach 13.5k BTU a/c using a low frequency 2000w PSW Aims inverter. The inverter was connected to the batteries using 2 ft. long 4/0 cables.

jplante4 wrote:
I have 4 GC2s at 450 aH total and a 2000 watt MSW inverter and the microwave is iffy. I don't even try the hair dryer at 13 amps (AC) continuous.

We have the same set up except a PSW inverter. Run a 1200w Micro and 950w hair dryer with ease( but not at the same time).

Dave