12v to 6v review?

Gdetrailer wrote:

ktmrfs wrote:


actually most 12V batteries have lower internal resistance than a comparable AH 6V because they have more and thinner plates per 2V cell than 6V. But the thinner cells and associated tradeoffs means lower cycle life and not likeing deep discharges.

But yes, using four 6 volt will give about 500AH capacity and suitability for reasonably high current draw. But four 12V in parallel will still give lower voltage drop due to lower internal resistance and load sharing amongst four batteries instead of two.

4 "12V" batteries will net you considerably less Ahr capacity when comparing similar square inches of space in comparable battery size.

For instance group 27 has foot print of one 6V GC2 and Ahr capacity of 80Ahr. Of that 80Ahr it is rated for only half of the capacity for the cycle life. Cycle life improves drastically if you only use 20% of the capacity.

GC2s cycle life are rated at 80% of the capacity, don't try that with group 27, you will degrade a group 27 very quickly if you try..

So, in reality, if you want max life, max draw with max capacity the GC2s are the better choice even with high current draw.

I don't know what folks are doing to bother an inverter with high current draw on GC2s, so far I have not had any issue. I know for a fact that my home fridge conversion does indeed spike 100A draw on the compressor startup surge. Even draining my GC2s down to 50% discharge I have never had any issue with my inverter low voltage alarm or shut down.

I do know this, I can easily go 24hrs without recharging my one pair of GC2s. In fact, I typically will travel 800 miles over two days, overnighting one night without power to get to my camping spot all without any commercial power or stopping for generator. As you know, vehicle charge lines provide very minimal charge support.

To get that kind of run time with group 27s I would need better than 4 of them, most likely 8 and then I would be replacing batteries every few yrs because I would be discharging very deeply..

So far the first set of GC2 batteries lasted me 9 yrs, could have gone 10, maybe 11 yrs but I did notice they didn't have as much capacity as they did when new and they were using twice the water as new.

You can continue using group24/27 in parallel, myself I am more than satisfied with the long, long battery life I am getting with GC2s in series..

I'll agree with GC2 for cycle life, ability to do hundreds of really deep discharges, and long life. And even 100A or so spikes in current draw from GC2's. That's why I like them.

where I had trouble with a pair of GC2's was running my panasonic true inverter variable output microwave for long periods (5-10 minutes) . it doesn't cycle between 0 and 100% but stays at a fixed %. On my 1000VA inverter with very short (18 inches) of 4/0 cable between the batteries and inverter it would run the microwave just fine at 50% input (90A 12V draw) as long as the battery bank was at 80% or more. much below that and it would shut down due to low input voltage after 30-60 seconds.

Keep current draw below 30A-40A or so and they perform wonderfully.

On one trailer I have a pair of GC2's running a small fridge on a MSW inverter. Like you mentioned current can spike, in my case in the 75A range, but then settles down to 15A or less. A pair of GC2's will do this all the way down to 50% SOC or less no problem.

I think BL13 and some others experienced the same thing at very high continous current draw (100A or so). I since switched to a bank of 4 GC2's, and no issues down to 50% SOC.

And I've run two sets of batteries on different trailers for 10 years on a bank of GC2, often averaging 60 days or so off grid so the batteries will last a decade if properly cared for.