2 12 volt batterys or 2 6 volt

Of course with a deep cycle 12V AGM battery you can get the best of both battery worlds:

- Power for small loads over a a long time-period into lower states of charge without damage to the battery, and

- power for short term large loads without much voltage sag due to the low internal resistance of AGM batteries.

Nirvana ... at a price.

pianotuna wrote:

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The marine batteries are intended for large loads where as the deep cycles are not. That helps with voltage drop and the inverter.
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Ah, geez now it all makes sense.

The V drop has nothing to do with whether it's a 6V or 12V battery, but whether its a "marine" versus true deep-cycle like the GC batts (6 or 12V).

The "marine" types are designed to handle large loads like starting a motor with less V drop than a true deep-cycle. So of course they will have less V drop with the heavy loads of an inverter. And guess all "marine" batts are 12V, but true deep-cycles can be 6 or 12V (like GC2 or GC12s).

And I now see why SoundGuy prefers a Group 31 batt over the T-1275 (a true deep-cycle) I was suggesting.

Really appreciate the clarification.

That high amp-hour 12V SCS220 Trojan sure looks like the one to use .... if you want to go the flooded route. A couple of them would give you 260 amp hours contained in about two Group 31 cases. Nice.

SoundGuy wrote:
With my G27 now 8 yrs old it's probably time to upgrade, which I intend to do with a pair of 12 volt G31s which together will allow the inverter to even more easily meet these demands I occasionally ask of it with less voltage sag under heavy load. For myself and others who don't dry camp often and won't often deeply discharge any battery on a regular basis a pair of 12s is therefore IMO the better choice than a pair of 6 volt GC-2s.

brulaz wrote:
Last I looked, Total Battery in Barrie,ON was selling Trojan 1275's (12V, 150AH, ~GC12) for CAN$241.

Think I would prefer that or similar deep-cycle GolfCart/Sweeper 12V over the 31 and 27 12Vs, most of which are more "Marine" multi-use bats.

East Penn here in Canada distributes the conventional flooded deep cycle Group 31 Deka DC31DT (105 AH 20 hr rate) under the RV Care dealer brand name and because "I know a guy" my cost will be ~ $125 Cdn apiece so that's probably what I'll go with when the time comes. If I were paying full retail for a 12 volt Trojan I'd probably go with an SCS200 or SCS225. :)

Brulaz,

The marine batteries are intended for large loads where as the deep cycles are not. That helps with voltage drop and the inverter. Either would work--but cost per amp-hour would be one of my choice criteria.

What I did was go to used Telecom batteries. They are AGM (no more laying the snow to check levels). They were the best bang for the buck. It is too soon for me to recommend them as they have not been in service long at all--but so far so good.

SoundGuy wrote:

...
With my G27 now 8 yrs old it's probably time to upgrade, which I intend to do with a pair of 12 volt G31s which together will allow the inverter to even more easily meet these demands I occasionally ask of it with less voltage sag under heavy load. For myself and others who don't dry camp often and won't often deeply discharge any battery on a regular basis a pair of 12s is therefore IMO the better choice than a pair of 6 volt GC-2s.

Last I looked, Total Battery in Barrie,ON was selling Trojan 1275's (12V, 150AH, ~GC12) for CAN$241.

Think I would prefer that or similar deep-cycle GolfCart/Sweeper 12V over the 31 and 27 12Vs, most of which are more "Marine" multi-use bats.

rjxj wrote:
What will a 1000 watt inverter run? Not a hair dryer, toaster, micro.
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brulaz wrote:
Wondering about that. Our new hair dryer has a low power setting that uses ~670W. Haven't tried it yet with our 1000W PSW inverter, but hopefully it works without blowing that expensive 75A DC fuse.

Good, true deep cycle, flooded 12Vs might be the best replacements as our inverter usage seems to be increasing. Might even get a 2000W inverter some day!

Contrary to Huntingdog's snide & childish assertions that this is "all about me" my view is that more and more RVrs, myself and yourself included, are increasingly interested in using an inverter to power a few appliances those times campsite power may not be available, for whatever reason. Certainly the budget priced Canadian Tire 1000 watt Motomaster branded version I have is hardly "lab quality" but it nevertheless does the job even though to date I've been powering it with just a single Interstate G27. With the battery reasonably charged this combination will successfully power a 2-slice toaster (measured 696 watts), a coffee machine (measured 505 watts), or my wife's hair dryer (measured 311 watts on LOW) without excessive voltage sag, causing the inverter to alarm. With my G27 now 8 yrs old it's probably time to upgrade, which I intend to do with a pair of 12 volt G31s which together will allow the inverter to even more easily meet these demands I occasionally ask of it with less voltage sag under heavy load. For myself and others who don't dry camp often and won't often deeply discharge any battery on a regular basis a pair of 12s is therefore IMO the better choice than a pair of 6 volt GC-2s.

rjxj wrote:
Very close in price. My problem with 12's is that my tray is too narrow. Four 6's (430ah)sit side by side but only two 12's (310ah) end to end. Mine had group 24's in it from the original owner and one of them was still working after 14 years!!! That's HALF a CAREER!!! I think it was an interstate.
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If you compare, or example, Trojan's # cycles vs depth of discharge charts, their T105s (6V GC2 FLA) should last ~1700 cycles when discharged down to 50%, while their T1275s (12V GC12 FLA) only last ~1200 cycles. Of course both will last a lot longer when discharged to less than 50%.

So if full-time boondocking, T105 GC2s might make more sense economically in the long run. But we don't boondock anywhere near 365 days per year, and even then only occasionally hit 50% discharge (especially if I double the battery bank size). So this isn't a concern to us.


Of more interest is V sag under heavy inverter load (especially if we move up to a 2000W inverter). If the 12V GC12 FLAs really do have less voltage sag under load for the same battery bank Ah, and there is no cost or weight penalty, then they are very attractive.

Apparently the the FLA GC12s will have less V sag under load, but I'm not sure how much relative to the same Ah of FLA GC2s, or why there is any difference? Hmmmmmmm?

Hi,

Also known as a surplus acid AGM. That means it can be seriously damaged by discharging too low. I believe they more or less ought to be treated as flooded batteries but carefully charging below the gassing voltage.

I'm using 4 of a slightly different rating to give me 566 amp-hours @ 20 hour rate (6.95 amps per jar). So far they have not objected to any load I've put on them. I will know more in a year. Charging rate is limited to c/5 or about 28 amps per jar.

I see that yours are listed as 145 amp-hours at the 8 hour rate (18 amps)

The 1 hour rate for mine is 95.5 amps. That suggests to me that I could do 4 times that (382 amps) for 15 minutes.

NinerBikes wrote:
Big Battery, AGM, low dough, big bang for the buck. YMMV, it won't run a big inverter, make electric coffee or run a hair dryer, but if recharged immediately, daily, and treated properly, not neglected, it will last a long, long, long time. Perfect for dry camping, forget it if you are a pedestal queen. This is a battery that likes long, slow distance discharges, forget the surges or blasts of instant high amperage energy discharge that NiMH and Li Ion batteries are so pricey and good at.

Teleccom AGM 12V 145 AH.

Should you care to learn how to properly dishcharge and recharge /maintain your RV batteries properly, here's a good read on the subject.

Care, use and recharging your RV battery by the book.

Very close in price. My problem with 12's is that my tray is too narrow. Four 6's (430ah)sit side by side but only two 12's (310ah) end to end. Mine had group 24's in it from the original owner and one of them was still working after 14 years!!! That's HALF a CAREER!!! I think it was an interstate.

155 AH $200.00


150 AH for $195


215 AH for $170 + extra core @ $15.00=$185

So what's better or easier on the life of these three hypothetical battery packs? Pulling off of 430 ah or pulling off of 315 ah? or 300ah of trojan?

I go down 100 ah or so per night so 2 Trojan 12's would cut my weight and still probably deliver what I need? Could I realistically pull 100 off the 150 available in the Trojan. I know there is no way I could pull 200 of my 430 gc 2 right now. It would probably be down around 11.5???? I have been down 120 and showed 11.9 or so. Guess I need to experiment.

I could shed 75 pounds