I Think I Just Bought Way Too Much Battery

[4gnomad]

Hi guys, I'm hoping I'm wrong and someone will point something out to me that I haven't considered. I just purchased 2 L-16 batteries from some off-brand (that is supposedly US Battery underneath it all) that cost me $810. They're 6V, 400AH, which, I thought, was going to be awesome for boondocking. I bought them, the seller ordered them and delivered them, and in the meantime I looked up the 'right' way to charge the bank.

From what I can tell from the spec sheet the "charge characteristic curve" (which is here: http://www.vision-batt.com/site/product_files/EVL16-400A-AM.pdf) has the charging current at .25CA. I think that means that these 400AH batteries want to be charged at 100A, which is a TON of amps to be pushing for my little class B RoadTrek (in fact, I think it's a 30A electrical system so I can't). The most I can reasonably expect to push is 33A, and that's with an install of 4 100W 12V solar panels on the roof.

So my question is, if this pair wants 100A and I'm only able to push 33A (max, not including management/wiring losses), and I going to sulfate these things like crazy really quickly? FWIW they're AGM, which I think tolerate lower charging currents a bit better, but I think it's still not a great situation.

Any thoughts or clarifications on what I'm getting wrong here are really appreciated. Or, if I'm understanding the situation correctly, confirmation of that. I'm thinking I need to off-load these brand new L16s and get a more modest 12V bank right now.

[4gnomad]

I think there is a standalone converter directly connected to the battery and I can hook shore power to it, so I can upgrade that whole set of wiring to push the 100A without worrying about the wiring through the whole rig. In terms of where the batteries are they're AGM and I have them in a closet (close to the ventilated compartment the existing marine battery sits in). I was thinking that with a controller + temp monitor I should be fine.

Trying to respond to the other comments but the post is failing for some reason.

[GordonThree]

Ed_Gee wrote:

GordonThree wrote:
Back of the napkin so to speak;

30 amps at 120vac is 3,600 watts... 3600 watts at 12v is 300 amps. You'll have no problem running a 100amp converter off your 30a electrical system.

Depending on efficiency you'll need 12-15 amps at 120vac.

3000 amp dead-short discharge on those bad boy batteries, make sure you use a CLASS T fuse, not a wimpy ANL or dc circuit breaker.

I doubt his class B has proper DC wiring to carry such high current, even if he does upgrade to a 100A charger. And I am wondering where two L-16 batteries can be safely mounted in such a comparatively small rig.

You raise several valid points. New batteries are not a "drop in" replacement for existing / old batteries. OP will require significant upgrades to several facets of the DC system.

[Ed_Gee]

GordonThree wrote:
Back of the napkin so to speak;

30 amps at 120vac is 3,600 watts... 3600 watts at 12v is 300 amps. You'll have no problem running a 100amp converter off your 30a electrical system.

Depending on efficiency you'll need 12-15 amps at 120vac.

3000 amp dead-short discharge on those bad boy batteries, make sure you use a CLASS T fuse, not a wimpy ANL or dc circuit breaker.

I doubt his class B has proper DC wiring to carry such high current, even if he does upgrade to a 100A charger. And I am wondering where two L-16 batteries can be safely mounted in such a comparatively small rig.

[GordonThree]

Back of the napkin so to speak;

30 amps at 120vac is 3,600 watts... 3600 watts at 12v is 300 amps. You'll have no problem running a 100amp converter off your 30a electrical system.

Depending on efficiency you'll need 12-15 amps at 120vac.

3000 amp dead-short discharge on those bad boy batteries, make sure you use a CLASS T fuse, not a wimpy ANL or dc circuit breaker.

[2oldman]

That's a whopping amount of battery, and a lot of weight for such a small rig.

I don't think you'll sulfate them as long as they stay reasonably charged. My 640ahs of 12v AGMs can handle much more than my solar or charger can pump into them, but they're still fine. Just takes longer. My max charge rate is around 50v x 17a= 900w.

You say 33a charging.. that means you have a 33x13 ~ 400w charger? That might be a bit thin.

They will be awesome for boondocking.. until you have to recharge them!

[pianotuna]

What make and model of converter is in your RV?

http://www.vision-batt.com/site/product_files/EVL16-400A-AM.pdf