LVD on AGM batteries?

[sheriff1]

Installing new Fullriver DC220-6 agm batteries and trying to figure out where to set the low voltage disconnect on the Xantrex freedom 1800 inverter. I appears about 40-50% discharge is maximum optimal according to their chart. Their charts are a bit confusing to me as to what voltage that would be.
Also, Fullrivers recommenced charging rates of 14.7 and 13.6 more closely match the flooded settings on the Xantrex. Thoughts?
Thanks!

[pteck]

Congratulations on some nice batteries. Good planning on installing an LVD to protect your investment.

My opinion, but I would set the LVD cut-off much lower than your anticipated capacity use. It should be there to protect the batts in a worst case, rather than artificially limit usable capacity. It's not everyday that one will tap full reserves, but it will be that day, in the cold, over a long night with furnace, that you don't exactly want the batts to cut out. Cold batteries show lower voltages, even if they aren't necessarily at deep DoDs. Something like 80% DoD which is ~11.7V.

What are the flooded voltage settings for the Xantrax? AGMs don't handle high voltages well. So even if the flooded settings are closer, if they are higher than the recommended voltages, I would avoid using that setting.

[sheriff1]

At this point I’m looking for a cutoff voltage for the inverter.

[pteck]

Is this a setting on the inverter itself or the LVD?

At high c-rate draws, the battery voltage will sag. A high cutoff could prematurely shut things down.

[sheriff1]

This would be a setting on the inverter to drop the AC outlets it is providing power to. Low draw items such as TV.

[pteck]

I would stagger the inverter to have a higher cutoff than the LVD.

I'm assuming your inverter loads are discretionary?

It's a balance. You don't want the inverter cutoff so high that it stops the party prematurely. Yet you want to leave some capacity that your critical loads still have reserve before the LVD cuts off.

You invested in great batteries for their capacity, reserve, and durability. IMO, there's no need to baby them. Yet agree that you want to protect them.

My opinion:
Inverter cutoff: 12.0
LVD cutoff: 11.7

I'd be comfortable setting them even .1V lower for each.

If you're conservative, you could go .1V higher for each.

[NoResults]

Sheriff1 you mention you mention a DC-220. I can only find a DC-224-6? Also since the 27 has such a high hitch weight well these still be ok on the tongue?


Dave

[sheriff1]