Anybody run Lithium battery bank with solar

Could get 2 or 3 -- 200AmpHR Deka 4D AGM batteries
They weigh in at approx 135# each, I have one and it is mated too a pair of 6v AGMs that are series for 12v, giving me an AGM bank of just over 400 AmpHrs , can't recall if it's 410 or 425 total, I consider the system to be 400, if I use 100 Ahrs, then battery SOC is actually slightly above the stated 75% on the monitor,
Even with the heater on, most mornings the meter is above 70% SOC, unless there was a all night TV/computer streaming binge, I don't like going down to 50% or less, I try keep the battery use to 30% or less of capacity, with a complete recharge each cycle
I have gotten as much as 5 years of use, from a set of batteries, that are used everyday of full-time RV living, around 1800 cycles total
This set is only a few months old, as I purchased them this summer

2oldman wrote:
48v 100ah li pack, big inverter, 800ah solar, victron monitor.

Don't you mean 800 watts of solar panels
800AmpHrs of solar at 50+ volts to change that 48v Lipo bank, would be exceedingly large, I think impossible to mount on an RV ,
What would it take to generated 40,000 watt Hours of solar electricity (800*50+)

BFL13 wrote:
You need 200AH a day and have two 225AH AGMs. I will guess that they are 6 volt so your bank is 225AH.

Now that BFL13 mentions it, this seems "odd".

12V AGM batteries are "typically" 100Ah-120Ah each. Two would give you a total of about 225Ah, not the stated 2 TIMES 225Ah !

6V AGM golf cart batteries do exist. Not common and they are $$$ !

CA Traveler wrote:

The panel wattage seems to be adequate, the batteries are up to 12.6 by afternoon, however the battery voltage is about 11.9 in the mornings after a night with 2 cpap machines running.

Battery voltage should rise to 14V+ for bulk charging and then taper down to absorb on the way to 13.4V for float. Up to 12.6V is way low for a full charge.

Experience is a fantastic teacher. Recommend you buy 2 more AGMs, a battery moniter I suggested in your other thread and learn. Then you'll have a better base of knowledge for upgrades. Start with your battery specs - what are the recommended charging voltages?

The 12.6 I mentioned is what the zamp monitor shows once the sun goes behind mountain and the charging is done for the day. When the sun is up and hitting the panels, it shows 14+ on a good afternoon, usually about 13.4+.

You need 200AH a day and have two 225AH AGMs. I will guess that they are 6 volt so your bank is 225AH. You can use half of that for "usable", so what you need is two more of those 6s so you can use 225 a day and recharge. Solar won't do any of that on an overcast day, so you have to be able to do it with no solar--especially with cpap in the picture.

It doesn't matter if they are Li or not, you need way more AH of a battery bank. And now you need to recharge that 200AH daily. Not likely to get that all done every day, if ever what with clouds etc. so the usual drill is generator and charger for most of it in say two hours of gen time, then solar to do the rest all day after the gen is shut down.

Doing that 200 from 50% SOC in two hours would be say a 100 amp charger running from a 3000w generator, to get say 150 done and then you need your solar to do another 50 or else leave the gen on for another two hours (amps now tapering, so gen time stretches out)

If those are 225AH 12s then they must be those monster 8Ds and you then already have enough bank. You still need to recharge what you used though.

Li is not going to change any of that, just cost you a ton of money. (Unless you believe in the "usable AH " smoke and mirrors where they try to say one 100AH Li is the same as two 100AH Flooded for usable AH--there is some advantage there, but not near double )

You also need an ammeter to be sure your AGMs are fully recharged--amps must taper to 0.5a/100AH of bank with voltage at 14.4 till you get to there. I bet you don't do that and now your AGMs are undercharged and sulphated (hope I am wrong!)

Sorry to be a party-pooper! Ignore what does not apply.

If possible, run your CPAP on 12V (most models have a 12v power supply available).

Switch to an MPPT charge controller. Make sure you buy one that supports flooded, AGM and LiOn. 12.6V does not sound "fully charged" to me !

Hello Q,

To answer your question; I am currently at Quartzsite running on 1000amps 12v Lifepo4, 1900watts solar with all Victron controllers and inverter/chargers. This is my third coach with similar systems and this set-up is the sweetest yet, but…

I’m not sure you need to jump to lithium to meet your goals.

Lots of good questions and points brought up so far. So just to be clear you have (2)-225amp 12v AGM’s, which would be group 8d’s weighing roughly 140#’s ea. or (2)-225amp 6v AGM’s, which would weigh roughly 70#’s ea.?

If you have the 12v’s then I don’t see how they could be fully charged, at a very rough 25amps/hr peak charge as it would take 10’ish plus hours of full sun to replenish the 250 amps, indicated by the 11.9v reading in the morning.

I am guessing you have the 6v’s for a total of 225amps@12v and you are burning roughly a 125amps by morning if the batteries were 100% at the end of the day. Again I think the amount of solar you currently have will not allow for a full charge.

I wonder if you just need to add more solar to achieve a full charge and maybe that will be enough to get thru the night with a few extra amps left over in the morning.

If you’d like to talk lithium-PM me with your #.

The panel wattage seems to be adequate, the batteries are up to 12.6 by afternoon, however the battery voltage is about 11.9 in the mornings after a night with 2 cpap machines running.

Battery voltage should rise to 14V+ for bulk charging and then taper down to absorb on the way to 13.4V for float. Up to 12.6V is way low for a full charge.

Experience is a fantastic teacher. Recommend you buy 2 more AGMs, a battery moniter I suggested in your other thread and learn. Then you'll have a better base of knowledge for upgrades. Start with your battery specs - what are the recommended charging voltages?

175 to 225 ah daily use? That's a bunch of power.

We have the Grand Design factory 300 watt solar option (300 watt panel, Jaboni charge controller, Magnum Dimensions inverter) and two Battle Born 100AH LiFePO4 batteries. We ordered it this way to run the residential refrigerator on long travel days or when the power goes out for a while at a park (as it did here at Aberdeen Proving Ground this summer when a contractor ran over the park transformer with a Bobcat). The system does a good job at what we wanted it for. It will also run the furnace and lights overnight and recharge the batteries the next day... providing there is some sun. If you want to run a BUNCH of stuff and seriously boondock, I think you would want more wattage and amp-hours. We've had zero issues with any of the equipment, though.

Rob

Just as a reference I'm using 175-225ah daily during late fall, winter, early spring with shorter daylight hours. I don't tilt the panels and can go long periods between full charges before either solar catches up or need a hold boost with the generator.

See sig for size of system.