Anything new in batteries for solar

[howardwheeler]

I have four 31 size lead acid batteries. They are heavy and you only get to used half their capacity. Is anything come up recently that could be a reasonable replacement--probably lithium?

[reed_cundiff]

2oldman wrote:

reed cundiff wrote:
LFP batteries are not that expensive when compared to the rest of a rig. They probably only make sense if one primarily boondocks as we do.

They make sense for me in that I can run my air at rest stops without things overheating, or run it an hour before I stop. And, should park power be low voltage, run air with solar supplement. That, and I save about 400lb. And yes, I boondock about 90% of the time.

The weight savings (400 pounds for you and 600 for us) and ability to run the air conditioner in the evening for an hour or more is well worth the cost.
Reed and Elaine

[N8GS]

On another subject; did any of you get to see the total eclipse. I made the trip from MI to WY for it and it was well worth the 2466 miles. I left on Friday and was back home Wednesday morning. Got a bunch of nice pictures including the Diamond Ring. Yes the lithium batteries worked very well.

[N8GS]

BFL13 wrote:
N8GS, thanks for the detailed reply. It is not obvious to me what went wrong. Now you have the new batteries with a different charging routine, at least you don't need to figure out exactly what went wrong with the old ones.

Thats right I am moving on. I have only had the new batteries in for a few months but I can say that everything works better with the higher voltage. Our last little camping trip was just a 3 day weekend w/ DW's family. We were at a camp site with power but I didn't plug in, got the batteries down to 80% DOD and ran the microwave to see how it would do. Battery voltage dropped to 12.68 volts after 3 minutes with a 124 amp load, inverter was very happy with that (I asked it and it replied in a very low voice "Its good"). The real test will come in January when we are camped in Quartzsite, AZ. Last year we were there for 53 days, this year we might get to stay there a little longer.

[BFL13]

N8GS, thanks for the detailed reply. It is not obvious to me what went wrong. Now you have the new batteries with a different charging routine, at least you don't need to figure out exactly what went wrong with the old ones.

[2oldman]

reed cundiff wrote:
LFP batteries are not that expensive when compared to the rest of a rig. They probably only make sense if one primarily boondocks as we do.

They make sense for me in that I can run my air at rest stops without things overheating, or run it an hour before I stop. And, should park power be low voltage, run air with solar supplement. That, and I save about 400lb. And yes, I boondock about 90% of the time.

[reed_cundiff]

LFP batteries are not that expensive when compared to the rest of a rig. They probably only make sense if one primarily boondocks as we do. Not running a generator at dispersed sites means that wildlife and birds wander in. We have only utlized line power on 5th wheel once in last several years. We had to leave 5th wheel in an RV park for 5 days and plugged in to make sure fridge ran. We can run fridge 24 hours a day (absorption cooling, not Stirling cycle so it is an energy hog) if we know it will be good sun the next day but we start with a 4 kW-hr deficiency.
Reed and Elaine

[reed_cundiff]

LFP batteries are not that expensive when compared to the rest of a rig. They probably only make sense if one primarily boondocks as we do. Not running a generator at dispersed sites means that wildlife and birds wander in. We have only utlized line power on 5th wheel once in last several years. We had to leave 5th wheel in an RV park for 5 days and plugged in to make sure fridge ran. We can run fridge 24 hours a day (absorption cooling, not Stirling cycle so it is an energy hog) if we know it will be good sun the next day but we start with a 4 kW-hr deficiency.
Reed and Elaine

[2oldman]

reed cundiff wrote:
$23,000 for this battery. Wow!

Yeah, wow! Here I thought Li was expensive! And the lightest one only weights 3,000 pounds!

The more RV suitable one, at its lightest, is 70lb.

[N8GS]

OldSmokey wrote:

BFL13 wrote:

N8GS wrote:

OldSmokey wrote:

N8GS wrote:
Just got more info from Battle Born. There batteries are designed for and the BMS permits charging down to 25 deg F. Below that they will not charge but can be discharged without damage.
Saw an post today on Facebook for a Chinese 12 volt, 300 Ah LiFePO4 battery in 8D size for about $1300. The prices are coming down. I have no idea what the quality of that battery might be.
I like my Battle Born batteries, no more issues with low voltage going to the inverter.

nothing really new for the solar market.. the FLA is still the best bang for your buck..

oh, and low voltage issues are mainly due to incorrect battery sizing..:B

That wasn't the case for me. I had 600 Ah of Trojan batteries. Installed in Jan 2012, in Jan of this year I could not use the microwave, the voltage drop was just too great. When I got home, (we had been in Quartzsite, AZ) I found that 2 of the batteries were shot and the other 2 were not performing very well. Switching to LFP batteries has saved me 215# and when running the microwave the voltage doesn't drop below 12.6 volts even when the batteries are 80% depleted. When running the microwave the inverter is drawing 124 amps. I am disappointed in how the Trojan batteries performed, they should have lasted a lot longer than 5 years considering the care that I took to keep them happy.

As you know, it is the number of cycles, and how deep the cycles, that matters- not years of service. However, given that you know that, it is curious they failed. Anything to do with how tall they are? ISTR Mena was always on about that for making sure he got his stirred up often enough.

I am using a set of two 6v Exide 135s from 2011 in parallel with two used T-1275s in parallel, also from 2011--but they did two years in golf cars first then I got them in 2013) - with about 435 AH total at last test for that, and get about 0.6v drop when using the microwave that pulls about 120 amps on the MSW inverter.

It was more like 1.0 volt drop, but I found a loose wire connection and also fattened a wire a bit to get it down to that now 0.6. The batts are not that new at six hard working years, but so far so good.

Anyway, I am interested in what went wrong more than what was stated.
N8GS is no fool, so anything he has to say about all this is worth paying attention to.

I wonder how often the batteries were equalized ?

one of the biggest problems with off grid/RV solar is equalization.
a proper cycle will take 12 to 24 hours. no solar system can do this without generator help.

on a remote solar design many moons ago I overheard the customer complaining why they needed a generator on site, this was supposed to be a solar powered installation ! LOL

First off I want to say thank you for the complement BFL13.
During the summer we only take the FW out 3 or 4 times for a long weekend, so the batteries get a good solid recharge between uses. I usually gave then an equalization charge in the late fall before going to AZ in Janurary. We boondock for 4 to 8 weeks then hit a couple campgrounds as we do some site seeing on the way home. When we get back home I set out the panels and let the batteries recharge for a week or two then equalize them for a few hours. Hydrometer readings always looked acceptable and I like to do individual cell voltage test to look for anything out of the norm.
This spring when we got home I ordered the LFP batteries and pulled the Trojans out. Took each of the Trojans and put then on a CC/CV 30 amp power supply, 2 of them were reading 6.something and would not accept a charge at all. The other 2 took a charge but their capacity is definitely not what it should be. I figure I put about 60 to 100 partial cycles on them each year. and only 1 or 2 cycles would be to 50% the rest were only 20 to 25% DOD.
For the equalization I followed the guidelines on the Trojan web site.

With my new batteries the battery monitor controls the charging. I have the Xantrex Link lite monitor and it has a set of contacts that can be set to operate at whatever SOC I choose. These contacts control a relay that turns the charger on. I have been tinkering with this and currently have it set to start charging at 50% SOC and stop at 95% SOC or 14.4 volts which ever comes first.

[reed_cundiff]

$23,000 for this battery. Wow!

[MrWizard]

I'll have to try and remember the 'outback nano carbon fiber AGM'
Something to think about as an upgrade to the next RV

[reed_cundiff]

We are full timers with solar/LFP battery banks in both systems: 34' fifth wheel and 19' (2002) Roadtrek.

5h wheel has 9+ kW-hrs LFP battery bank at 48 V (nominal). Our son designed and fabricated system 4.5 years ago and there is no noticeable degradation. He (with me standing about) trialed it with air conditioner (2+ kW), water heater, and microwave operating simultaneously through the 4.5 kW PSWI. We were drawing over 4 kW (0.5 C). We have run a/c for 4.5 hours as combination of solar/battery suite. We generally are outside on hot days and just run a/c for half an hour to drop cabin temperature below 90 F. 12 V fans are sufficient after that.

The Roadtrek has about 4.5 kW-hr of LFP (two Manzanita Micros batteries as opposed to four in 5th wheel) and it is sufficient to run the smaller a/c for two hours.

So we do a minor discharge/charge cycle each day since we primarily boondock even if we are in an RV park. Read that Liberty Coaches had done full cycles of their batteries over 3000 times. I mentioned this on a thread and a Liberty Coach ($1.8 M and up) said they had done far more cycles since that 3000 cycle article had been posted.

We do try to keep the charge to 50% SOC and higher but have gone below at times.

Our solar has allowed us to use line power less than 10% of our stops. We did use line power for a bit in Yucatan and San Cristobal de las Casas since we did have several days of rain (Roadtrek). We have run into a lot of "dirty power" in USA as well as Mexico so we always run line power through battery charger to the LFP banks.

Do not go to Solar Panel Talk for LFP information. Two of the primary posters are absolute Luddites.

Reed and Elaine

[brulaz]

pianotuna wrote:
That is why LI is so attractive even at the premium price.

However the Firefly, and Outback batteries can handle undercharging for 30 cycles and still come back to full capacity. They don't have a price advantage over LI, and of course they are heavy as the dickens. But they can be charged in extreme cold without dying.
...

That Outback Nano-Carbon AGM 100A 12V is US$255 at the Alt-E store you linked to earlier. That's similar in price to other quality AGMs I've seen. And apparently it's not as fussy as other AGMs about PSOC (like LandYacht's NorthStar), and can do 2500 cycles down to 50% or thereabouts. So if I were buying an AGM, that's what I go for.

More cycles than 2000, heck, more cycles than 1000, I don't really care about. We're not full-timers. I figure 100 deep discharges per year max. So 1000 is more than enough. The batteries will age out, get stolen, or I'll be dead, or new technology will make them obsolete in ten years.


On the other hand, I do like those BattleBorn LiFePO4 because their BMS seems to be very proactive in protecting the cells. With the low temp charging cutoff (assuming 7 below freezing is good enough), you could possibly leave them out through the winter. They would stop charging when it got too cold, and prolly stop feeding loads later on when the battery V dropped too low. But when it warmed up, they could go back into business, or at least that's the way their literature reads. Haven't seen any other LiFePO4 BMS with such thorough protections built in.

[pianotuna]

That is why LI is so attractive even at the premium price.

However the Firefly, and Outback batteries can handle undercharging for 30 cycles and still come back to full capacity. They don't have a price advantage over LI, and of course they are heavy as the dickens. But they can be charged in extreme cold without dying.

I solved the charging problem with twin banks that could be switched so one bank was in use and the other was charging.

2oldman wrote:
Li handles undercharging just fine. I rarely equalized my acids because it's so darn difficult to get a full charge first.