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-   -   1000 Amp Hours and 800 Watts of Solar (https://www.airforums.com/forums/f382/1000-amp-hours-and-800-watts-of-solar-202949.html)

jackearnest 11-15-2019 05:47 PM

1000 Amp Hours and 800 Watts of Solar
 
4 Attachment(s)
For Boondocking, I have installed 1000 amp hours of lithium in my 30' 2016 International, with 800 watts of solar. And I just upgraded my computer to one that I can see every cell remotely...

This is due to me living in Aspen CO...and it can get as low as -20 here occasionally...and my batteries cannot go below -4 before experiencing damage. In addition I cannot charge them below about 32 degrees.

So I am keeping them warm with 2 external 100# propane tanks...about 40 degrees. Since the snow covers the panels I have to have it plugged in at the storage place I use. But I can only draw about 5amps since I share the circuit with their heat tape and Christmas lights.

I am using a cradle point Internet router with ATT and Verizon and a 25 foot flagpole with an omni directional antenna.

I am potentially planning on figuring out a solution where i can just keep the batteries warm like a Tesla. Does anyone have experience with this?

pcskier 11-15-2019 06:18 PM

What batteries do you have? My research indicated that Li Ion batteries can be charged up, then disconnected from any loads and will be fine well into subzero weather, and stored without needing to charge, keep warm, or have any concerns. Curious to hear what you've heard from your battery manufacturer.


There was some discussion recently on this post.
https://www.airforums.com/forums/f449...es-202064.html

AdvToaster 11-15-2019 07:38 PM

Why not just wrap heat tape around the batteries with a thermostat on it?

jackearnest 11-15-2019 08:55 PM

Quote:

Originally Posted by pcskier (Post 2308320)
What batteries do you have? My research indicated that Li Ion batteries can be charged up, then disconnected from any loads and will be fine well into subzero weather, and stored without needing to charge, keep warm, or have any concerns. Curious to hear what you've heard from your battery manufacturer.


There was some discussion recently on this post.
https://www.airforums.com/forums/f449...es-202064.html

https://www.elitepowersolutions.com/...-ion-batteries

they are elite power systems...says operating temperature -4F...or -20C...and the BMS will not let them charge below 32....

RChrisClark 11-16-2019 10:09 AM

Airstream in Las Vegas has an employee named Jake that makes 12volt battery wraps. Mine are currently being installed. We will be spending our 2nd winter in Breckenridge,

uncle_bob 11-16-2019 10:30 AM

Hi

I think the key qualifier on the -4F or -20C limit is "operating". If there is no current coming out of the batteries ( = disconnect them) then you are in "storage" rather than operation. Storage limits often get quoted as -40F or -40C.

At what point does operation cross over to storage? Is one nano amp of current operation? One would guess not. Leakage internal to the cells is higher than that. Indeed until you get into the hundreds of microamps range you still are sorta / kinda the same rates as self discharge.

Bob

guskmg 11-16-2019 12:51 PM

I have the same amount of solar/lithiums. I keep a remote temperature monitor on my batteries installed under the bed. They are always 10 degrees warmer than the inside of the trailer. If you keep the heat on the lowest setting (40 degrees) they could always be in use. However, I believe AM Solar recommends using an aquarium heating pad under the batts to keep them warm below freezing. Does your battery cut of temp feature shut them off when you reach the lower temperature of -4. It may. Ask their tech support about that.
guskmg

bradt 11-16-2019 08:57 PM

I'm interested to know which cradle point router you are using and whose antenna. I would be using verizon.
Thanks,
Brad

wulfraat 11-16-2019 11:16 PM

1000 Amp Hours and 800 Watts of Solar
 
Are you living in the trailer or storing it for the winter?

If storing for the winter....Discharge to 40-60% SOC, disconnect the batts from any draws, let them sit dormant, you are fine.

I have 600ah of victron lithium here in Colorado and luthium cells can be *stored* dormant / no discharge currents to -45C without issue.

It will never get that cold inside your trailer in aspen for any length of time.

If you are living in it, 40 degrees is a chilling domicile! Turn up the heat [emoji4]

wulfraat 11-16-2019 11:31 PM

Quote:

Originally Posted by jackearnest;
they are elite power systems...says operating temperature -4F...or -20C...and the BMS will not let them charge below 32....


Operating temp and storage temp are two different things.... :)

uncle_bob 11-17-2019 06:31 AM

Hi

I don't know of any BMS setups that will halt *discharge* at low temperatures. If there is one out there that does, it would be good to know about it.

Even sitting in the battery box outside the trailer, I have never seen my batteries get to within 5 degrees of the weather station numbers for a low temperature. They always seem to be warmer. If you are looking at -4F as a cutoff, the weather station likely would have to be at -10F. If the batteries are inside the trailer, the offset would be larger (as noted above) .....

I suspect the same thing happens sitting in enclosed storage. The temperature outside gets to -10, but inside the "barn" it may not get near that low.

Yes this all *assumes* a brief overnight low with the daytime temperatures running much higher. If it's -10 all day long and the low is -10 as well, none of this matters. It's all going to get to -10.

Bob

jackearnest 11-18-2019 12:35 PM

BMS system
 
1 Attachment(s)
My BMS will stop charging, and disconnect the batteries from the rest of the coach (not the internet and the bms because it is on the inside side of the shunt)...then there is a low voltage cuttoff that kills everything when they get to the dangerous level of causing damage due to discharging. You can see the blue thing at the bottom that is the low voltage cuttoff. I just really like to know everythings ok and monitor it which means 40+ degrees all the time. Its at a self storage place outdoors, and they were kind enough to give me 120v power...but i dont want to get kicked off of it so I have my magnum inverter set to not exceed 5amps (they have christmas lighting and gutter heat tape on the same circuit)..they dont give power to anyone else as far as I know...and when the solar gets covered in snow I either have to have some shore power or I have to go and wipe off the solar panels everytime it snows.

Anyway...only problem I have now is not to run out of propane (power is covered)...and I do that with 2 external 100# tanks. I am going to goto MB sturgis and build an external 2 tank failover rig to help with that too..what I am really concerned about is a -20 degree few days here and I run out of propane...then I loose my monitoring and potentially have the cells go below -4...

PS I didnt do this myself this was a setup from Marv at PrecisionRV. I did do the cradlepoint internet and the gps and cellular antennas.

Jay

wulfraat 11-18-2019 07:36 PM

You are going to plow through propane keeping that trailer at 40 degrees. After you burn through the first 200lbs of propane in the month of December and pay the bill you may decide to simply disconnect the batteries altogether and let them hibernate :)

Ive got a similar setup (and investment) with mobile internet, remote monitoring capability, etc and I most definitely choose to let the batteries rest disconnected for the winter months. Ill pop in every month or so and check in but aside from that no need to watch via internet portal, etc...

Just my $0.02 :)

uncle_bob 11-19-2019 07:22 AM

Hi

If you are trying to run propane all winter long, call up the local dealers and get one to put in a residential tank at your storage location. They can then service it with a truck, just like the other homes in the area. Way easier to deal with !!!

Temperature wise, without multiple monitoring points, you really don't know how cold this or that part of the trailer is getting. It might be worth putting a bit of effort into that side of things. The alternative would be to bump the temperature up a bit.

Bob

jackearnest 11-20-2019 09:00 AM

multiple temperature points
 
2 Attachment(s)
So the new computer version of the elite power BMS...shows me the low and high temperature of all 20 cells remotely on my android device. In addition I have a samsung smarthings hub installed and one of those motion sensor/temperature sensor ($25) in the battery space underneath the front couch.

Seems like my options are
1. find storage place insude
2. find storage place with 15amp shore connection and place small heater facing battery department.
3. find storage place with 15 amp service and take the front vent from the furnace that comes out at the front door (i have a rear bedroom 30 ft international) and route a duct into a connection on the front couch where the batteries are...
4. store in warmer place like palisade co.

Main issue on the packs is that there is not much circulation around the batteries under the front couch, although the magnum 3000 watt inverter does do some. The low circulation means that the temperature in the coach is 45-50 and the lowest battery can still dip down to 32...sometimes...so adding the heater or circulation ductwork when I store it is the issue.

I do like the idea of keeping monitoring turned on all the time...it can get -19F here for a few days...afraid I am going to damage them at this temp if it gets there.

In the future, best thing would be able to build the batteries in a "removable" wooden tray (prob have to make two trays so the wood would not be too heavy to carry (300+lbs).

Two photos attached of the remote BMS (non bluetooth) screen on the android phone for the BMS.

Jay

uncle_bob 11-20-2019 09:21 AM

Hi

If you simply disconnect the batteries, they should be fine to -40F. You loose the monitoring when you do that. You also loose the monitoring if you pull the batteries out of the trailer. A Blue Sea 7000 series latching solenoid cutoff will let you put the disconnect wherever you wish and run it from a pushbutton in a convenient location.

Bob

pcskier 11-20-2019 07:04 PM

Quote:

Originally Posted by jackearnest (Post 2309493)
Seems like my options are
1. find storage place insude
2. find storage place with 15amp shore connection and place small heater facing battery department.
3. find storage place with 15 amp service and take the front vent from the furnace that comes out at the front door (i have a rear bedroom 30 ft international) and route a duct into a connection on the front couch where the batteries are...
4. store in warmer place like palisade co.

Or the fifth option mentioned several times on this thread: disconnect them and let them be. Perhaps a call or email to an engineer at your battery manufacturer would confirm if (or if not) your batteries are safe to -40F, and the -4F is indeed the 'operating' low temp, i.e. when batteries are 'in use.' If that's the case, you seem to be going through a lot of thought gyrations that really are not necessary.

If they confirm that your specific batteries are different than other brands, and indeed should not be stored below -4F even if disconnected...they I'll shut my trap and eat a big slice of humble pie :-) I do appreciate your concern given the cost (I don't want to even know!) of those batteries!

ghaynes755 11-21-2019 03:54 PM

For Jackearnest’s Elite Batteries, same ones that I have in my trailer, here is what Rick Sutter at EPS sent me. This is only for EPS cells. Please get exact specs for the cells that you run and don’t accept general statements as the truth for your setup.

-4F (-20C) is the lowest temperature you can discharge or store batteries in. Anything lower will freeze the electrolyte and damage the battery.

On Wed, Nov 20, 2019, 6:19 PM Squarespace <no-reply@squarespace.info> wrote:

Name: Gary Haynes
Email: classic@reflectionsimaging.com
Message: I understand that the Elite batteries should not be discharged/supply power below -4 F. What is the negative temperature where batteries in storage, not being used and circuits turned off, will sustain damage from sustained negative temperatures?
(Sent via Elite Power Solutions)


Not sure what humble pie looks like ;)


wulfraat 11-21-2019 06:48 PM

I guess Im glad I own victron :) storage to -45C no problemo.


https://www.victronenergy.com/upload...s-Smart-EN.pdf

uncle_bob 11-22-2019 07:32 AM

Hi

Virtually all of these batteries have the same basic cells buried deep inside of them. Making cells is *very* equipment intensive. There are only a handful of outfits set up to make them. There are a massive number of people reselling those basic cells. There also are a number of people turning those cells into useful stuff. If you want to see what sort of money / scale is involved in making cells, take a look at the Tesla battery plant out west.

Since the chemistry is pretty much same same and the cells likely came off the same line, it is unlikely that one outfit's batteries store ok to -40 and another's die at -4F. One would guess that some outfits are more conservative in what they will sign up for. There isn't a lot of field data on this yet.

Indeed some *have* put lithiums into very cold environments for multiple years. There has been no alarming feedback from those people (yet). Just how cold "very cold" is other than well below -4F, is unclear.

Lots of questions and not a lot of hard data ....

Bob


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