this is why

time2roll wrote:
I don't think I could survive at that temperature unless I had continuous utility power to heat both the battery and propane cylinders. In which case LFP would be fine.

If power went out, I think I could still make the night to roll out in the morning.

I can't imagine SiO2 retains all its rated energy at that level either.

When do we get a trip report? ;)

it doesnt, at -20C it only has 80% of its original capacity, 60% at -30C, and at -40C/F it only has 40%.

https://azimuthsolar.ca/wp-content/uploads/2019/01/Lead-Crystal-Chart.png

Steve

FWC wrote:
Firstly it doesn't seem like the OP is planning on going camping at -40C.

I believe he lives in that right now.

valhalla360 wrote:

pianotuna wrote:
valhalla360,

Exactly so. I'll be glad when I can get to B.C. to buy 7 or 8 SiO2 batteries.

I'm still not seeing the point of your original post.
- If you need a big battery bank for other purposes but will have access to shore power during extreme cold, there are simple solutions to make lithium work.
- If you don't need a big battery bank and will always have shore power, just get the standard single battery and save yourself a lot of money.

Maybe it would be better if you lay out your use case.

Agreed. This has been described for years, but doesn't make sense to me either. Firstly it doesn't seem like the OP is planning on going camping at -40C. But if he is, it would be very interesting to see what sort of camper could survive this. A mass market RV certainly wouldn't be useable for a whole variety of reasons, lack of insulation, insufficient heat, moisture management, tanks etc.

Secondly, I assume if he is planing on using the camper, he has some sort of auxiliary power and heat, shore power, a generator and a furnace with which to warm his camper. If you are actually going to inhabit the camper, humans, water and food are more temperature sensitive than any sort of batteries.

valhalla360,

My use is rural business trips of two weeks, often in cold weather. I may have a single 15 amp circuit, but not always.

Since I'm in a class C, the propane tank is fixed. There is no access to refill in small towns. Therefore I wish to run off 120 power for all energy needs including space heating.

I will not sleep with a generator running. Hence the need for a large capacity battery bank.

I have room for 7 group 29 batteries. If it will fit, I'll replace the starter battery with an SiO2 as well. That ought to leave me close to 7 kwh of usable storage.

Bionic Man wrote:
Sounds like a good reason to move south. I have no desire to live anywhere where those temps are common.

x2 . . I have no idea why anyone would endure that kind of cold.

Having lived and worked in similar temps as pianotuna,I wouldn't own lithium either..To many things to go wrong that could permanently damage the lifepo4 batteries...I don't miss those days..


Jayco

pianotuna wrote:
valhalla360,

Exactly so. I'll be glad when I can get to B.C. to buy 7 or 8 SiO2 batteries.

I'm still not seeing the point of your original post.
- If you need a big battery bank for other purposes but will have access to shore power during extreme cold, there are simple solutions to make lithium work.
- If you don't need a big battery bank and will always have shore power, just get the standard single battery and save yourself a lot of money.

Maybe it would be better if you lay out your use case.

valhalla360,

Exactly so. I'll be glad when I can get to B.C. to buy 7 or 8 SiO2 batteries.

3 tons wrote:

SDcampowneroperator wrote:

LittleBill wrote:
this has been solved. they now sell bms's with heating options. When I make the switch they will be used in 0f unprotected temps.

Wont the heating option then use battery power?

No, the heating option is powered by the battery’s charging source.

3 tons

If there is a constant charging source, no need to mess about with a large battery bank...which is the primary reason to install lithium.

Of course, if there is a charging source, a small heating blanket negates the temperature issue of cold.

3 tons wrote:

SDcampowneroperator wrote:

LittleBill wrote:
this has been solved. they now sell bms's with heating options. When I make the switch they will be used in 0f unprotected temps.

Wont the heating option then use battery power?

No, the heating option is powered by the battery’s charging source.

3 tons

s/b able to wire it either way and still have low voltage stop the heating to protect the battery. Otherwise need to keep warm to keep the solar controller active. If low voltage turns everything off it waits in storage mode for a power source.