Unattended, frozen environment battery recommendations

[posegate]

I need your recommendations.

I'm looking to install solar with 48v battery storage in northern Wisconsin. The scenario:

• This is an unattended, non-climate controlled building (occasional use cabin)
• Weather service data shows that more than 50% of the days have had a low temperature below 35F (2C) in the last 10 years.
• The closest grid-sourced power is 1000 feet away, so grid tie-in is not an option
• Prefer rack-mounted, contained system versus wiring multiple together

Are there battery systems that are designed for this sort of situation?

Thanks in advance for your recommendations. What additional information would be helpful?

 

[Supervstech]

I need your recommendations.

I'm looking to install solar with 48v battery storage in northern Wisconsin. The scenario:

• This is an unattended, non-climate controlled building (occasional use cabin)
• Weather service data shows that more than 50% of the days have had a low temperature below 35F (2C) in the last 10 years.
• The closest grid-sourced power is 1000 feet away, so grid tie-in is not an option
• Prefer rack-mounted, contained system versus wiring multiple together

Are there battery systems that are designed for this sort of situation?

Thanks in advance for your recommendations. What additional information would be helpful?

The weather there would dictate lead acid is safest. As long as it’s full charged, it tolerates low temps well.

Lithium would need heavy insulation, heating, and safety monitoring. Doable, but not recommended.

 

[Tecnodave]

In very low temperatures it is also very important to keep your batteries fully charged as the higher the specific gravity of a lead acid battery, the lower the temperature it will freeze at. A fully charged battery at 1.280 s.g. will not freeze at 70 below zero but a battery at 1.100 will be frozen solid at that temperature.

If you do manage to freeze a battery do not in any case attempt to charge it in that condition, It will be destroyed.

In Alaska we commonly used “Arctic batteries” which were specifically designed for the winters we had in Alaska.
These were designed and built by Alaska Husky battery in Fairbanks Alaska. These batteries had a very high specific gravity of 1.320 which had far better endurance in Arctic conditions.

The drawback of these batteries is that they would not survive summer under hood temperatures, they need to be kept under 45-50 deg. F.

When we changed from snow tires to street tires we also changed from winter batteries to summer batteries...

Contrary to popular belief, it does get rather toasty in Alaska in the summer, 109 deg. F has been recorded, remember we had very long days..

 

[posegate]

Thank you. Does that also mean that an all-in-one like the Titan is out of the question for my scenario?

 

[Tecnodave]

I have no idea just what an “ all in one” battery is. If that is a battery with a CCA “cold cranking amps” rating that is a poor choice for a solar system battery. Personally I use flooded lead acid large format batteries. L-16 case size 6 volt 426 a.h. rated at 20 hours These are used in traction vehicles such as the big floor sweepers used in big stores as well as dedicated solar batteries like my Rolls-Surette S-530 set which are now 20 years old and still at rated capacity.

The Interstate and U.S. Battery L-16’s are an excellent lower cost long life battery as well as 6 volt 225 a.h. golf cart GC-2 sized battery.

In any case, keep it charged up, even if that means a small solar panel that is only used when you are not there.

 

[Quattrohead]

Silicate Chemistry Low Temperature – Watts247 Wholesale

watts247.com

 

[posegate]

The Titan has a battery, generator, and inverter all-in-one package.
Link (not an affiliate)

 

[posegate]

I have no idea just what an “ all in one” battery is. If that is a battery with a CCA “cold cranking amps” rating that is a poor choice for a solar system battery. Personally I use flooded lead acid large format batteries. L-16 case size 6 volt 426 a.h. rated at 20 hours These are used in traction vehicles such as the big floor sweepers used in big stores as well as dedicated solar batteries like my Rolls-Surette S-530 set which are now 20 years old and still at rated capacity.

The Interstate and U.S. Battery L-16’s are an excellent lower cost long life battery as well as 6 volt 225 a.h. golf cart GC-2 sized battery.

In any case, keep it charged up, even if that means a small solar panel that is only used when you are not there.

If using lead acid batteries, does that mean the amp hours I get are half of what the battery rating is?

 

[upnorthandpersonal]

If using lead acid batteries, does that mean the amp hours I get are half of what the battery rating is?

Yes, you shouldn't discharge below 50% for long cycle life. Discharging lead acid to 0% will destroy it rather quickly.

By the way, if you don't use power while your batteries are on location, you can keep LiFePO4 in the cold. As long as you don't charge/discharge them, storing them at those temperatures is no problem. Research indicates it slows down calendar aging as well:

How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries –...

By: Rob Beckers You have just sold your first-born into slavery, remortgaged the house, and bought yourself a lithium-ion battery! Now you want to know how to take care of your precious new purchase: How to best charge lithium-iron batteries, how to discharge them, and how to get the maximum...

www.solacity.com

Quote:
"Storing batteries below freezing is fine, even at very low temperatures such as -40 Centigrade (that is the same in Fahrenheit), or even less! The electrolyte in LiFePO4 cells does not contain any water, so even when it freezes (which happens around -40 Centigrade, depending on the particular formulation) it does not expand, and does not damage the cells. Just let the battery warm up a bit before you start discharging it again, which is OK at -20 Centigrade and above. You will see an apparent loss of capacity when discharging at below-freezing temperatures that reverses when the battery gets above freezing, and there is a slightly accelerated effect on aging. Storing them at low temperatures is certainly much better than storage at high temperatures: Calendar aging slows down dramatically at low temperatures. Try to avoid storing them at 45 Centigrade and above, and try to avoid storing them completely full if possible (or nearly empty)."

 

[wiseacre]

What to suggest depends on how much power you require/use.

The titan would suffice for very light use - stated 2000w usable
with a 100w constant load the battery wouldn't last a day
The inverter is capable of 3000w - less than an hour use
While it would be convenient to use it does come at a premium price

another advantage is you can bring it home
but that can be said of a store bought LiFePo4 battery

IMO, buying separate components could provide more capacity at a lower price.
exactly what you need goes back to the first line
How many watts will you need, both, max at a time and total daily usage.

 

[posegate]

So looking at this from the idea of buying separate components, I want to make the following assumptions on electrical requirements:

While occupied:

• Mini-fridge (100 watts?)
• A few LED lights
• Charging electronic devices (phone chargers, maybe a laptop)
• Charge batteries for overnight backup
• Occasional power tool usage
• Powering the inverter generator
• 24v or 48v batteries

While unoccupied:

• Small heater to keep battery storage area warmer than 35F
• Possible USB video camera
• Powering the inverter generator
• 24v or 48v batteries

We thought we could use a wood-burning stove and propane space heaters for heat while occupied. Eventually, we may add a well and pump and need to keep pipes from freezing. That's not going to be the case at the onset.

With this in mind, what should I plan on for

• Solar panel wattage/voltage?
• Battery amp hours
• Inverter wattage?

 

[upnorthandpersonal]

need to keep pipes from freezing.

Make it so you can drain the pipes instead.

 

[posegate]

Make it so you can drain the pipes instead.

That's a good idea!

 

[wiseacre]

Knowing a fairly accurate estimate of wattage needed/used (both max load and daily total) is required to plan out any system

My heated battery box (4 x 2 x 2 ft) is not ideal because the seed starting heating pad I use is on 24/7 but it does keep the box above 45F with -12F outside. Colder temps on the way but I'm confident the heat pad will suffice. I'd have better efficiency if I bothered to tape the foam board seams
My setup works for me but other/better heating pad solutions can be found on the forum

Extended unattended use combined with extended no sun days calls for a fairly large battery bank to keep things warm and running.
On the plus side, you'll have some nice capacity for when you are there.

Add my heating pad load (21w) and my inverter idle draw (25w) and I'm using 1100w per day.
with my 9600Wh battery bank (two - 24v, 200Ah batteries) I can go 8 days of no sun and keep the batteries warm.

 

[Horsefly]

Make it so you can drain the pipes instead.

Yeah, that's what we do at our cabin in the Rockies. No one is there from about mid-Nov until sometime late April to late May (depending on the snow season). I live far enough away I don't get stuck with the winterizing, but I know all the pipes are drained, and I think they put a small amount of glycol in the drain traps to prevent them from freezing too.

 

[posegate]

Yeah, that's what we do at our cabin in the Rockies. No one is there from about mid-Nov until sometime late April to late May (depending on the snow season). I live far enough away I don't get stuck with the winterizing, but I know all the pipes are drained, and I think they put a small amount of glycol in the drain traps to prevent them from freezing too.

We will be occupying during cold months, but intermittently.

 

[Horsefly]

We will be occupying during cold months, but intermittently.

That makes it tough. If it is a dry winter, we've been able to go up and visit on day trips, but no water, and no flushing toilets (time to reacquaint ourselves to the 60 year old outhouse).

It hasn't been mentioned but: Is there a way to keep your batteries in a kind of sub-basement, below grade? If you could it would work much like a root cellar, keeping the batteries above freezing through the winter and cool during the summer.

I really wish we could have put in a sub-basement with an insulated ceiling in our cabin. I'm certain it would keep the LFP happy all winter.

 

[posegate]

with my 9600Wh battery bank (two - 24v, 200Ah batteries) I can go 8 days of no sun and keep the batteries warm.

I see there are 24v, 200Ah batteries for around $1100 (SOK) to $1500 (EG4) each. Now I get messed up on the math. If I use two of them, am I getting 24v at 400Ah or 48v at 200Ah? Which is better?

 

[AE4KR]

Do you know the depth of the frostline at the cabin? Perhaps burying a battery box for LiFePo4 batteries would be reliable enough to keep them above freezing. It certainly would be elegant from an efficiency standpoint.

 

[posegate]

Do you know the depth of the frostline at the cabin? Perhaps burying a battery box for LiFePo4 batteries would be reliable enough to keep them above freezing. It certainly would be elegant from an efficiency standpoint.

By code, the frost line is 48". It could be possible to bury the lines and the box just outside the foundation. Perhaps within a root cellar (yet to be built).