[Wyocalm]

Finally got the van. Planning to have it built out as camper -- I'm not a DIY-type.
Planning on Lithium house. Live where it gets below 0 degrees F often (already 32 in morning), and planning to keep the van on my driveway.
I have read about lithium issues in the cold.
Here's what I am thinking:
Bring lithiums in the house for winter -- just use van as daily driver (have engine block heater).
If I do want to use as camper in winter, put lithium back in (already warm from the house) and go.
While camping, winter or otherwise, the lithiums should stay warm as they are inside the van -- kept reasonably warm for us humans.
Possible hitch: We decide to stay in a motel for a night on route to warmer climes, but motel parking lot goes to 0 degrees F.
Maybe shut down any draw on lithiums overnight, and don't return draw until camper is warmed up in the morning -- I suppose monitoring battery temp.

Let me know if am on a right track as an end user.
Many thanks!

 

[rf17830]

For your usage case you might consider purchasing a battery box from Hein and install some lead acid batteries. The battery box makes it easy to install the 150 lbs of house batteries under the van. Then you can charge the batteries in cold temperatures. You could also install a second alternator to keep the house batteries charged. Sometimes the easy approach is best.

 

[AzB]

Cold doesn't really hurt lithium unless you charge them. Static, or discharging is fine. Charging a lithium battery below 32 degrees can damage it permanently.

I have lithium batteries on my bikes and frequently ride in temps below freezing. (Maybe not as cold as you, but far more exposed) The only issue I have is that they need to be warm for enough power to start a motor. But turning on the lights for 20 seconds or so seems to warm the batteries fine after that.

Just get a battery with a good bms. That will prevent accidental charging, discharging, or extreme temp issues. Probably no need to bring them into the house.

 

[kenryan]

What brand batteries do you have? What is their spec for cold weather storage? Battleborns spec for cold weather storage is -10F but I don't think that is a magical number where at -11F suddenly the batteries implode. Battleborns spec for discharging is -4F.

The bigger problem is charging them when cold, and most now have protection against that built into the BMS.

For the motel problem, you could let your heater run. Or better, plug into the motel's power and run an electric heater.

 

[AzB]

I should clarify that lithium batteries can be discharged down to -20 degrees.

Also, there are some lithium ion batteries that can be charged at extreme cold temps... I think Relion makes some.

No need to take them into the house for the winter. Just install a disconnect switch and turn them off if you're paranoid.

 

[GaryBIS]

Hi,
You might consider the new SOK battery that has a built in heater. The BMS prevents any charging of the battery until the heater gets the temperature above 32F for safe charging.
The LiFePo4 batteries are OK to discharge at cold temps, its only charging at temps lower than 32F that will damage the battery, and the heater makes sure the battery is above 32F before allowing charging.

The SOK batteries get very good reviews and the prices are very competitive. One main reason I went with them is that the they are serviceable - you can open the case with ordinary tools and the BMS or a cell can be replaced. For me it seems likely that the BMS is going to prove the weak point as LiFePo4 batteries age, and if the BMS is not replaceable, you are out of luck when it fails.

I did some temperature measurments on my batteries, which are located in a battery compartment. When looking at the outside ambient temp and the van interior temp, the battery compartment temp (in my case) ran about half way between the ambient and van interior temp - so, don't just look at the van interior temp - the battery compartment may be quite a bit colder. It might be worthwhile to have a small fan circulate warm air from the van interior into the battery compartment.

Gary

 

[andyl]

This summer I mounted a lithium hub heated battery in a hein box. It's late Sept and only gotten below freezing a few times. Should have good cold-weather experience to share in few months.

 

[Wyocalm]

..No need to take them into the house for the winter. Just install a disconnect switch and turn them off if you're paranoid.

Ah, a reason I wanted feedback was to see if I was being, uh, overly concerned.

 

[Wyocalm]

Thanks all for the feedback -- trying to understand the issue and possible approaches.
I'll think about this more and discuss with the builder.

 

[Sams stock van]

There are a few batteries out there with heating built in. Some may pull power from the battery for heat. Others use the incoming charger current to preheat the battery before the BMS allows the battery to charge.

SOK, Battle Born and Relion are three that come to mind. Good luck.

 

[Checkswrecks]

I should clarify that lithium batteries can be discharged down to -20 degrees.

Also, there are some lithium ion batteries that can be charged at extreme cold temps... I think Relion makes some.

No need to take them into the house for the winter. Just install a disconnect switch and turn them off if you're paranoid.

As AzB wrote, the issue is with charging below freezing, which inside the van is rarely an issue.

If you do the discharge trick to warm them, one warning is to wait after using the headlights or whatever the load is. The heat will be in the core but it takes a while to saturate and un-freeze the layers or windings closer to the surface.

 

[TCADMAN]

I had planned on moving to the PNW, but stuff happens. Anyway I want to design this low temp protection into my system. I want to set it up so I don’t ever need to worry about this. I will program the mppt not to charge below 35 deg F. I plan the same for the inverter charger for when on shore power. I will use Victron equipment for this purpose. I know it is expensive but It was the system I found that I was sure would do this. It was equipment I could understand and program to do this myself. I also want a system that ties everything together with something like Victron connect so I could check status from the house. I will have a remote Bluetooth temperature monitor directly attached to one of my batteries. My concern is the solar panels charging the batteries in low winter temps when the van is setting parked. My batteries do not have low temp charge protection in the BMS.
If I planned to be in temperatures this low regularly. I would build an insulated battery box inside the van. The top would come off for when I am in the van with the diesel heater running. I would place the remote Bluetooth battery temperature monitor inside the box directly on the battery. I would add enclosure heat pads to that box with a thermostat set to come on at 35 deg F. With enough solar power to keep the charge up on the batteries with the battery box heater load going. The batteries could stay warm, charged and ready for whatever you need to do. I really don’t see any reason to ever remove the batteries because of low temp. If you are far enough north to run out of sunshine. You could power this battery heater system and an engine block heater with shore power. If you can’t keep the battery warm, don’t worry about it they will be ok.

 

[Van Gogh]

Finally got the van. Planning to have it built out as camper -- I'm not a DIY-type.
Planning on Lithium house. Live where it gets below 0 degrees F often (already 32 in morning), and planning to keep the van on my driveway.
I have read about lithium issues in the cold.
Here's what I am thinking:
Bring lithiums in the house for winter -- just use van as daily driver (have engine block heater).
If I do want to use as camper in winter, put lithium back in (already warm from the house) and go.
While camping, winter or otherwise, the lithiums should stay warm as they are inside the van -- kept reasonably warm for us humans.
Possible hitch: We decide to stay in a motel for a night on route to warmer climes, but motel parking lot goes to 0 degrees F.
Maybe shut down any draw on lithiums overnight, and don't return draw until camper is warmed up in the morning -- I suppose monitoring battery temp.

Let me know if am on a right track as an end user.
Many thanks!

Depending on the size of your power system, if you have a little capacity to spare, inexpensive tank heaters coupled with a timer relay and/or a temperature relay could fix the problem. Tank heaters actually have built-in temp sensors, but I found them to have a lot of variance. They're probably fine for a smaller battery bank, especially if you can get one large tank pad to fit under all of your batteries. It's only when buying 3-4 pads that you may see some notable variance between each pad.

My system will keep the batteries above 40F using my MPPT's temp sensor and an inexpensive 12V timer relay that drives another inexpensive slightly higher-amp 12V automotive power relay (tons of them on Amazon to choose from). It's almost certainly more complex than what you need, but the basic idea of a timer relay (on late evening, off mid-morning) and a tank heat pad might work for you. More about it in the links below:

Original pad design:

7.2kW Altrntr, 42SEER Minisplit, 1.1kW Solar, 20.5kWh...

Might be too late but if you're still considering reworking the system, I went w/ a fuel vent barb for my breather hose. https://www.amazon.com/gp/product/B001443JFO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 Interesting solution. So far so good with my screen gasket after a long...

www.fordtransitusaforum.com

Timer and temp relays:

7.2kW Altrntr, 42SEER Minisplit, 1.1kW Solar, 20.5kWh...

Holy smokes. You got it done. You're right: it's not attractive; but the energy usage is super impressive! I hope you find a solution to the noise issue. Nice work, @Van Gogh !

www.fordtransitusaforum.com

Solenoid removal:

7.2kW Altrntr, 42SEER Minisplit, 1.1kW Solar, 20.5kWh...

Holy smokes. You got it done. You're right: it's not attractive; but the energy usage is super impressive! I hope you find a solution to the noise issue. Nice work, @Van Gogh !

www.fordtransitusaforum.com

Cheers.

 

[andyl]

@TCADMAN and @Van Gogh - I too collected heat pads, temp sensors and blue tooth modules. Was ready to build, then I read lithium hub's heated battery docs. Their battery comes with internal bluetooth & internal heater controlled by thermostat and powered by charge current.

 

[Van Gogh]

@TCADMAN and @Van Gogh - I too collected heat pads, temp sensors and blue tooth modules. Was ready to build, then I read lithium hub's heated battery docs. Their battery comes with internal bluetooth & internal heater controlled by thermostat and powered by charge current.

At least at the time I bought my batteries (2020) I paid $0.24 per watt-hour, whereas these run $0.75 per watt-hour, so a 300% premium. That kind of premium, and even higher premiums from other vendors I looked at (e.g. lithionics) was the reason I went with a DIY heat system which only added $0.01 per watt-hour to my cost, so $0.25 total.

But you could argue there's a labor cost to a DIY system, and depending upon the size of the battery bank the savings might not be worth the time and effort. I was aiming for a really big system so the only way to make that cost effective was to avoid large premiums. Internal heat seems like a really high margIn money maker for battery vendors.

Cheers.

 

[andyl]

@Van Gogh many thanks for these numbers can you post a link to the battery vendor that you used?

 

[TCADMAN]

Andyl - I like you idea but my batteries, mppt and remote battery temp sensor are here now.
Van Gogh - like your ideas. I think if op is truly that far north that it is below freezing a lot of the time. The battery box with remote temperature at / on the battery would be worth thinking about. My mppt also has built in temperature sensing. But it would be ambient temp inside the mppt. How much heat would it take to warm up the mppt from a mat under the battery? How much heat does the mppt create on its own to possibly throw off the reading? I would not want to heat more space than needed using the mppt temperature sensor for this control. An insulated battery box would save energy keeping the battery above freezing. A remote temperature sensor may help in that situation. I like what you did with your system. But I would want to keep mine as simple as possible. Two separate systems, If temp is low thermostat turns on heat to battery. If battery temp is low, mppt does not charge. No relays required. If the heat fails it has no effect on charging the battery. That is up to the mppt.
There are many ways to do this effectively. As long as you understand what you did, and you can maintain and repair it. That will protect your equipment.

 

[Van Gogh]

Andyl - I like you idea but my batteries, mppt and remote battery temp sensor are here now.
Van Gogh - like your ideas. I think if op is truly that far north that it is below freezing a lot of the time. The battery box with remote temperature at / on the battery would be worth thinking about. My mppt also has built in temperature sensing. But it would be ambient temp inside the mppt. How much heat would it take to warm up the mppt from a mat under the battery? How much heat does the mppt create on its own to possibly throw off the reading? I would not want to heat more space than needed using the mppt temperature sensor for this control. An insulated battery box would save energy keeping the battery above freezing. A remote temperature sensor may help in that situation. I like what you did with your system. But I would want to keep mine as simple as possible. Two separate systems, If temp is low thermostat turns on heat to battery. If battery temp is low, mppt does not charge. No relays required. If the heat fails it has no effect on charging the battery. That is up to the mppt.
There are many ways to do this effectively. As long as you understand what you did, and you can maintain and repair it. That will protect your equipment.

My mppt has a remote temp sensor. I wouldn't use one that had an internal temp sensor, and can't imagine how that would even work unless the mppt was embedded in the battery or something.

While my mppt has some great features like ultra high efficiency for 48V systems with ~130Voc solar arrays, it unfortunately it doesn't have a programmable low battery temp cutoff. Instead they let you program a built-in relay with dozens of possible triggers, including low battery temp. But that means you have to use external relays to control things. Thankfully my system already had a Blue Sea MLSD as part of the pre-charge, so it wasn't much extra work to drive that with the mppt internal relay. So far it's never actually cutoff charging due to low temps because the heating system has always worked.

But again, the real issue was cost. I saved $12,500 doing it this way. Worth it.

Cheers.

 

[kenryan]

One possibility would be to put the batteries in an insulated box and run a 12 volt bulb directly off the batteries. A bulb such as used for a tail light bulb, which would be around 10 - 15 watts, seems appropriate. You would need to recharge the batteries periodically. The time between re-charges would depend upon the size of your battery bank.

 

[andyl]

12 volt bulb

I've done that before. There are also 12v heaters at different power levels.