Best solution for low temperature cutoff?

[Phrench]

Buy lithium batteries with built in low temp protection, upgrade to charge controller with low temperature protection, or other?
I have my first pv system on my new travel trailer. I am upgrading from 190w to 380w, adding 200 ah of
lifepo4 batteries and upgrading the charge controller to a mppt, and adding a shunt/battery meter. I am about to purchase components to do this. I am in the north and worry about forgetting my expensive lithium batteries in the trailer when the temperatures drop. I would appreciate advice on whether I should:
a) spend an extra $150-$200 to get batteries with low-temp protection built in (ie. Chins smart 200ah)
b) i am upgrading the charge controller to mppt. I am considering a 30a epever. It looks like the AN series has low temperature protection after adding a sensor. Upgrade cost here seems to be only $20 or so and would allow for purchase of cheaper “dumb” lithium batteries (a couple of cheaper Chins 100ah)
c) something better that I don’t know about
I am a newbie, so please feel free to let me know if I am doing anything dumb. Planning to buy a 190w HQST panel (add to existing 190w GoPower in series), upgrading to a epever 30A mppt charge controller, buying 200ah of Chins lithium battery, and Victron shunt.
Thanks for your input

 

[Browneye]

Recently built a very similar system in size, with DIY pack, so the BMS has low-temp charge shut off.
For a pre-built pack I would get the low-temp sensor if you're in a sub-zero environment. And a way to heat them so they don't freeze.
Are you planning any other charging methods? Or just solar charging?

While I do like the Tracer controllers - I have two - I wouldn't want to solely rely on their settings for sub-freezing control.

I also have a shore-power/generator-power converter/charger, and a dc to dc charger from the chassis battery - in a motorhome.

Some more experts will come along for some more suggestions.

 

[JoMac]

I'm in the same boat as Phrench. I have the Renogy Rover 40a, and now realize it has no Low Temp protection. (The temp sensor doesn't work with Lithium.) If I go with the Sok 12v 10Ah LiFePO4 Battery with Bluetooth & Built in Heater, would that solve the problem? (I also built an insulated box to store it in. (I have a Rich Solar 200w panel. I haven't bought an inverter yet.)

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[Browneye]

What are you going to power with an inverter? 100Ah doesn’t go very far making 120VAC. A 100W appliance, like a chest freezer, might go for a day. A 200W panel might take a couple of days to recharge.

SOK seems to make a good product. If the ambient is going to see sub-freezing you’ll need something to terminate charging, or keep it warm. Heating pad is an option, something like this:

https://www.amazon.com/12V-Flexible-Polyimide-Heater-Plate/dp/B07P2RJDPL

 

[JoMac]

Right now I'm just using a few 20-50w items intermittently. I plan on adding another 100Ah battery and 200w panel next year. I hace a seedling mat for the battery box.