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jetske avatar image
jetske asked

How do i keep my batteries in good shape during cold?

Hi everyone,

i have zero understanding of all this and after reading manuals and posts on this forum i am even more confused so i really would appreciate (and in bad need of) some help, since i am having my van up north and i don't want the cold to kill my batteries.

I bought a converted van with the following:

  • solar panels connected to LifePO4
  • Victron Blue smart IP65 charger
  • Victron MPPT 100/30

and of course the van battery (Ford Transit) connected to the other system
It works all totally fine in good weather, however we are having minus temperatures almost the entire winter where i am right now. I have read that you shouldn't try to charge a LiOn when temperatures are below 0°C.
I am trying to understand how cold weather will affect the system, and am afraid i am already torturing it..
The car battery should be charged by the LifePO4. The latter is at 100%, but when i started the van yesterday it took me 2 turns to get it running, so feels like the car battery is not being fed by the other one?

I would like to plug him in on the regular electrical network so both batteries are being charged, but then that's bad for my LifePO4.. and i don't know if i can only charge the car battery and not the LiFePO4?
so i guess the only solution is try to get the temperature inside above 0°C, but will they overcharge?
To keep the temperature above 0°C i thought about buying these car heaters, kupevarmer in Norwegian i figured out. Or is it too risky to keep them constantly running?

I really have no clue about what would be damaging the battery or not, and since i'd rather not kill it i would really appreciate some advice..
Because i don't dare to unplug the LifePO4 (I will never get it installed correctly again), and i would like it if the car battery gets charged by the LifePO4...
But as a said, this is all new to me.. (is BMS short for battery management system? there's so much vocabulary i have never heard of)
This is the liFePO4 battery, the other picture of my victron equipment didn't want to load..

Thanks for your advice, it is really appreciated!!


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5 Answers
snoobler avatar image
snoobler answered ·

Charging LFP below freezing permanently damages it. Many battery BMS's have low-temp charging protection that simply refuse to allow the battery to accept charge when below freezing (or somewhere between 2-3°C).


If you are charging the battery below freezing, you are damaging it.


A smart battery sense (SBS) in a bluetooth network with your MPPT can be used to prevent charging from the MPPT. I don't know if it works the same way with the IP65.

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kevgermany avatar image
kevgermany answered ·

If the kupevarmer is the sort made by webasto etc. that runs off the car fuel, it won't help. They use a lot of electricity to run the fans and pumps, and a lot of fuel.

There are quite a few threads on maintaining battery temperature here. Most are a combination of insulation and electrical heating.

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jetske avatar image jetske commented ·
Hi there

thanks for your help. I do have a webasto system but didn't intend on using that one since it indeeds runs on fuel and won't do the trick long term..
I thought to buy one that works on the 12V or electrical net (found some at Biltema), but then i guess these are made to run for shorter amounts of time, and not days in a row?
Would it be sufficient to heat the cabin where my LifePO4 is located (it's in the back under the bed and behind a wooden panel) once a week while he's connected to the electrical net, for like 10 hours?

Thanks so much!

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kevgermany avatar image kevgermany ♦♦ jetske commented ·

That will require really thick insulation. I'd guess not practical.

I guess you're going to have to insulate thoroughly, install electric heating pads with thermostatic control and set that as low as practical. Whether or not the batteries have enough capacity for that off a weekly charge, you're going to have to monitor.

Suggest at least 100mm rigid foam such as cellotex, and heating pads at battery voltage.




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KämpingVan Conversions OÜ avatar image
KämpingVan Conversions OÜ answered ·

Check if you battery has a built in BMS(battery management system) via the bluetooth. It should have it and the BMS should not allow the battery to be charged/discharged when the temperature is below -0°C. The main reason of the BMS is to keep the battery healthy and not allowed to "be tortured" in exactly the case you mentioned.

As for keeping the temp above 0°C, some batteries have built in heating pads. Otherwise sufficient insulation and some kind of electrical heating should do the trick.



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jetske avatar image jetske commented ·
Hi KampingVan

Thank you so much for your answer! As a girl who has 0 knowledge of all this, i am learning a lot :) I already put some insulation around the battery but its in a tricky corner so i cannot insulate every part of it.. That's why i think putting an electrical heater in there will be better. But do you know if it is sufficient to run this heater like once a week for an entire day while i am connected to the electrical net? or isn't that going to help and should it be permanently connected?
The issue is not the LiFePO4 because that one is fully charged (for now), it's moreover the car battery that i want to keep loaded as well. So i start the car on a regular basis right now, but usually running the car also charges the LiFePO4, however the BMS will prevent charging then?
thanks so much again! and have a great day

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Ivar Eisma avatar image
Ivar Eisma answered ·

Question: Is the IP65 wired to the LifePO batttery permanently? Depending on how this is wired, you might not be charging the car starter battery with the IP65 at all. The simpelest solution for you would be: get another set of leads with eyelets and plug for the IP65 and regulary charge the car starter battery with it. Simply unplug if you want to charge the lifePO, you can leave the leads connected to the starter battery. 271-574-20170712115034.png

Chaging the car starter battery about once a month should be good enough if you give it a full charge. Even driving it for 30 minutes would likely do the trick.

You LifePO not giving power when cold or charging is less of a problem I think? Once you are using the van, it will warm up and you will be able to use it and charge it. A Lifepo will keep its charge a long time when not used.


Can you post a picture of the IP65 and where the red and black wires go. And of the Mppt and where the wires of that go? I have a van as well with solar and two batteries, so I've build a few of these smaller systems. they are not complicated once you figure them out.


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jetske avatar image jetske commented ·

Thank you so much Ivar, this was already really helpful! :)

So cool that you have built your own van!
"They are not complicated once you figure them out", loved that! Hope it will be true and i finally will figure it out..

The previous owners told me that, if i plug the van onto the electrical net (on the outside of the van) i should also plug in the IP65. Usually that one is not in use, unless i plug it in in the grey box on its left side saying 220V. If it is plugged in both batteries will be charging, they said..
I do recognize the equipment of your photo and i have a similar one. I think maybe it's best to make a small movie about the entire installation? There are so many wires in that corner of my van. Today it worked to upload the picture i wanted to add yesterday. (Don't mind the green circle, it's an old picture.)
electr.jpeg

I will try making a short video tomorrow during daylight and upload it up here.
Many many thanks, it really means a lot to me

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Ivar Eisma avatar image
Ivar Eisma answered ·

Zoek even op Vreemd punt nl mijn email adres op dan proberen we het via whatsapp op te lossen met een videotje ofzo...

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