Lithium LiFePo4 in the cold weather

[meza]

It was -4C inside my van this morning when I went out to turn on the diesel heater to warm things up for the school run!

I thought it would be prudent to isolate the leisure battery (LiFePo4 200ah) to prevent any charging from either the alternator or solar in this weather, as the specs for the battery warns to not charge it under 0C.

Anyone else done this or something different to manage the cold?

 

[drinfinity]

My Renogy DCDC 50 has a battery temp probe, so reduces/prevents charging at low temperatures.

 

[meza]

Good point. I've got the Renogy DCC30S which has the same. I should get the app open to check.

 

[TallPaul_S]

It was -4C inside my van this morning when I went out to turn on the diesel heater to warm things up for the school run!

I thought it would be prudent to isolate the leisure battery (LiFePo4 200ah) to prevent any charging from either the alternator or solar in this weather, as the specs for the battery warns to not charge it under 0C.

Anyone else done this or something different to manage the cold?

You need to have an automatic low temp cut off, either on the battery BMS or on the DC-DC and MPPT, as a bare minimum. And a heater inside the battery is an option too to allow for charging when it's below zero.

 

[Dellmassive]

Most modern lifepo4 have a cold charge protection built in...

What battery have you got?

 

[ginkster]

My battery (Fogstar) has a heater and BMS protection, however I’ve added switches to my DC-DC and solar panels to turn of charging when it’s not needed. I did this as I don’t want the battery charging every time I start the van or the sun comes out as that’s not great for lifepo4 unless you are draining it regularly. I don’t, as the van is only used for camping every couple of months or so.

My battery was at -2.5 degrees yesterday but no issues as I had my chargers off.

 

[TallPaul_S]

I've left my Fogstar to do it's thing, it's still sub zero inside the van at the moment I but I can see on the Fogstar app the UTC protection is kicking in and the cell temps a few mins ago where at about 4 degrees. I get very little solar this time of year, 25w at most.




My only issue with the system is that the few Ah that the solar has sent to the battery this morning had been used for the heating but the shunt has seen this as battery charge, so the % is now out. But, it'll reset and sync on the next 100% charge so not a big issue.

This is my panel at the moment!

 

[Bigsidavies]

I think I might install a small heater pad under my Renogy LiFePo.
I’ve had 2 trips away in the last week and whilst the battery works fine in sub zero temps it doesn’t get warm enough to accept charge whilst driving from one place to the next. This will be a problem in prolonged periods of cold weather such as the alps/pyrenees.
It’s a tad cold this morning at home too.

 

[Dellmassive]

I think I might install a small heater pad under my Renogy LiFePo.
I’ve had 2 trips away in the last week and whilst the battery works fine in sub zero temps it doesn’t get warm enough to accept charge whilst driving from one place to the next. This will be a problem in prolonged periods of cold weather such as the alps/pyrenees.
It’s a tad cold this morning at home too.View attachment 270584

it might be easier to swap the battery out for on with a built in heater . . .

your renogy battery has a plastic case and foam isulation at the botton of the box - basicaly the heater wouldnt do very much, as the heat will not get to the cells.

where as the purpose built ones have the heater pads inbetween the cells . . and the heater is controlled via the BMS and onbly uses the charger power. . . . so no self discharge.


they all do heated versions now.


Renogy
Roamer,
Fogstar
Poweroad.
etc etc etc


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[Bigsidavies]

it might be easier to swap the battery out for on with a built in heater . . .

Thanks for that info Lee, saved me wasted time and money. If I swap then it'll be for a fogstar as I recently put one in another T6 and it's a neat little thing with a great app.

 

[Dellmassive]

My gen4 roamer low temp has kicked in.

Blocking any charge. As it's now -2.0


..



..

 

[TallPaul_S]

My gen4 roamer low temp has kicked in.

Blocking any charge. As it's now -2.0


..

View attachment 270596

..

The roamer's don't have heaters, do they? But their cold weather versions use a slightly different cell chemistry to allow charging well below zero - clever stuff!

 

[Dellmassive]

The roamer's don't have heaters, do they? But their cold weather versions use a slightly different cell chemistry to allow charging well below zero - clever stuff!

Yes as you say.

 

[moomin-j]

My gen4 roamer low temp has kicked in.

Blocking any charge. As it's now -2.0


..

View attachment 270596

..

@Dellmassive
Your Roamer app is showing 100% @ 13.27v
Mine is showing 32% @ 13.42v!!

 

[Drive Wayne]

Interesting watch? Heated batteries... Putting a turkey in a frying pan?

 

[TallPaul_S]

Interesting watch? Heated batteries... Putting a turkey in a frying pan?

That's a particularly bad heater set up, the Fogstar has heater elements between the cells as well as around. But it does what some cheap LiFePO4 battery heaters will be like.

Roamer take a different approach and thier extreme series can be charged with no heater down to -30!

 

[Dellmassive]

@Dellmassive
Your Roamer app is showing 100% @ 13.27v
Mine is showing 32% @ 13.42v!!
View attachment 270598

thats fine, nothing to worry about.

 

[moomin-j]

thats fine, nothing to worry about.

Should it be showing 100%, but it’s just a glitch in the matrix?

 

[Dellmassive]

Should it be showing 100%, but it’s just a glitch in the matrix?

no, your battery is 32% charged and needs charging. . .

mines 100% charged.

the voltage will vary from 10-100% but not by much.

 

[TallPaul_S]

Should it be showing 100%, but it’s just a glitch in the matrix?

The voltages on LiFePO4 between 90 and 20% isn't very different:



But also these are are all resting voltages. Any load or charge current in the last 30 mins will increase or reduce the voltage far more than the difference between 40% and 80%.