LIfepo4 charging in winter.

[somawheels]

I see. I am Considering Lithium batterries, because I think they may be more suited to small offgrid systems in UK weather.

I have had lead acid Batteries once before, however they only lasted 3 years.
I think this is mainly due to too many deep discharges and too little charging. However, I have read Lithium Batterries are not supposed to suffer much from undercharging and over draining, and are more efficient, so they seemed like a good idea, as they should last much longer than lead acid in a system like mine.


I do have a generator, however I dont think my generator charger worked properly. I am planning to upgrade this.
My lead acid bank was was a 400AH 24V batterry bank. I have 1.5kw of solar panels, which is no where near enough to keep the lead acid batteries in good health.

[Mike90250]

it's even worse ! Below 40F. ( 4.5C) power output starts to fall off, and you need to be careful recharging. You usually don't get the full package of data sheets till you purchase the battery and start filling out the warranty registration forms.

But foam sheeting and a modest blanket heater should keep them warm enough IF you lay out the heaters well.

[NEOH]

I am considering buying Lithium batteries for my offgrid home where I live permanently.
Here in the UK, winter temperatures can go bellow 0 degrees, in which case charging the battery would ruin the battery.

The system (inverter-charger and solar charger) is located in an un-heated shed.

Does anyone know of a possible solution to this problem?

Can you put the battery inside a box made of three layers of 2" Solid Foam Insulation?
Add an electronic thermostat and very low wattage heater, to keep battery above freezing.
This has been done successfully with lead acid batteries.

Add a power vent if you need to cool it down, in the summer.

[PNjunction]

If you want to wing it, you do what some motorcycle LFP guys do - put a small load on the batts to warm them up internally, and then charge. Most often, they'll turn on the headlamp for 30 seconds, and then fire up. That way their alternator doesn't just burn up the LFP's that aren't rated for sub-zero temps.

Still, that's a risky business between an motorcycle LFP and a whole-house system!

Considering the initial cost of the system, the extra heater etc etc - it may not be worth it.

The only successful diy solar systems in the UK or elsewhere with cold temps, and limited sun hours was the use of PURE-LEAD agm's. With a very large solar array. Low internal resistance from the pure-leads can take the large array up to 0.5 to 1C if you can afford it. And the agm's don't freeze.

Try LFP if you want. But will it be your *first* venture? Then the risk of wallet expansion on a system you change later anyway may be an eye opener if you make a mistake in your power budget and repurchasing more LFP all over again.

If the need is large, instead of tacking a bunch of Optima / Odyssey / other pure-leads together, there are some big boys like Lifeline pure-leads I believe.

Keeping them from walking down in capacity if the issue - from not getting a truly decent full charge. Once every two weeks or so, you can use a gas-generator for bulk, and let the sun, such as it is, do the rest. More often if you can afford the petrol cost.

Old-school, but it STILL works!

[somawheels]

Indeed the temperatures are in Celcius. The generator is in another separate shed unfortunately.
I am thinking I could wrap the battery in heating mats and something insulative. I am thinking of using low power heating elements with a thermostat. How-ever, I am unsure how much heat and electricity I would need to keep the battery above 0 degrees in -15 degree weather.

[Ampster]

Two systems are better than one. Can you use the heat from the generator for one system? Can I assume the temperature is Celsius?

[somawheels]

It is rare for the temp to be bellow 0. Some years it does not get this cold, some years it could be between 0 and -12 degrees for a couple of weeks.

I considered using a thermostat heater, however, im not sure this is a good idea because well.. what if the heating system fails? what if there is not sufficient power to run the heating system? I do have a generator, so I could disconnect the battery, then heat up the batterey via generator power, then re-connect batterries. However this is a very risky, impractical solution.

Edit: on second thoughts, perhaps I could setup two heating systems - one which runs of an external batterry, and one which runs of the inverter/main power. Does that sound OK?

[Ampster]

How often and how long is it at those temps. Is that temperature C or F. Do you use a generator for power?

[somawheels]

I am considering buying Lithium batteries for my offgrid home where I live permanently.
Here in the UK, winter temperatures can go bellow 0 degrees, in which case charging the battery would ruin the battery.

The system (inverter-charger and solar charger) is located in an un-heated shed.

Does anyone know of a possible solution to this problem?