LifePo4 vs winter

[Kenny_]

In all my years off grid I have never used my genny to recharge my batteries.

If your system is sized and oriented correctly for winter you shouldn't need a genny for that.

The main problem is most people put their panels on their house roof that doesn't have good orientation for lower winter sun and the panels don't get cleared of snow. I had that issue the first year I put my panels on my porch roof and learned my lesson.

I moved them to a ground mount with angle and tilt to optimize winter sunshine and was able to use a smaller system and have plenty of power even in hard winters and we get lots of snow and overcast days here. I have 3 small ground mount systems and 800Ah of battery are usually full charged by noon on a sunny winter day and will last me 3 days of low sunshine.

I still have a genny but it is only used for running HD power tools outside. One thing I do now is to recharge several small power stations for back up when ever I have a sunny winter day and just keep them handy for low sun days.

Having multiple smaller systems also means redundancy so if a component in one system fails I still have power from the other systems and the genny is only a last resort.

Good Advice!

 

[Crowz]

Put some panels on top of the rv and then setup heating for the batteries like this :

I used these for heating :


https://www.amazon.com/gp/product/B075WVPP5Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I simply taped one pad on each of the 4 sides of each battery.

I then used these :


https://www.amazon.com/gp/product/B011VGAPOC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

to control the heating pads.

I placed the sensor for each control unit on top of each battery it controlled the pads for.

I believe I have them wired 2 in series on each of the 4 pads but I may have all 4 in series I cant remember which worked out the best.

I set the controllers to 37F turn on 40F turn off. I havent noticed much in the way of shortened battery life with this setup on my lifepo4 batteries.

So far using a infrared thermometer the batteries have stayed above 34F at all times. My batteries will function to 0C and they have a 32F limit on charging with the bms they have. So I have it setup to keep it over 34F to ensure they will charge each morning no matter how cold it gets.

That said it doesnt get that cold here in Alabama with 20F being the normal lows most of the time in the winter.

Even with your colder temps this system should work fine I would think if you can use panels on the roof to put the power back each day.

Also the pads could be used to melt snow on the panels possibly.

 

[Crowz]

Oh I also use this setup to heat the water pipes that go from my workshop to the house since I had so much extra power left over on that particular battery bank

 

[Kenny_]

Put some panels on top of the rv and then setup heating for the batteries like this :

I used these for heating :


https://www.amazon.com/gp/product/B075WVPP5Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I simply taped one pad on each of the 4 sides of each battery.

I then used these :


https://www.amazon.com/gp/product/B011VGAPOC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

to control the heating pads.

I placed the sensor for each control unit on top of each battery it controlled the pads for.

I believe I have them wired 2 in series on each of the 4 pads but I may have all 4 in series I cant remember which worked out the best.

I set the controllers to 37F turn on 40F turn off. I havent noticed much in the way of shortened battery life with this setup on my lifepo4 batteries.

So far using a infrared thermometer the batteries have stayed above 34F at all times. My batteries will function to 0C and they have a 32F limit on charging with the bms they have. So I have it setup to keep it over 34F to ensure they will charge each morning no matter how cold it gets.

That said it doesnt get that cold here in Alabama with 20F being the normal lows most of the time in the winter.

Even with your colder temps this system should work fine I would think if you can use panels on the roof to put the power back each day.

Also the pads could be used to melt snow on the panels possibly.

Nice. I may do something like that if I decide to install my system in my garage.

 

[Solarcabin Channel]

Facon on Amazon sells RV 12 volt holding tank heater pads with a built in thermostat in various sizes

These use about 60 watts and if the batteries are in an insulated box probably wouldn't run much at all.

Only issue I see is they raise they are set to 45F on and 68F off and you really don't need them to raise the temp that much for batteries.

If you could wire them with a timer so they just come on an hour before sunrise that would be even better or you could use a manual switch.

Just another option.

 

[NCislander]

Put some panels on top of the rv and then setup heating for the batteries like this :

I used these for heating :


https://www.amazon.com/gp/product/B075WVPP5Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I simply taped one pad on each of the 4 sides of each battery.

I then used these :


https://www.amazon.com/gp/product/B011VGAPOC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

to control the heating pads.

I placed the sensor for each control unit on top of each battery it controlled the pads for.

I believe I have them wired 2 in series on each of the 4 pads but I may have all 4 in series I cant remember which worked out the best.

I set the controllers to 37F turn on 40F turn off. I havent noticed much in the way of shortened battery life with this setup on my lifepo4 batteries.

So far using a infrared thermometer the batteries have stayed above 34F at all times. My batteries will function to 0C and they have a 32F limit on charging with the bms they have. So I have it setup to keep it over 34F to ensure they will charge each morning no matter how cold it gets.

That said it doesnt get that cold here in Alabama with 20F being the normal lows most of the time in the winter.

Even with your colder temps this system should work fine I would think if you can use panels on the roof to put the power back each day.

Also the pads could be used to melt snow on the panels possibly.

I like it. I need to do this for my DIY Batteries in the shop/garage/pole barn. No climate control.
Any specific 12V power supply you use to power this? Maybe a 48vdc - 12vdc step down buck converter?

 

[Crowz]

I like it. I need to do this for my DIY Batteries in the shop/garage/pole barn. No climate control.
Any specific 12V power supply you use to power this? Maybe a 48vdc - 12vdc step down buck converter?

4 wired in series with a 48v battery will be the same draw as 1 pad at 12 volts.

 

[Horsefly]

I've built two insulated battery boxes (8S, 24V) for our cabin in the Colorado mountains. I did something similar to @Crowz but only used 2 12W pads. I did lots of testing and collecting data, confirming that low and slow was the way to go.

Here's the first one I built (and towards the end of the thread is graphs showing the testing):
https://diysolarforum.com/threads/horseflys-cabin-solar-lifepo4-upgrade.27472/

Here's the second one that simplified the heating logic a bit, based on what I learned on the first battery:
https://diysolarforum.com/threads/horseflys-2nd-cabin-battery-build.68711/

A couple of the main things I would recommend:

1. Heating slowly (using lower wattage heating elements) allows the heat to migrate from the side where you are applying the heat through the cells without risking "cooking" the cells before they are warmed through.
2. I added the Victron Smart Battery Protect to cut off the whole heating operation if the battery voltage falls below a set limit. This would only happen if the panels were covered with snow for more than a couple of weeks. Once the panels clear the SCC should power the heating circuit back on, which will eventually get the BMS to allow charging again.

 

[NCislander]

4 wired in series with a 48v battery will be the same draw as 1 pad at 12 volts.

Perfect. Thanks Crowz. That works.

@Horsefly - Laughing, because your DIY Battery box project is what I am aiming for, but less extensive (Nice). Same type insulation in my boxes.

 

[timselectric]

I call my climate controlled battery enclosure a house.

 

[NCislander]

I hear you Tim, My powerplant is adjacent to the house. Insulation for it won't happen until next winter. Though our winter's here a fairly mild.
Don't laugh, My battery boxes are going to be made from the larger EVE LF280K shipping containers (Trimmed Smaller)

 

[markbron123]

Hey guys,

I am new to this. Anyone please suggest an online store to buy a 12V 100Ah lithium battery in Canada. Any lead would be much appreciated.

 

[garetwo]

We routinely get -30 I didn’t remove mine just charged them up and disconnected them

What a perfect idea if you need zero output. If one is removing them, then leaving them in place and disconnecting them sounds great!

 

[garetwo]

It's not designed to keep the battery warm. Only to warm it up before charging.
Discharging in cold is not a problem. Charging is.

so, it will pull power from whatever is going to charge. if there is no sun, that could be anything else, like a genset, alternator, or whatever. It makes complete sense.

 

[garetwo]

That didn't really answer the question?

What power source is it using to warm it up if solar is not producing and you said it uses the outside power source?

"The heating is only active, while a charging source is available. They aren't powered by the battery."

I think you both answered the question. If you have zero solar but want to charge the power must come from some other source, like a generator or alternator?

 

[garetwo]

Self heating means the battery is heating them not an outside source.

What watts are needed to trigger that heater. Do you know?

In cold climates you may go days with very low sunshine and extremely cold nights and how long does it take to warm that battery up from -20 to start charging in those conditions?

It is not as simple as you think and this needs to be tested under actual cold climate conditions because it sounds like a gimmick to me!

So self-heating is good if you know it will soon be charging, it may be a short window, and you want the batteries at the correct temperature so you may immediately take advantage of the power? I see where all of you who live in much colder climates have a lot more to consider. Then, anything introduced to control heating startup and run-time may also consume energy...would it not be easier just to move to Hawaii?