Heat pad

[Wilecoyote]

I have a cabin in northern Ontario. -30 easy. 2 100 w panels and 2 12v lifepo4 100ah batteries. I’m thinking of doing the sewer tank warmer for them. With an insulated battery box. Anyone done this ? I have dreams of cabin burning down .

 

[HRTKD]

There are a lot of threads in the DIY subforum. Search there.

DIY LiFePO4 Battery Banks

Advanced user discussion on BMS/ Cell Configurations/ Temperature Regulation/ Cell Sources and more

diysolarforum.com

I think you'll want more PV.

 

[Wilecoyote]

What is PV ? Thanks for the response. I found lots of info in the forums. Thank you.

 

[Wilecoyote]

So more panels ?

 

[Wilecoyote]

We run 6 led lights and charge phones. Nothing more.

 

[outboard1196]

I have a cabin in northern Ontario. -30 easy. 2 100 w panels and 2 12v lifepo4 100ah batteries. I’m thinking of doing the sewer tank warmer for them. With an insulated battery box. Anyone done this ? I have dreams of cabin burning down .

I just built a cold weather battery box, those RV heater pads I found wont keep up with super cold temperatures. You need bigger pads and an adjustable temp controller. See page 32 for mine. There good info in the rest of the thread.

Thread 'LiFePO4 heating pad for cold temperatures'

Sep 20, 2019

If you are trying to use a lifepo4 battery in freezing cold temperatures, battle born just released a 12v heat pad for keeping the batteries warm without melting the case. This pad should work for any standard lifepo4 battery. Just slap it under your batteries and connect it to 12v and you are done.

I think it is over priced though. It can be found here: Click Here for battle born heater pad


If you cannot afford the battle born pad, you can use a septic tank heater pad. It works in the same way but may possibly melt your battery case if you are not careful. You can avoid this by...

• Will Prowse
• Replies: 788
• Forum: Off-grid Living Discussion

• 

 

[Wilecoyote]

The sewer tank pads come as a pair. Can I utilize both somehow to get more heat ? I only have 2 batteries.

 

[SunDave]

We run 6 led lights and charge phones. Nothing more.

You are forgetting about the heating you are proposing. It needs power too. A lot of it.

The batteries, and other solar equipment also use some power all the time. Trust the others when they say that 200 watts of solar is not enough to maintain 200ah of 12v and run heaters.

 

[HRTKD]

Exactly what SunDave said.

LiFePO4 batteries are fairly dense. Once you get them up to temperature they'll stay there as long as the heat isn't allowed to dissipate. Plenty of insulation helps with that.

 

[Wilecoyote]

I’m thinking of sending the batteries back to Amazon and get 2 6 volt deep cycle. That’s all we had for years. 30 years. 3 sets of batteries. This seems like a pain. Mind you 2 more 100 watt panels are cheap. Would 400 watt do it ?

 

[Wilecoyote]

I’m trying to upgrade from 30 year old sun save 10. One 70 watt panel to new. I have 200 watt kit from eco worthy and the 2 lifepo4 batteries. I’d consider 2 more panels. Seems like over kill for 6 lights and a phone chargers.

 

[HRTKD]

I’m thinking of sending the batteries back to Amazon and get 2 6 volt deep cycle. That’s all we had for years. 30 years. 3 sets of batteries. This seems like a pain. Mind you 2 more 100 watt panels are cheap. Would 400 watt do it ?

I kept two LiFePO4 batteries toasty warm with 640 watts of PV mounted flat as a pancake on the roof of my RV. If you can tilt 400 watts toward the sun better than that, you'll have enough power to keep the batteries warm.

 

[outboard1196]

I’m trying to upgrade from 30 year old sun save 10. One 70 watt panel to new. I have 200 watt kit from eco worthy and the 2 lifepo4 batteries. I’d consider 2 more panels. Seems like over kill for 6 lights and a phone chargers.

I'm probably using 75-100 ah in a 24hr period just for heating.

 

[Wilecoyote]

For what I’m doing are the lifepo4 that much more amazing. ? I’ve never walking into my shack and had a dead battery until last week. I noticed all summer system was bagged out. Do I need the lifepo4. The heaters , 400 watts for 5 led bulbs? I feel like in northern Ontario it’s just too cold for them. -30 c is common for weeks on end. I only go 3-4 times in winter. Need lites to work. Batteries will sit months on end no one there. I’m thinking back they go. Stick with what has worked.

 

[ksmithaz1]

Insulation and an electric blanket on low? . . . Dig them in the ground. Spray foam.

 

[ksmithaz1]

I feel like in northern Ontario it’s just too cold for them. -30 c is common for weeks on end.

-30C for weeks in the middle of the day? You should dig it in, no matter the battery type, keeping the compartment warm should be fairly easy. Are you there when it's -30C all day and night for weeks on end? Is this a research station?

 

[SunDave]

Hi Wilecoyote,
I have a small cabin with 800 watts of solar that is in a similar climate. Can be very cold for extended periods. I stuck with AGM (lead acid) for the cabin, and we have a panel mount that can be put vertical to shed snow.

I have lithium at home, but personally I don't think it is there yet for very cold climates with very low amounts of sun. Like you see, you can chase your tail trying to keep the batteries warm instead of powering loads. There are ways to do it, but they are expensive vs. lead acid in my opinion.

 

[ksmithaz1]

What is the frost line there? 5 feet? Dig in a small compartment or a tiny cellar if a little more ambition, and put the batteries and/or electrical stuff in it. Drop an extra fat 400-500W panel on a pole at a steep pitch a couple feet up. Geothermal heating will never let you down. Can't run at 0C but it won't kill the batteries. Should be fairly simple to keep a few extra watts of heat just to keep it from dipping below 2C.

 

[Wilecoyote]

No it’s not a research station. Lol. It’s a log cabin in the bush. The batteries need to be charged when I get there. Jan Feb very cold. -30 nights common. -15 to -25 c days common. We have used 2 6 volt deep cycle for years in series. No issues. Was trying to upgrade. The lifepo4 were on sale. But I feel it’s a mistake. Heaters. 400watts. We only have 5-6 led 4 watt lights. And a phone charge port. I only go 4-5 times in winter.

 

[Wilecoyote]

What is the frost line there? 5 feet? Dig in a small compartment or a tiny cellar if a little more ambition, and put the batteries and/or electrical stuff in it. Drop an extra fat 400-500W panel on a pole at a steep pitch a couple feet up. Geothermal heating will never let you down. Can't run at 0C but it won't kill the batteries. Should be fairly simple to keep a few extra watts of heat just to keep it from dipping below 2C.

Frost line ? I dunno. Camp sits on bedrock. Digging holes takes a long time. lol. Northern Ontario is rocks. Or swamps. lol

 

[Wilecoyote]

Hi Wilecoyote,
I have a small cabin with 800 watts of solar that is in a similar climate. Can be very cold for extended periods. I stuck with AGM (lead acid) for the cabin, and we have a panel mount that can be put vertical to shed snow.

I have lithium at home, but personally I don't think it is there yet for very cold climates with very low amounts of sun. Like you see, you can chase your tail trying to keep the batteries warm instead of powering loads. There are ways to do it, but they are expensive vs. lead acid in my opinion.

I think I agree with you. Back they go. Thank you for the input. Much appreciated.

 

[SunDave]

I think I agree with you. Back they go. Thank you for the input. Much appreciated.

No problem. Or use them somewhere else. Good luck with your cold weather setup. 12 volt batteries come pretty large now. Consider 1 instead of 2x 6 volts if it isn't too much to lift. That way there are no issues with one dying first, or getting out of balance, or extra wiring.

More importantly, do what ever works best for you.

 

[HRTKD]

Given the track record you've had with 6v deep cycles, I would stick with that. All lead acid batteries need to be kept charged if they're going to be subjected to extreme cold temperatures.

 

[FishHog]

While I get -30 at my northern Ontario cottage the odd time it is rare these days. Since you heat your cottage bring them inside. Or run off one at night. Bring one inside to warm up. In the morning switch them. It will stay warm enough most days to charge. Switch the next day.

 

[Wilecoyote]

So it’s looking like not cost effective to return the batteries in Amazon. What else will I need to make this work ? 600watts of panels ? Heated box ? These batteries live inside the cabin. But I only go to camp 4-5 times in winter. I don’t go -30. My son is there tonight. It was -35c , the batteries will be alone there weeks on end. I need a safe system. I’m worried about heating sewer pads running under batteries. Cabin is 2 hours NE of Thunder Bay Ontario. Near top of Lake Superior.