LiFePO4 heating pad for cold temperatures

[technerd1988]

Then what is the thermostat for? How did you get it to come on only during charging? Did you use the canbus on it? same thing I have. If it don't get below 0C for charging or -20C for discharge in there you dont need to worry about heaters I think. The problem with using heaters is that you are cycling that pack and slowly degrading it as your not using it. just such a dumb waste idea to me unless your standed in a tent in the freezing cold and you need to radio in help or something. The other problem with over insulating the packs is that your not allowing heat to escape either

 

[HRTKD]

Then what is the thermostat for? How did you get it to come on only during charging? Did you use the canbus on it? same thing I have. If it don't get below 0C for charging or -20C for discharge in there you dont need to worry about heaters I think. The problem with using heaters is that you are cycling that pack and slowly degrading it as your not using it. just such a dumb waste idea to me unless your standed in a tent in the freezing cold and you need to radio in help or something. The other problem with over insulating the packs is that your not allowing heat to escape either

Who are you asking this of? Please specify a name or quote a post.

My warmers are active 24 hours a day. They cycle between 35° F and 45° F, in a well insulated area. The net draw from the batteries is miniscule. I haven't seen my state of charge dip below about 95% from the warming pads. I want my batteries nice and warm, so that when the sun comes up, they're ready to take a charge.

 

[TGPB]

Seriously why not just use fans like I did? Use the power your using already in your space to keep them at a comfortable temp 24/7? Unless your using them in a shed, which the battery heaters aren't such a bad idea..but then you'd have to worry about cooling too. Its so simple

My batteries are in an Off-Grid location that is used very little in the winter. I'm not going to keep the place heated when the batteries are the only thing that require heat.

 

[TGPB]

I spent half what you did on my two thermostats. I get individual control over the heat for the two batteries. The watts required for the thermostats is negligible.

From experience the heater control I'm using has a stellar record of dependability. I don't want to depend on cheap Chinese electronics to protect my battery investment.

 

[time2roll]

My warmers are active 24 hours a day. They cycle between 35° F and 45° F, in a well insulated area. The net draw from the batteries is miniscule. I haven't seen my state of charge dip below about 95% from the warming pads. I want my batteries nice and warm, so that when the sun comes up, they're ready to take a charge.

Can you repost a link to your heaters and controller?

 

[RStone13]

This works for me

Off Grid Cabin Alarm

Hello; Will, my name is Bruce F. I watched & enjoyed your live stream the other day. I learned quite a bit about you & I must say we agree a lot. But that is not why I am writing. You pointed out it's "DIY" solar and your enjoyment is seeing other peoples build ideas. So my way of thanking you...

diysolarforum.com

I also have a question. If BMS trips and shuts off battery, is that the same as disconnecting battery 1st. What happens to charge controller because panels are still connected? Up in smoke?

 

[HRTKD]

Can you repost a link to your heaters and controller?

LiFePO4 Battery Warmer Install

This is my install of a custom set of battery warmers from Ultra Heat. I had contacted them through email asking about a warming profile for LiFePO4 batteries. They responded with a design to my specifications, including warming pads that fit my batteries exactly. While I initiated the...

diysolarforum.com

This works for me

Off Grid Cabin Alarm

Hello; Will, my name is Bruce F. I watched & enjoyed your live stream the other day. I learned quite a bit about you & I must say we agree a lot. But that is not why I am writing. You pointed out it's "DIY" solar and your enjoyment is seeing other peoples build ideas. So my way of thanking you...

diysolarforum.com

I also have a question. If BMS trips and shuts off battery, is that the same as disconnecting battery 1st. What happens to charge controller because panels are still connected? Up in smoke?

If the BMS shuts off due to low temperature or low voltage, the solar charge controller would indeed turn off. However, if either of those thresholds were encountered, that would mean that I'm not getting any sun at all and turning off the solar charge controller should be OK.

 

[jwelter99]

I took a different approach and my heat system is always powered unless the main battery fuse blows, or the main battery switch is off. I then used a small low voltage shutoff set to 11.6V that the heat system is connected to.

Heat comes on at/below 10C and shuts off at 15C or above. The low voltage shutoff makes sure I don't over-discharge the bank, with the logic being if it gets that low something else is wrong as not charging back up (snow on solar panels, shore trickle power disconnected)

 

[GSXR1000]

Just spotted this nice and cheap and might be workable if you add a thermostatic switch to control it?

only 8 watts won't do much

 

[Trabuco]

only 8 watts won't do much

Not to mention, I personally would be hesitant to tuck a cloth pad in with my battery build.

There are other, better solutions.

 

[Sanwizard]

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 adding some protection or a way to distribute the heat across your entire battery bank. I would personally put the batteries in a insulated container, then add a thin sheet of conductive material like sheet aluminum over the pad so that the heat it produces can warm up your entire battery bank.

Cheaper heater pad source: Click here for heater pad

Thanks Will. I have seen folks put together rube goldberg solutions using silicon pads and homegrown thermostats that seem complex. The pads in your link seem to be self contained with an internal thermostat built in! I like simple. Just picked one up. Wish they made a 48v version. Now I have to also buy a stepdown dc to dc converter to 12v.

 

[GSXR1000]

Thanks Will. I have seen folks put together rube goldberg solutions using silicon pads and homegrown thermostats that seem complex. The pads in your link seem to be self contained with an internal thermostat built in! I like simple. Just picked one up. Wish they made a 48v version. Now I have to also buy a stepdown dc to dc converter to 12v.

why not wire 4 in series... the only downside the warmest pad will decide the cycle

 

[Horsefly]

Thanks Will. I have seen folks put together rube goldberg solutions using silicon pads and homegrown thermostats that seem complex. The pads in your link seem to be self contained with an internal thermostat built in! I like simple. Just picked one up. Wish they made a 48v version. Now I have to also buy a stepdown dc to dc converter to 12v.

I hope you realize you are replying to a post that Will made 18 months ago. I'm thinking Will would say some things have changed. I don't think solutions should get the "rube goldberg" moniker if they are now working for quite some time and people are reporting as such. This board is a wealth of information, including more recent experiences with keeping LFP cells in a safe temperature zone. Just sayin.

 

[Sanwizard]

I hope you realize you are replying to a post that Will made 18 months ago. I'm thinking Will would say some things have changed. I don't think solutions should get the "rube goldberg" moniker if they are now working for quite some time and people are reporting as such. This board is a wealth of information, including more recent experiences with keeping LFP cells in a safe temperature zone. Just sayin.

Yeah, I searched for "heating pad" before posting, as I imagined it was better to not start a new thread if one was already here with the same topic. I was not a member 18 months ago, but the info imparted by Will, including the link he provided, was still relevant to me now.
I imagine as a new member I still need to figure out how to get the most recent results during a search on a topic.

 

[Horsefly]

Yeah, I searched for "heating pad" before posting, as I imagined it was better to not start a new thread if one was already here with the same topic. I was not a member 18 months ago, but the info imparted by Will, including the link he provided, was still relevant to me now.
I imagine as a new member I still need to figure out how to get the most recent results during a search on a topic.

The good news - and the bad news - is that there is a TON of good info on this board. Real people like you and me reporting their experiences. The nuggets of info you are looking for are all there, but it may take lots of reading to find them. Simple searches probably won't do justice to the knowledge that is available. However, while looking for what you want an answer to, you will almost certainly find answers to questions you hadn't thought of yet!

I say all this as someone who hasn't been here on this board very long myself. I'm still learning!

 

[HRTKD]

The Battle Born heating solution uses an external temperature sensor. It is not embedded within the heating pad.

My solution started with that same temperature sensor. It failed. The replacement sensor worked but didn't come on until well below 32 F. That's why I went with the "rube goldberg" programmable thermostat.

 

[Horsefly]

The Battle Born heating solution uses an external temperature sensor. It is not embedded within the heating pad.

My solution started with that same temperature sensor. It failed. The replacement sensor worked but didn't come on until well below 32 F. That's why I went with the "rube goldberg" programmable thermostat.

Hey Jim, if and when you ever see the system I'm coming up with, you will gladly hand the Rube Goldberg award over to me! ?

 

[jwelter99]

If you are running a Victron Venus OS platform....

The latest "large" images include node red. It becomes a trivial issue to attach a temp sensor and set one of the relays on a Cerbo, etc, etc, to come on/off based on temp.

I use a temp sensor on the batteries, one on the Multiplus fan inlet ("ambient temp" in the electrical compartment), and one outside the RV on the belly for exterior temp.

Combined with node-red this gives me all the control I need to keep the batteries toasty, etc, etc. Since node-red also knows the SOC and power production state, and power input state you can get some pretty good logic setup to run heaters.

 

[Sanwizard]

The Battle Born heating solution uses an external temperature sensor. It is not embedded within the heating pad.

My solution started with that same temperature sensor. It failed. The replacement sensor worked but didn't come on until well below 32 F. That's why I went with the "rube goldberg" programmable thermostat.

Ok ok, sorry I used the term Rube Goldberg. If it works better, then it is better. Perhaps Lishen or EVE will invent a better cell that can incorporate a self heating coil used during charging.... I like simple.

 

[Horsefly]

Ok ok, sorry I used the term Rube Goldberg. If it works better, then it is better. Perhaps Lishen or EVE will invent a better cell that can incorporate a self heating coil used during charging.... I like simple.

Ummm. I don't think anyone wants the guys that are cranking out individual cells to start building heating coils in them. That's not their sweet spot. They need to crank out lots and lots of LFP cells. Many applications do not need heat. Many applications (like electric vehicles) will already be building whatever heating / cooling that is needed into the mounting of the large packs they build.

If you find this stuff too complicated, then I do think you are better going with one of the pre-packaged batteries like Battleborn. How they keep things warm may not be ideal, but it is hidden from you and you don't need to understand or worry about it. You pay more for it, but maybe it's worth it to keep it simple.