LiFePo4 battery heater

[K12]

I am putting in some LiFePo4 batteries this weekend. They are both charged, voltage matched and ready to go. They do not have the internal heater so I am am taking a spare holding tank heater pad laying around the house and attatching it to a 20x18 sheet of metal to cover both batteries. From everything I have read, too much over the last couple months, this works to spread the heat enough to not melt the battery plastic, and has an internal temp control to turn on at 40° and off at 68°. My question is what would the easiest wiring be for the HQ19. Should I wire power to the bus bar and negative to either battery? Could I wire direct to one battery? since they are in parallel I think that it would only draw from the one battery which would be a no-no.

 

[smritte]

Pull off one battery, you will be fine. I am assuming the wiring between the batteries is large enough to flow whatever you need.
Good call on the heating pad. I'm going to be building my own battery bank and that was one part I haven't figured out.

My question to you is, your surrounding the batteries in sheet metal and the heating pad is heating the batteries through the metal? Also what are the dimensions of the heating pad your using and if the pad shuts off ~70, why are you worried about melting anything?

I ask because I haven't researched the heating part only the how to assemble part.

 

[K12]

Pull off one battery, you will be fine. I am assuming the wiring between the batteries is large enough to flow whatever you need.
Good call on the heating pad. I'm going to be building my own battery bank and that was one part I haven't figured out.

My question to you is, your surrounding the batteries in sheet metal and the heating pad is heating the batteries through the metal? Also what are the dimensions of the heating pad your using and if the pad shuts off ~70, why are you worried about melting anything?

I ask because I haven't researched the heating part only the how to assemble part.

The sheet metal is only at the bottom and going to be built into the battery tray. I am using a 12"x18" heater pad. 70° is not enough to melt the plastic, esspecially when dispersed over the metal platform. Having the auto cuttoff on the thermostat is a good option, but you can also hook it up to a switch to turn it on/off as needed. I am am also linking the victron SmartSolar MPPT to temp sensors I'll put on the batteries to ensire it does not charge under 5°c

I have heard of people insulating the box and basically doing an ambient heating element using the same strategy but not actually touching the batteries. In the trailer I am limited on space and wont be able to insulate other than the provided insulation in the exterior walls. This is generally enough to keep the inside warm and there is a heater inside so I can see the pad heater turning off relatively quick.

I will try to remember to take pictures through the install. I usually forget but would be good to have a decent write-uo for people who want to do the same... and tell me what i did wrong so the rig doesnt burn down.

 

[M Rose]

The heating pad for RV tanks is safe to touch the batteries them selves. I built my battery box using an RV tank heating pad as the floor of my battery box. Temp is set to come on at 37 degrees and shuts off at 42 degrees. You don’t want the box getting colder than 35 degrees or over 110 degrees during the charging cycle. This is why most of us build our boxes with insulation. For insulation I used DynoMat. And I used a 120mm pc fan on a thermostat to turn on and vent when temps reach 80 degrees to keep from cooking my batteries.

 

[DaleRF]

I am putting in some LiFePo4 batteries this weekend. They are both charged, voltage matched and ready to go. They do not have the internal heater so I am am taking a spare holding tank heater pad laying around the house and attatching it to a 20x18 sheet of metal to cover both batteries. From everything I have read, too much over the last couple months, this works to spread the heat enough to not melt the battery plastic, and has an internal temp control to turn on at 40° and off at 68°. My question is what would the easiest wiring be for the HQ19. Should I wire power to the bus bar and negative to either battery? Could I wire direct to one battery? since they are in parallel I think that it would only draw from the one battery which would be a no-no.

I also have two LiFePo4 Batteries w/two warmer blankets, and they have adhesive to directly contact the battery. I power each one from the battery that it will warm, although I don't think it matters. One thing to note, ensure that if you have a temp sensor, that you bury it under the blanket, sandwiched between the blanket and the battery.

 

[DaleRF]

The heating pad for RV tanks is safe to touch the batteries them selves. I built my battery box using an RV tank heating pad as the floor of my battery box. Temp is set to come on at 37 degrees and shuts off at 42 degrees. You don’t want the box getting colder than 35 degrees or over 110 degrees during the charging cycle. This is why most of us build our boxes with insulation. For insulation I used DynoMat. And I used a 120mm pc fan on a thermostat to turn on and vent when temps reach 80 degrees to keep from cooking my batteries.

The "...a 120mm pc fan on a thermostat..." is a GREAT idea - Thanks!

 

[K12]

The heating pad for RV tanks is safe to touch the batteries them selves. I built my battery box using an RV tank heating pad as the floor of my battery box. Temp is set to come on at 37 degrees and shuts off at 42 degrees. You don’t want the box getting colder than 35 degrees or over 110 degrees during the charging cycle. This is why most of us build our boxes with insulation. For insulation I used DynoMat. And I used a 120mm pc fan on a thermostat to turn on and vent when temps reach 80 degrees to keep from cooking my batteries.

I may use an audio cabinet fan. Most have a thermostat build in and setup to turn on and off. My only question is would I be able to take a fan like this: https://a.co/d/4R2hVH9 and do a direct to DC for it? Since the power cord is an ac>dc cable.

 

[M Rose]

The heating pad for RV tanks is safe to touch the batteries them selves. I built my battery box using an RV tank heating pad as the floor of my battery box. Temp is set to come on at 37 degrees and shuts off at 42 degrees. You don’t want the box getting colder than 35 degrees or over 110 degrees during the charging cycle. This is why most of us build our boxes with insulation. For insulation I used DynoMat. And I used a 120mm pc fan on a thermostat to turn on and vent when temps reach 80 degrees to keep from cooking my batteries.

I may use an audio cabinet fan. Most have a thermostat build in and setup to turn on and off. My only question is would I be able to take a fan like this: https://a.co/d/4R2hVH9 and do a direct to DC for it? Since the power cord is an ac>dc cable.

Not without an inverter. What I like about the PC fan is that it is 5 volts instead of 12 so it uses a lot less power than a 12 volt fan, and you can get a PC fan controller with temp sensor.

 

[K12]

Not without an inverter. What I like about the PC fan is that it is 5 volts instead of 12 so it uses a lot less power than a 12 volt fan, and you can get a PC fan controller with temp sensor.

What would be the process in wiring that into the system with it being a 5v fan?

 

[grubworm]

Could I wire direct to one battery? since they are in parallel I think that it would only draw from the one battery which would be a no-no.

wiring in parallel essentially makes the two batteries one big battery with double the amperage output but still 12v, so tying in anywhere in the circuit is drawing on both batteries equally.
i'd wire off the bus bar just because i think its better to tighten and loosen screws on a bar rather than mess with a battery terminal.

power is power...so a 5v fan doesnt use less power then a 12v fan, if its pushing the same amount of air, the 5v fan will draw more amps since it is lower voltage. to simplify things, if your heat pad is 12v and controlled by a thermostat already, i would just skin back some of the wire somewhere between the pad and the thermostat and tap a 12v computer fan off of that. when the pad is energized, so is the fan. a 12v computer fan is going to use a super small amount of current, so hooking it up to the pad will not make a difference and you wont need a 2nd thermocontroller.

 

[M Rose]

Not without an inverter. What I like about the PC fan is that it is 5 volts instead of 12 so it uses a lot less power than a 12 volt fan, and you can get a PC fan controller with temp sensor.

What would be the process in wiring that into the system with it being a 5v fan?

You need a buck converter. Cheapest place to find a buck converter is a USB 2 amp car charger. I used the buck converter in the fan controller. The PC Fan controller plugs into the 12 volt rail of the PC Power Supply and then distributes power to the fans, switches, thermostat, and sometimes an LCD display.

I used this kit from CoolGuys. And remote mounted the controller so I could monitor the fans from my driver seat.

Coolerguys Dual 92mm Fan Cooling Kit with Programmable Thermal Controller

Coolerguys Single 120mm Fan Cooling Kit for Cabinet / Home Theaters with Thermal Controller, Acrylic, Wood or Metal Bracket

www.coolerguys.com

 

[K12]

Not without an inverter. What I like about the PC fan is that it is 5 volts instead of 12 so it uses a lot less power than a 12 volt fan, and you can get a PC fan controller with temp sensor.

What would be the process in wiring that into the system with it being a 5v fan?

You need a buck converter. Cheapest place to find a buck converter is a USB 2 amp car charger. I used the buck converter in the fan controller. The PC Fan controller plugs into the 12 volt rail of the PC Power Supply and then distributes power to the fans, switches, thermostat, and sometimes an LCD display.

I used this kit from CoolGuys. And remote mounted the controller so I could monitor the fans from my driver seat.

Coolerguys Dual 92mm Fan Cooling Kit with Programmable Thermal Controller

Coolerguys Single 120mm Fan Cooling Kit for Cabinet / Home Theaters with Thermal Controller, Acrylic, Wood or Metal Bracket

www.coolerguys.com

Ok, so the thermostat do you have plugged into ac power?

 

[M Rose]

Ok, so the thermostat do you have plugged into ac power?

No, the thermostat is 12 volt DC…all computer components are either 12 volt or 5 volt.

 

[K12]

Ok, so the thermostat do you have plugged into ac power?

No, the thermostat is 12 volt DC…all computer components are either 12 volt or 5 volt.

Since that come with a ac to dc power cable how is it integrated into the system for the thermostat?

 

[M Rose]

Since that come with a ac to dc power cable how is it integrated into the system for the thermostat?

I didn’t use the provided power supply in this project. In fact I don’t use 110 volt AC current in my everyday life other than to run my battery maintainer and A/C. Every other appliance runs off of either DC voltage or propane.



Unit Specs:
Speed: 1500 RPM
Operation Voltage: 6.5~13.8 Volts
Input current per fan: 0.09A
Operation temperature: -10 to +65 C
Storage temperature: -40 to +70 C
RPM: 1500 +/- 10%
CFM: 60
dB: 22
Fan Connector: 3 Pin w/ 30" Tail
Life: 67,000 hours

Notice the operating voltage input is 6.5-13.8 volts. The power supply isn’t needed because the battery is the power supply. I just cut the power supply output cord about 6” from the power supply and wired it according to the diagram on the fan controller with a 1 amp fuse on the positive side.
I used Gorilla Tape to secure the fan temp sensor to the side of the box. I wired the fan controller up to the positive and negative power distribution box as an accessory. The DC/DC and Solar Charge Controller are wired between the battery and the power distribution center.

 

[K12]

As I was taking it all out I found that Black Series already had a vent fan inside to the exterior. I think this will work for now and maybe ill take the other hole drilled and have it as another vent fan. Here are pics of the install. Went up to 600ah (2x 300ah) of useable LiFePo4 batter capacity. It also cut the total weight in about half. Those AGMs are heavy! Wire the heating pad as well as the temp sensor the the bus bar. All is working well, the mppt controller topped them off in a few minutes and went to absorption to level them out.

 

[DaleRF]

As I was taking it all out I found that Black Series already had a vent fan inside to the exterior. I think this will work for now and maybe ill take the other hole drilled and have it as another vent fan. Here are pics of the install. Went up to 600ah (2x 300ah) of useable LiFePo4 batter capacity. It also cut the total weight in about half. Those AGMs are heavy! Wire the heating pad as well as the temp sensor the the bus bar. All is working well, the mppt controller topped them off in a few minutes and went to absorption to level them out.

Outstanding!