48V battery heaters?

[niteraven78]

Hi all, I have 3 EG4 LifePower4 Lithium Battery | 48V 100AH batteries that I keep in an exterior inclosure that I use for my solar car port. I am really struggling to keep them warm enough as the temperature has been falling to 22F here in Asheville, NC at night. The batteries cut off charging at 32F.

I am thinking about installing battery heating pads and found these on Amazon:

https://a.co/d/1jMKc9U

Can I attach these directly to the battery terminals? Is there a terminal switch I can use in between the pads and the batteries?

Alternative solutions are appreciated as well.

Thanks!

 

[TomC4306]

At 300 watts, it would depend on how many hours it took raise the pack temperature 10 or 15° before morning.
Sounds like a good experiment to try.

300 watts x 5 hours equals 1500 watt hours which is about 10% of your capacity.

How much solar do you have?

Oops.. x3 packs.

 

[Samsonite801]

You should have some kind of thermostat on there too to turn it on and off according to temperature.

Here is an example of a thermostat (runs on 12v but should be able to switch a 48v load fine). Would need a 12v power source like a DC-DC buck converter to power the thermostat electronic board (just has a relay to move the 48v battery power to the heatpad).

W1209 12V -50-110°C Digital Thermostat Temperature Control Switch Sensor + Case 732387203216 | eBay

W1209 Board(LxWxH) : 48mm x 40mm x 14mm (1.9" x 1.6" x 0.6"). Looking for a W1209 without the case?. The on-board relay can switch up to a maximum of 20A at 14V DC, 16A at 24V DC, or 7A at 125V AC. Refresh Rate: 0.5 Seconds.

www.ebay.com

I would also recommend getting some polystyrene insulation sheets (like maybe 4" thick), and making up a box you could seal around the battery rack, or your heating could cost a lot more electricity than you want.

 

[time2roll]

Yes I used similar heat pads attached direct on my cells. Works great. Recently tested camping in Yosemite at 25F and the thermostat kept them 40 to 44.

Directly powered they produce a lot of heat. I ran pairs in series to cut the wattage to 1/4 rating.

 

[niteraven78]

Thanks, you guys are awesome! That is a lot of power, these would only need to kick on for like an hour before the sun comes up and then the solar charging would continue to warm the batteries... then again I would need a thermostat and timer.

You've given me a few good ideas to work off of.

 

[Crowz]

I used these :

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.

 

[Crowz]

I also use this setup to heat my water pipes that run to my workshop.

 

[12vDC]

once you warm the core of your battery, it will stay warm for a significant amount of time. if you have an (insulated) enclosure, your energy usage will be significantly less to get it there and keep it there.

problem is, its also the same for cold core - but depending on your temp relay start/stop values you can mitigate this.

thats a really cool find - 48V silicone pad. if you want different power options, and to spread the heat around uniformly, you could get 4-12V or 2-24V pads and wire them in series.

if all else fails, i heard the old incandescent bulb trick works
??‍

 

[Daddy Tanuki]

Thanks, you guys are awesome! That is a lot of power, these would only need to kick on for like an hour before the sun comes up and then the solar charging would continue to warm the batteries... then again I would need a thermostat and timer.

You've given me a few good ideas to work off of.

300 watts is crazy. i run 25 watt pads in series to get the temps I want and even if i added all of the pads together they would not equal 300 watts . you will cook your battery without some form of temp controller with a pad that high temp. there are a bunch of threads about battery warming from the last two years. i advise you read some of them from tart to finish.

my system is 48 volts (54 to be honest) and I simply wire the 12 volt pads in series. 4 x 25 watts equals about 1/8 of the heat out put compared to one pad direct wired. wire enough of them in sereis and guess what? no controller needed. just turn on in november and shut off in april (for me) and it keeps the batteries at about 15°c~20°c with no electronics or relays to fail. others use the inkbird controllers with a 12/48 buck converter and some other odds and ends.

 

[smr.ruby]

I run these in from Battery Hookup in my batteries. I believe I'm running them three in series https://batteryhookup.com/products/...9&_sid=d266c98d1&_ss=r&variant=42670803878050

Looks like they are out at the moment but they are pretty nice commercial grade silicone rubber heating pads and $6 is a steal if they come back in stock.