Fitting heat pads to LIFEPO4 battery

[OllieGBR]

OK - So I had 1/2 day in the [bloody freezing] garage yesterday and setup my science experiment.
Forgot to take photos, but similar setup as previously but with the actual Lithium battery this time.
I removed one of the heat pads, as the plate was sitting above 50C.
I had a thermometer sat on the plate and move this one between the plate and battery terminal.
The relay’s thermometer was 1/3 from the top of the battery case.
The plate started at 3C and the casing of the battery at 3.8C

Minutes	1	2	3	4	5	6	7	8	9	10
Plate	9	17	23	28	32	34	37	39	41	43
Battery case	3.9	3.9	4.0	4.1	4.1	4.1	4.2	4.3	4.4	4.4

Minutes	11	12	13	15	20	25
Plate	44	45	46	47	47	47
Battery case	4.6	4.7	4.8	4.8	5.3	6.0

The plate warmed up evenIy, and didn’t get above 47C. There is a case and air in between the plate and battery intervals, so actual heat transferred will be significantly less.
I occasionally measured the -ve battery terminal. It was some way behind the case, 4C when the case was at 6C and 5C when the case was at 8C.

Question is, where should one measure the internal temperature of the battery? I would assume the terminal as it’s conductive to the internal temperature.
At 8C batter case the terminal temperature was a steady 5C

The draw on the battery was 3.1Amp, (two heat pads).

I decided to add the spare heat pad to the left side of the battery and add foam insulation to cover it, (after silver tape).
The heating process just not quick enough, and this now reduces the temperate of the plate by applying heat elsewhere.

I then started the process of adding everything installed to date back in.
I also invested in the Renology battery monitor. This plugs into the link port and has the ability to turn the battery off completely. I‘ve been caught out a few times on the BMV-712 being too generous on battery charge remaining.

I’ll get some pictures later.

 

[BigDean]

Thanks Ollie

The biggest concern I have is this 5 degrees and below issue. I have a motorhome as well as my new T6.1 so I am slightly skewed in my thoughts, but.... I like to be “connected” to my vehicles. I travel extensively and like to know what’s going on. I have CCTV, temp, battery and various other monitoring systems connected via WiFi.

What I was hoping to do is stop having to be hooked up to the power the whole time and just keep the batteries topped up with solar. From dissecting the thread here, and another on a motorhome forum, it just seems like it is hassle. If we have a cold couple of days, then the battery can’t cope and all systems will be down.

I understand completely the benefit of the chemistry with regards charge/discharge/cycles/DOD which would be a benefit (weight not an issue), but this temp issue just makes it unworkable for me, I may as well just stay hooked up and kill my AGMs over time.

Thanks for everyone’s input.

UPDATE

I have decided to build the lithium into a battery box. Thanks @Dellmassive

 

[BigDean]

UPDATE

I have decided to build the lithium into a battery box. Thanks @Dellmassive

And I will finish this time before publishing....

Once it is built I will charge in the house before venturing out. I will be fitting a Victron Orion and wiring in to both the T6 and my Motorhome so I can charge on the go from the alternator. THEN, I will also be able to do a reverse charge to my Leisure batteries using the Orion. So if Leisure batteries get low, I can charge from the Lithium.

I know this will be strange to some, but both my T6 and MoHo could be below 5 degrees, so, I think, this gives me the best of all worlds.

Bison battery box on order and a couple of DPDT switches along with some Anderson connectors next and I think I am good to go....

 

[OllieGBR]

And I will finish this time before publishing....

Once it is built I will charge in the house before venturing out. I will be fitting a Victron Orion and wiring in to both the T6 and my Motorhome so I can charge on the go from the alternator. THEN, I will also be able to do a reverse charge to my Leisure batteries using the Orion. So if Leisure batteries get low, I can charge from the Lithium.

I know this will be strange to some, but both my T6 and MoHo could be below 5 degrees, so, I think, this gives me the best of all worlds.

Bison battery box on order and a couple of DPDT switches along with some Anderson connectors next and I think I am good to go....

@BigDean Looking forward to seeing that progress, interesting project

 

[OllieGBR]

A little more time managed over the weekend.
Again, I'm no expert and making this up as I go along - using the forum's input and guidence.

After ripping everything out I added two heat pads to the aluminum plate and one to the side. Wrapped the lot in one layer of foam insulation.
Put everything back together adding fuses to the cable runs and separating the battery out, (via the battery protect) and battery in, (DC-DC charger, external solar, MPPT and AC-DC charger).
I remade every single cable and got much better at using the hydraulic crimping tool I purchased. I added nylon armour to the cables rather than the bulky plastic corrugated tubing. That is fiddly and adds time but it's worth it.
I added heat shrink onto every connection too. Maybe overkill, but makes me happy.

I built a small platform for the fused battery protect and mains switch to sit on. This is now revision 3, as I found an off-cut from the cupboards.


I put the battery 'out' into a separate fuse box rather than use the existing CBE.
Here I have power for the heat pads, temperature solenoid, Bluetooth temperature sensor shared with MPPT, Planar diesel heater, Water heater and other ancillaries.


On the left hand side I have my common earth for everything.

I then added my new edition of a BMS monitor for the Renology battery. This has the ability of completely shutting down the battery from an easy location. It also displays current, SOC, voltage and Watts/ Amps.

I then cut these into the panel and wired up


I'm going to run a test shortly. The battery temperature is -2C

 

[OllieGBR]

Right, test over. I'm super happy.
Started at -2C and took some photo's over the next 70 minutes


The solenoid switched off the heater. 45W for ~70 minutes.
I'm not worried about the small power drain, as the whole reason to have this option to heat the battery is I'm going to be ready to charge it, (for example going for a drive where the DC-DC charger would kick in).

Happy Days
Ollie.

 

[Whiz]

Right, test over. I'm super happy.
Started at -2C and took some photo's over the next 70 minutes
View attachment 102579View attachment 102580View attachment 102581View attachment 102582View attachment 102583

The solenoid switched off the heater. 45W for ~70 minutes.
I'm not worried about the small power drain, as the whole reason to have this option to heat the battery is I'm going to be ready to charge it, (for example going for a drive where the DC-DC charger would kick in).

Happy Days
Ollie.

@OllieGBR - looks very impressive well done. Just wondered if you had a view with this severe weather should I be covering the "Flexible solar panel" with anything.... have gently been clearing the snow off daily - but going to be -9c tonight - so would you do anything else to protect it?

 

[OllieGBR]

@OllieGBR - looks very impressive well done. Just wondered if you had a view with this severe weather should I be covering the "Flexible solar panel" with anything.... have gently been clearing the snow off daily - but going to be -9c tonight - so would you do anything else to protect it?

I've done nothing with mine, I've had solar on my [house] roof for 5 years and don't even clean them. I gently cleaned my panel in the summer but they are extremely robust and my only worry is from low hanging tree limbs when out driving.
I have an isolator on my panel input to MPPT, and have this switched off for the moment anyway.

 

[Whiz]

I've done nothing with mine, I've had solar on my [house] roof for 5 years and don't even clean them. I gently cleaned my panel in the summer but they are extremely robust and my only worry is from low hanging tree limbs when out driving.
I have an isolator on my panel input to MPPT, and have this switched off for the moment anyway.

Many thanks @ OllieGBR, Have you switched off Isolator because Van not being used or some other reason?
Sorry I am new to this and been leaving my Solar Panel feeding the Leisure battery and keeping the USB live, and Hifi fitted in back back so we have a Radio/CD's in the back etc etc. I also have an isolator fyi.

Thanks Ollie for your answer on covering/cleaning etc.

 

[OllieGBR]

Many thanks @ OllieGBR, Have you switched off Isolator because Van not being used or some other reason?
Sorry I am new to this and been leaving my Solar Panel feeding the Leisure battery and keeping the USB live, and Hifi fitted in back back so we have a Radio/CD's in the back etc etc. I also have an isolator fyi.

Thanks Ollie for your answer on covering/cleaning etc.

It's off for that reason, I'm not using the van
It's fine to leave it on IMHO - as long as your leisure battery is lead based, (if Lithium then shouldn't charge below 5C).
We're all new to this at some point

 

[Whiz]

It's off for that reason, I'm not using the van
It's fine to leave it on IMHO - as long as your leisure battery is lead based, (if Lithium then shouldn't charge below 5C).
We're all new to this at some point

Thanks @OllieGBR especially the tip on Lithium charging .... another thing I have learnt on here! Cheers.

 

[srprose]

I’m intending to put the original lead acid battery back in our van once the temp drops in say November and keep the Lithium indoors over the winter. Not perfect but takes the worry of something going wrong away.

 

[Dellmassive]

I’m intending to put the original lead acid battery back in our van once the temp drops in say November and keep the Lithium indoors over the winter. Not perfect but takes the worry of something going wrong away.

What lifepo4 have you got?

Most modern units have "charge blocking below 0degc" built into the bms.

Drawing from the Battery below 0 is fine, it's just charging below 0 is not good.

...

Eg Renogy, Poweroad, etc have this built in.

 

[Ayjay]

All this talk reminds me that I've got a mains powered heat pad somewhere in the loft that used to sit under a pet bed on the cold kitchen floor in the winter. TBH, I can't remember how much power it uses or how warm it gets but it certainly did the job for our ageing cat at the time. Would it be a really stupid idea to put it in the unventilated black hole by the wheel arch that the van electrics (inc. Roamer Smart Battery) are installed during the really cold periods. That said, the van doesn't get used for camping when it's really cold and as @Dellmassive says, the BMS should take care of things anyway.

 

[Dellmassive]

All this talk reminds me that I've got a mains powered heat pad somewhere in the loft that used to sit under a pet bed on the cold kitchen floor in the winter. TBH, I can't remember how much power it uses or how warm it gets but it certainly did the job for our ageing cat at the time. Would it be a really stupid idea to put it in the unventilated black hole by the wheel arch that the van electrics (inc. Roamer Smart Battery) are installed during the really cold periods. That said, the van doesn't get used for camping when it's really cold and as @Dellmassive says, the BMS should take care of things anyway.

I wouldn't bother.

The roamer has charge blocking below 0degc built in.

The batteries with heat pads normally are powered from an incoming charge power, so they don't self consume power.

And if you was to use heat pads smallest wattage is best.....or you might end up as @RoamerBatteries says.

It's like "Pan frying a frozen chicken....." Or have a massive temp differential between the outside of the cell block and the middle, so it's to not bother for UK use.

Most ppl in the UK will have the battery fitted internally and will have some form of heating in the van.

If your worried about the solar kicking in on a bright chilly winter morning charging a frozen lithium then just disable the solar charger....

But as mentioned above most modern lithiums have cold charge blocking built in.

 

[srprose]

What lifepo4 have you got?

Most modern units have "charge blocking below 0degc" built into the bms.

Drawing from the Battery below 0 is fine, it's just charging below 0 is not good.

...

Eg Renogy, Poweroad, etc have this built in.

Ecoworthy 100AH. Don’t think it has charge blocking, I could be wrong though..

 

[Dellmassive]

Hmm.. sec and sheet doesn't specify.

It just says don't charge below 0.

That would need testing.

...




...

 

[srprose]

All this talk reminds me that I've got a mains powered heat pad somewhere in the loft that used to sit under a pet bed on the cold kitchen floor in the winter. TBH, I can't remember how much power it uses or how warm it gets but it certainly did the job for our ageing cat at the time. Would it be a really stupid idea to put it in the unventilated black hole by the wheel arch that the van electrics (inc. Roamer Smart Battery) are installed during the really cold periods. That said, the van doesn't get used for camping when it's really cold and as @Dellmassive says, the BMS should take care of things anyway.

funnily enough I have the same, was thinking of this as well, but the hassle of mains hookup on our drive is probably not worth it for us. Another idea is to just disconnect the leisure battery in the cold temps

 

[srprose]

Hmm.. sec and sheet doesn't specify.

It just says don't charge below 0.

That would need testing.

...

View attachment 217304View attachment 217305


...

Yes, they are cheap and I guess you get what you pay for!

 

[Dellmassive]

Yes, they are cheap and I guess you get what you pay for!

Very true.... But it's a cheap and easy feature on a BMS board....

I'd like to see some testing.
.. I might get one as they are cheap ATM.?