TEC battery water heater/cooler

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joromy
Posts: 367
Joined: Fri Jun 28, 2019 12:56 pm

TEC battery water heater/cooler

Post by joromy »

Made a new topic on the TEC battery heater/cooler. Because it may not be very interesting or a little off topic.

Have used this for a few years now.
Did actually expect it to fail, but no, it works!
I first ran it directly on HV turning it ON/OFF with a SSR, but it gave to much stress on the peltier elements. They don't like PWM either.
So I went for a adjustable 250VDC PSU, this way it can be run directly on AC when plugged in, and from battery pack when unplugged.
The power is rather small 1.5kW pluss the peltier added "free" energy.

There are two water loops, one for the battery and the other is using the original cooling loop for motor, inverter DC/DC and Tesla charger.
Had it for two winters now, and It keeps the battery warm from day to day with very little power.

This is first test setup:
20180119_114119.jpg
Thomas A. Edison “I have not failed. I've just found 10,000 ways that won't work"
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joromy
Posts: 367
Joined: Fri Jun 28, 2019 12:56 pm

Re: TEC battery water heater/cooler

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I made it from 20mm aluminium.
20161207_221438.jpg
Isolated around the TEC with some PU plate.
20161201_174111.jpg
Conductive "sheet" added. And mounted temp sensor on the first and last TEC.
20161212_171705.jpg
Mounted the TEC's in series.
20161212_142603.jpg
Test connected to battery pack, the ising was a problem, the first TEC's died after a while.
Probably because of wet and 300VDC don't work well :) And to much PWM test, they don't like that either.
20170330_131535.jpg
Mounted in water tight enclosure. No condensing at all. Also put in some Silica dry-packs.
20171123_203324.jpg
Thomas A. Edison “I have not failed. I've just found 10,000 ways that won't work"
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joromy
Posts: 367
Joined: Fri Jun 28, 2019 12:56 pm

Re: TEC battery water heater/cooler

Post by joromy »

Some efficiency consumption test:
There is 10C outside, and I increase the temp to 20C in the battery pack.
Have a AC wattmeter on the perltier heater PSU and on the 12V PSU for the water pumps.

This draw 650-700W for 15min, and then it stabilizes on 35-50W.
I think this is pretty acceptable!?

I don't know if a'm going to have it on all time or just before charging.
The temp is not very often under zero degrees Celsius outside.

I have not run the main fan (engine coolant radiator) yet, because that uses huge power, 15A/12V on LOW!!!???
On full I can probably use it as traction if the main engine fails :)

The best would be to have a waterflow/temp gauge to find the efficiency of the peltier elements (COP)
Thomas A. Edison “I have not failed. I've just found 10,000 ways that won't work"
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joromy
Posts: 367
Joined: Fri Jun 28, 2019 12:56 pm

Re: TEC battery water heater/cooler

Post by joromy »

Have "finished" the code for the battery heater/cooler. Have put the control for it in the main ECU/display unit.
It can now run from the EVSE in AC only mode, with all the DC contactors off.

https://github.com/jomy-tech/Teensy-CAN ... ller-in-EV
Thomas A. Edison “I have not failed. I've just found 10,000 ways that won't work"
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joromy
Posts: 367
Joined: Fri Jun 28, 2019 12:56 pm

Re: TEC battery water heater/cooler

Post by joromy »

It's mounted where the original charger was, together with a small coolant reservoir.
Tesla chargers are installed inside the truck.
IMG_20200507_150433_1.jpg
Thomas A. Edison “I have not failed. I've just found 10,000 ways that won't work"
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