[Tremelune]

Does anyone have a converted car with electric air conditioning working well? I'm specifically not interested in belt-driven systems, as the complexity involved with driving them outweighs their low cost.

On the high-end, it's a solved problem with a 15k+ BTU aftermarket compressor for around $1500. There are various 12v compressors (which would put more of a strain on a DC-DC converter than it's worth), and this 400v New Eagle EV36BNx:

https://stealthev.com/product/new-eagle-ev-ac-compressor/

For around $1000, you can control a Denso ES34C with a PWM signal according to this thread:

https://www.diyelectriccar.com/forums/showthread.php/tesla-c-compressor-questions-189978.html

For under $200, you can get a Tesla and Nissan Leaf compressors all day, but...then what do you do with it?

For that money, I'm inclined to spend a few days figuring out how to control an OEM compressor via CAN bus messages. If anyone has any leads, I'm all ears...So far, this is what I have (I have a Leaf compressor):

https://www.mynissanleaf.com/viewtopic.php?t=23038

Worst case, can I bypass all computers and just turn one on/off with relays and what not? Poor man's PWM?

If anyone has any insight into how do to design the rest of the system, well, I'm pretty ignorant there, too...

 

[rob_kr]

I'm in mid-conversion and have spent a good bit of time trying to figure out the AC system. I've got my setup as bench-top right now (still need to work out where the bits & pieces go in the car), but it runs really well.

My donor-car had AC, so I am re-using the coils/radiators that came with the car. I swapped the ICE_driven compressor for a Benling 350V unit. EVwerks sells one http://store.evtv.me/proddetail.php?prod=Benling but it's "only" 27cc / 16,000 BTU which should be totally fine for an average-size EV. My car is too large for this one so I went with the 34cc/22,000 BTU unit direct from the factory in China https://benling.coowor.com/shop/product-detail/20170802102659859QK7IQ7.htm

The scroll-compressor is quiet, and it's simple to run straight off the traction battery. It uses a cheap 12V PWM circuit. I use an Arduino to set fan-speed and compressor speed based on duct temp <> cabin temp (cooling and heating) but almost any PWM circuit will do. Including S&H and tariffs it came to $650.

I did look at the used Tesla compressors, they're all over ebay for $200, but I couldn't find a wiring diagram anywhere. I half-expect them to have a CAN-bus control interface, my project does not, so I let it be.

All in all, for straight AC I would definitely recommend the Benling.

I am trying to get the AC system to also run in heat-pump mode so I can use it for heating and cooling (same idea as the Nissan Leaf), and I'm still figuring out the expansion valve reversal. It shouldn't take much longer to get this to work, but I'm not there yet. Still, compared to the typical 5 kW water-boiler units, the heating capacity should go up and the power-requirement gets cut in half, there's only 1 coil in the fan-duct and no dampers/flappers to move so a pretty elegant under-dash system, it's a very clean setup...

 

[Tremelune]

jkelly steered me towards a Ford compressor which has some CAN and source code:

http://www.ev-guide.com/rx8-conversion-blog/2016/3/9/air-conditioning-can

https://malfunction.faed.name/2013/04/azure-dynamics-air-conditioning.html

https://www.usedpartsrus.com/produc...pressor-a-c-clutch-am6419d623bb-mercury-milan

 

[Downunder55]

I am trying to get the AC system to also run in heat-pump mode so I can use it for heating and cooling (same idea as the Nissan Leaf), and I'm still figuring out the expansion valve reversal. It shouldn't take much longer to get this to work, but I'm not there yet.

Any update on your progress, as this would be a significant step fwd !

 

[rob_kr]

Sorry, I've been buried between working on battery-containment and working around corona-containment.... Will get back on this one as soon as time frees up....

 

[Adam S]

Hi Rob,
I'm also really interested in your findings when you get the chance. I have been after a retro fit solution for my VW T5 camper van that I can use on the road and also when parked up connected to 240V supply at my campsites. This maybe the solution.

Regards
Adam

 

[rob_kr]

Hi Rob,
I'm also really interested in your findings when you get the chance. I have been after a retro fit solution for my VW T5 camper van that I can use on the road and also when parked up connected to 240V supply at my campsites. This maybe the solution.

Regards
Adam

Hi Adam, DownUnder,

some progress but not done yet.

I have the capacity numbers & flow rates on the condenser side figured out based on the Benlinq compressor. A 17"x24" (40cm x 60cm ?) condenser with a 2200 cfm (60 m3/min) fan should be adequate to run the compressor at full capacity in Texas summer (100F/40C). From there, I can get things to run "slower" than peak to save battery/range but in the end that's luxury. As long as the setup can handle the 100% load, a half-load should be possible too.

The cabin end looks like two smaller "radiators", one for heat and one for cold. It's the only way I could solve things to where the flow of gas/liquid through the dryer & compressor wouldn't get messed up. Plus, with this setup I can run hot or cold, and I can run both to get dried warm(ish) air to keep the windows from fogging up. I was stuck here for a while, then found the idea in the image below. I'm not sure where the artwork came from but it was a definite ah-ha moment.

Now it's down to piece-parts. Once I get it all plumbed together I will figure out whether the original expansion valve will work or if I need a different one, but from what I can tell it should be fine (flow, temperature etc), I just need 2 of them now. The open/close electrical valves look very straightforward (as long as they're coolant-proof). I could wire it all directly into the dash switches with a couple of relays, but that'd kill the half-speed option so for now I'm planning on using a few open IO's on the PLC I have to control everything else.

The next round of work is mostly just getting all of it to fit (back) into the car.

The OEM radiator is very close to the minimum calc dimensions (it's 18x26) so I'll try to put that back in as-is. The OEM core support is gone so it's work but not too bad. The major work is figuring out how to get all of the cabin-side parts mounted out of sight. The original heater/AC box sat under the hood and piped in through the firewall, and that space is gone with the battery pack moving in. I'll likely need to make a new fiberglass housing to fit inside the passenger-side fender-well. That looks medium-difficult as long as I use outside air for heat & AC, but getting re-circulation to work will be a major challenge.

Oh well, same as always, you solve one puzzle and win the prize of another one.