David's 2001 Civic EV (80-100 mile range; 65+ MPH; 8 second 0-60)

[TheSGC]

Originally Posted by CFECO

It would be interesting to know if your home electric bill has changed, since your car charging at home began. I know the away charging will not be reflected though. Great work on you car!

If the power bill has changed, my parents haven't complained.


Last week I ran into a strange problem. One of my cells was 100 AH lower than the others, after drawing 80 AH from the pack the MiniBMS through the Low Cell alarm. I recharged the whole pack then threw that cell on the power supply until it hit 3.55v and now its working fine. I have no clue what happened, I'm doing some investigations on possible cell drainage or defect.

[Daox]

Did you capacity test your cells, or just bottom balance them?

[TheSGC]

Originally Posted by Daox

Did you capacity test your cells, or just bottom balance them?

When I first got the pack I top balanced then did a capacity test. I did a single test to 180 AH then I've been limiting myself to no more than 80% (144 ah) for driving since.

[TheSGC]

The batteries all seem perfectly fine now and I don't have a solid explanation for it!

Anyways, I've been driving it a lot recently and now it's time to start working on cleaning up the interior. The interior of the car, like headliner and rear seat, weren't in the best condition. The headliner needs new upholstery or just be replaced.

[Cobb]

I dont think I ever got a good night sleep til I switched the main and bms off on my setup. I never had any problems, but I worried about the what ifs.

[Astro]

Originally Posted by mechman600

I have also contemplated refrigerant compressors for portable A/C units, powered by an inverter. Probably a colossal waste of power.

I was also thinking that a split system A/C unit might be a good idea. With reverse cycle it could do heating as well as cooling. The conversion of electrical power to heat using a resistive wire is 1:1 whereas a good A/C unit will have a conversion of 1:4 or better.
Also with many of the manufacturers touting the benefits of "Inverter" technology surely there is a way to hack an A/C unit to supply DC direct, bypassing their "Inverter" and thereby getting rid of any AC to DC losses?
Put the outdoor compressor under the bonnet, maybe where the radiator used to be, bit of a fiddle adapting the indoor unit into a dash but it could probably be stripped down and maybe use the cars own cabin fan and basically just replace the heater core or A/C core with the split systems indoor unit's core?
I am sure there is a reason why this won't work but i can't see it.

[CFECO]

Air-conditioning requires a mechanical compressor, which you could drive off your drive motor, but instead you want to run an AC compressor off of DC current...? I don't know of any DC powered refrigeration units except for small Ice Chest coolers. Standard automotive AC is a "Split system"...
Perhaps to reduce the power consumed you could drive the compressor with a variable speed drive and regulate the air temp with speeding up or slowing down the compressor mechanically, instead of cycling it on and off as is usually done in normal AC Systems. There is also Absorption Cooling, which uses Heat to make cold, like the Propane RV refrigerators use, while driving they uses an electric heating element to provide the heat, though not very efficiently. Good luck!

[Astro]

Originally Posted by CFECO

Air-conditioning requires a mechanical compressor, which you could drive off your drive motor, but instead you want to run an AC compressor off of DC current...? I don't know of any DC powered refrigeration units except for small Ice Chest coolers. Standard automotive AC is a "Split system"...

The inverter type air conditioners use a rectifier to change the AC to DC then a PWM circuit to generate the varying frequency AC used to vary the compressor speed.
I was suggesting that if using one of these inverter systems it may be possible to put DC direct to the PWM circuit bypassing the rectifier section.
Air conditioner inverter - Wikipedia, the free encyclopedia

Running an A/C compressor from the cars drive motor will probably result in the same/similar overheads as the motor draws more kw/H to turn when loaded by the A/C compressor. Also driving the A/C compressor from the drive motor means that it only operates whilst moving (unless the motor is set to idle).

Running the compressor via the A/C's own PWM circuit direct from the traction pack (batteries) would allow it to run whenever needed. This would be very important for me as my daily commute is in very stop/go traffic with long periods waiting for traffic to clear and with no A/C it would get hot real quick. (During summer there are many days that the outdoor temperature goes over 110F).

So i saw the advantages as :
Runs when needed.
Doesn't rob the drive motor of capacity. (A 20hp motor doesn't have a 3hp load on it)
Inverter technology units use constantly variable drive so no large on/off loads which may be felt through reduced drive motor output. (I can feel the impact of the A/C switching on and off even on cars running on internal combustion)
Is reverse cycle so it solves the heating and the cooling for the vehicle.
May be able to pre-heat/cool the car whilst still in the garage and connected to the mains.
Another advantage is that the inverter systems seem amazingly quiet. My residential A/C is whisper quiet, both internal and external units. Whereas the A/C on my ICE car has a fan that roars so loud in operation it almost drowns out the ICE noise, when standing at the front of the vehicle.

With everyone making suggestions on a heating system i just thought that the inverter A/C system was worth mentioning.

[CFECO]

"The variable-frequency drive uses a rectifier to convert the incoming alternating current (AC) to direct current (DC) and then uses pulse-width modulation in an electrical inverter to produce AC of a desired frequency. The variable frequency AC drives a brushless motor or an induction motor. As the speed of an induction motor is proportional to the frequency of the AC, the compressor can now run at different speeds."
I see, so you would put the DC into where it would have been created in the original inverter. I've never heard of these, been out of that business about 20 years. Then the DC is converted to AC to run the motor at various speeds, that drives the compressor...mechanically. It sure seems like a lot of convertin goin on, to drive a mechanical compressor. Small DC motor running the compressor slowly at stop, and driveline drive when moving with a mechanical variable speed drive. Hmmm....?

[Astro]

I just thought of another advantage if it was possible to fit an inverter type A/C.
Because it is totally separate to the controller and motor you don't need to have included it in the original design. It could be retrofitted to an existing set up.
Especially for those that have fitted a single ended shaft motor.
I imagine the existing vehicle A/C evaporator and blower could be re-used but the expansion valve would have to be changed to a reverse cycle type expansion valve (works in both directions). So really you would only need the outdoor unit as long as it didn't rely too much on the electronics of the indoor unit.
I had better stop derailing David's thread. I will investigate this further and if i have more information to share i will start a new thread.