The Corolla has been very reliable for the 850km that I have driven so far. During this time I have not had to use my gasoline powered car at all so I took it off from street use. The trips outside corolla's range can still be made by my wife's diesel car, so no problem there.
I'll try to use the corolla on my everyday driving through the whole winter. It will not be easy though. So far -7 degrees celcius is the lowest temperature that the car has faced and that time it survived from work to home. The low temperature increases friction due to gearbox oil which had a remarkable effect on driving. To minimize that effect I searched for the lowest viscosity oil at cold temperatures from local shops filling API-GL4 requirements. After a careful search I decided to use Redline D4 ATF oil that can be used in both automatic and manual gearboxes. After the oil change a good improvement could be noticed at below freezing temperatures while no difference could be noticed on warmer days. I do not know which oil the corolla had before, but most likely it was mineral oil that gets very stiff on cold days.
As the temperature drops so does lifepo4 battery performance as well. The unloaded cell voltage is not affected much, but the internal resistance of the cells is increasing remarkably as temperature decreases. The battery pack is so well cooled in its current location that I am thinking of insulating the battery pack thermally so that their internal losses would increase the cells temperature hopfully to a better working level. Otherwise I am expecting the PCM to shut down the operation at around -20 degree celsius due to too low cell voltage on a long uphill where 200-300 amps are drawn from the batteries for quite a long time.
Despite the very cold driving experience I very much enjoy driving the corollaefx. The 300W windshield heater has been great to keep the windows clear but it definitely does not warm the cabin!
1 comment:
If you do bottom balance, you don't have to stop until average cell voltage reads around 2 volts per cell under load. Actually what happens on my motorcycle is that I've set the controller low limit to 50 volts (2 volts per 25 cells) and the controller will throttle down when that gets reached. Even the batteries themselves cannot provide much current when they're empty so the vehicle will stop by itself anyway. If they're bottom balanced no harm can be done since none of them have any punch left to drain their buddies either. This is opposite from top balancing in which better cells will kill their weak friends unless you stop them in time.
Post a Comment