Cold Weather Performance (power/regen)

A cold front came through last night, dropping a little snow and providing Potsdam with its coldest morning so far this year (about 7F/-14C).

I _thought_ I noticed some reduction in both power output and regen level.

I almost always drive in E mode, occasionally using B to "downshift" coming up to a stop. I'm 90% sure that regen was reduced this morning as I let off the throttle.

I'm only about 50% sure of the reduced output, although when I floored it, there was still plenty of response.

Nothing different this morning other than the thermometer- car garaged, pre-heat on for about 10 minutes before leaving. Fully charged, RR at departure 71 miles/56 miles when heat came on.

Sandange, did you go out this morning?

The car does have traction control which works kinda like ABS, but with the motor instead of the brakes. On slippery surfaces, it would reduce the regen I think

Don

Don said:

The car does have traction control which works kinda like ABS, but with the motor instead of the brakes. On slippery surfaces, it would reduce the regen I think

Don

Click to expand...

The effect was the same even on bare pavement, so it wasn't the ABS.

On a related note, so far on snowy roads, it's pretty hard to get the rear wheels to spin- the traction control lights up and keeps the excitement to a minimum.

One of these days I need to go find an empty snowy parking lot and turn the traction control off and relive my rear-wheel-drive childhood for a minute or two...

I also experienced the regen was not as aggressive in the cold temps.
It was slippery at a few stop signs and the traction control bucked a few times getting my attention.

What was the temperature on your instrumentation?

According to our cold temperature chart -15 is when you are going to be seeing that reduced regen and a 30% power reduction. If you felt it, you probably were at that threshhold.

So far in Niagara we have only experienced -1C down here. I'm feeling for you two up in the real cold zones. :|

Temp was around -15C or -16C before I left .

Too much trouble to toggle through the gauge while driving, They've got to fix that.

We had some -6C or 21F last night. Other cars produced smoke and sputtered but our i-MiEV performed great. Yes we see the batteries dont like it at the first moment but they come to live almost immediately except when charging. Charging takes longer.

We are living 1/3 from the top of the hill (230 meters above sea level) and we usually have to go up and down the other side. When we get down batteries are more than filled to the rim and I have to use the breaks because regen stops working.

Right now regen works because the heater takes care of that. :twisted:

I am usually driving in "B" and yes it feels a bit softer but not for long.

Hi all,

I believe the that the car protects the batterys at the extream ends of the temp operation. Not sure of the numbers on the hot side but I think the cold side is -15 Deg C 20% power reduction and -25 Deg C 50% reduction and that applies to regen as well.

It also looks like this power reduction is based on the dash temp sensor. I'm saying that because the dash sensor reactions very quickly to moveing the car from inside to out but I'm sure the actual battery temp does not change too much in the same period of time. If your car is in a garage and you experiance the power down just after leaving it would seem that the computer is using the dash temp decide to reduce power. This to me is very conservative and probably the best thing for the batteries.

I wonder which temp sensor it uses for the battery charging logic ? Anyone know ?

Don.....

hi all,

lately I've started to notice the regen kicking out during sharp turn, as if a function of lateral acceleration. It's CA here so I don't think 40-50F is "cold". I don't recall noticing lost of regen in the past, though in the past I usually leave the house (at 2200-ft) with the pack rather full so the lack of regen was due to full SOC. But lately I've surrendered to try to do my 50-mile commute with just home charging, so I leave partially charged and thus started to notice the lost of regen coming down around those rather sharp turn. Speed is only around 15-20 mph. Has any one notice this ? may be it's behaving normally as regen resumes pronto once the road straight out.

Thanks

Paul, that's normal behavior on our bumpy California roads, especially in your neck of the woods. I get this all the time - a long sweeping downhill curve with a few bumps and regen cuts out, often accompanied by random ABS activity. Try the same road with ASC turned off.

Hello all, it was -24c yesterday and the car regen worked normally.

I agree with Joe observation that the regen will definitely kick out when going down sweeping hill with bumps.

I get this from time to time in the Montreal area when coming off a highway to a secondary artery via a long downward curve road ... the regen cuts and the abs will flash.

Imiev engineers definitely design the car to be nervous with its safety features kicking-in quickly when it thinks the car is getting into trouble.

Brian

thanks, good to know to watch out of the sudden loss of regen since it's cold enough here now for icy road.

JoeS said:

Paul, that's normal behavior on our bumpy California roads, especially in your neck of the woods. I get this all the time - a long sweeping downhill curve with a few bumps and regen cuts out, often accompanied by random ABS activity. Try the same road with ASC turned off.

Click to expand...

Probably the car is trying to avoid overloading the grip of the rear tires.

Depending on the condition of the car's shock absorbers, it's really common for a tire to momentarily lose contact with the road surface with even a moderate irregularity in the road's surface - It happens to some degree even on a new car with new shocks. 99% of the time the driver doesn't feel it so he/she has no idea it's happening, but I'm sure the car's regen programming does - The regen should kick out when the car detects any wheel isn't turning as fast as it should be . . . . because it's momentarily lost contact with the road surface

It happens way more times than you would guess . . . . probably several times per mile if you have worn shocks. The #1 job of a modern automotive shock absorber is to keep the tire in contact with the road

Occasionally when following a car with 100K plus on it you can actually see daylight between a tire and the road over a rough surface - The shocks are shot and the rebound of the wheel/tire is uncontrolled, so the wheel/tire may lose contact with the road 2 or 3 times as a result of a single bump the car went over 10 or 20 feet back - The bump sets up an oscillation and the shock isn't dampening it

Shot shocks make for a comfy ride, but they're definitely a safety factor as the vehicle can't accelerate, decelerate or change direction nearly as well as it should with one or more tires up in the air!!

Don

Indeed, that traction loss on the rear axle during regen is the most discombobulating part of driving the car in wet weather. My wife drives so sedately that she hadn't experienced it at all, until recently in the passenger seat. :roll: "Ack, what's that!"....

OF course, it was all for her educational benefit...

Now for my educational benefit. Don, is there a test for when to replace the shocks more scientific than pushing down on the bumper and watching the rebound? (and looking for fluid leaks)
The KYB website recommends replacement every 50k miles, on average...

I'm about to rebuild the struts on our minivan as they are one of the only remaining 'wear parts' in the suspension that hasn't been touched in the last 60k.

There isn't a good test that I know of other than putting them on a shock dyno. How long they last largely depends on how good the shock was when new, how many miles you have on them and what sort of road surfaces you drive on

Most factory OEM shocks aren't of the best quality, so 50K miles is probably a reasonable life expectancy. I usually change my shocks somewhere between 60 and 75K and I always use a better than stock replacement, but then I frequently keep cars for 150K or so. Great shocks and good tires are always cheaper than new fenders . . . . or worse

Sadly, probably 80% or more of vehicles with 100K plus on them are still bouncing along on their OEM shocks

Don

Mine does it too, even on a level road. Since I drive the same back roads every day, I know when I will hit ones that kick out the Regen. I have gotten used to it.
You just learn to plan for it. Once you get the hang of it, it's not so bad... if you are paying attention