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Discussion Starter · #1 ·
After driving my Karma for 1400 miles so far, often on the same route, it's becoming very clear that range is very much influenced by outside temperature and by the battery temperature.

When I got the car, it was 5 to 8 Celcius outside and I got to 35-38 miles (highway travel at 70 mph), after that it dropped to -5 to -15 Celcius (the coldest winter for us in many years) and my range dropped to 28-30 miles.

Something interesting: on the way to my business in the morning I get less range than on the way back in the evening. First I thought it had to do with the outside temperature, but even if there is no difference in temperature (or wind), there is a notable difference in range. Then I realized that in the morning the car hasn't been charging for a whole night (it usually finishes at 1 AM in the morning). On the way back it has just finished charging, maybe 15 minutes or so. The battery probably is still hot from charging and I guess that's what makes it go 10-15% further on a full charge.

I can't wait for spring and summer to see how much further it will carry me. I'm confident that even without regenerative braking (I hardly ever have to brake on the highway) I can get to 45 miles.
 

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Dutch said:
When I got the car, it was 5 to 8 Celcius outside and I got to 35-38 miles (highway travel at 110 mph), after that it dropped to -5 to -15 Celcius (the coldest winter for us in many years) and my range dropped to 28-30 miles.
Do you mean 110 km/h? 110 mph (177 km/h) would be quite fast even for Netherlands
 

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A few things:

1. Out and back ranges for me are different too, but it has nothing to do with temperature. My house is at about 950ft. elevation and downtown is about 700ft. Therefore, I get better mileage (by around 4 to 7 miles per charge) going downtown than coming home. Hills have a *huge* effect on battery range. Even the slightest incline causes the battery to drain super-quick.

2. I noticed that if I take the car out immediately after pulling the plug on the charger while it was still charging - hence warm batteries from charging - I get better initial range out of the gate. For example, if I start up the car totally cold, I lose 1 mile of range just for backing out of my driveway (100 feet). By the time I get to the big intersection about ~3.5 miles down the road I'm almost always at exactly 41 miles of range (because most of that is uphill). But if I do the exact same drive with warm batteries the car will usually say 43-44 miles at that intersection, and it at least lets me get to the end of my road before it drops from 50 to 49.

-Brian
 

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Discussion Starter · #4 ·
svp6 said:
Dutch said:
When I got the car, it was 5 to 8 Celcius outside and I got to 35-38 miles (highway travel at 110 mph), after that it dropped to -5 to -15 Celcius (the coldest winter for us in many years) and my range dropped to 28-30 miles.
Do you mean 110 km/h? 110 mph (177 km/h) would be quite fast even for Netherlands
You're right, 70 mph. I fixed that. It's sometimes a bit confusing with kilometers/miles, celcius/fahrenheit, dollars/euros :-/
 

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Dutch said:
You're right, 70 mph. I fixed that. It's sometimes a bit confusing with kilometers/miles, celcius/fahrenheit, dollars/euros :-/
At least the conversions between the first two pairs are always the same! :) Every time I go to NZ the US$/NZ$ conversion rate is different. I finally opened an NZ bank account a couple of years ago, except I waited one year too long: I could have got in when US$1 was NZ$2, instead of when US$1 was NZ$1.35. Ah well. (And now I only get NZ$1.20... haven't made it there yet this year though, and won't any time soon, too busy locally.)

If the Euro implodes, you'll be back to Guilders? :D
 

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brian said:
A few things:

1. Out and back ranges for me are different too, but it has nothing to do with temperature. My house is at about 950ft. elevation and downtown is about 700ft. Therefore, I get better mileage (by around 4 to 7 miles per charge) going downtown than coming home. Hills have a *huge* effect on battery range. Even the slightest incline causes the battery to drain super-

-Brian
I have the same thing happen to me when I take the kids to school every day. It's up hill going to school and it uses 9 miles of range. But I only use 2-3 miles of range coming home. It's pretty cool how the works.
 

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Discussion Starter · #7 ·
ct-fiskerbuzz said:
Dutch said:
You're right, 70 mph. I fixed that. It's sometimes a bit confusing with kilometers/miles, celcius/fahrenheit, dollars/euros :-/
At least the conversions between the first two pairs are always the same! :) Every time I go to NZ the US$/NZ$ conversion rate is different. I finally opened an NZ bank account a couple of years ago, except I waited one year too long: I could have got in when US$1 was NZ$2, instead of when US$1 was NZ$1.35. Ah well. (And now I only get NZ$1.20... haven't made it there yet this year though, and won't any time soon, too busy locally.)

If the Euro implodes, you'll be back to Guilders? :D
I finally stopped the habit of calculating everything back to guilders (euro x 2.20371). If the euro fails I would have to start all over again with the calculations :dodgy: But it won't :cool:
 

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This morning was the coldest it has been here since I got my car, and my battery range was awful. I only made it about 30 miles before it was done.
 

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flying dutchman said:
How cold is cold?
Oddly, not that cold. Only like 35º. Still, we had the heater on and my girlfriend had her seat warmer on. An observation I've made about this:

1. If the A/C is totally off then the car uses about 1 to 2 kw while idle at a stoplight.

2. If the heater is on it uses 4-5 kw.

3. If the heater + 1 seat warmer is on it's 5-6 kw.

4. The car when running at ~55mph on a flat road uses 15-20kw.

So, that would imply that heating the car chews up around 20-30% of the battery range which would be consistent with what I experienced. Hard to say how much the battery being near frozen also contributed to it tho.

-Brian
 

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brian said:
flying dutchman said:
How cold is cold?
Oddly, not that cold. Only like 35º. Still, we had the heater on and my girlfriend had her seat warmer on. An observation I've made about this:

1. If the A/C is totally off then the car uses about 1 to 2 kw while idle at a stoplight.

2. If the heater is on it uses 4-5 kw.

3. If the heater + 1 seat warmer is on it's 5-6 kw.

4. The car when running at ~55mph on a flat road uses 15-20kw.

So, that would imply that heating the car chews up around 20-30% of the battery range which would be consistent with what I experienced. Hard to say how much the battery being near frozen also contributed to it tho.

-Brian
I like your icon, Brian. Apple just broke $500/share today and you are ES Owner #500 :thumbup:
 

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I see aboout 35kw on a flat highway at 70 mph on cruise control. Which equates to about 34.17 miles range at that speed, considering 15% unusable leaving 17kw of usable battery / 35 kw draw = 0.488 hours * 70 mph. Using brian's worst figure of 20kw @ 55 mph should give about a 46.75 mile range.
 

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yeah, I just got back from dinner and I was trying to get a steady kw number at 55mph. It was really hard, even with cruise control on because the slightest variation in the road causes it to go bezerk. It seemed to be giving me numbers between 15-30kw most of the time. If there's an incline it goes to 35-50kw.

The thing is, however, is is for the "maintenance power" required to keep the car going. Getting from 0 to 55 is where the big drain happens, and hills are pretty darn close to the same power draw. Just getting the car to 55mph from a stop can take 1/4 mile or so of charge off the battery, and you don't get anywhere near the same thing back when you slow down in Hill 2.

The long hill that I have to drive to get out of my neighborhood shows something like 50-70kw on the way up, but in Hill 2 going down the same hill it usually just shows aroune 16-20kw of regen, so like 1/3rd of the power lost going up it gets reclaimed on the way back down.

-Brian
 

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It is my understanding that Hill 1 limits itself to 35 kw of regen without applying the brake and Hill 2 limits itself to 45 kw of regen without braking, when one brakes I have seen regen as high as 75 kw. And as someone else stated, the first 0.5g is all regen and then it starts blending in friction braking. It would be nice to have a g-force meter in the car so that I can keep braking below 0.5 g when possible to ensure maximum use of regen. Until then I usually apply the brake and watch the regen/accel meter and press the brake until I see the needle of the meter go as far left as it goes while increasing the brake pedal pressure, when the needle stops, I stop pressing down further, unless of course I need to apply more braking force not to end up in the intersection or someone's rear end.
 

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kabalah70 said:
It is my understanding that Hill 1 limits itself to 35 kw of regen without applying the brake and Hill 2 limits itself to 45 kw of regen without braking, when one brakes I have seen regen as high as 75 kw. And as someone else stated, the first 0.5g is all regen and then it starts blending in friction braking. It would be nice to have a g-force meter in the car so that I can keep braking below 0.5 g when possible to ensure maximum use of regen. Until then I usually apply the brake and watch the regen/accel meter and press the brake until I see the needle of the meter go as far left as it goes while increasing the brake pedal pressure, when the needle stops, I stop pressing down further, unless of course I need to apply more braking force not to end up in the intersection or someone's rear end.
There is an Android app called 'Accelerometer'. Haven't tried it. May be it will give you some feedback.:dodgy:
 

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kabalah70 said:
It is my understanding that Hill 1 limits itself to 35 kw of regen without applying the brake and Hill 2 limits itself to 45 kw of regen without braking, when one brakes I have seen regen as high as 75 kw. And as someone else stated, the first 0.5g is all regen and then it starts blending in friction braking. ...
The article I read said "0.25g". (Useful in case you find an accelerometer. :))
 

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Discussion Starter · #17 ·
brian said:
2. If the heater is on it uses 4-5 kw.

3. If the heater + 1 seat warmer is on it's 5-6 kw.
That's why the manual advises us to use the seat heating as much as possible instead of the heater. Would have been nice then to have a heated steering wheel too (like the Jaguar XF for instance). Then I would turn off the heater.

It's nice to know that the heater chews up so much battery power. Most of the year I don't need it, so that will automatically give more range (hardly need the A/C either; no Texas heat here).
 

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Yes, I love the heated seats but my hands got quite cold and wished a heated steering wheel was available and I would be happy never using the heater.
 

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kabalah70 said:
Yes, I love the heated seats but my hands got quite cold and wished a heated steering wheel was available and I would be happy never using the heater.
My last car, Jaguar XK, had a heated steering wheel but it was not particularly effective since I used to keep the convertible top open pretty much all the time, even at night. I just kept a pair of good driving gloves in the -- what else -- glove compartment for the really cold nights.

-- Fab.
 
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