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Discussion Starter · #1 ·
What happens if you let the battery drain right down to 0 miles?

I worry because even in Sport mode the battery seems to drain just a little.
 

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You're then powered by the ICE... which limits the power to a peak of 260hp, so your 0-60mph times will likely be around the 8s mark rather than the 6s in true 'Sport' mode.
 

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SoCalGuy said:
You're then powered by the ICE... which limits the power to a peak of 260hp, so your 0-60mph times will likely be around the 8s mark rather than the 6s in true 'Sport' mode.
Yesterday I learned from one of the mechanics that the engine only runs at a few different RPM levels. They found that at 2400 rpm the generator was producing 97% of the current that it produced at 6000 rpm. This is one of the ways they reduced the noise from the ICE.
 

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dennis said:
SoCalGuy said:
You're then powered by the ICE... which limits the power to a peak of 260hp, so your 0-60mph times will likely be around the 8s mark rather than the 6s in true 'Sport' mode.
Yesterday I learned from one of the mechanics that the engine only runs at a few different RPM levels. They found that at 2400 rpm the generator was producing 97% of the current that it produced at 6000 rpm. This is one of the ways they reduced the noise from the ICE.
...and probably much more fuel efficient at that lower RPM...
 

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bigdaddyo811 said:
What happens if you let the battery drain right down to 0 miles?

I worry because even in Sport mode the battery seems to drain just a little.
Even at 0 Miles, the battery still has around 15% charge in it according to the battery SOC meter in the instrument cluster. I think the car "borrows" from that reserve for better performance and to give the ICE time to start up and come to speed, and the generator than pays it back when it is generating power so that the reserve stays constant. I don't think you ever want to see the battery SOC meter (as opposed to the "miles to go" meter) get close to zero.

-- Fab.
 

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Fabulist said:
bigdaddyo811 said:
What happens if you let the battery drain right down to 0 miles?

I worry because even in Sport mode the battery seems to drain just a little.
Even at 0 Miles, the battery still has around 15% charge in it according to the battery SOC meter in the instrument cluster. I think the car "borrows" from that reserve for better performance and to give the ICE time to start up and come to speed, and the generator than pays it back when it is generating power so that the reserve stays constant. I don't think you ever want to see the battery SOC meter (as opposed to the "miles to go" meter) get close to zero.

-- Fab.
I can't imagine that Fisker would allow you to have the battery deplete fully to zero - in fact, its odd that they would display its true state of charge. My recollection in the gas analog world is that when your fuel gauge reads "empty" it actually still has 1-2ish gallons on reserve or so... I would presume Fisker would be smart enough to do that in the battery analog too!
 

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Discussion Starter · #7 ·
My dealer told me all the problems with stranded cars etc.. occurs if you let the miles go below 5m and told me not to do so.

I assume even if your battery (miles left) goes to zero, you should be able to drive the car around indefinitely in sport mode?
 

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SoCalGuy said:
Fabulist said:
bigdaddyo811 said:
What happens if you let the battery drain right down to 0 miles?

I worry because even in Sport mode the battery seems to drain just a little.
Even at 0 Miles, the battery still has around 15% charge in it according to the battery SOC meter in the instrument cluster. I think the car "borrows" from that reserve for better performance and to give the ICE time to start up and come to speed, and the generator than pays it back when it is generating power so that the reserve stays constant. I don't think you ever want to see the battery SOC meter (as opposed to the "miles to go" meter) get close to zero.

-- Fab.
I can't imagine that Fisker would allow you to have the battery deplete fully to zero - in fact, its odd that they would display its true state of charge. My recollection in the gas analog world is that when your fuel gauge reads "empty" it actually still has 1-2ish gallons on reserve or so... I would presume Fisker would be smart enough to do that in the battery analog too!
That's correct if you are draining the battery by driving the car. However, if the car has spent a lot of time turned off, for example, sitting on a ship for a few weeks, then sitting at the port for another couple of weeks and then spending two weeks on a transport, the battery charge my dissipate and the computer can't do anything about it because the car is turned off. Now if the car is not properly charged before you attempt to use it, you may be in for a world of hurt, as I briefly experienced when I picked up my car on Saturday. As long as you drive and/or charge the car regularly, there should be no problem.

-- Fab.
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bigdaddyo811 said:
My dealer told me all the problems with stranded cars etc.. occurs if you let the miles go below 5m and told me not to do so.

I assume even if your battery (miles left) goes to zero, you should be able to drive the car around indefinitely in sport mode?

siliconkiwi said:
I drove around in Sport with the battery at 1 mile for about 20 miles, with no problems (touch wood)
I drove my car all the way down to 0 in Stealth mode for 25+ miles yesterday and nothing bad happened. The generator comes on when the battery gets low enough and the car keeps on going. I did not even have to switch to Sport mode. The car knew what to do.

-- Fab.
 

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Discussion Starter · #10 ·
When I drive in SPORT, the battery slowly decreases. Doesnt that mean that if you drive around for a long time with the battery miles at 0 that you will run into problems as the battery will completely run out and the car will be dead?
 

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bigdaddyo811 said:
When I drive in SPORT, the battery slowly decreases. Doesnt that mean that if you drive around for a long time with the battery miles at 0 that you will run into problems as the battery will completely run out and the car will be dead?
No, you can continue to drive as long as you have gas in your tank. The engine-generator combo generates enough elecricity to run the car without any help from the battery (this is the "charge depleted mode") The amount of power available to the motors will be reduced so you will not get full sport mode performance, but in theory you could drive the car coast-to-coast stopping only for gas without ever recharging the battery, even if it's at zero. While it may not be technically true due to continuity, theoretically the car would run in this mode even with the battery removed.

There seems to be some consensus however that manually switiching into sport mode while you still have some remaining charge (say 10 miles to go) is preferable. This will put you in "charge sustaining" mode, meaning the engine-generator will pump out enough power to operate the car AND maintain the current charge level.

Sport mode does not replenish your charge level (it used to in pre-production vehicles but was changed) but it will maintain the charge level you have. (Although there appear to be some tricks you can play with Hill mode to actually increase your available stealth range back up to about 26 miles. Look around for a thread describing this method)

You shouldn't have any range anxiety. That's the whole point of the EVer powertrain.


Brent
 

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LonePalmBJ said:
No, you can continue to drive as long as you have gas in your tank. The engine-generator combo generates enough elecricity to run the car without any help from the battery (this is the "charge depleted mode")
My experience this Saturday was that with an almost fully depleted battery (below the 15% threshold), even with a full tank of gas, the car refuses to start up at all in either mode. The battery in this car acts like a flywheel and smooths out the flow of electricity to the drive motors. It the battery charge level dips low enough, the car stops working, even with a full tank of gas. Obviously, my situation was unique and the computers in the Karma would not allow that scenario to develop under normal operation, but without some charge in the battery, I don't think the car can function.

-- Fab.
 

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Discussion Starter · #13 ·
Why is this unique to you?

These are the stories my dealer told me about and why not to drop below 5. What concerns me is that at 10 when I go into sport the batter miles keeps on dropping. I haven't seen it go to 5 because I haven't driven that far but I'm afraid if I'm making a long trip it runs so low or drained that the car won't start even in sport
 

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Fab- that's news to me. I think since the car starts in Stealth by default, if there is insufficient charge in the battery, perhaps the system isn't yet smart enough to start the ICE rather than try to start on battery only.
 

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I'm with Brent -- the whole point of EVer is that there is no range anxiety. The car must be able to function fully without miles left on the battery. There may be some software issues getting in the way right now, but clearly anything other than full functionality would be a HUGE issue for Fisker's main marketing claim.
 

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bigdaddyo811 said:
My dealer told me all the problems with stranded cars etc.. occurs if you let the miles go below 5m and told me not to do so.

I assume even if your battery (miles left) goes to zero, you should be able to drive the car around indefinitely in sport mode?
When I picked up my car from the dealer it only had 1 mile of battery range and I was able to drive it no problem in Sport all day (approx 100 miles).
 

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When the car reads 0 miles battery range the charge on the battery should be about 15%, you can see this if you plug it in and watch on the Energy Flow screen of the System page. I have also done some driving around with the Energy Flow screen up and in Sport it will actually provide up to +10kw +/- 4kw on the generate side, if the car is not currently demanding it. I also floored it in Stealth and it read -179kW which is nice to know that the battery is providing the stated 180kW. I couldn't get a long and safe enough run to see what Sport shows, but I did try it, and it seems to me that the bottom level meter is battery power, so with Sport engaged and the pedal to the floor, I am imagining that I will see the meter read between -180kW, if it lets the battery provide the brunt of the power leaving the gen to produce one 120kw, or if the full 175kw of the generator is in play, then the battery should only read -125kw. It may have fluctuations higher than that while the generator spools up. This is, of course, with a fully charged battery, I want to test it again in Sport when it drops below 26 miles battery range and again when the battery is close to 0.
 

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I believe there is a difference between driving a charged car in Stealth mode until the battery range indicates 0 (normal case), and trying to drive a car with a depleted battery because the car has been sitting for weeks without any charge (Fab's delivery experience).

I have put about 850 miles on my Karma in 3 weeks. I routinely drive the car in Stealth mode until the battery range reads 0. The ICE automatically kicks in and I continue to drive with the battery range indicating 0 until I pull into my garage and plug in. Works perfectly every time.

I don't know why a dealer is saying to switch to Sport when 5 miles remain on the battery. IMO, Fisker could not possibly have designed the engine/battery management software to work in that way. They can't depend on every driver being smart/aware enough to switch to Sport when the battery range drops to 5 miles, with the consequence of being stranded if they forget.
 

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dennis said:
I believe there is a difference between driving a charged car in Stealth mode until the battery range indicates 0 (normal case), and trying to drive a car with a depleted battery because the car has been sitting for weeks without any charge (Fab's delivery experience).

I have put about 850 miles on my Karma in 3 weeks. I routinely drive the car in Stealth mode until the battery range reads 0. The ICE automatically kicks in and I continue to drive with the battery range indicating 0 until I pull into my garage and plug in. Works perfectly every time.

I don't know why a dealer is saying to switch to Sport when 5 miles remain on the battery. IMO, Fisker could not possibly have designed the engine/battery management software to work in that way. They can't depend on every driver being smart/aware enough to switch to Sport when the battery range drops to 5 miles, with the consequence of being stranded if they forget.
That's exactly right. The car functions perfectly and seamlessly as long as you start up with a battery charged above 15%. In my case, the battery was well below that when the car was delivered for reasons other than the car being driven and the computer would not allow the car to start, even with a full tank of gas.

The main point of my post was that if the overall SOC (i.e., the Battery Guage or the percentage shown on the Energy Flow screen and NOT the "miles to go") is close to zero, you need to get the car charged at least to 15% before you attempt to start the car. The car will not allow the main battery to drain that low under normal conditions so there has to be some unusual circumstances that would create that situation. In my case it was the car sitting around for several weeks combined with the dealer's charging system not working properly.

But to be clear. my car switches from battery to ICE absolutely flawlessly at 0 miles to go. I don't have to manage that in any way. The car knows what to do.

-- Fab.
 

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Just a quick warning from my dealer: don't rely too much on the 'total range', which indicates how much fuel the car still has. It turns out this reading may not always be accurate. Last week, on an empty battery, it said I still had 20 kms of range left (about 2 liters of gasoline), but I was actually running on fumes (the following day it actually swallowed 36,75 liters, in a tank that can hold 35+ liters). The fact that I was running on fumes is what caused my engine to behave erratic. So the advice is not to wait until the very last moment to get gasoline. It might be too late.
 
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