REVA announces lithium electric car and fast charge stations

[clickwhirr]

I have taken my Gwiz up the motorway a few times. I am lucky enough that when I have done it I am able to keep up with the traffic on the small incline when I can only get upto about 45mph. On the way down the other side I easily hit 55mph.

[oldoilenergy]

I have taken my Gwiz up the motorway a few times. I am lucky enough that when I have done it I am able to keep up with the traffic on the small incline when I can only get upto about 45mph. On the way down the other side I easily hit 55mph.

Well i'm delighted to find that my guess was correct!

But why are we talking about going on motorways? no one in their right mind wants to travel dangerously at 50 or 60 for long distances [bear in mind that the air resistance goes up as almost a cube of the speed, so the range drops accordingly]

Why don't we lobby virgin with their eco conciousness to offer a Gwiz carriage with charging points on the back of every intercity train? A few fold out ramps and you could take you luggage and vehicle to Inverness in a sensible and untiring fashion at 125mph!

[oldoilenergy]

Sounds good.  I guess the "faster acceleration" comes exclusively from the reduced weight of the batteries - somewhere around 75kg-100kg I'd guess.

No sign of the promised upgrade option for the AC models.

I wonder how much it will cost?  A retro-fit might not be worth it...

The faster acceleration will also come from the higher tolerance of large currents that Lions [especially polymer types] can tolerate. The AC cars are currently limited by how much the batteries can tolerate without buckling/overheating the plates. A lot of the battery failures are down to hard driving - i've often thought that Pb customers should be offered the choice of longevity vs acceleration.

[marctorrance]

The current is limited to 400A by the controller and ~310A (+ a bit for ancillaries) by European legislation (15kW for heavy quadricycle).  I think they pretty-much max that out using the lead-acid pack already.  And the motor is only rated 6kW continuous (4.1 kW DC), so I don't think the li-ion replacements will do that much to remove those bottlenecks.
Also the total weight of cells will be much lower than the lead-acid.  Li-ion might have higher W/kg, but what about W/Ah?  That's what matters.

[oldoilenergy]

The current is limited to 400A by the controller and ~310A (+ a bit for ancillaries) by European legislation (15kW for heavy quadricycle).  I think they pretty-much max that out using the lead-acid pack already.  And the motor is only rated 6kW continuous (4.1 kW DC), so I don't think the li-ion replacements will do that much to remove those bottlenecks.
Also the total weight of cells will be much lower than the lead-acid.  Li-ion might have higher W/kg, but what about W/Ah?  That's what matters.

in that case all the current gwiz's are illegal - 400*48 [nominal] = 19.2kw!

[marctorrance]

You can have as much braking power as you like.  The 15kW is mechanical power when accelerating.  I think the overall efficiency can't be much higher than 80%, so you're probably only just getting 15kW mechanical when you draw 400A, but yes, it is right at the limit for this class of vehicle.
(Un)fortunately, the motor is only rated at 6kW.  If you try to give it that much welly for more than 30 seconds, something will go up in smoke, especially if you need to brake immediately after accelerating.
Fortunately, the controller doesn't allow you to draw 400A for very long.

[MB]

The biggest discharge I've ever had from my G-Wiz was around 360 amps, and that was for around 3 seconds before it dropped.

I believe the lead acid batteries are causing a bottleneck in performance and the more rapid discharge available from lithium-ion batteries will make significant improvements to performance.

In a couple of months we'll know for sure...

[marctorrance]

You're probably right.  I wonder how long the motor is rated at 15kW for.  Maybe some water-cooling will be needed next.

[clickwhirr]

oldoilenergy - your right - no one wants to travel dangerously at 50 or 60 mph - I always like to travel safely.
Even in my ICE car I always do 50 to 60 mph - safely.

[ST]

You'll see plenty of people pottering along quite happily at 50-60mph on the motorway. Sure, 70mph is the norm (and sometimes a lot more - especially at weekends), but I would dispute the comments that it is unsafe to travel at those sorts of speeds.

I'm not advocating a G-Wiz for motorway travel every day, but I would have thought a G-Wiz Li-Ion would be okay for the occasional jaunt.