# Re: [EVDL] Hybrid Mustang: batteries

```There is no issue here.
The OP brought up the continuous rating of the motor at certain RPM,
which just says something about the ability to sustain a certain current
at a certain speed indefinitely, but which does NOT limit the motor to
that
power, so accelerations (which by definition are not limited by
continuous ratings anyway) are certainly possible at *much* higher power
levels - as long as the current limit on the *controller* allows for
them.
Note that current limits *can* play a part in the acceleration,
especially at lower speeds. My previous EV had a very low (250A) motor
current limit, combined with 200A battery current limit. That was OK
since it was a 312V pack, but the motor current limit caused the launch
of the vehicle to be somewhat slow, but at modest speeds the
acceleration picked up because the power to the motor continued to rise
with increasing RPM (voltage on motor)
so there is an effect of motor current limiting that affects the way the
EV behaves.```
```
Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.com Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626

-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Peri Hartman
via EV
Sent: Saturday, July 26, 2014 3:37 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Hybrid Mustang: batteries

Yep, areo drag is proportional to square of the speed:

1/2 * Cd * A * air density * speed^2

where
Cd == drag coefficient (you can look this up for many car models)
A == frontal area: the area of the vehicle as viewed in 2D from the
front, in meters^2
air density = roughly 1.2 kg/m^3 at standard temperature and pressure.
speed: in meters/second

will give you the resistance (i.e. force) in N (newtons).

Peri

------ Original Message ------
From: "EVDL Administrator via EV" <ev@lists.evdl.org>
To: "Electric Vehicle Discussion List" <ev@lists.evdl.org>
Sent: 26-Jul-14 2:23:20 PM
Subject: Re: [EVDL] Hybrid Mustang: batteries

>On 26 Jul 2014 at 8:24, Ben Goren via EV wrote:
>
>>  At 55 MPH with the 4.11 is 3000 RPM; with a single AC-51, that's 22
>>hp.
>>  The single motor would be okay... At the slow end...1000 RPM is ~19
>>  MPH. Five horsepower might not cut it by itself, and 15 MPH school
>>  zones might be a problem...
>
>IIRC, aero drag increases proportional to the square of the speed, and
>it's
>going to be pretty minimal at 15mph, no? So something just doesn't
>quite
>ring true here.
>
>In fact I've driven some pretty underpowered cars, DC EV, AC EV, and
>ICEV.
>I've encountered some that could maintain 15-20mph just fine, but could
>barely (in some cases just couldn't) make 55mph. NEVER vice versa.
>
>David Roden
>http://www.evdl.org/
>
>
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>
>
>

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```