DIY Electric Car Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Unfortunately, the freeway onramp leads to a very steep climb for maybe 1/2
mile. You hit the freeway going about 50 mph, and have to accelerate to 65
mph on that climb. In 3rd gear, my EV just doesn't have the torque to do
it. In fact, it loses speed. I've got an ADC 8-inch motor, which has a
redline of 8,000 rpm. According to my calculations, the motor would be
doing 7,600 rpm at 60 mph in 2nd gear. Would it be save to accelerate up to
60 in 2nd gear for that short stretch? That way, at least, I wouldn't be
typing up traffic.

Thanks.

Bill

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
 

·
Registered
Joined
·
70 Posts
Discussion Starter #2
Hi Bill,

> I've got an ADC 8-inch motor, which has a
> redline of 8,000 rpm. According to my calculations, the motor would be
> doing 7,600 rpm at 60 mph in 2nd gear. Would it be save to accelerate up
> to
> 60 in 2nd gear for that short stretch?

Your motor will have *very* little power at that rpm.

at what rpm does your controller come out of motor side current limit?
is there a range in which you are in battery current limit?

either of those events determines your max power (torque at the wheel).
use your gearbox to keep the motor at max power, and you will get the best
possible acceleration.

if you try to spin the motor past the point where your controller comes out
of current limit and goes full on, torque falls off exponentially.
for most DC motor, controller, battery setups, this occurs between 2000 and
3000rpm.

Matt

----- Original Message -----
From: "Bill Dennis" <[email protected]>
To: "'Electric Vehicle Discussion List'" <[email protected]>
Sent: Monday, November 22, 2010 5:45 AM
Subject: [EVDL] The Torque is the Torque, of course, or course


> Unfortunately, the freeway onramp leads to a very steep climb for maybe
> 1/2
> mile. You hit the freeway going about 50 mph, and have to accelerate to
> 65
> mph on that climb. In 3rd gear, my EV just doesn't have the torque to do
> it. In fact, it loses speed. I've got an ADC 8-inch motor, which has a
> redline of 8,000 rpm. According to my calculations, the motor would be
> doing 7,600 rpm at 60 mph in 2nd gear. Would it be save to accelerate up
> to
> 60 in 2nd gear for that short stretch? That way, at least, I wouldn't be
> typing up traffic.
>
> Thanks.
>
> Bill
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.869 / Virus Database: 271.1.1/3269 - Release Date: 11/21/10
03:34:00

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
 

·
Registered
Joined
·
70 Posts
Discussion Starter #3
On 21 Nov 2010 at 14:45, Bill Dennis wrote:

> In 3rd gear, my EV just doesn't have the torque to do it.
> In fact, it loses speed.

I know it sounds odd, but try 4th, not 2nd. Especially with a DC series
motor, torque is much higher at low RPM. When you need more acceleration,
you actually have to >upshift<.

Just watch out for motor heating and battery stress from the high currents
that result.

David Roden - Akron, Ohio, USA
EVDL Administrator

= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
EVDL Information: http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Note: mail sent to "evpost" and "etpost" addresses will not
reach me. To send a private message, please obtain my
email address from the webpage http://www.evdl.org/help/ .
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =


_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
 
1 - 3 of 3 Posts
Top