# [EVDL] How much motor current can a Netgain Impulse 9 motor take?



## EVDL List (Jul 27, 2007)

Hello Rob,

In my design of my EV using a Netgain motor, Z1K controller, selection of =

overall gearing, diameter of tires, and battery types, I first contacted =

George F. Hamstra at NetGain and provide him with the specifications of the =

EV as to:

Weight of EV
Controller type
Transmission type with or without a flywheel-clutch or torque converter
Each gear ratio of the transmission
The differential gear ratio
The overall gear ratio in each selection of the gear
Battery type
Battery Ampere-Hour rating
Battery Pack voltage
Frontal Area of the EV.
Rolling resistance of the tires or what type of tires.

George than e-mail me a spread sheet of what the performance of my EV would =

be either with a WarP 9 and a WarP 11 motor.

It is best to keep the WarP 9 motor as close to 3300 rpm to provide the =

maximum torque at that rpm or call the sweet spot of the motor. This means =

that the gear selection has to be chosen to maintain 3300 rpm at different =

speed selections.

In using the WarP 9 motor, the continuous motor ampere rating is 199 amps a=
t =

3300 rpm. The motor ampere may go higher for a very short time.

I found that driving the EV with a Warp 9 with a manual transmission, clutc=
h =

and flywheel, the motor ampere would surge to 600 amps to start moving in a =

first gear overall ratio of 19.495:1 and decreases to 200 amps at 3300 rpm =

or 15 mph. Shifting to 2nd gear at 13.925:1 ratio, again the motor ampere =

would surge to about 400 amp and again decreases to 200 amps at 3300 rpm or =

20 mph.

Shifting to 3rd gear overall ratio of 5.57:1 which causes the motor to surg=
e =

to about 300 amps and again decreases to 200 amps at 3300 rpm at 50 mph.

I drove the EV for 8.8 years using the same Trojan T-145 180 volt battery =

pack using these shift points monitoring the motor ampere and rpm.

According to George F. Hamstra at NetGain, A more suitable motor for my EV =

weight (over 5000lbs) would be a WarP 11 with more gear ratios closer =

together.

The WarP 11 has it sweet spot at 1800 rpm where the motor ampere is rated a=
t =

200 amps continuous and to eliminate the startup motor ampere surge up to =

600 amps. To do this, I experiment in pre-idling the motor to 1800 rpm by =

switching in another 5k pot in series with the accelerator 5k pot which the =

motor rpm was adjusted for about 500 rpm in a neutral gear.

Shifting into 1st in a modified GM TH-400 automatic (which was change to a =

manual shift with no torque converter, governor and modulator control) the =

motor ampere now only surges to 100 amps at 500 rpm and increases to about =

200 motor amperes at about 1800 rpm. The shifting between gears is very =

violent as there is no clutch or torque converter to cushion this effect.

Then I install a large 12 inch torque converter with a stall speed of 1700 =

rpm (make this as close to the sweet spot rpm of the motor). I now can =

either pre-idle the motor, or slowly bring up the motor rpm which will star=
t =

to move the EV at again at 100 amps without a high ampere surge.

Note: A torque converter adds another 1.8:1 ratio to the overall ratio. At =

startup it becomes 1.8:1 and at 1700 rpm it now becomes 1.0:1. My manual =

1st gear overall ratio was 19.495:1 and with the TH-400, it is now 1.8 x =

2.75 x 5.57 =3D 27.57:1!!

As the rpm increases from about 500 rpm to 1800 rpm this 1st gear ratio =

varies from 27.57:1 to 15.3175:1 keep the motor ampere at about 200 ampere =

at 1800 rpm at 10 mph or at the sweet spot rpm.

Shifting to 2nd at 1800 rpm, the overall ratio goes up to 18.1:1 and now =

varies down to 10.0:1, the motor ampere now goes to about 225 motor ampere=
s =

and start to lower to 200 amperes at 1800 rpm.

Shifting a motor at the sweet spot, the EV has the same or even has less =

Ampere-Hour per mile as the Warp 9 with the wide ratio manual transmission.

Now as the discussion of using no transmission. My motor ampere with no =

transmission gears is way over 600 amps which is over the Z1K continuous =

running amperes. If you look at the Caf=E9 Electric Manual at there site, =
it =

will list a lower continuous motor ampere rating.

Roland









----- Original Message ----- =

From: <[email protected]>
To: <[email protected]>
Sent: Tuesday, April 19, 2011 10:59 PM
Subject: [EVDL] How much motor current can a Netgain Impulse 9 motor take?


> Hi all -
> I have a VW cabby with an Impulse 9 and Z1K motor controller. The Zilla =

> can deliver 1000 amps to the motor, but can this kind of motor take this =

> current?
> I seem to be drawing less current that the motor limit setting, even when =

> the motor current is set to 1000A.
> Thanks in adviance !
>
> Rob
> [email protected]
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## EVDL List (Jul 27, 2007)

Rob,

If you go to http://jackrickard.blogspot.com/2011/04/graphs-is-always-greener.html
and look at the graphs you can see motor current and battery current
graphed together. There were several dyno runs in different gears.
These were done with a Soliton1 controller and a Warp9. You can see
where there was 1000 motor amps as the battery amps rose until it the
two currents were the same. The motor handled it just fine.

HTH,

-- 
David D. Nelson
http://evalbum.com/1328

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