[EVDL List]

My Electricar has a Curtis 1221B, and I will be installing an adapter to make the tach indicate battery amps.
The stock tach maxes out at 7,500 RPM. If Inset the adapter in 4 cyl mode, 1,000 RPM = 100 amps. In 6 cyl mode 1,500 = 100; 8 cyl 2,000 = 100.
Since I haven't driven the Electricar very far (12 year old batteries are now at the recycler) how much power does a 1221B actually put out? How many battery amps accelerating at full throttle up to freeway speed?
If cruise speeds are in the 100 amp range, it would seem best to 'expand' the scale and use 8cyl mode, but if 400 amps are really (and commonly) used by a 1221B, I don't want to bury the tach needle at the top peg. If the max is really about 350 battery amps, it might work well. Anyone drive a 1221B?

Tom Keenan


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The pack voltage will be 108v. Specs for the 1221b say 400 amps, but I've heard that Curtis controllers tend to cut back fairly quickly.

Tom Keenan


[quote] Jay Summet <xxx@xxx.xxx> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> What's your pack voltage? The lower the voltage, the higher the amp
> draw.....
>
> Assuming you have a 120 volt pack, I doubt you will ever draw more
> than 400 battery amps.
>
> As a point of reference, On my S-10 pickup with a 120 volt pack and a
> Curtis 1231C-86, I can peg my motor amp gauge at 500 amps, but this is
> due to current multiplication (lower motor voltage than battery
> voltage). My battery amp meter ranges from 50-150 for light to heavy
> crusing, and up to 250-350 amps for heavy acceleration (uphill).
>
> Jay
>
> On 06/28/2012 07:28 PM, Tom Keenan wrote:
>> My Electricar has a Curtis 1221B, and I will be installing an
>> adapter to make the tach indicate battery amps. The stock tach
>> maxes out at 7,500 RPM. If Inset the adapter in 4 cyl mode, 1,000
>> RPM = 100 amps. In 6 cyl mode 1,500 = 100; 8 cyl 2,000 = 100. Since
>> I haven't driven the Electricar very far (12 year old batteries are
>> now at the recycler) how much power does a 1221B actually put out?
>> How many battery amps accelerating at full throttle up to freeway
>> speed? If cruise speeds are in the 100 amp range, it would seem
>> best to 'expand' the scale and use 8cyl mode, but if 400 amps are
>> really (and commonly) used by a 1221B, I don't want to bury the
>> tach needle at the top peg. If the max is really about 350 battery
>> amps, it might work well. Anyone drive a 1221B?
>>
>> Tom Keenan
>>
>>
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[EVDL List]

Thanks for the link to the manual! I must have an odd/ one off controller, because it is a 1221B-74XX (I'll have to verify that...) which would make it a 72-120v model, but an unknown amperage. At this point I'm guessing 400 amps - perhaps it is an early 1221C. It sounds like a single frequency controller while in operation, however.

Tom Keenan


[quote] Lee Hart <xxx@xxx.xxx> wrote:

> On 6/28/2012 6:28 PM, Tom Keenan wrote:
>> My Electricar has a Curtis 1221B, and I will be installing an adapter to make the tach indicate battery amps.
>> The stock tach maxes out at 7,500 RPM. If Inset the adapter in 4 cyl mode, 1,000 RPM = 100 amps. In 6 cyl mode 1,500 = 100; 8 cyl 2,000 = 100.
>> Since I haven't driven the Electricar very far (12 year old batteries are now at the recycler) how much power does a 1221B actually put out? How many battery amps accelerating at full throttle up to freeway speed?
>> If cruise speeds are in the 100 amp range, it would seem best to 'expand' the scale and use 8cyl mode, but if 400 amps are really (and commonly) used by a 1221B, I don't want to bury the tach needle at the top peg. If the max is really about 350 battery amps, it might work well. Anyone drive a 1221B?
>
> The exact current varies with the model number, temperature of the
> controller, and how the current limit trimpot on the side of the case is
> set.
>
> A manual for the controller is at
> http://www.kta-ev.com/v/vspfiles/assets/images/1209.1221b.1221c.1231c%20product%20manual.pdf
> See the chart on page C-1 (page 51 of 52) for the maximum currents of
> the various models of the 1221B. They range from 400-600 amps.
>
> As the controller warms up, the maximum current it allows will fall. It
> drops to about half in about 10 minutes.
>
> The current adjustment pot is behind the center screw on the side of the
> case. It can turn down the maximum current at least 2:1.
>
> These are all *motor* currents. Peak battery current only matches motor
> current at one particular motor speed (where the pedal is floored and
> the controller just comes out of current limit). Above and below this
> speed, battery current is less than motor current.
>
> --
> *BE* the change that you wish to see in the world.
> -- Mahatma Gandhi
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net
>
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[EVDL List]

> From: xxx@xxx.xxx
> Date: Fri, 29 Jun 2012 01:00:06 -0700
> To: xxx@xxx.xxx.edu
> Subject: Re: [EVDL] Curtis 1221B Actual Amps
>
>
Thanks for the link to the manual! I must have an odd/ one off
controller, because it is a 1221B-74XX (I'll have to verify that...)
which would make it a 72-120v model, but an unknown amperage. At this
point I'm guessing 400 amps - perhaps it is an early 1221C. It sounds
like a single frequency controller while in operation, however.
>
> Tom Keenan
>




Hi.

I have the same, the model, the car was 96VDC and took about 110-120battAmps at "highway", 400 motor Amp in almost all accelerations as there is no gearbox, "4.7kW" 48V motor, series type. So I guess I see a short peak of 400 battamps somewhere on the way up in rpm, as Lee says. in very low speed high torq it is really amazing with the current multiplication. But I guess this old models dont use syncron Rectifier-stuff, so the freewheel diode will probably get hot, but in normal city driving it was never a problem.

1221b (at least my model) was a 72-120V single freq, (15khz..something)
and yes it has 400 motor Amps, work nice, totally quiet.



I mounted it under a very tight hood of metal, with a SMALL fan in the end, fast air-flow over the surface, also it is
mounted to a aluminium plate under the controller, so it gets a bit more
"thermal mass" and have some heat sink effect, maybe it can take a bit longer to get hot in a hillclimb. In theory. But I have never seen any thermal problem at
all. It runs pretty cold.



Im happy with that model.

A bit of a "rubberband"-feeling at the accelerator-pot , probably can be
adjusted on the other screw at the side of controller. I got used
to it and did not care, sometimes it saved me.. act as a
safety-feature: A fast touch or step on accelerator by misstake will
not throw the car in to X-things in "zero mS"...

bad for racing, but good when mistakes happen IRL, very small car, not enough room for the shoes :-)


I think "B" model was re-designed to 1221C (with low freqv at startup)
and I think it was after some controller fails with very low impedance
motors, at high battery voltages.



If I remembre, (Lee?) correct it was the current rise to fast to cut
of, at each pwm cycle.., With a very low impedance motors it was a bit
like "short circuit" to the controller I guess, + the stored energy
added up in the motors magnetics,



and made some setups to fail. If I remember correct, this was some where in 1995-1999, (I guess.)

/John







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Good info - thanks!
There is a spare heat sink in the car, and might mount it to the controller mounting plate in case it wants to get warm.

Tom Keenan


[quote] "Hoegberg ." <xxx@xxx.xxx> wrote:

>
>
>
>
>
>
>> From: xxx@xxx.xxx
>> Date: Fri, 29 Jun 2012 01:00:06 -0700
>> To: xxx@xxx.xxx.edu
>> Subject: Re: [EVDL] Curtis 1221B Actual Amps
>>
>>
> Thanks for the link to the manual! I must have an odd/ one off
> controller, because it is a 1221B-74XX (I'll have to verify that...)
> which would make it a 72-120v model, but an unknown amperage. At this
> point I'm guessing 400 amps - perhaps it is an early 1221C. It sounds
> like a single frequency controller while in operation, however.
>>
>> Tom Keenan
>>
>
>
>
>
> Hi.
>
> I have the same, the model, the car was 96VDC and took about 110-120battAmps at "highway", 400 motor Amp in almost all accelerations as there is no gearbox, "4.7kW" 48V motor, series type. So I guess I see a short peak of 400 battamps somewhere on the way up in rpm, as Lee says. in very low speed high torq it is really amazing with the current multiplication. But I guess this old models dont use syncron Rectifier-stuff, so the freewheel diode will probably get hot, but in normal city driving it was never a problem.
>
> 1221b (at least my model) was a 72-120V single freq, (15khz..something)
> and yes it has 400 motor Amps, work nice, totally quiet.
>
>
>
> I mounted it under a very tight hood of metal, with a SMALL fan in the end, fast air-flow over the surface, also it is
> mounted to a aluminium plate under the controller, so it gets a bit more
> "thermal mass" and have some heat sink effect, maybe it can take a bit longer to get hot in a hillclimb. In theory. But I have never seen any thermal problem at
> all. It runs pretty cold.
>
>
>
> Im happy with that model.
>
> A bit of a "rubberband"-feeling at the accelerator-pot , probably can be
> adjusted on the other screw at the side of controller. I got used
> to it and did not care, sometimes it saved me.. act as a
> safety-feature: A fast touch or step on accelerator by misstake will
> not throw the car in to X-things in "zero mS"...
>
> bad for racing, but good when mistakes happen IRL, very small car, not enough room for the shoes :-)
>
>
> I think "B" model was re-designed to 1221C (with low freqv at startup)
> and I think it was after some controller fails with very low impedance
> motors, at high battery voltages.
>
>
>
> If I remembre, (Lee?) correct it was the current rise to fast to cut
> of, at each pwm cycle.., With a very low impedance motors it was a bit
> like "short circuit" to the controller I guess, + the stored energy
> added up in the motors magnetics,
>

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