# Expected life for Curtis 1221c ?



## dtbaker (Jan 5, 2008)

I just had my 1221c fail catastrophically.... accelerating from a light in traffic.... POP, no juice.

I put about 7000 miles on it in a 96v nominal lead-acid system, then another 17,000 miles with a 120v nominal li system. total miles just at 24,000 when it failed.

I should add.... my system has the controller mounted on a pretty good air-cooled heat sink with great airflow direct from a hood scoop. most driving is 'urban/suburban' rolling terrain. Longest uphill section is typically a 2 mile stretch at 50mph. Average around town I accelerate at full throttle, and pull an average of 100amps or less while cruising.

is this anything like what other people have seen?
how many people have diven them till they fail? 

please post if you have!


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## TheSGC (Nov 15, 2007)

dtbaker said:


> I just had my 1221c fail catastrophically.... accelerating from a light in traffic.... POP, no juice.
> 
> I put about 7000 miles on it in a 96v nominal lead-acid system, then another 17,000 miles with a 120v nominal li system. total miles just at 24,000 when it failed.
> 
> ...


I haven't used a Curtis controller in my own EV, however over the past few years I've purchased components from other EV'ers in MA whose Curtis controllers released the magic smoke, mostly under 5,000 miles of use, and they would strip their EV and sell off parts out of frustration. 

The consensus was that the Curtis couldn't handle the excessive current required for all the hills in my area, and the inductance of the newer motors. It's also a 20 year old design with a rather slow response to current swings.

I have a Zilla Z1K and recently added liquid cooling due to the highway driving and hills and it was throttling down due to heat as some of the hills I have pull 450a to the motor to climb at a modest 35 MPH.


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## Russco (Dec 23, 2008)

dtbaker said:


> I just had my 1221c fail catastrophically.... accelerating from a light in traffic.... POP, no juice.
> 
> 
> is this anything like what other people have seen?
> ...


My 1994 Geo Metro has the original 1221 Curtis controller that was installed when the car was new. 

So, the controller is also 20 years old and operates perfectly.

Mileage in the 20 years is just over 6000 miles.

No complaints.


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## dtbaker (Jan 5, 2008)

Russco said:


> My 1994 Geo Metro has the original 1221 Curtis controller that was installed when the car was new.
> 
> So, the controller is also 20 years old and operates perfectly.
> 
> ...



uuummmm, so your car was converted when it was NEW?
and only driven 6000 miles in 20 years?
really?


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## dragonsgate (May 19, 2012)

The Curtis I have now is going on 10 years and 30k miles. I average about 200-250 miles a month or 2400 plus miles a year.  My first one in 1999 when I first did the conversion didn’t make it quite 2 years. I didn’t put any cooling on it and hammered it every take off. No ones fault but mine. Second one lasted from 01 to 04. I made a heat sink with fan and everything seemed to be working fine then one very hot day I was pulling a long hill and part one of those little square black things with the three prongs popped off and the power dropped. I managed to limp home and took the controller apart to see what I could see. After some searching around I found some parts that matched and replaced them. Drove for another few months and everything seemed normal then the controller shut down completely. EVA gave me such a good deal on a new Curtis I figured the third time is the charm and bought it. This time I thought warranty be damd and cut the ends out of it and hooked up a blower to push the air filtered straight through. It has been that way from the start and so far so good. Just had everything out for inspection not more than six months ago and all looked to be in good shape.


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## Russco (Dec 23, 2008)

dtbaker said:


> uuummmm, so your car was converted when it was NEW?
> and only driven 6000 miles in 20 years?
> really?


Yep. 

Here's the story on my car:

http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/fsev/eva_results/batmetwt.pdf

VIN's match, car looks just like the picture of 20 years ago except different 13" aluminum wheels. Now equipped with 38 CALB gray cells, otherwise original drivetrain and EV components as done in 1994. 

Current picture enclosed.


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## dtbaker (Jan 5, 2008)

very interesting info backing up the hypothesis that HEAT is the killer, and perhaps a liquid-cooled heatsink is worth doing.....


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## Russco (Dec 23, 2008)

dtbaker said:


> very interesting info backing up the hypothesis that HEAT is the killer, and perhaps a liquid-cooled heatsink is worth doing.....


Yes, heat is the enemy of semiconductors. It is said that for every 10 degrees C, semiconductor life is halved. 

Liquid (water + anti-freeze) is much more dense than air and liquid cooling is greatly superior for transferring heat.

Back in the day when I manufactured EV controllers in the eighties, the air cooled 105 CFM muffin fan cooling was marginal on hot days. However, my liquid cooled 600 amp Darlington controllers only had a 10 degree F heat sink rise over ambient. 

That said, my current Curtis 1221 in Geo George was getting too toasty with the factory 105 CFM fan. I changed the fan to a 220 CFM unit and the controller runs much cooler.


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## dtbaker (Jan 5, 2008)

Russco said:


> Yes, heat is the enemy of semiconductors. It is said that for every 10 degrees C, semiconductor life is halved.
> 
> Liquid (water + anti-freeze) is much more dense than air and liquid cooling is greatly superior for transferring heat.



hence the beauty of the built-in chill plate for the Zilla and Soliton.... my miata has the fluid circulating through a heater core mounted behind the front bumper.... seems to be very effective.


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## elevatorguy (Jul 26, 2007)

One of the guys in our EV club is on his third controller, the first failed under warranty, the second lasted almost 20 years before failing. The vehicle was converted 20+ years ago and 216,000 ev miles before the recent controller change.


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## dtbaker (Jan 5, 2008)

elevatorguy said:


> One of the guys in our EV club is on his third controller, the first failed under warranty, the second lasted almost 20 years before failing. The vehicle was converted 20+ years ago and 216,000 ev miles before the recent controller change.


very curious about what kind of cooling he had on the controller.... any idea? also curious about his average drive; 10k per year is a LOT for an EV back in the days of limited range on lead!


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