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Curtis 1231C with Warp 9 - Maxed at 250A?

828 Views 5 Replies 4 Participants Last post by  ekthor
I was just recently gifted an old EV conversion and have been working to get it road worthy again. It has been sitting for maybe 4-5 years supposedly untouched? Not entirely sure.
It is a 144V LFP pack with a Curtis 1231C and a Warp 9 motor. All in a 1996 Subaru Outback with 5-speed and AWD.

My current problem is a lack of torque. So much so that I can’t go up small hills even in 1st gear.
There is an ammeter gauge that reads motor current and it maxes out at ~250A. This should be going up to 500A for this controller right?
I’ve tried adjusting the current and acceleration rate pots on the controller and that has made no difference (does it need more turns?)

I have checked the throttle pot, it’s fine with 0 to 5kOhm. And the KSI is getting pack voltage.
All connections are tight. Voltage to the motor also goes up from 0 to Vpack

No limit from the battery pack either. I can see the current coming out and it’s barely anything when taking off but once I’m up to speed it will pull 100A+. (I’ve only been driving around the neighborhood)

Unfortunately this car does not come with schematics or a manual, but I do know the engineer that converted it. Though I’m trying not to bug him too much with questions. Haha

So, any clue as to why the controller seems to be stuck at half the power?
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How's the battery voltage when you floor it ? Controller may be cutting back the current if there is a significant voltage drop.

Looking at the docs undervoltage cutback will happen at 64V, which sounds unlikely. That controller also has a thermal cutback at 85C. The controller isn't even rated for 250A continuous. The 1hr rating is 225A, 5min 375A and 2 mins at 500A. I'd say put a temp probe on it and see how hot it gets when you're driving around.
 

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Discussion Starter · #3 ·
How's the battery voltage when you floor it ? Controller may be cutting back the current if there is a significant voltage drop.

Looking at the docs undervoltage cutback will happen at 64V, which sounds unlikely. That controller also has a thermal cutback at 85C. The controller isn't even rated for 250A continuous. The 1hr rating is 225A, 5min 375A and 2 mins at 500A. I'd say put a temp probe on it and see how hot it gets when you're driving around.
I have a pack voltage reading from the BMS and there is a voltage gauge on the dash (though I don't yet know where that is reading from) and there is voltage drop, but not till after I'm already going and picking up speed. The current draw from the pack is very linear with the vehicle speed.

Its been quite cold out during my test drives and they've all been short. I haven't thought about temperature derating though. Perhaps the temperature sensor is faulty? That would be hard to diagnose though.
 

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Check battery condition. Been sitting and even lithium degrages after years of sitting, but much slower than FLA. You don't even know if it went to storage in a storable condition. CHARGE it, let it set for a couple of days then check cell voltages
 

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There are several checkpoints you must do:

1) Battery health: make a list of cells, labeled them from 1 to 48?, then make your readings cell by cell and write all values so you can compare them, there should not be voltage differences beyond 0.5v+ or - . LFPs from 2012-2014 may have failed after years of use or abuse or storage without recharge. Most popular cells back then were 100Ah, or 180Ah and most factories documented a max discharge rate of 2C, but most EV builders abused cells (and motors) with 1000Amp controllers or beyond that. Curtis seems to avoid that problem. No single cell must have less than 3.0V open circuit reading during your tests, ideally all of them should be 3.33 or 3.34 or 3.35v at 100% SOC, once your re-charge is over. If one cell is < 2.9 in your list... then that's the reason, the chain of cells is basically broken there. If there is 2.9v open circuit then trying to get 400A... that cell is dead, one or two or many. That tragedy happened to me after winter season, I lost 90% of them, 6 months of them unused. The most expensive "investment" I ever did.

2) That Curtis has no computer program interface, it is possible to limit current using a simple tool. Make sure it has the max amperage well set.

3) Check all the power wires are properly tighten.

I believe your problem is the battery pack or BMS. I sell Samsung 2170 Cell modules 48V100Ah each, also DC controllers if you need them.

Regards,

Hector
 
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