[nesc76]

Hello.

Long time reader, first time writing. Needing some help and advice.

I've being working on a Citroen C3 conversion for the past year. I'll create a thread discussing the project, but in the mean time, this is basically what it is:

I'am converting a Citroen C3 using an AC-50 motor (1238 controller) and Lead acid batteries. This is the first stage on the conversion, and in the next 2-3 years I will move to Lithium. The conversion was done in Brazil, and lithium prices are still prohibitive, so I decided to run it on Lead acid first, so I can have more data from the car performance before designing the lithium pack.

I kept the clutch and the 5 gear manual transmission. I'am also adding a lot of electronics to it to collect all sort of data in real time (acceleration, speed, power and etc) to save as telemetry for study later on. Final weight for the car is at about 1300 Kg (~2800 pounds)

The performance objectives are: ~20 miles range (30km) and close to original performance (acceleration/speed) from the 1.6 litter engine. The motor specs are comparable up to 3500 RPM. I'am expecting to drive it mostly on 2nd or 3rd gear. In this first stage with lead acid, it will be limited to city drive ( ~ 80km/h max ).


After a lot of initial problems (ranging from customs holding the parts, to the electric motor actually falling and damaging the encoder) we got everything running last week.

Problem is that "running" is wishful thinking. Even tough the 1238 Spyglass shows Max Amps at 650 AMP (so I'am assuming the batteries can provide enough power to the controller), the car acceleration is really bad. It takes ~13 seconds to accelerate from 0 to 30km/h in first gear (12,9 on a 3,77 final drive, 185/60 tires).

Bad enough that it cant be driven in the street, even in first gear. It cant go over some mild inclinations. And it doesn't have that kick one would expect from electric motors. It slowly accelerates toward the 3000 RPM mark, so its dangerous to go over intersections for example.

I already adjusted accelerator pedal TMAX (when clutch is disengaged I can accelerate to 5000+ rpm), and ordered equipment to measure battery internal resistance, since I'am puzzled on how they charge (some charge at lower voltage than others, even tough they are brand new and from the same batch). Even tough they are new, they were sitting charged for 8 months while we waited for parts, making me wonder if that could have caused them to loose releasing all energy at once.

Other than that I'am kind of clueless on where to go next.

I'am attaching some pictures, will add more on the thread I'll create about the conversion.

Thanks in advance to any tip or help to increase the performance an improve the conversion. Any help os appreciated.

 

[Yabert]

Nice conversion!... except for the lead acid

My advice: Stop to play with the Spyglass and use a clamp on ammeter.
First, verify the battery current on an acceleration. Also verify the voltage during the acceleration.
Voltage x Current = power in watt.
What you need to know is if your batteries are the cause of your poor performance. If they aren't, you will be able to continue to the others possible causes.

 

[nesc76]

First of all, thanks very much for your reply and help!!!

Nice conversion!... except for the lead acid

Thanks!!! I have to agree about lead, but thats whats possible now. Lithium is more than twice the cost here in Brazil. A 72v, 200Ah pack is close to US$ 22k.

I hope in the next two years I can come up with a decent enough lithium pack. I'll need it for my target of 100 miles on a charge in the second phase.

My advice: Stop to play with the Spyglass and use a clamp on ammeter.

I ordered some equipment last week to do this kind of measurements. I also have a shunt in place, I'll install some electronics to get the output from it.

For the clamp, I got a GoPro this weekend so I can put it in the engine bay and keep an eye on it while I drive.

Will do the measurements and post back.

First, verify the battery current on an acceleration. Also verify the voltage during the acceleration.

I see some massive sag when I accelerate. According to the spyglass, voltage goes down from ~99v to the upper 80s (87-89v) when the car start moving. It seems excessive to me, thats why I plan on testing battery resistence this week. Maybe its ok, I dont have any reference for sags, it seems just excessive 10% for a charged pack.

Voltage x Current = power in watt.
What you need to know is if your batteries are the cause of your poor performance. If they aren't, you will be able to continue to the others possible causes.

The good thing is that they are still on warranty, so if I can come up with a good test that I can show my supplier a few (or all of them) have some problem, I can ask for a replacement.

Is it common for lead acids that are stored charged to develop some resistence over time? Would 8 months be enough for damaging some/all of them? Also not sure if maybe its just because I never actually cycled them yet.

My plan as of now is to test resistence (I ordered a tool for that) the clamp meter and build the electronics for the shunt. I'll also add some per battery voltage monitors to see if I can detect if some are sagging more than other. Also checking with HPEVS if maybe I have some bad setting in my controller that could be holding it back.

Once again, thanks for the reply and help.

 

[piotrsko]

Get a battery hydrometer and check your specific gravities. Yes storing them uncharged tends to sulphate them. Ill bet they needed to be charged when you installed them. My 192v pack sagged to 120 pulling 400 amps.

 

[nesc76]

Get a battery hydrometer and check your specific gravities. Yes storing them uncharged tends to sulphate them. Ill bet they needed to be charged when you installed them. My 192v pack sagged to 120 pulling 400 amps.

Thanks piotrsko!!!!

By "storing uncharged" you mean without a floating charge? They were charged before storing them. They were stored with 12.9 volts, and 8 months later they had 12.7 volts.

We only did one single charge at this point on them (not counting the pre-storage charge done at the battery shop). Interesting is that some charged at 14.5-15v, and other never charged at more than 13.7V, even tough I supplied 6v to the pack. Tomorrow I plan on leaving it with a floating charge for several hours, hoping it will change something before the more precise instrumentation arrives.

Not sure a hydrometer would be an option. The battery is sealed gel. Don believe it will work right?


Thanks!!!

 

[nucleus]

Something is up with your controller. You should see way more sag on acceleration.

 

[nesc76]

Something is up with your controller. You should see way more sag on acceleration.

Thanks nucleus for the information.

I checked the controller, but could not find anything that would explain it. I double checked the connections to see if there was anything warm, but everything was fine. The warmest thing was the contactor, but it was still cool to the touch. I use 70mm wires for everything, except one leg to the batteries I had to use 95mm, but I dont believe this would be a problem in this case.

Will search and see what kind of parameters people are using for the 1238 and compare to what I have. Hope I can find some thing misconfigured. It would be a easier fix than removing the batteries.

Thanks again.

 

[piotrsko]

Didn't know they were GEL. HYDROMETER doesnt work on those. Uncharged meant no float charge. Try to get them all to the same resting voltage. The low one sounds like you sulphated / shorted a cell and I am basically a FLA person so I don't know how to remedy that. Do your currents go up when you bypass the low cell?

 

[nesc76]

Uncharged meant no float charge. Try to get them all to the same resting voltage.

Thanks piotrsko.

Yes, they had no float charge for more than 8 months. Voltage did not drop much, but apparently that alone wont mean much if they sulphated right?

Will try them today. I got the ammeter and the tools needed to measure battery resistence, will check on those today.

The low one sounds like you sulphated / shorted a cell and I am basically a FLA person so I don't know how to remedy that. Does your currents go up when you bypass the low cell?

I'll try that once I can find the worst ones measuring the internal resistence.

 

[nesc76]

Some more information:

I checked the resistance in some batteries today (I'll have them all checked later this week). When I was charging the pack, i noticed some would charge at 14.5-15volts, and others would charge at 13,7, even tough the pack was receiving enough voltage to charge all at 14.5.

I picked one that was charging at 14.6, and one that was limited to 13,7 and measured internal resistance. The one that accepted more voltage while charging was at 3mohm (the nominal resistance for the battery). The other one was at 7mohm. It also had lost more voltage since charge than the one with lower resistance. Not sure if that difference (although more than double) is significant enough to declare the battery as being bad.

I took it of the pack (made it 84v) and the car improved. Its not good enough yet, but I still have at least 2 other batteries similar to the one removed, an could be causing problems.

So it does seems that its more battery related than controller config at this point.

I'll work on getting those batteries replaced, but in them mean time I would like to know if keeping them charging (mostly floating) would pose any threats to the other batteries. Or if multiple charge cycles could get those bad batteries up to par with the better ones?

Thanks for all the help.

 

[Moltenmetal]

You poor fellow! I feel sorry for you that your brief investment in lead has come to such a bad end.

Some say that sulphated batteries can be recovered. Others deny that. But in the end, you'll be ditching the lead anyway.

I can tell you that my AC50/1238 + lithium car doesn't weigh anything close to 2800 lbs but must be over 2200 lbs with me in it, and it gets up to 60 mph (100 km/h) in under 13 seconds. 30 km/h in 30 seconds is terrible. You must be experiencing a lot of voltage sag indeed.

Note also that there is an acceleration parameter in the Curtis setup which you can access with the menu button and Spyglass. That may need adjustment.

Note also that there is also a parameter which can be accidentally re-set which is the RPM at which the controller starts changing the output waveform to the motor- for mine it was set to 2200 rpm, and when it was accidentally reset the controller went into some kind of limp mode which made the car essentially un-driveable. I forget the parameter name in the HPEVS programming list right now and my notebook isn't at hand to look it up for you. If you put the controller in program mode you can check all the parameters one by one without changing any of them.

 

[nesc76]

You poor fellow! I feel sorry for you that your brief investment in lead has come to such a bad end.

Some say that sulphated batteries can be recovered. Others deny that. But in the end, you'll be ditching the lead anyway.

Thanks Moltenmetal!!! Fortunately (unfortunately?) my days with Lead are not over yet. I spoke with the technical support from the batteries supplier and they agreed to replace the batteries that are not up to par.

So Friday I'll take them from the car and take to be replaced. Hope this improves things substantially.

I can tell you that my AC50/1238 + lithium car doesn't weigh anything close to 2800 lbs but must be over 2200 lbs with me in it, and it gets up to 60 mph (100 km/h) in under 13 seconds. 30 km/h in 30 seconds is terrible. You must be experiencing a lot of voltage sag indeed.

Thats great!!! Having some benchmark helps a lot. The original car, depending on the motor, does 0-100kmh between 10 and 13 secs.

I wont get near your numbers probably (heavier car and lower current from the batteries), but shows me I'am really far from what the motor can do.

My voltage sag from the pack itself is not that big. I'am wondering how much single batteries are sagging and increasing resistance and if it's enough to impact the performance that much.

I havent ruled out some other issue (like a controller configuration for example), but focusing on that battery problem first.

Note also that there is an acceleration parameter in the Curtis setup which you can access with the menu button and Spyglass. That may need adjustment.

Note also that there is also a parameter which can be accidentally re-set which is the RPM at which the controller starts changing the output waveform to the motor- for mine it was set to 2200 rpm, and when it was accidentally reset the controller went into some kind of limp mode which made the car essentially un-driveable. I forget the parameter name in the HPEVS programming list right now and my notebook isn't at hand to look it up for you. If you put the controller in program mode you can check all the parameters one by one without changing any of them.

I adjusted some acceleration parameters and they helped initially. Those 30 secs are with the parameters already adjusted tough.

I googled for some curtis parameter related to rpm/limp. Unfortunatelly I only have spyglass, so if its something spyglass doesnt expose, it will be hard to check right now (working on getting something more than spyglass).

But if you can find out the parameter I would appreciate.

Thanks for the help and the infos.

 

[Moltenmetal]

There are actually two motor control parameters which can be adjusted wrong or by accident, which for my AC50 are:

Field weakening: 60%
Base speed: 2200 rpm

The controller implements field weakening starting at a base speed of 2200 rpm.

When the car had the wrong base speed set, the highest current I could pull was 100 A. Note that the instantaneous peak current recorded as max current on the Spyglass may be very brief indeed- you really need an ammeter and preferably a voltmeter too so you can know exactly what is going on with your pack.

Torque is related to current- if you're pulling the current, you should be generating the torque- and it's torque which gets you up to speed.

You can access and adjust both parameters using the menu button, key switch and Spyglass method.

 

[nesc76]

There are actually two motor control parameters which can be adjusted wrong or by accident, which for my AC50 are:

Field weakening: 60%
Base speed: 2200 rpm

The controller implements field weakening starting at a base speed of 2200 rpm.

Interesting. Not sure why, but my base speed is set to 0 rpm.

When the car had the wrong base speed set, the highest current I could pull was 100 A. Note that the instantaneous peak current recorded as max current on the Spyglass may be very brief indeed- you really need an ammeter and preferably a voltmeter too so you can know exactly what is going on with your pack.

Usually I'am testing it alone. I have the tools, but I believe I'll need to invite a friend over to help keep an eye on the tools while I drive.

Torque is related to current- if you're pulling the current, you should be generating the torque- and it's torque which gets you up to speed.

You can access and adjust both parameters using the menu button, key switch and Spyglass method.

I guess changing the basespeed is a quick test. Do you know what was the default for it? Theres a disclaimer in the docs mentioning that I should contact HPEVS before changing it, but I belive my is not the default value for some reason.

The docs tell it should be between 200 and 6000. So, being 0 smells wrong.

Thanks for looking the values up!!!

 

[nesc76]

My base speed setting ...

 

[nesc76]

Field weakening: 60%
Base speed: 2200 rpm

This did it!!!!!! Thanks you SO much!!!!

I actually set Base Speed to 3000 and Field weakening to 36% (per HPEVS docs). The car is amazing now. And I'am running at 84V nominal (I had remove one battery for testing).

It could barely go up the drive way. Not it goes up in second gear without breaking a sweat.

I believe Field weakening could go to 60%, apparently base speed is what did the trick.

 

[Moltenmetal]

Puzzled by why your AC50 settings for base speed and field weakening are so much different than mine. But glad it solved your problems. Best to get with HPEVS and find out what your settings really should be.