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Severe jerking at acceleration

 
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Art Marquardt



Joined: 20 Nov 2005
Posts: 99
Location: 625 N25th st Sheboygan,Wisconsin

PostPosted: Tue Oct 24, 2006 4:13 pm    Post subject: Severe jerking at acceleration Reply with quote

Help!!

I recently changed over to 144Volts from 120, sounds good right! Well, now the truck stutters and the whole rear starts to shake when we take off. The shaking goes away almost immediately and it smooths out drives O.K. Mind you, we haven't driven it much because of the shaking it seems like something is really out of whack. Any ideas of what might be the cause.
Note I was not pressing hard on the accelerator. We never did get up to highway speed because to many stop signs between here and the highway.
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ThomasHudson
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Joined: 26 Sep 2005
Posts: 130
Location: Port Washington WI

PostPosted: Tue Oct 24, 2006 9:14 pm    Post subject: Reply with quote

Just changing the voltage shouldn't be a big deal, unless it's causing the DC-DC to not function properly. Check the no-load voltage on the truck before you try to drive it. Compare that voltage to the voltage listed on the DC-DC converter. If it's higher than the maximum listed on the DC-DC box, maybe it's causing the 12 volt system to not work properly, which would probably screw up the ignition signals. My thoughts here are that once you start driving, the pack voltage drops a bit and everything works properly.

If that doesn't seem to be it:

Try unplugging the power connector on one of the motor controllers and test to see if it shudders when starting. Then plug that one back in and unplug the other one and see if that shudders.

If it's smooth with one of them, maybe something is wrong with part of the drive system. Possibly the motor speed sensor in one of the motors, which I've heard can cause jerky starts if they're out of whack.

If this is the case, try unplugging the 9-pin connectors from the motors to the controllers and making sure their pins are clean and not corroded.

Also, make very sure you didn't cross-connect one motor's 9-pin connector to the other controller and vice-versa. That would probably screw things up as well, making it jerky with power to either controller.

Let us know what you find, Art.

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Tom Hudson
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Art Marquardt



Joined: 20 Nov 2005
Posts: 99
Location: 625 N25th st Sheboygan,Wisconsin

PostPosted: Tue Oct 24, 2006 10:59 pm    Post subject: Jerking revisited Reply with quote

Tom:
Thank you for your quick response. I have egg on my face Embarassed the problem turns out to be at least I hope a simple one. I should have known better. We were so eager to test out the truck that when we connected the controllers (left sitting 3 days disconnected) they were not precharged so one controller may have been bucking the other. After a while I did the one controller at a time test, it worked OK albeit sluggish. When I hooked up both again it worked great. This worried me untill I talked to Jeff Wilson who hit on it right away. It made so much sense I am pretty convinced this is what the problem is. Although your Idea about the DC-DC Convertor sounds interesting. I believe that it is 144V. It will be interesting to see how the truck runs now that I have 144Volts worth of group 27 batteries in it at 210 amp hours.
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ThomasHudson
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Joined: 26 Sep 2005
Posts: 130
Location: Port Washington WI

PostPosted: Wed Oct 25, 2006 12:07 am    Post subject: Reply with quote

I'm glad to hear that the problem is solved, Art. I've never had a problem after having my controllers unplugged, but maybe I was just lucky!
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Art Marquardt



Joined: 20 Nov 2005
Posts: 99
Location: 625 N25th st Sheboygan,Wisconsin

PostPosted: Sat Oct 28, 2006 2:22 am    Post subject: Jerking Reply with quote

Tom:

Apparently the problem is not entirely gone. However, it has shifted. My brother informs me that the jerking is occurring early in his ride to work
when he steps off the gas and the regen kicks in. Later this goes away.
I'm going to have him turn off the regen initially and then turn it on later to see if this solves the problem. I'm suspecting that since these controllers were originally set up for Nicads it may have something to with the parameters. Got the new voltmeter with the 100-200 VDC range today. So, between the higher voltage and the lower range scale we should be able to read the voltage easily. Now I have to redo the power cheq modules 4 new ones and rewiring. I've also got some EDTA on order so I will experiment with that on the batteries.
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ThomasHudson
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Joined: 26 Sep 2005
Posts: 130
Location: Port Washington WI

PostPosted: Sat Oct 28, 2006 10:42 am    Post subject: Reply with quote

That's actually normal, but my guess it's being made worse by the higher pack voltage.

The regen is limited so that if the voltage gets too high during regen, it'll cut out until the voltage drops below that threshold. Your controller is probably programmed to cut off around 165V, and the 144V pack is getting up there easily.

The solution will be to reprogram your controllers to a higher regen cutoff voltage (whatever is standard for 144V packs). I have an interface box for those controllers but I've never tested it. When things calm down around here a bit, I'd be willing to help you get those reprogrammed. Until then, I'd leave regen off until the truck uses around 8-10Ah.

Actually, now that I'm thinking about it, what controllers do you have? I have software and the interface for the AMC series.

Incidentally, the regen shudder won't ever completely go away, even with the higher voltage programmed in. Our truck will shake the daylights out of you if you regen coming out of our driveway when the pack is full!

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Art Marquardt



Joined: 20 Nov 2005
Posts: 99
Location: 625 N25th st Sheboygan,Wisconsin

PostPosted: Mon Oct 30, 2006 8:14 pm    Post subject: Jerking Reply with quote

Tom:
Thanks for the offer. I would like that. Isn't the interface just a cable that adapts the 25 pin output to 9pin serial port on a computer the problem being most computers don't have 25pin serial ports or am I confused again?
For now though I am trying to troubleshoot what appears to be an intermittant problem. The jerking occurs on both acceleration and braking with regenerative. I jacked the truck up and got the wheels spinning it jerked at low speed. So I disconnected the drivers side controllers' speed sensor. It shuddered briefly I think and then was fine. The rest of the tests were fine with no problem. Hooked every thing up and put it on the road it worked fine. Later it acted up at one point it was almost undrivable in forward at low speed and this is with 10 amp hours on. It seems that disconnecting one of the controllers and reconnecting them fixes the problem. The thing is if two controllers are fighting each other disconnecting one will mask the problem. I have never had the problem occur with one controller disconnected. If this is a speed sensor problem why now?? The contacts on the connectors at the controllers are clean and in good shape I even cleaned them with contact cleaner.
I have also run the simple diagnostic for the pot box. The speed pot on the 1995 was turned low, I floored the acclerator pedal while adjusting speed with the pot only it still had some problems so I don't think it is the pot box.
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MajorWilson



Joined: 26 Sep 2005
Posts: 236
Location: Peoria, AZ

PostPosted: Wed Nov 15, 2006 6:43 pm    Post subject: Reply with quote

Art, did Tom ever get with you to check out the interface box?

I know that your controllers were set up for 120v pack of nicads. Max voltage would be between 140v and 145v because the nicads would max at about 7 volts each. Because of that, when you are at initial charge, way over the controller voltage, you would have problems. Initial charge on your 144 pack would be in the 165v range. Even discharged to 50% you would still be over max voltage for the controllers.

I think you need to get with Tom soon and get the controllers changed over to a 144v system.

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Jeff Wilson
US Army (Ret)

Plug in the cord... not the pump!
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Art Marquardt



Joined: 20 Nov 2005
Posts: 99
Location: 625 N25th st Sheboygan,Wisconsin

PostPosted: Wed Nov 15, 2006 7:46 pm    Post subject: REPROGRAMMING CONTROLLERS Reply with quote

Thanks Major...

I wished I had known that. Strangely, the problem has gone away. I hate that because you never know what caused it so you don't know if you fixed it. If a tree falls in the forest and no one knows did it make a sound?
If you accidently fix something, but don't know how, did you fix it?
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MajorWilson



Joined: 26 Sep 2005
Posts: 236
Location: Peoria, AZ

PostPosted: Wed Nov 15, 2006 9:28 pm    Post subject: Reply with quote

if you make a decision and you wife isn't around to hear it, are you still wrong????? Wink
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Jeff Wilson
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Plug in the cord... not the pump!
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