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Discussion Starter #1
Hi everyone, It's my first post and probably not my last now that I own an electric vehicle.. I just bought a converted Datsun ute with a single direct drive transwarp 9 motor, net gain classic 160v. 1000 amp. Controller and Nissan Leaf battery pack 166v. 40 cells at 4.1v each cell. From memory the dude I bought it from said they were 60ah per cell but were bridged to achieve 120ah per unit. Sorry if I'm a bit vague but I am just getting my head around this having lived a life involving and educating myself with the ICE.. my issue I am having is the motor is dropping out under load mainly when the car is at a stand still. When I take my foot back off the throttle and put it back on it drives fine. Actually I can put my foot down hard from around 50 km/h upwards and it really takes off! I have the controller set to 1000amps and would really love this thing take off from the get go without it dropping out. I suspect I may need more battery power but I'm not 100 percent sure. Any comments will be greatly appreciated!
 

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Sounds like you are hitting the high current limit on start off. If the only time it does that, you are attempting to run too many amps for the controller so a lighter foot is needed until the motor is spinning. Try the ice technique of revving motor then slip the clutch if you have one.

Could also be the low battery limit due to sag.
 

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Sounds like you are hitting the high current limit on start off. If the only time it does that, you are attempting to run too many amps for the controller so a lighter foot is needed until the motor is spinning. Try the ice technique of revving motor then slip the clutch if you have one.

Could also be the low battery limit due to sag.
But at zero rpm the battery current will be minimum (compared to motor current)
so I would expect the sag to be minimum as well
 

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Discussion Starter #4
Would voltage sag cause the motor to shut down momentarily though? It makes a pretty ugly clunk sound when it happens. I have tried running the battery current via the controller @600 amps but I still get the same thing. I definitely think if it were running through a powerglide or a clutch it would lighten the load and potentially fix the problem but I'd really love to leave it direct drive ie no clutch..
 

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Discussion Starter #5
... just to note, I have a Batrium BMS. After a fair bit of fanging around I put it on charge and noticed one battery cell in particular had dropped almost half its voltage. The rest of the cells seemed to be consistent with each other and only dropped to around 3.3 volts from 4.1.
 

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Betcha it is the bad battery cell then. Can you bypass it? The clunk happens in an older car because of the wear of components. Maybe you need new universal joints, or the play adjusted out of the diff or bearings....
 

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Discussion Starter #7
Ok cool, thanks. I'll try bypassing it that cell and see what it does. May I ask why one potentially bad cell would cause the motor to drop out all together? Is the controller logging a fault?
 

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Another thought

Pre-charge
Is it possible that you are not precharging the controller? some people use a system that drops the controller out of the circuit when at zero throttle - a contactor wired to the throttle

If you were busy charging the controllers capacitors AND you demanded current then it may draw more current and sag the batteries
 

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Discussion Starter #9
Good point Duncan, after reading the operations manual for the controller it is understood that the main contactor will not turn on unless the precharge has occurred. Precharge happens in less than 1 second and then you hear a click. Now it will take throttle input... so I step on the throttle.. car moves slightly then dies... back off the throttle.. back on and away she goes. Having said that though, I have to ease the throttle on otherwise I will just get a clunk, then have to repeat process of lifting throttle and getting back on again. If car is moving.. 40kph or more it will take full throttle.
 

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dunno if this has anything to do with it but?
most controllers r set up so that if you turn the car on with the throttle pressed, it wont move. youll have to take ur foot off and then put it back on.
so could it be that your throttle cable is a bit tight? so when you let your foot off and back on its enough to let it return to 0.

just a thought?
 

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Discussion Starter #11
Hey arklan, I'm almost positive my throttle is returning to zero. As you say.. otherwise once started, the car wouldnt drive because if the controller detects any throttle input the contactor won't click on. I will double check though.. Once driving, when the cutout occurs, it does get some throttle initially but then cuts out depending how quick I depress the throttle. I had to learn how to ease the throttle on so not to allow it to cut out.
 

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I have been thinking about this

You have a 160 v 1000 amps controler

Going by my experience 160 v is enough to push 1000 amp to the motor at low speed - but above 40 kph 160v simply won't give you 1000 amps even with the controller at 100%
I'm currently running 340v

With my controller (Paul & Sabrina) there is a current hardware limit
When I first put it in the car it was set too low and would trip

So when you demand full current - 1000 amps - then the controller will hit the overcurrent and trip

But if you do the same at 40 kph + then it can't reach the overcurrent limit so it does not trip
 

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Discussion Starter #13
Ok that makes sense, so you suggest running more volts? I think my controller is upgrade able to 360v 1400 amps. I'm yet to contact net gain and I've heard they ain't easy to get in contact with over product support. I would have to double my battery supply also... sounds like an expensive exercise!
 

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Hi
Increasing the voltage would only make the situation worse as you would be able to hit the hardware trip at higher speeds

Can you dial the 1000 amps down a wee bit? - or put a block under the throttle?

If I'm right it won't reduce your power higher up but it will enable you to give it full welly from lower down

I use switches on the dash - I've got an old fashioned 0-5kOhm throttle so putting a 5kOhm resister in parallel means the full throttle drops from 1200 amps to 600 amps
 

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Discussion Starter #15
Yep I think that would work however I really want this car to hook up hard down low, especially from a standing start. I don't want to limit it in any way. I'm willing to spend more money but I want to make sure I'm not doing things twice. Do you have a similar setup? What car is it in?
 

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Hi
This is my "Device" - no gearbox direct drive to the diff

http://www.diyelectriccar.com/forum...dubious-device-44370p15.html?highlight=duncan

The current drop is just a suggestion for a short term fix until you fix the real issue which I suspect is a hardware current limit on your controller but you will need to get the specs and diagrams from your controller to check that

On my P & S controller the max current is set by software but there was one of those little adjustable resisters that set a hardware limit - I had to adjust it so it didn't trip
 
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