72V batteries -> lyen MK I -> BMC V3T = stutter w/load

The Stig

The Stig

100 kW
Joined
Nov 15, 2008
Messages
1,032
Location
Boston
UPDATE 2012/2/1(problem in thread title has been resolved): I have a question for you guys/gals. My charger cuts off at 42V but my pack should be charged no more than 41.5V, is there any way to lower the voltage of the charger by 0.3-0.5 V? I've tried using a diode(0.7V voltage drop) to take it down to 41.3V but the charger won't turn on again unless it drops below 41.1 V. This may be a problem because this battery is in series with another battery that stays at 41.5V off the charger so thats almost 0.5V a difference. I would like to keep the two batteries balanced.

==============

UPDATE 2012/1/10: Good News and Bad News! The MK II controller runs well! I was very happy about it.
The Bad news, in my infinite stupidity I hooked up the charge leads backwards on the external battery and now the BMS won't charge the battery anymore :x :evil: :( :cry:
I went ahead and hooked up the charger directly to the battery, which brings me to my....

Question: Will an A2B battery be ok being discharged and charged completely BMS-less for some time??? The BMS is actually still hooked up, including the balancing leads, but the red charge wire has been connected to the battery main red wire. Charger is 42V 4A. When I hooked it up w/out BMS the battery was at 40.8 and the charger was trickle charging it at 2.8A.

Voltages of the each string are on last page. Pictures of the BMS are at the top and pics of the cells are bottom of the first page.

I'd like to go with a replacement BMS by some other manufacturer. Last time I tried to get a replacement BMS from A2B they wouldn't give it to me. They insisted I send in the entire battery. kind of a waste of my time and money.

==============

UPDATE 2012/1/9: i don't know why my lyen mkI (infineon) cant run the BMC and MAC gear motors at high voltage. Lyen and I couldn't figure out the problem so I spoke to some others and to Ilia at ebikessf.com and i ended up purchasing one lyen mk2 controller through ebikessf.com. thanks for same day shipping.

Question: should i leave the BMSs Bypassed for discharge or should I reconnect them? These are lithium manganese as far as i know. Reconnecting them for discharge means i have to reinstal the diodes that protect the BMSs incase one cuts out. Its very tight fitting those diods and a relay into the bottom of the A2B frame. would like to avoid all this work if there is very little chance these packs could get unbalanced and one falls way beloe lvc. They will still charge through theyre BMSs.

==============

UPDATE and summary: With bypassed BMS on two a2b batteries at 72V I have in series and a no load current of 1-2A spinning smoothly at full RPM... the BMC 600w-T motor stutters when under load at low RPM not with low current usage. It also does this when powered by a 60V 5A power supply when powered by the batteries @72V with a MAC motor. However when powered by one 36V battery the system runs properly and smoothly with both motors... whats going on here

==============

ORGINAL POST:

I have an A2B metro with both batteries, Lyen 9fet controller, and the new generation BMC 600W torque motor. A huge thank you to Lyen for helping me out finding the problem, definitely buy controllers/things from him if possible.

I recently finished hooking up the two A2B batteries in series using a Diode in parallel with each battery and I nice relay for my on off switch. 83.5V fully charged :twisted:
...However I am having intermittent current issues. The motor runs smoothly no load, but stutters and is underpowered when under load. If I disconnect one of the batteries and run it at 36V it runs smoothly. It's probably the BMS. Does anyone know if theres a way to remedy this and avoid bypassing the BMS during discharge?

This is video of no load test. Its not the best quality video but you can hear the motor stuttering when I hold the break:http://www.youtube.com/watch?v=JYJyybWwxz8

Picture below: BMS of A2B External Battery. Charge leads connect in the bottom right. Main battery leads top right and bottom left.
2011-04-08_13-28-09_623-1.jpg

2011-04-21_22-10-05_709-1.jpg

2011-04-08_13-28-14_520-1.jpg

2011-04-21_22-10-11_645-1.jpg

2011-04-21_22-10-18_864-1.jpg

2011-04-21_22-10-53_972.jpg

2011-04-21_22-10-57_821-1.jpg

2011-04-08_13-22-50_4-1.jpg
 
You should just try to return the bike. Looks very complicated what your doing.
 
Jason27 said:
You should just try to return the bike. Looks very complicated what your doing.
Click to expand...
@Jason27, you should either try to be genuinely helpful (and relevant), or please stay out of threads; it's getting tiresome. :(


@The Stig: Have you measured the voltage across each battery during the stuttering? It might tell you if only one of them is causing the problem, or if perhaps it matters which position it is in (most positive pack or most negative pack)? I'm not sure what the problem might be yet, so I haven't got anything more definite to propose for now.
 
At the moment I have the BMS bypassed in one of the batteries. I suspect the BMSs are either identical or similar as they are both stock batteries. During the test I had the throttle Maxed and slowly applied the break. The volt meter is connected to the battery with the BMS and the CA shows total voltage. It ran smoothly until the voltaged reached 72V (from 80V) when it started stuttering and the voltage across the battery with a BMS rised and the voltage across the battery without a BMS dropped even more.

Heres the video but there is no sound for half the vid. It didn't upload properly.
http://www.youtube.com/watch?v=nxpDUYxxRok
 
is the CA a direct plugin or standalone ?... the display shows 5000w at no load, that's not right, so either the Rshunt is not set correctly , or you have a wrong hall/motor phase combination..

The a2b battery packs will not like 20+ amps sustained, and with that motor and 9fet lyen controller, i suspect this will be the case...... keep an eye on voltage sag and pack temps.
 
Yeah something is wacky with the CA ever since it was rewired. The wire was cut, shortened and reconnected by someone else, maybe correctly maybe not. But the CA reads the same voltage as my multimeter. The stuttering problem persists whether the CA is plugged in or not.

I have no problem limiting the current to 25-28A. That would be plenty.

I've pretty much ruled out the color combination being wrong. Both Color codes lyen gave me work with this motor no load and my MAC shanghai.

Heres another video of no load and the load test showing the stuttering at low RPM.
http://www.youtube.com/watch?v=JYJyybWwxz8
 
Just for grins, have a good hard look at all wiring and particularly connectors. Could easily be a poor phase connection or wire with most of the strands cut or broken.
 
Just more evidence that points to the real problem having nothing whatsoever to do with the batteries. What you are descirbing does match perfectly with a bad connection on halls or phase wires, or the same wires connected wrong.
 
Ypedal said:
you did not answer one of my questions... direct plugin CA.. or standalone ?

if it stutters without the CA used, and BMS bypassed, likely wrong wire combo.
Click to expand...

Oh sorry, the CA is a direct plug in.

I have tried too combos that also work with my MAC shanghai and run smoothly at high rpm with no load at 72v. Under load at low RPM both motors stutter. However if i run them off one battery at 36v they both run smoothly under load. I could upload videos of the MAC tests but they dont show that much. You can hear the freewheel of the motor clunking when i apply the brakes.
 
A while ago we had tried all the phase/hall combinations.

Here is a video showing how the system runs on one of the 36V batteries that I'm trying to use in series. I used the disc brake as a load which makes a soft and quick clicking sound that gets louder the harder its applied.
http://www.youtube.com/watch?v=EC-Eq18L0L0

I did a test with a 60V 5A power supply and reproduce the stuttering. During the stuttering the meter shows the voltage fairly stable around 59.5V and current jumping around from 0.5A to 2.5A.
http://www.youtube.com/watch?v=usuH-xFGcus

I'm not sure how this controller works but could it need more current just to run smoothly at higher voltages? Does the success of the 36V test not mean anything for two of these batteries in series??

The two lyen controllers I've had have been great but I'm wondering if there is a different controller I should buy for this (low current?) purpose. Right now the only alternative I can think of is a 30A one from hipowercycles.com where I bought the motor.
 
if the color combination is wrong, the motor will run rough, regardless of voltage, but more pronounced at higher voltages ( or more noticable .. ) .. what really tells the story is how many amps the motor draws " No load " and full throttle..

A proper color combination, on that type of motor, no load, should be something along 100~200w ... a wrong combo will draw much more.. like 500+


this is why i was asking about the CA type... if it's a Standalone type, it's calibrated and we can rely on the numbers shown, however if it's a direct plugin you need to set the " Rshunt " value in the setup in order to know exactly how many amps the controller is drawing...
 
Ypedal said:
if the color combination is wrong, the motor will run rough, regardless of voltage, but more pronounced at higher voltages ( or more noticable .. ) .. what really tells the story is how many amps the motor draws " No load " and full throttle..

A proper color combination, on that type of motor, no load, should be something along 100~200w ... a wrong combo will draw much more.. like 500+


this is why i was asking about the CA type... if it's a Standalone type, it's calibrated and we can rely on the numbers shown, however if it's a direct plugin you need to set the " Rshunt " value in the setup in order to know exactly how many amps the controller is drawing...
Click to expand...
I think the 2.3A-2.5A at 60V would indicate correct combination the you describe it. As we see in this vid(added to my updated previous post) http://www.youtube.com/watch?v=usuH-xFGcus
 
UPDATE 2012/1/9: i don't know why my lyen mkI (infineon) cant run the BMC and MAC gear motors at high voltage. Lyen and I couldn't figure out the problem so I spoke to some others and to Ilia at ebikessf.com and i ended up purchasing one lyen mk2 controller through ebikessf.com. thanks for same day shipping.

Question: should i leave the BMSs Bypassed for discharge or should I reconnect them? These are lithium manganese as far as i know. Reconnecting them for discharge means i have to reinstal the diodes that protect the BMSs incase one cuts out. Its very tight fitting those diods and a relay into the bottom of the A2B frame. would like to avoid all this work if there is very little chance these packs could get unbalanced and one falls way beloe lvc. They will still charge through theyre BMSs.
 
Being able to leave the BMS disconnect on discharge will depend on your cells and how you use them. If you have reasonably equal cell, even if you deep discharge, it will not matter. If you have a weak cell and you deep discharge, you can destroy it.
I only use my BMS to charge my LiFePO4, and I have 3 weak cell in 20. Works OK for me, but I've only done two cycles so far.
You will need to monitor your cells for a couple of cycles and make the conclusion your self.
 
This is what I would do, run it without the CA, if the problem persists then run it without the bms, if possible. You will know then if it's the ca, bms or controller.
 
UPDATE 2012/1/10: Good News and Bad News! The MK II controller runs well! I was very happy about it.
The Bad news, in my infinite stupidity I hooked up the charge leads backwards on the external battery and now the BMS won't charge the battery anymore :x :evil: :( :cry:
I went ahead and hooked up the charger directly to the battery, which brings me to my....

Question: Will an A2B battery be ok being discharged and charged completely BMS-less for some time??? The BMS is actually still hooked up, including the balancing leads, but the red charge wire has been connected to the battery main red wire. Charger is 42V 4A. Fully charged with the BMS the pack would have a voltage of 41.5V. When I hooked it up w/out BMS the battery was at 40.8 and the charger was trickle charging it at 2.8A.

Pictures of the BMS are at the top and pics of the cells are bottom of the first page.

I'd like to go with a replacement BMS by some other manufacturer. Any ideas? Last time I tried to get a replacement BMS from A2B they wouldn't give it to me. They insisted I send in the entire battery. kind of a waste of my time and money.


Voltages of Strings (A2B External Batt):
40.8
36.8
32.7
28.6
24.5
20.4
16.33
12.25
8.16
4.08

Pictures of the charging part of the BMS: [img]http://i247.photobucket.com/a...139/kostasf/2012-01-10_18-33-37_973.jpg[/img]
 
It's quite possible that the BMS will still do all the things it's supposed to except cut off charge at HVC and discharge at LVC, if it's left connected to the balance leads and pack +/-, if you are charging/discharging it directly to pack +/-.

Assuming the HVC/LVC functions still work but the FETs are dead, you could either replace them or run the gate line to an external alarm or light so you know when they would have triggered, and manually stop.

You'd have to test that the functions (including balancing) are still working, though.
 
Amberwolf,

The charger goes up to the 42V and the pack when charged with the BMS used to reach a voltage of 41.5. Do you think the extra 0.5V is too much to leave the charger on the battery without HVC? LVC i stopped caring about many days ago...

Not sure how to test if balancing is still working if I can't leave the charger on the battery without babysitting it. Don't have time for batterysitting. If I can I will make sure every string is 4.2V apart.

I was cautiously hopeful that the BMS still balances.
 
Well, to test balancing, if the charger goes higher than the eventual pack voltage after sitting for a day....

Measure each cell at charger cutoff.

Wait a few hours, and measure each cell again.

All cells should be draining down to the shunt cut-off voltage.

Actual time it takes to do that depends on the capacity of the cells, the over-voltage each gets, and the size of the shunting resistors; if they can dissipate a lot of power and take high currents then it won't take long, but if they're tiny SMD resistors it'll probably take a while.

Then after at least another couple of days, remeaseure each cell and make sure they're not continuing to be drained by the BMS after shunt cutoff. If you tend to use and then charge the pack every day it won't matter but if you ever leave it for days it could make a world of difference.
 
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