Earth Day , too bad my Pie doesn't work , Bikemad found the problem

[Rodmiami]

  Happy Earth Day , I wanted to go for a ride on my MP 2 today . I am recovering from Shoulder surgery and today would have been the first time in 8 weeks that I was able to lift my arm high enough to ride . The bike was used by a friend of mine 6 weeks ago , all was well when I put it away on charge . Today I went out  unplugged it , charger was green , turn the key and nothing . No lights on the throttle . I measured 36v to the front wheel , Internal controller . I checked the charger ,41v . I changed the charger to the one  from my previously failed GM battery . The charge light still shows green , even though the battery needs a charge at 36 v . I think it is the BMS as it was in my previous GM battery . I am beginning to think that GM knows that there was a problem with the Lmn36v16ah batteries which is why they  only sell LiPos now . I have already spent close to $1000 in GM batteries . When I got my MP from China last year the internal controller did not work , thanks to Gary and Alan they convinced GM to send me a new controller for my new motor , which worked . Tomorrow I will contact Gary since I bought this Lmn3616Ah battery from him last August . I will probably will be offered a discount on a Lipo which I will probably spend more money on . My 1995 Toyota 4x4 cost me less to drive than my Magic Pie . The only thing that I see Magical about Golden Motors products is how fast your money disappears . Rod

[Pwd]

Frustrating for sure, I would try to do a bit more troubleshooting to see if you can solve the problem first. Doesn't sound like its a definite problem with your battery; you should be getting some lights/throttle response. Do you have another throttle to test your Pie with? Is the controller plug lined up perfectly? Whats the voltage right from the battery?

P.S.... you must like my avatar.

Good luck,

 - Paul

[Henry Chang]

      Really sorry ,so the best buy to the dealers.

[Rodmiami]

I have opened the motor and tested all wiring in and out of the internal controller . All of the wiring and all connections test good . This is my second controller , the first one was defective out of the box . Now this one has failed . The only reason I was concerned about the battery is that it is only putting out 37v with 41v going in and it has always given me 41v off a fresh charge . Also at 36v the charger still shows green when plugged in , it does not attempt to charge to 41v . So now I have another failed internal controller . I will decide what to do this week .  I don't want to install another controller in the motor . I may change it to an external , the price of internal and external are the same I think,but then once again I have an internal USB cord and would have to change it also . This wheel has no more than 30 or 40 miles on it , mostly up and down my street , the longest ride was 5.5 mi round trip . The Magic Pie was a toy for me , a very expensive toy . Rod

[Rodmiami]

I ordered a new internal controller from Gary . I will post the results when I get the controller and its soldered , which I am no good at . Rod

[Bikemad]

Also at 36v the charger still shows green when plugged in , it does not attempt to charge to 41v . So now I have another failed internal controller .

Rod, I'm puzzled as to why an unusually low battery voltage/charging problem would make you conclude that your speed controller has failed.
If your battery is only putting out 37V after a full charge, then something is seriously wrong.
If you take a look at the following graph, you can see that at 3.7V/cell (37V divided equally by the 10 cell groups in series) your battery is almost completely exhausted:


The battery problem needs to be sorted before you do anything else. When you have an acceptable battery voltage to start with, you can then carry out further checks and diagnosis if you then find that it still doesn't run.

I ordered a new internal controller from Gary . I will post the results when I get the controller and its soldered , which I am no good at .

I think that replacing the speed controller will probably turn out to be a pointless exercise, as it will not increase your battery voltage, nor will it make the battery gauge LEDs light up.

It will be interesting to know the exact cause of your problem, so please keep us updated.

Alan
 

[Rodmiami]

I thought that a 36v battery cuts out at 32v . I need to know as soon as possible because I bought the battery from Gary last August and it should still be under warranty . I had battery going in to the wheel 37v but none at the throttle connection . I mentioned that the battery was losing voltage in my first post . The battery charger when plugged in is always green . I swapped out that battery charger for my old charger and the results are the same , it shows green . Therefore I should not have taken the advice of PWD that said my problem could not be the battery . I still think it is the BMS telling the charger its full , since both chargers show the same green light . Anyone else got any ideas . Alan I wish you would have posted earlier . Thanks Rod

[Rodmiami]

Also I am not taking the battery apart to test inside . Either this battery is defective like my last one or its not . Rod

[Bikemad]

Rod, unfortunately I don't know what the cut-off voltage is for a GM pack, but whatever its set value, it could occur with a considerably higher pack voltage if the cells were not evenly balanced, because the lowest individual cell (or group of paralleled cells) would trigger the low voltage cut-off, thereby preventing further discharging of the lowest cells.

You also need to realise that the cut-off would typically occur when the pack is under load, and the cells would then be registering an even lower voltage than when there is no load on the battery.

If your pack is reading less than the 37V nominal voltage without any load, I'm pretty sure that your pack will be almost completely exhausted!

My LiPo Packs are charged to 4.2V per cell, and the voltage range from fully charged to discharged is similar to the LiMn cells in your GM pack.
I don't have a BMS to safeguard my pack, but I do however use a battery monitoring device which beeps and flashes when the pack voltage is getting too low. This happened earlier in the week just before I blew my controller while I was pulling over 97Amps from the 5Ah pack (almost 20C).
My minimum recorded voltage was 44.98V, which works out to be approximately 3.21V per cell. The cell voltage at the end of this particular ride (which was more like an intensive workout for the motor) was back up to 54.02V (3.86V per cell) without any load.
In the eighteen months prior to this, the lowest the pack has ever been on a run was 45.12V while under a mere 60.19 Amps (12C) load  , which at the end of that ride was showing 52.3V (3.74V per cell), and that's the only other time that my battery warning device has been activated while riding, and it started beeping just as I was nearing the end of the return trip.

I hope someone with a GM pack has recorded their voltages at the end of a long run and will be kind enough to post the details here for us to compare.

Alan
 
P.S. If I had read this topic earlier, I would have posted earlier!
Regardless of what my wife says, I do not spend all my computer time on this forum.
Home accounts, Emails, Facebook, YouTube, eBay and general surfing all have to be fitted in as well

[Rodmiami]

Alan , you are correct(as always) , my previous failed battery always showed 41v even though the battery would cut off on any acceleration . I will contact Gary about a replacement battery, although I don't think that he has any LiMn batteries in stock anymore . I feel that GM knew that these packs had a high failure rate and went to LiFePO₄s for better longevity . I am willing to pay the difference . I just keep throwing money at this bike. The last battery that I bought in August of 2011 with shipping was almost $475.oo . The previous battery bought from China Dec. 2009 $490.00 . The motor was purchased from GM China $410.oo  . Thats $1375.00 plus the USB cord which should come with the controller whether its internal or external. All this and I still don't have a reliable package . Rod

[Rodmiami]

 This is an update , today the battery is reading 35v with the charger on last night . It appears to be loosing about 1v per day even on charge . Rod

[Bikemad]

Rod, your battery is obviously not charging, and if it were my battery, I would remove the end cover and make sure the charging connector wires are still properly attached at both ends.

If all the wires are still attached in their correct places, I would temporarily bypass the BMS with the charging leads and then charge the pack while monitoring it carefully to see if the cells begin to recharge again. If the cell voltages gradually start to rise and remain reasonably even, they might well be fine, in which case a replacement BMS is probably all that's required.



Alan
 

[Rodmiami]

Alan , the only thing is that this battery is still under warranty .Your assumption sounds reasonable but , I will not open it until I contact Gary on monday . Gary works hard and deserves the weekend off , I am retired and to me a day is a day . Rod

[Rodmiami]

Bikemad, you are the man . Yesterday I opened the battery . Nothing was loose or not connected inside . This morning I rigged up a reverse charging setup . I used an old anderson connector to the charger and plugged it in to the battery out port . I turned on the key and the red light on the charger came on . I let it charge for about 20 min . ( the battery was down to 34v this morning)after 20 min on the reverse charge the battery was up to 41v . I plugged it into the Pie and the lights on the throttle came on, a beautiful thing that hasn't happened in a while. Tried the throttle , the wheel spun . Mounted the battery correctly and went for a ride down my street . The Magic Pie is working as good as before . Mikemad was right the BMS went bad , I ordered a controller that was not needed . I will keep the controller when it gets here , it was my mistake and I will eat the $80+ . But now do I attempt to replace the BMS or hit Gary up for a new battery . If I can get a new BMS I will replace the BMS . Rod

[Bikemad]

Rod, it might be worth trying to charge it normally again to see if it will work properly now the cell voltages have substantially increased. I don't know whether a low cell voltage can cause the BMS to stay disconnected, thus preventing the pack from accepting any charge from the charger.  Now your cell voltages are higher, you might find that the charging will function correctly again.

Give it a try and see if the red light comes on when you charge it normally via the charging socket, you can also check the voltage with your voltmeter to see if the battery voltage rises with the charger connected.

If it's still not charging, you will need to contact Gary regarding the suspected BMS problem and see what he suggests.

Please let us know the outcome.

Alan