Controller shutting down when full throttle.

[Enpro]

My controller has a cuttoff voltage of 60v and my pack gives me 78v on the meter.
They're both fully charged then when i go riding it gives me a few seconds of full power (which is awesome!) before it starts shutting down the controller. The battery indicator starts tripping and there is no power anymore, I have to turn the key on one of the battery's to restore the power?
After a few minutes it starts to shut down even at 25% throttle...
I havnt wired up the hall sensors yet , does that matter or are my battery's just bad?
I got a crystalyte 72v / 45 amp hall sensored controller , A magic pie 3 , and 2x 36v 16ah golden motor limn2o4 packs.

 

[dogman dan]

Batteries compatible with 20 amp controllers or less. So you are whacking it with 45 amp controller. Most likely that is the problem.

Hobby king lipo is what you need to fly.

 

[Enpro]

The battery's have a 30amp continuous and 60amp burst rating so that isn't the problem.
http://goldenmotor.com/SMF/index.php?topic=646.0

 

[parabellum]

The battery's have a 30amp continuous and 60amp burst rating so that isn't the problem.
http://goldenmotor.com/SMF/index.php?topic=646.0

The battery indicator starts tripping and there is no power anymore, I have to turn the key on one of the battery's to restore the power?

If battery indicator goes off, then it is your BMS that cuts the power. It resets when you switch off the controller usually. 30amp continuous BMS works 30amp continuous it runs only few seconds over 30amp and/or instant cutoff at 60amp.

 

[dogman dan]

Exactly, and then when you have done the standard cut all claims in half procedure, you have

15 amps continuous 30 amps burst. and you run a 45 amp controller. That's a 20 amp controller battery buddy.

Go to HK, buy some 20c lithium. Cut all ratings in half, and you still have a 5 ah battery that can pull 50 amps.

 

[neptronix]

2x 36v 16ah golden motor limn2o4 packs.

Hm, i cannot see anything other than a lifepo4 pack for sale on goldenmotor.com and goldenmotor.ca ...

I'm going to take a wild guess that those are 1-2C capable cells and you are asking almost 3C out of 'em..

An eye on a voltmeter, or cycle analyst hooked up to the battery while you hit the throttle, will probably reveal the problem - you are likely hitting a low voltage cutoff, as others mentioned.

 

[Enpro]

The battery's have a 30amp continuous and 60amp burst rating so that isn't the problem.
http://goldenmotor.com/SMF/index.php?topic=646.0

The battery indicator starts tripping and there is no power anymore, I have to turn the key on one of the battery's to restore the power?

If battery indicator goes off, then it is your BMS that cuts the power. It resets when you switch off the controller usually. 30amp continuous BMS works 30amp continuous it runs only few seconds over 30amp and/or instant cutoff at 60amp.

Then why does it works fine the first minute?

 

[Enpro]

The battery's have a 30amp continuous and 60amp burst rating so that isn't the problem.
http://goldenmotor.com/SMF/index.php?topic=646.0

The battery indicator starts tripping and there is no power anymore, I have to turn the key on one of the battery's to restore the power?

If battery indicator goes off, then it is your BMS that cuts the power. It resets when you switch off the controller usually. 30amp continuous BMS works 30amp continuous it runs only few seconds over 30amp and/or instant cutoff at 60amp.

Then why does it works fine the first minute?
Also when bought the battery packs one of them was empty, it gave like 7 volts then only after about half an hour charge it got back to 36v and the charger indicated it was full.
Never fully tested the battery after that until now so thats why i'm worried about the battery's
And If the bms was the problem wouldn't it cut the power of immediately? Because i actually can pull full throttle the first couple of times. Then over time it gets worse.
I mean wouldn't this happen when i got a bad cell in one of packs?
Sorry for dubble post. I'm a little frustrated

 

[neptronix]

Go to HK, buy some 20c lithium. Cut all ratings in half, and you still have a 5 ah battery that can pull 50 amps.

1 thing to add.. for 20C Turnigy packs, this rule applies.
For 20C zippy, the packs are more like 10C packs and are overrated badly ( but they're lighter and smaller ), so you get to cut that in half.
The lifepo4 crap hobbyking sells seems to not live up to it's rating. I'm not sure how bad they are.

BMSed A123 packs would work well in this situation too. Then you don't have to learn how to manage RC Lipo or listen to me and other members on this forum argue about the best way to do it.

 

[Enpro]

Okay then explain this to me.
I just took another test run.
First 30 seconds i can hit full throttle and it accelerates like a beats.
Then it cuts power. The only way to regain power is switching one of the battery's off (doesn't matter which one) .Restarting controller only doesnt work.
Then it starts cutting of at 50% throttle and after a like 3 minutes of half throttle riding it starts cutting at at 25%.
I leave it rest and cool down for a while (30 minutes) still only 25% throttle max.
I recharge the battery for 15 minutes, bang 100% throttle back?
I mean if its just the bms that cuts power at a certain strain it should cutoff power right from the start no matter if its fully charged right?

 

[parabellum]

Then why does it works fine the first minute?

Every BMS is different, some extend over current cutoff depending on over current, it means if you drain 35amp it can take minutes, 55amp seconds. But it is just my guess on your problem.

Also when bought the battery packs one of them was empty, it gave like 7 volts then only after about half an hour charge it got back to 36v and the charger indicated it was full.

Your BMS was probably off, trying to protect some undervolted cell, or BMS is faulty.

And If the bms was the problem wouldn't it cut the power of immediately?

Again, some BMS have reset function dictated by time of voltage difference.

Then over time it gets worse.

Could you measure amps used? Voltage sag at full throttle? Even if you have bad cell or BMS that can be changed, in short term you will run this pack to died, it is not the type of pack you need for 45amp controller (which probably allows short bursts wide over 45A).

Dogman and Neptronix are totally right, you need to switch to LiPo or A123, my personal favorite is LiPo.

 

[Enpro]

I will take some measurements first thing tomorrow.

 

[parabellum]

Then it starts cutting of at 50% throttle and after a like 3 minutes of half throttle riding it starts cutting at at 25%.
I leave it rest and cool down for a while (30 minutes) still only 25% throttle max.
I recharge the battery for 15 minutes, bang 100% throttle back?

Just for example.
I have LiMn pack with stated 10C discharge rate (Before David starts asking, it is heavy konion pack, no BMS).
They are useless in over 5C use below 25%SOC, because of the massive sag that lowers voltage to controllers LVC. I suppose at near 10C they become useless under 50%SOC.
So I try to use it in 3C up to 5C max.

 

[Enpro]

Ok just took another test run and this time i tried to ride it as long as possible and after 5 minutes of 25% throttle it went completely death. Even the 36 battery meter went to half full.
I couldn't even ride it at 10% throttle.
Now if this was a bms error is it normal to go down at only 10% power.
It was barely moving and it was still cutting of power.
Even after some cool down it still wouldn't go only a few meters while i was barely touching the throttle.
I just cant see the logic in a bms cutting off power at only a few % power draw after it did fine at 50% for 5 minutes...
I know I'm not an expert on this but it just feels exactly like my bad battery in my drilling machine that runs nice and strong for 2 minutes and then it goes death within seconds while the other power pack can drill for hours and dies slowly over time.

 

[Spicerack]

I think you've answered your own question- bad battery pack.

 

[parabellum]

It is definitely LVC cut down, the question is which one.
1) Cell/groop level voltage (BMS)
2) pack level voltage (BMS but have not heard that before, since 1 cell will hit LVC first)
3) Input voltage (controller LVC) if it recovers with just going down on throttle, it is most probable.

What wire gauge are you using between battery and controller?
What connectors?
Wire or connection hot?
How do you know LVC of controller? (60V)
Do you have tester to hang on controller leads to see voltage when it happens?

 

[Enpro]

It is definitely LVC cut down, the question is which one.
1) Cell/groop level voltage (BMS)
2) pack level voltage (BMS but have not heard that before, since 1 cell will hit LVC first)
3) Input voltage (controller LVC) if it recovers with just going down on throttle, it is most probable.

What wire gauge are you using between battery and controller?
What connectors?
Wire or connection hot?
How do you know LVC of controller? (60V)
Do you have tester to hang on controller leads to see voltage when it happens?

-There is 12 gauge with huge andersons (the 2" wide ones) coming from the battery packs but the controller has a smaller anderson and probably 6/8 gauge wiring.
-Noting is even beginning to get warm and i cant even do anything to get anything warm.
Also testing was done in below 0 temperatures.
-Not sure what lcv means but the cutoff voltage of the controller is 59v.
-i did measure the output voltage of the pack right after testing and they show 41v on and 36v. (36v on pack that was empty when i bought it and never tested it since).
Havnt got the time yet to test it with a voltmeter yet but doing so in a couple of hours

 

[neptronix]

One other idea is that you have a dead or weak cell in that pack, and it's cutting out on a big load.. when that 1 cell bangs up against the individual cell LVC.

Lithium battery manufacturing is not an exact science. Bad cells get into cheap Chinese packs very often, sometimes even into the more expensive ones.

You have two packs in series, right? try a high amp load on a 36v controller, see if one pack acts wonky and the other doesn't. That will help isolate the problem.

 

[Enpro]

One other idea is that you have a dead or weak cell in that pack, and it's cutting out on a big load.. when that 1 cell bangs up against the individual cell LVC.

Lithium battery manufacturing is not an exact science. Bad cells get into cheap Chinese packs very often, sometimes even into the more expensive ones.

You have two packs in series, right? try a high amp load on a 36v controller, see if one pack acts wonky and the other doesn't. That will help isolate the problem.

Thats the whole problem. I cant test it or even run it dry on something else .
I only have the 72v controller to do anything with it.
I'm thinking if taking the battery to a electronic shop and test it?

 

[neptronix]

Always good to have a spare controller anyway... Maybe time to pick yourself up a cheapo 36v controller or a 12-18FET infineon?

To properly test, all parallel groups will have to be measured under a heavy load. hm.. luckily there are only 10-12 in a 36v battery.

A cellLog 8s would help here a lot. i used mine on the balance connector to check the balance cells of my lifepo4 pack when i had it.. you can set a low voltage threshold so that it starts beeping at a low voltage.. this could potentially help.. if you could provide a gradually increasing current ( maybe run the bike upside down and gradually press the brakes - this could work for a short period of time. )

 

[DAND214]

i did measure the output voltage of the pack right after testing and they show 41v on and 36v. (36v on pack that was empty when i bought it and never tested it since).

Dead when you got it?
Takes only 16 minutes to get to full?

Bad cell group or more than 1 if it's at 36v.

How long do you let them charge? 15 minutes won't do it. If it does they are junk.

It's the battery not BMS or controller.

Dan

 

[dogman dan]

Now that we have the rest of the story, it does sound like one of the packs is a dud. Charges too fast = no capacity.

Maybe test the batteries with some kind of load, like headlights or whatever. See if one battery performs and the other doesn't. You'll need an ampmeter, even if just a cheap one intended for a car. Wattmeter better, but you can get some kind of comparison by knowing the load in amps, then watching voltage and time. Suggest a test with about 10 amps of load if possible. Then see what load they can take, then cut that in half for use expected to last awhile.

Doesn't change the fact that you are flogging it though. Not gonna last very long even if you do get the bad pack replaced.

 

[sangesf]

It's SOOOO funny that I saw this post...
Same EXACT thing was just happening to me on the way to Starbucks..

Guess what it was???

LOL, stupid me... One of the (two) balance lead plugs, that I was measuring voltage of the cell groups, I had inadvertently forgotten to put back on..

I would say, one of the battery pack's BMS balance leads are either cut or dislodged...

 

[Enpro]

It's SOOOO funny that I saw this post...
Same EXACT thing was just happening to me on the way to Starbucks..

Guess what it was???

LOL, stupid me... One of the (two) balance lead plugs, that I was measuring voltage of the cell groups, I had inadvertently forgotten to put back on..

I would say, one of the battery pack's BMS balance leads are either cut or dislodged...

One of the battery's does have a little dent from when i dropped it once
That might have damaged a balance wire?
You guys think i can just open the thing without any explosions

 

[sangesf]

Go to goldenmotors website and go to the forums and read about the guy who opened his lifepo4 battery..
It will give you big hints on how to open it up without breaking anything.