Pie shutting down on start

[vapid2323]

One last thing, should my charger be giving the output that its rated for? Or is that ONLY when the battery is connected?

[Leslie]

Ok let me try and clear things up...

Originally I never had a volt meter, for instance when I recorded that video I had no way to test the volts.

When fully charged I only show 48.5v on the battery connectors (also the charging port shows the same number)
The output of the Charger itself is 53.1v (I don’t have a way to test if this is the same when connected to the battery)
While the battery is charging the outputs will show the battery’s current voltage, for example is will start at 40v and slowly increase over time to 48.5v.

I love the test idea with the lights but I don’t really have the time to do that.

I don’t believe it’s the Pie, as I am able to ride it up hills and really push it without it over heating or cutting out (hell I am 260lbs) the issue seems to show up because of the drop in voltage and because I am not receiving a full charge so I am only able to ride for about 1 mile before running into issues.

Yes this new information is the most important.  The fact you get 1 mile is the sign.  And your battery is charging from 40v to 48.5v.

Bruno I think has hit the nail on the head.

A damaged cell will give lower volts on a cell block maybe.

[Leslie]

One last thing, should my charger be giving the output that its rated for? Or is that ONLY when the battery is connected?

No only with the yellow light on.

This 53.1v on the charger is standby voltage made to keep the pack fully charged at its best without damaging the cells.. Which should be around 49v 50v when connected depending on the battery cycle life and size.

Your fully charged battery should read around 49.4v resting on no charger.

You can not trust the cheap volt meter for exact voltages and maybe expect a battery a few runs to get up its full charged resting voltages.

[Leslie]

Bruno I think has hit the nail on the head.

A damaged cell will give lower volts on a cell block maybe.

I keep calling Bruno Gary and Gary Bruno.  I am very sorry.  

Its your avatars that confuses me, they have the same colour and the user name has GM in it,  they are alike and I get mixed up.

Thanks Bikemad  

[vapid2323]

Thank you everyone,

I will work on getting a replacement!

[Bikemad]

One last thing, should my charger be giving the output that its rated for? Or is that ONLY when the battery is connected?

Your fully charged battery should read around 49.4v resting on no charger.

You can not trust the cheap volt meter for exact voltages and maybe expect a battery a few runs to get up its full charged resting voltages.

The voltage of Lithium batteries (unlike lead acid) does not tend to drop very much after they are fully charged, and I would expect the battery to still be up around 53-54V when unplugged from the charger.

I charge my LiPo packs to 4.2V per cell and they only drop around 0.1V per cell if unused for a couple of days!

From experience, I've found that my cheap digital voltmeters are all within ±0.02V, which is normally close enough.

This battery should be accepting full charge, but for some reason it is not. This could be due to faulty cells, or the BMS/charger not supplying enough current/volts.

It should be relatively simple to check the voltage of each group of cells to determine whether they are all at a similar low level (indicating a BMS or Charger fault), or if just one or two groups of cells are low.

If a single cell fails in a short circuit condition, it will take the two other paralleled cells with it. If you lose 1/13th of you pack voltage, the LVC will cut in much earlier than it should, even if the rest of the cells are still quite full.

To do this would require removal of the end cover to access the balance lead connector on the BMS (see attached diagram) but I wouldn't advise doing this without obtaining Tom's permission to do so first, because the battery is presumably still under warranty.

Alan
 

[vapid2323]

Yah and they have stickers on the caps that will show removal...

[Leslie]

One last thing, should my charger be giving the output that its rated for? Or is that ONLY when the battery is connected?

Your fully charged battery should read around 49.4v resting on no charger.

You can not trust the cheap volt meter for exact voltages and maybe expect a battery a few runs to get up its full charged resting voltages.

The voltage of Lithium batteries (unlike lead acid) does not tend to drop very much after they are fully charged, and I would expect the battery to still be up around 53-54V when unplugged from the charger.
I charge my LiPo packs to 4.2V per cell and they only drop around 0.1V per cell if unused for a couple of days!

From experience, I've found that my cheap digital voltmeters are all within ±0.02V, which is normally close enough.

This battery should be accepting full charge, but for some reason it is not. This could be due to faulty cells, or the BMS/charger not supplying enough current/volts.

It should be relatively simple to check the voltage of each group of cells to determine whether they are all at a similar low level (indicating a BMS or Charger fault), or if just one or two groups of cells are low.

If a single cell fails in a short circuit condition, it will take the two other paralleled cells with it. If you lose 1/13th of you pack voltage, the LVC will cut in much earlier than it should, even if the rest of the cells are still quite full.

To do this would require removal of the end cover to access the balance lead connector on the BMS (see attached diagram) but I wouldn't advise doing this without obtaining Tom's permission to do so first, because the battery is presumably still under warranty.

Alan
 

Yes Ok.  Thank you.  Good to know about the rest voltage.

What if 2P out of 3p are faulty and only have a low voltage?  There would be a voltage difference potential between the low cells and high cell, creating a discharge of watts until the good cells sits closer to the low cell voltage.  

Then draw 20 amps through this series.  Say there is a 1v difference between the good cell and bad cells when they are solo unconnected, 20 amps @1v = 20 watts.  We have one cell providing 20 watts between the p connections of the bad cell and good cell and a two bad cells proving nothing at all.

Each cell can produce around 23 watts 70 watts in total for a 3p block.   So the broken P block is actually useless and takes from the whole pack.

Possibly no current is allowed through the broken block at high load because the only good cell power is wasted on the bad cells instead of passing its energy to the next p block.  Creating a high load bottle neck.

On a 20 amp draw at 48v = 960 watts.  1/13th of 960 watts is 76 watts.  One cell block equals approx to 70 watts.

Could this be correct?

[vapid2323]

Doing some tests with Tom

without BMS (B- and battery anode)  46.8V~53.95V (positive of battery(+) and B- 47.5)
with BMS (D- and battery anode)  46.8V~53.95V (positive of battery(+)  and D- 47.6)
 
B1 green wire   to:                              Specification
B2 yellow wire(the second wire)   3.6V  ~   4.15V I get 3.7v
B3 yellow wire(the third wire)        7.2V   ~  8.30V I get 7.3v
B4 yellow wire(the fourth wire)     10.8V  ~ 12.45V I get 10.9v
B5 yellow wire(the fifth wire)         14.4V ~  16.60V I get 14.6v
B6 yellow wire(the sixth wire)       18.0V  ~ 20.75V I get 18.3v
B7 yellow wire(the seventh wire) 21.6V ~  24.90V I get 21.9v
B8 yellow wire(the eighth wire)    25.2V  ~ 29.05V I get 25.6v
B9 yellow wire(the ninth wire)      28.8V  ~ 33.20V I get 29.2v
B10  yellow wire (the tenth wire)   32.4V ~  37.35V I get 32.9v
B11 yellow wire(the eleven wire)  36.0V ~  41.5V I get 36.6v
B12 yellow wire(the twelve wire)  39.6V ~  45.65V I get 40.2v
B13 black wire(the thirteen wire)  43.2V ~  49.8V I get 43.9v

[Leslie]

Sorry my last post was wrong..


Look for the largest voltage jump and the smallest jump.

Oh dear its getting confusing.

Give me a minute.  LOL


                      
43.9v - 40.2v = 3.7v
40.2v - 36.6v = 3.6v
36.6v - 32.9 =  3.7v
32.9v - 29.2v = 3.7
29.2v - 25.6v = 3.6v
25.6v - 21.9v = 3.7v
21.9v- 18.3v = 3.6v
18.3v - 14.6v =  3.7v
14.6v - 10.9v = 3.7v
10.9v - 7.3v = 3.6v
7.3v - 3.7v = 3.6v


Cell 1   3,6v
Cell 2   3.6v
Cell 3   3.7v
Cell 4   3.7v
Cell 5   3.6v
Cell 6   3.7v
Cell 7   3.6v
Cell 8   3.7v
Cell 9   3.6v
Cell 10  3.7v
Cell 11  3.7v
Cell 12  3.6v
Cell 13  3.7v

I am no expert here but the cell voltages appear to be good here.

[vapid2323]

Yah I just updated my post, the odd readings where user error I have fixed them.

Could it be the charger?

[Leslie]

Why was you battery 48.5v and now 43.9v?

Can you charge it to 48.5v again.

You say.

While the battery is charging the outputs will show the battery’s current voltage, for example is will start at 40v and slowly increase over time to 48.5v.

If it charges to 48,5v this should enough to get you a lot further than 1 mile up the road. A lot further.

Even if the charger doesn't get you to full pack voltage and it is faulty you should be able to ride your bike until the pack voltage is down to 32.5v not 40v.

If your batteries are good the volts wont tell lies and pretend to be charged.

Maybe your BMS LVC is set too high.

Unless you do a load test I really cant tell you the absolute truth.  The load test is definitive and allways tells it is your pack as you don't need the damned controller to get results.  It is what professionals do to test batteries..

[vapid2323]

When I did the test the battery was at 47.5v (one volt under my normal level)

[Leslie]

Battery load test. google it.

There are a few ways you can do this.

Id would just short it out with 20 meters of 10 amp cable through an amp meter designed to take 15+ amps and drain the pack until the wire was insulation was melting. 

It takes me longer to do this post really than to do a load test..

[Bikemad]

Cell 1   3,6v
Cell 2   3.6v
Cell 3   3.7v
Cell 4   3.7v
Cell 5   3.6v
Cell 6   3.7v
Cell 7   3.6v
Cell 8   3.7v
Cell 9   3.6v
Cell 10  3.7v
Cell 11  3.7v
Cell 12  3.6v
Cell 13  3.7v

I am no expert here but the cell voltages appear to be good here.

Good because they are pretty well balanced, but unfortunately they are in a low state of charge.

The readings for these cells would appear to be perfectly acceptable for an almost flat battery, which is basically what it is.

The cells are not being charged anywhere near enough. If it's only reaching 48.5V, that's only just over 3.7V per cell.

If you look at the attached diagram, you can see that it probably has less than 5% of its total capacity available for use, which is why it is cutting out so quickly.

I don't know whether the fault lies with the charger or the BMS, but having seen the cell readings, I'm now 100% sure it's just going to be a charging problem.

Hopefully Tom can come up with the answer.

Alan