Cuts out under load, 52v battery shows 57v fully charged.

[Paulpmpmpm]

Each 3.7v cell group has 9 batteries in parallel. 14 of those make 51.8 volts

Fully charged, each cell group would be 4.2v. a4 x 4.2 = 58.8v. Your 57v is a bit low.

I see I just be looking at it all wrong cause I can only see 7 groups of 18 batteries.e

 

[peter.c]

When first looked i thought the pack was not looking right but as it had worked it must of been ok, is it a joint bad weld on the tin strips
But how you can power 2000watts fully enclosed it must be a cross between a toaster or a microwave the heat must be extreme can you try just one controller and motor at a time

 

[vfr400]

I see I just be looking at it all wrong cause I can only see 7 groups of 18 batteries.e

If you look, there are 18 cells all welded together, but 9 are one way up and 9 the other. Underneath, you will see that there is a divide between each group of 9 and each 9 are welded to another 9 next to them, so still 18 welded together but not the same 18 on the top. On one side at the ends, there will be a group of 9 on their own.

 

[Paulpmpmpm]

When first looked i thought the pack was not looking right but as it had worked it must of been ok, is it a joint bad weld on the tin strips
But how you can power 2000watts fully enclosed it must be a cross between a toaster or a microwave the heat must be extreme can you try just one controller and motor at a time

I have no idea mate as know hardly anything about electrics but there is a few scooters on the market with specs like mine.

I can try tomorrow. Main controller must be plugged in second controller is plugged into main controller.

 

[Paulpmpmpm]

If you look, there are 18 cells all welded together, but 9 are one way up and 9 the other. Underneath, you will see that there is a divide between each group of 9 and each 9 are welded to another 9 next to them, so still 18 welded together but not the same 18 on the top. On one side at the ends, there will be a group of 9 on their own.

AHH I see thanks mate I see now

 

[Nealh]

Looking at the battery can you see any writing on the pink cells ?
If so take pic and show us then we might be able to cypher which cells and specs are used, they look like Samsung pink cells maybe.
The issue will likely lie with the cells and whether they can supply the current.
In post six the Op said cells measure 4.11 & 4.18 can you re -check the voltages and list them 1 -18 as 4.1x so we can see there true readings. nearly 0.1v difference is an issue and shows some groups are weaker then others and voltage sag/collapse may well be occurring.

 

[Paulpmpmpm]

Looking at the battery can you see any writing on the pink cells ?
If so take pic and show us then we might be able to cypher which cells and specs are used, they look like Samsung pink cells maybe.
The issue will likely lie with the cells and whether they can supply the current.
In post six the Op said cells measure 4.11 & 4.18 can you re -check the voltages and list them 1 -18 as 4.1x so we can see there true readings. nearly 0.1v difference is an issue and shows some groups are weaker then others and voltage sag/collapse may well be occurring.

Hi I stuck the pack back together I'll have to cut it open again.

I just tested the battery now it's only 52.2v but while on charge 58.3.

Does this mean IV damages some cells while having it open?

 

[Nealh]

One can't damage cells simpy by opening a pack open, a short would have to occur to cause damage.
Use a new battery for your meter to make sure erroneous readings aren't measured.

52.2v will be the pack reading then and equates to an average of 3.72v per cell group which is about 50%.
58.3v equates to 4.16v per cell group but the reading with the charger connected is likely the charger output.
What is the actual reading of the charger voltage at it's connector ?

 

[Paulpmpmpm]

One can't damage cells simpy by opening a pack open, a short would have to occur to cause damage.
Use a new battery for your meter to make sure erroneous readings aren't measured.

When checking the voltages I did arc when using the multimeter on the BMS.

 

[Paulpmpmpm]

When checking the voltages I did arc when using the multimeter on the BMS.

Hi I just checked all voltages again on the BMS and they are all 4.1 to 4.17.

So I tested 14 X 4.1 is at least 56v.

So does this possibly mean BMS is faulty? Not sending out correct voltage?

 

[Paulpmpmpm]

Charger is reading at 58.6v.

Before I took pack apart yesterday battery was 57v now only 52.2

 

[Nealh]

If you have arced the bms then you may have damaged it, when checking the 14 cell group voltages one should have disconnected the BMS sense wire connector to measure the cell readings safely then you can't arc the bms pcb.

Disconnect the multiwire sense connector and measure the 14 cell groups properly.
Write out on paper listing 1,2,3,4 etc,etc to 14, then note each voltage reading against each test and list then here so we can see. Just saying they are 4.1 - 4.17 doesn't give a full picture and gives to wide a disparity for a balanced pack.

A good balanced pack will have all cell groups read the same so for example, 4.17v
or within 0.01v so 4.16v - 4.17v is pretty well balanced. Once they start straying further a field it indicates weaker cells/cell groups or cells not matched correctly at construction.

 

[Nealh]

The bms has 15 pins measure it in two ways, accumulative voltage reading or individual cell group reading. Don't take readings directly off the BMS as it may/could give a false reading, disconnect the sense wire connector (it may be tight but will pull off). Take your voltage readings from the multi wire connector.

 

[Paulpmpmpm]

If you have arced the bms then you may have damaged it, when checking the 14 cell group voltages one should have disconnected the BMS sense wire connector to measure the cell readings safely then you can't arc the bms pcb.

Disconnect the multiwire sense connector and measure the 14 cell groups properly.
Write out on paper listing 1,2,3,4 etc,etc to 14, then note each voltage reading against each test and list then here so we can see. Just saying they are 4.1 - 4.17 doesn't give a full picture and gives to wide a disparity for a balanced pack.

A good balanced pack will have all cell groups read the same so for example, 4.17v
or within 0.01v so 4.16v - 4.17v is pretty well balanced. Once they start straying further a field it indicates weaker cells/cell groups or cells not matched correctly at construction.

1. 4.17
2. 4.17
3. 4.11
4. 4.17
5. 4.16
6. 4.16
7. 4.14
8. 4.13
9. 4.10
10. 4.17
11. 4.10
12. 4.17
13. 4.16
14. 4.17

 

[Paulpmpmpm]

The bms has 15 pins measure it in two ways, accumulative voltage reading or individual cell group reading. Don't take readings directly off the BMS as it may/could give a false reading, disconnect the sense wire connector (it may be tight but will pull off). Take your voltage readings from the multi wire connector.

Hi mate yeah I just done that now thanks taken my readings from the white block. No Arc this time.

My readings posted above thanks.

I followed this video to test first time

 

[Nealh]

The way I suggested (disconnecting the bms) and most would recommend is the safe way, other wise bms damage is likely from arcing. You will have to carefully check the bms both sides for signs of damage with a mag glass or for burning, resistors/diodes can easily be fried as can the mosfets.

 

[Nealh]

1. 4.17
2. 4.17
3. 4.11
4. 4.17
5. 4.16
6. 4.16
7. 4.14
8. 4.13
9. 4.10
10. 4.17
11. 4.10
12. 4.17
13. 4.16
14. 4.17

As can be seen 5 groups are very different, 3, 9 & 11 are by most standards way out of line.
Your battery is unbalanced with a final voltage of 58.08v, a bms will not balance such a wide disparity very easily and one may have to try and manually charge up the individual cell groups keeping a an eye on them. We can guide you to do this though each low cell group may take about 20 -40 minutes each to raise the voltage to about 4.16/4.16v then the bms will balance them (if it is working correctly).

If when you plug the bms back in and the battery discharge voltage reads a lot lower then you will have damaged it and will have to replace it first. The shorting out will have damaged one or two of the 14 bms sense wire circuits and is not reading those two cell groups also this will compromise charging.

 

[Paulpmpmpm]

As can be seen 5 groups are very different, 3, 9 & 11 are by most standards way out of line.
Your battery is unbalanced with a final voltage of 58.08v, a bms will not balance such a wide disparity very easily and one may have to try and manually charge up the individual cell groups keeping a an eye on them. We can guide you to do this though each low cell group may take about 20 -40 minutes each to raise the voltage to about 4.16/4.16v then the bms will balance them (if it is working correctly).

If when you plug the bms back in and the battery discharge voltage reads a lot lower then you will have damaged it and will have to replace it first.

Thanks so much for this information I think I have a

As can be seen 5 groups are very different, 3, 9 & 11 are by most standards way out of line.
Your battery is unbalanced with a final voltage of 58.08v, a bms will not balance such a wide disparity very easily and one may have to try and manually charge up the individual cell groups keeping a an eye on them. We can guide you to do this though each low cell group may take about 20 -40 minutes each to raise the voltage to about 4.16/4.16v then the bms will balance them (if it is working correctly).

If when you plug the bms back in and the battery discharge voltage reads a lot lower then you will have damaged it and will have to replace it first.

Thanks so much for this information I think I have a charger that can do this.

I will be back with updates.

 

[vfr400]

IMHO, those cell voltages are quite acceptable and not anything to worry about. Yes, it is a little out of balance, but I'd expect that on a battery with unbranded cells, where you're taking 5.6 amps per cell. Also, there’s somthing wrong with your measuring. Those cell voltages add up to around 58v, but you were measuring as low as 52v on the output, and every time you measured the output voltage, you seemed to get a different value.

Before deciding anything, you should put a new battery in your meter and measure everything again carefully - cell voltage and voltage on the battery terminals.

Let's assume that your measurements were correct and your cell voltages add up to 58v, but you terminal voltage is only 52v. The reason for that would be what's causing your problem.

 

[Nealh]

To be safe you can only charge the low cell group singularly with a max 5v charger with a low 300- 500ma charge to be safe and then you have to very carefully monitor the live voltage rise for each cell group.