October 10, 20205 yr 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.
October 11, 20205 yr Author 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?
October 11, 20205 yr 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 ? Edited October 11, 20205 yr by Nealh
October 11, 20205 yr Author 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.
October 11, 20205 yr Author 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? Edited October 11, 20205 yr by Paulpmpmpm
October 11, 20205 yr Author Charger is reading at 58.6v. Before I took pack apart yesterday battery was 57v now only 52.2
October 11, 20205 yr 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. Edited October 11, 20205 yr by Nealh
October 11, 20205 yr 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.
October 11, 20205 yr Author 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
October 11, 20205 yr Author 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
October 11, 20205 yr 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. Edited October 11, 20205 yr by Nealh
October 11, 20205 yr 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. Edited October 11, 20205 yr by Nealh
October 11, 20205 yr Author 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.
October 11, 20205 yr 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.
October 11, 20205 yr 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.
October 11, 20205 yr A pic of any cell writing might be useful but if they are China cells they might not even be 10a capable ?
October 11, 20205 yr Author A pic of any cell writing might be useful but if they are China cells they might not even be 10a capable ? That's all I can see on the cells.
October 11, 20205 yr Author 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. That's what I thought tbh i don't understand why I'm only getting 52.2v when all cells add up to.more individually. What could be the reason for that? Faulty BMS? I don't have another battery to test unfortunately. Edited October 11, 20205 yr by Paulpmpmpm
October 11, 20205 yr Author 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. Oops I just finished charging the first one to 4.16 at 1ah, I'll turn it down to 0.5 for the rest.
October 11, 20205 yr I don't have another battery to test unfortunately. Your meter has a battery in it - normally a PP9 9v. That's what you should change, then do all your measurements again, not measure another battery. First you have to determine the facts by measurement, then we can think about the cause.
October 11, 20205 yr Author Your meter has a battery in it - normally a PP9 9v. That's what you should change, then do all your measurements again, not measure another battery. First you have to determine the facts by measurement, then we can think about the cause. Oh sorry I misunderstood. I just try with a second multimeter and the readings are the same.
October 11, 20205 yr That's all I can see on the cells. They are 2600mah China cells, that's to that can be said, 9 x 2600 gives you the 23.4ah capacity.
October 12, 20205 yr Oh sorry I misunderstood. I just try with a second multimeter and the readings are the same. What’s the total voltage from the cells and what's the voltage on the output teminals? What's the same? The output voltage can't because you gave 3 or 4 different values before.
October 24, 20205 yr Author They are 2600mah China cells, that's to that can be said, 9 x 2600 gives you the 23.4ah capacity. Hi sorry for late reply I have been away. I charged everything individually like you said then connected BMS back on and charged for a few hours and new readings are now : 1. 4.15 2. 4.15 3. 4.14 4. 4.15 5. 4.13 6. 4.13 7. 4.13 8. 4.13 9. 4.14 10. 4.15 11. 4.14 12. 4.15 13. 4.14 14. 4.15 And total output was 52.5v
October 24, 20205 yr Author What’s the total voltage from the cells and what's the voltage on the output teminals? What's the same? The output voltage can't because you gave 3 or 4 different values before. Hi sorry for late reply I have been away. 1. 4.15 2. 4.15 3. 4.14 4. 4.15 5. 4.13 6. 4.13 7. 4.13 8. 4.13 9. 4.14 10. 4.15 11. 4.14 12. 4.15 13. 4.14 14. 4.15 And total output was 52.5v
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