Trouble Balancing brand new 52V pack, help please 😅

[Klauts]

Hello again everyone! So I decided against buying that used Biktrix pack and ended up having one custom built for me by the folks over at http://affordableebikes.ca

The specs on the pack:
52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly

The BMS is a dumb 40a 14s Daly module, the balance detection voltage is 4.18v and if my math is right the cells are stopping their charge at 4.17v...

It stops charging at 58.4 volts rather than 58.8...

Is there anyway short of opening the pack and manually balance charging to get the cells to charge that extra 0.01v so balancing gets triggered?

 

[Klauts]

Hello again everyone! So I decided against buying that used Biktrix pack and ended up having one custom built for me by the folks over at http://affordableebikes.ca

The specs on the pack:
52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly

The BMS is a dumb 40a 14s Daly module, the balance detection voltage is 4.18v and if my math is right the cells are stopping their charge at 4.17v...

It stops charging at 58.4 volts rather than 58.8...

Is there anyway short of opening the pack and manually balance charging to get the cells to charge that extra 0.01v so balancing gets triggered?

 

[999zip999]

As long as they're balanced you're fine at 4.17v

 

[eMark]

The specs on the pack:
52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly
The BMS is a dumb 40a 14s Daly module, the balance detection voltage is 4.18v and if my math is right the cells are stopping their charge at 4.17v...
It stops charging at 58.4 volts rather than 58.8...

• First Question: Why do you believe the parallel groups aren't already balanced close enough at 58.4V?

You may need to leave the charger ON (plugged in) after the green light comes ON for however long it takes to balance the p-groups. This shouldn't be necessary with a brand new pack with brand new A-grade cells.

Is there anyway short of opening the pack and manually balance charging to get the cells to charge that extra 0.01v so balancing gets triggered?

• Second Question: Assume you've already discussed the above question with - http://affordableebikes.ca - before posting this thread. WHY were they unable to answer your question(s)?

What has led you to believe that the 40A 14s Daly BMS won't balance the p-groups at 4.17V? Is it really that "dumb"?

NOTE: Supposedly a slight advantage charging to 58.4V instead of 58.8V (cyclelife). There's really little, if any, advantage charging to 58.8V. Leave well-enuf alone.

 

[Klauts]

The specs on the pack:
52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly
The BMS is a dumb 40a 14s Daly module, the balance detection voltage is 4.18v and if my math is right the cells are stopping their charge at 4.17v...
It stops charging at 58.4 volts rather than 58.8...

• First Question: Why do you believe the parallel groups aren't already balanced close enough at 58.4V?

You may need to leave the charger ON (plugged in) after the green light comes ON for however long it takes to balance the p-groups. This shouldn't be necessary with a brand new pack with brand new A-grade cells.

Is there anyway short of opening the pack and manually balance charging to get the cells to charge that extra 0.01v so balancing gets triggered?

• Second Question: Assume you've already discussed the above question with - http://affordableebikes.ca - before posting this thread. WHY were they unable to answer your question(s)?

What has led you to believe that the 40A 14s Daly BMS won't balance the p-groups at 4.17V? Is it really that "dumb"?

NOTE: Supposedly a slight advantage charging to 58.4V instead of 58.8V (cyclelife). There's really little, if any, advantage charging to 58.8V. Leave well-enuf alone.

Answer to the first question Is I honestly don't know a ton about batteries yet I assume they aren't balanced according to the spec sheet of the BMS

Which says it should stop charging a balanced pack at 4.25.

The spec sheet is also why I think it's too dumb to balance from 4.17v, it specifically states it needs to hit minimum 4.18v to trigger balancing?

If no one is concerned though I shall take the wisdom of the pros and leave well enough alone haha thanks

 

[Voltron]

Have you metered your charger to see how many volts it's actually putting out?

 

[Klauts]

That I have not done... I'll check it out tonight. Cheers!

 

[amberwolf]

EDIT: some of the below is redundant, but was typed as a reply to the first thread the oP made for this, which had no replies. Then I found his second thread for the same thing, whcih had the above replies, and merged the two together.

So I decided against buying that used Biktrix pack and ended up having one custom built for me

That's a pretty fast build, doesn't seem like it would have had much testing time in before shipping it out to you, given that shipping usually takes a few days.

I'm curious: Last post of yours in that thread was five days ago. How long did it take to ship to you, and when was it ordered? (to determine maximum possible time they could've spent building it)


Question: if you haven't opened the pack to test cell (group) voltages, how do you know it's not balanced? (the only way to know an imbalance exists is to measure those, or have a BMS that does this and displays them for you or otherwise reports the imbalance as an imbalance).

The charger might simply not be set to the voltage you expect. Is it supposed to be, according to the builders of the pack? Or did they set it lower for some reason (which could be in the manual, if there is one, for the pack)?

If you asked them, what did the builders have to say about the problem you're having?

52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly

Voltage matching prior to assembly is simply a required step of building a pack from paralleled cells. It's not a special quality.

Were they all from the same batch of cells, and tested/matched for identical internal resistance, capacity, etc.?

If not, that's the usual reason for imbalance. When there is a problem because of it, it will only grow worse with time as the cells age and become more different from each other..

 

[amberwolf]

Answer to the first question Is I honestly don't know a ton about batteries yet I assume they aren't balanced according to the spec sheet of the BMS

Which says it should stop charging a balanced pack at 4.25.

Since this is overcharged for most of the typical cylindrical cells out there, that's generally a bad thing.

The spec sheet is also why I think it's too dumb to balance from 4.17v, it specifically states it needs to hit minimum 4.18v to trigger balancing?

Is there an external indicator on the pack that indicates that it is or is not doing balancing? If not, there's no way to know that it is or is not doing it, regardless of the voltage you see on the main battery leads.

For instance, if you had cells that were at 3.5v, then ohter cells would have to be higher than full to add up to the voltage you see. Thus, the pack would be doing balancing trying to drain those high cells down.

You can see this happen by measuring cell(groups) inside the battery, or by the BMS's display if it has one. Otherwise, unless the pack builders installed some other method of seeing that balancing is or is not occuring...you can't know what is happening inside.

 

[Klauts]

EDIT: some of the below is redundant, but was typed as a reply to the first thread the oP made for this, which had no replies. Then I found his second thread for the same thing, whcih had the above replies, and merged the two together.

So I decided against buying that used Biktrix pack and ended up having one custom built for me

That's a pretty fast build, doesn't seem like it would have had much testing time in before shipping it out to you, given that shipping usually takes a few days.

I'm curious: Last post of yours in that thread was five days ago. How long did it take to ship to you, and when was it ordered? (to determine maximum possible time they could've spent building it)


Question: if you haven't opened the pack to test cell (group) voltages, how do you know it's not balanced? (the only way to know an imbalance exists is to measure those, or have a BMS that does this and displays them for you or otherwise reports the imbalance as an imbalance).

The charger might simply not be set to the voltage you expect. Is it supposed to be, according to the builders of the pack? Or did they set it lower for some reason (which could be in the manual, if there is one, for the pack)?

If you asked them, what did the builders have to say about the problem you're having?

52v 19Ah Samsung INR18650GG cells all brand new and voltage matched prior to assembly

Voltage matching prior to assembly is simply a required step of building a pack from paralleled cells. It's not a special quality.

Were they all from the same batch of cells, and tested/matched for identical internal resistance, capacity, etc.?

If not, that's the usual reason for imbalance. When there is a problem because of it, it will only grow worse with time as the cells age and become more different from each other..

Sorry this is all so confusing haha I was already in the process of getting a custom pack built when I found the Biktrix one, I was going to maybe get both and ditch the 48v so the parallelling wasn't as much an issue.

Didn't do that, got the custom pack finished and delivered now I'm working on the parallelling/balancing In this thread.

I checked the voltage on the charger and it's only putting out 58.56V so that could be the source of the problem there.

The builder of the pack said this is behavior they see pretty frequently with the Daly BMS and not to worry about it if I'm not experiencing voltage sag or any other wierd issues. So I'm not overly concerned but if it's a simple thing like the charger being .26v under voltage then I'd rather get it sorted so the cells are balancing proper in the long term?

It took 8 days for the pack to be built and tested and then another 5 to ship out to me so it wasn't an quick process by any means

 

[Voltron]

Some chargers have an adjustable potentiometer in them you can tweak the output voltage with.
It's not really designed as a user feature, so be careful if you open up the charger case.
There's a few different threads about how to do it on here if you search.
One drawback to waiting, I've had dumb bms that by the time being unbalanced was actually being felt in the pack performance, the spread on the voltages between the groups was so big the bms would just give up trying to balance and cut off the charge.
Then I had to cut into the thing to get to the bms plug, to manually bring up the really low ones one group at a time with an RC charger. Then the bms would take over again after they were all closer. It's a pain in the ass.

 

[999zip999]

Talk to the manufacturer ask if the pack is able to balance at that voltage with the BMS.
Only certain chargers can be adjusted if you do open it up the parameter is next to the positive outlet inside the charger it would be a very very slight adjustment if you over adjust it you could pop the inside of the controller and I use a chopstick that I filed into a screwdriver so as not to Short the charger as you can only adjust the charger when ON or hot.
But I would not advise you to adjust the charger I would advise you to talk to the company who made the battery and find out if it will balance at 4.17 volts per sale. It's all about how the BMS was designed to work.
Daly also makes a BT BMS I'm guessing this is not BT