HELP PLEASE I think I may have some bad cells

[Dzl]

Wouldn’t there be some big efficiency problems running that heater off of one cell through a dc-dc booster? I’d imagine you’d get a better capacity test from a cell configuration that was closer the V requirement of the heater. Not only that but you could test your BMS at the same time and have protection for your cells.

From the pictures I believe what people are referring to as a "heater" here is a capacity tester like this one it should have a wide voltage input range

 

[Gazoo]

I do have a 10a bench charger.
i am charging a single cell at the moment its at 3.3 iam charging it at 3.65
When it gets fully charged I am going to turn the heater down to 10 A And see if I can pull more amp hours out of a cell.

The proper term is capacity tester, not heater although it does produce a lot of heat.

 

[Fallingaway]

There hasn’t been any reason to suspect any of the cells are bad, just user error not knowing how to charge them. The capacity is what it is, so why bother testing each cell and through a boost converter. Putting them in a pack, doing a charge and capacity test would tell him right away if there should be reason to be concerned or suspect a bad cell. The second point I was trying to make is there’s clearly some confusion because they’re doing capacity test in the 3.3v range so it would be better to have the BMS on there do cells don’t get damaged

 

[Moltensurf]

I think you need to slow down and regroup, and approach more systematically and slowly/deliberately.

Speaking for myself (and from context I think others too) its hard to follow some of what you are saying possibly because it seems there are some misunderstandings on the fundamentals (units, process, amps vs volts, series vs parallel, etc).

Mentally, it would be beneficial probably to dismiss the feeling of urgency/fear, if your cells are all currently at 3.3V you are okay there is no urgency to do anything. As others have said. Hit the pause button until you are confident you understand what you are doing and have the proper tools to do it. The cells are quite happy at their current voltage. Don't overstress.

Questions that have been asked that need answering:
1. Explain what you mean when you say current was jumping all over the place from 30 to 80. Is this milliamps? In what context and with what charger did this occur?

2. When you say "the cells were way short on amp hour capacity" how short are we talking (what are the numbers) and how did you test/verify?

3. You have a 12V charger and a 24V BMS and battery, why? Is the 12V charger just something you had laying around, is a 24V charger a planned future purchase? I would not charge in series until you have a charger that will work with your BMS.

So when I was balancing my cells, the amps on the bottom were dropping. Right now I am topping off one cell. I have it set at 3.65 V the closer it gets to charged the bottom numbers will drop the amps correct? When I was top balancing my cells Milla amps never dropped to zero.
2). I got 133.35 amp hours at 2.60 bottom cut off. I ran the battery down to 2.5 and got another six amp hours.
3). I do have a 12 V battery charger at lying around. I’m planning to get a 24 V charge controller for a solar panel array.

 

[Gazoo]

I have it set at 3.65 V the closer it gets to charged the bottom numbers will drop the amps correct?

Yes. And this is when you should be measuring the cell right at the cell terminals with a multimeter.

 

[Moltensurf]

Yes. And this is when you should be measuring the cell right at the cell terminals with a multimeter.

This is what’s going on on the battery I am topping off

 

[Just John]

I got some battery cells on Alibaba I hooked the cells together, to top balance them but it was taking forever. 8 cells. I decided to break the pack in half into two separate 12 V batteries. I put one on a standard battery charger that works well. The other I left on a TuffIom battery charger 3.65amps. When I came back sometime later the 12 volt bank I hooked up to my smart battery charger said bad battery. The cells in the bad 12 volt block; I am individually charging the cells with the small charger.
I am charging the other 12 V bank with the smart charger.
The batteries are wired in parallel with bus bars. What I find strange is if I touch my DC meter to the positive and negative on that 12 V block it still reads 3.31 if they are joined together in parallel should they not be 12 V?
I am trying to test these babies, so if there is something wrong I can file a dispute. Any advice out there would sure be helpful
thank you

OK, when you say "TuffIom battery charger" do you mean THIS? I'm hoping you mean 3.65 volts, that is a good start.
The "smart battery charger", what exactly is that? Does it have a Lithium battery setting? Did you use a BMS? What brand/model? If it is seeing something it doesn't expect (like a dead short, which is what lithium cells will look like to a charger) it will say you have a bad battery, and be wrong.

I wouldn't charge these without a BMS, even if the smart charger has a lithium setting. I was just curious about what you had tried first.

You shouldn't have any problems reading individual cell voltages as long as you are going across the positive and negative of each cell, that's exactly what a BMS does (that's what all the wires are for). Parallel means all positives are connected to each other, and all negative are connected to each other. Serial means you take the negative from one and connect it to the positive in the next cell (like to build a 12 volt battery from cells that are only 3.2 volts each). 4 cells in a series gives 12.8 volts (close enough to 12 volts, which is actually 6 lead acid cells in series at 2 volts each).

So, parallel you should read somewhere between 2.5 and 3.65 volts (depending on state of charge, most likely 3.3 volts when you received them).
In series, it really depends on how many cells in a series, 4 would be approximately 12 to 13 volts, 8 cells in series would be over 24 volts).

People are confused because you seem to be mixing up series and parallel, which isn't that big a deal.

 

[Moltensurf]

OK, when you say "TuffIom battery charger" do you mean THIS? I'm hoping you mean 3.65 volts, that is a good start.
The "smart battery charger", what exactly is that? Does it have a Lithium battery setting? Did you use a BMS? What brand/model? If it is seeing something it doesn't expect (like a dead short, which is what lithium cells will look like to a charger) it will say you have a bad battery, and be wrong.

I wouldn't charge these without a BMS, even if the smart charger has a lithium setting. I was just curious about what you had tried first.

You shouldn't have any problems reading individual cell voltages as long as you are going across the positive and negative of each cell, that's exactly what a BMS does (that's what all the wires are for). Parallel means all positives are connected to each other, and all negative are connected to each other. Serial means you take the negative from one and connect it to the positive in the next cell (like to build a 12 volt battery from cells that are only 3.2 volts each). 4 cells in a series gives 12.8 volts (close enough to 12 volts, which is actually 6 lead acid cells in series at 2 volts each).

So, parallel you should read somewhere between 2.5 and 3.65 volts (depending on state of charge, most likely 3.3 volts when you received them).
In series, it really depends on how many cells in a series, 4 would be approximately 12 to 13 volts, 8 cells in series would be over 24 volts).

People are confused because you seem to be mixing up series and parallel, which isn't that big a deal.

That is the battery charger I am talking about, and I am using. The charger I was speaking of was a 12 V smart charger schumaker. Sorry I was definitely mixing up series and parallel

 

[Moltensurf]

OK, when you say "TuffIom battery charger" do you mean THIS? I'm hoping you mean 3.65 volts, that is a good start.
The "smart battery charger", what exactly is that? Does it have a Lithium battery setting? Did you use a BMS? What brand/model? If it is seeing something it doesn't expect (like a dead short, which is what lithium cells will look like to a charger) it will say you have a bad battery, and be wrong.

I wouldn't charge these without a BMS, even if the smart charger has a lithium setting. I was just curious about what you had tried first.

You shouldn't have any problems reading individual cell voltages as long as you are going across the positive and negative of each cell, that's exactly what a BMS does (that's what all the wires are for). Parallel means all positives are connected to each other, and all negative are connected to each other. Serial means you take the negative from one and connect it to the positive in the next cell (like to build a 12 volt battery from cells that are only 3.2 volts each). 4 cells in a series gives 12.8 volts (close enough to 12 volts, which is actually 6 lead acid cells in series at 2 volts each).

So, parallel you should read somewhere between 2.5 and 3.65 volts (depending on state of charge, most likely 3.3 volts when you received them).
In series, it really depends on how many cells in a series, 4 would be approximately 12 to 13 volts, 8 cells in series would be over 24 volts).

People are confused because you seem to be mixing up series and parallel, which isn't that big a deal.

If I am using that battery charger you posted above and topping off my individual cell. At my battery terminals I show 3.37 V I have my bench charger set at 3.6 V right now it shows 4 A. Is that where I need my charger set to top this battery off?

 

[Just John]

That is the battery charger I am talking about, and I am using. The charger I was speaking of was a 12 V smart charger schumaker. Sorry I was definitely mixing up series and parallel

From the pictures you posted, you are on the right track. I hope you set the power supply to 3.65 volts (or as close as these cheap supplies will let you). It is important you set the voltage without a battery hooked up, otherwise it won't be getting the correct reading. Then hook the battery up to it and adjust the current to maximum (a cheap 10 amp supply might last longer if you set it to 8 or 9 amps, but you are really not close to any power limits, 36.5 watts even at 10 amps).

As you can see, the power supply and the cell will display different voltages as you charge. The closer you get to full, the closer they will get (and the amps put out by the supply will drop). Like DZL said, so far, no damage done to the cells and no apparent problems that I can see. When the voltage measured on the cell is 3.65, and amps put out by the supply is less than 1, you have a full cell for capacity testing.

They are supposed to ship the cells between 20 to 50 percent charged, but don't count on that. So when you tried and got 139 amp hours, it means that cell was about 60% full. Don't stress, take your time and ask questions. It's a time consuming process.

 

[Just John]

That is the battery charger I am talking about, and I am using. The charger I was speaking of was a 12 V smart charger schumaker. Sorry I was definitely mixing up series and parallel

Is your smart charger one of these:

Battery Chargers Archives - Schumacher Electric

Whether you need a battery charger for your automotive repair shop, home garage, or simply to keep handy in case of emergencies, the charging and maintaining products available from Schumacher Electric are designed to fit your needs. With several models to choose from and a variety of features...

www.batterychargers.com

 

[Moltensurf]

From the pictures you posted, you are on the right track. I hope you set the power supply to 3.65 volts (or as close as these cheap supplies will let you). It is important you set the voltage without a battery hooked up, otherwise it won't be getting the correct reading. Then hook the battery up to it and adjust the current to maximum (a cheap 10 amp supply might last longer if you set it to 8 or 9 amps, but you are really not close to any power limits, 36.5 watts even at 10 amps).

As you can see, the power supply and the cell will display different voltages as you charge. The closer you get to full, the closer they will get (and the amps put out by the supply will drop). Like DZL said, so far, no damage done to the cells and no apparent problems that I can see. When the voltage measured on the cell is 3.65, and amps put out by the supply is less than 1, you have a full cell for capacity testing.

They are supposed to ship the cells between 20 to 50 percent charged, but don't count on that. So when you tried and got 139 amp hours, it means that cell was about 60% full. Don't stress, take your time and ask questions. It's a time consuming process.

I have had the battery charging for quite a while now but I haven’t seen any change in the numbers at the battery post. I have a DC amp clamp and 4 A are going into the battery

 

[Moltensurf]

From the pictures you posted, you are on the right track. I hope you set the power supply to 3.65 volts (or as close as these cheap supplies will let you). It is important you set the voltage without a battery hooked up, otherwise it won't be getting the correct reading. Then hook the battery up to it and adjust the current to maximum (a cheap 10 amp supply might last longer if you set it to 8 or 9 amps, but you are really not close to any power limits, 36.5 watts even at 10 amps).

As you can see, the power supply and the cell will display different voltages as you charge. The closer you get to full, the closer they will get (and the amps put out by the supply will drop). Like DZL said, so far, no damage done to the cells and no apparent problems that I can see. When the voltage measured on the cell is 3.65, and amps put out by the supply is less than 1, you have a full cell for capacity testing.

They are supposed to ship the cells between 20 to 50 percent charged, but don't count on that. So when you tried and got 139 amp hours, it means that cell was about 60% full. Don't stress, take your time and ask questions. It's a time consuming process.

I also checked the temperature of the battery it’s around 74°

 

[Gazoo]

I have had the battery charging for quite a while now but I haven’t seen any change in the numbers at the battery post. I have a DC amp clamp and 4 A are going into the battery

What is the voltage measured at the cell terminals.

As a side note, It helps if people use the correct defining words. A cell is a cell. A battery is comprised of cells hooked in series to achieve the desired voltage. A terminal is the cell connection point. Not to quibble but using proper terms helps with less confusion.

 

[Moltensurf]

What is the voltage measured at the cell terminals.

As a side note, It helps if people use the correct defining words. A cell is a cell. A battery is comprised of cells hooked in series to achieve the desired voltage. A terminal is the cell connection point. Not to quibble but using proper terms helps with less confusion.

3.359 at cell terminals

 

[Moltensurf]

What is the voltage measured at the cell terminals.

As a side note, It helps if people use the correct defining words. A cell is a cell. A battery is comprised of cells hooked in series to achieve the desired voltage. A terminal is the cell connection point. Not to quibble but using proper terms helps with less confusion.

There is less current now at the terminals then there was a few hours ago

 

[Moltensurf]

What is the voltage measured at the cell terminals.

As a side note, It helps if people use the correct defining words. A cell is a cell. A battery is comprised of cells hooked in series to achieve the desired voltage. A terminal is the cell connection point. Not to quibble but using proper terms helps with less confusion.

Do I need to raise the voltage on my machine until it gets to be 3.6 at the terminals

 

[Gazoo]

Great. So far so good. I believe you are out of the flat part of the curve. Your power supply is set to 3.6 volts. Leave it. As you have noticed the current is coming down. When the current reads 1 amp or less, you are good to go for a capacity test.

 

[Gazoo]

Here is a chart that shows SOC. It might be helpful.

 

[Moltensurf]

Here is a chart that shows SOC. It might be helpful.

What c charge cycle am I on at the moment?