I have a 48 volt 200 amp hour battery pack it seems to be degrading

[Buick39]

I have done that before. Most of time the IR or capacity of the cell is a little different and it just shoots back up to OVP.

Best way I have found it to bring all cells up to 3.65 individually or parallel.

so purchase a power supply and charge one battery at a time to 3.65? Should I remove the EQ back off the unit?

 

[Nobodybusiness]

so purchase a power supply and charge one battery at a time to 3.65? Should I remove the EQ back off the unit?

2 ways to do it.

Leave everything intact and fully charge each battery until it won’t accept anymore charge.
Look at your individual cell voltage in each battery.
If close then no worries.


If not you charge each individual cell to 3.65 and 0 input amps.

If you have one cell cutting off your BMS charging( which it looks like) the other cells won’t be able to charge hence you will lose AH total.

@400bird has explained it well.

I personally have not had much luck discharging the high cells.
Had better luck charging the low cells.

EQ? You mean that balancer? I pretty sure that’s not the right one for your setup.

Battery and cell are not interchangeable.
They are different.
You have 16 cells in each battery.

 

[Buick39]

2 ways to do it.

Leave everything intact and fully charge each battery until it won’t accept anymore charge.
Look at your individual cell voltage in each battery.
If close then no worries.


If not you have to disconnect the BMS and charge each individual cell to 3.65 and 0 input amps.

If you have one cell cutting off your BMS charging( which it looks like) the other cells won’t be able to charge hence you will lose AH total.

@400bird has explained it well.

I personally have not had much luck discharging the high cells.
Had better luck charging the low cells.

So would you remove the EQ and replace it with a power supply and charge each battery and hope the BMS will keep it balanced? As I have showed in the pictures it has been slowly degrading in the few months of operation I rath not have to keep doing this to keep amp hours at where it rated would I be better to put a balancer in there?

 

[Nobodybusiness]

So would you remove the EQ and replace it with a power supply and charge each battery and hope the BMS will keep it balanced? As I have showed in the pictures it has been slowly degrading in the few months of operation I rath not have to keep doing this to keep amp hours at where it rated would I be better to put a balancer in there?

Obviously the BMS isn’t keeping it balanced during charging. You have 2 cells shooting up to 3.65 volts and shutting down charging leaving your battery a little flat.

Is it worth worrying about? I wouldn’t but that’s me.

Why you have lost 19ah in 8 months could be old cells, cheap cells or something else.

If you want to try to remedy it you can try to charge each CELL in your battery to 3.65.

Will that give you back your lost AH?
Maybe, maybe not but it will balance it.

I don’t think that EQ or balancer is going to do anything for you. I would shelve it.
The problem is each individual cell within the battery not total voltage of each battery.

 

[Buick39]

Obviously the BMS isn’t keeping it balanced during charging. You have 2 cells shooting up to 3.65 volts and shutting down charging leaving your battery a little flat.

Is it worth worrying about? I wouldn’t but that’s me.

Why you have lost 19ah in 8 months could be old cells, cheap cells or something else.

If you want to try to remedy it you can try to charge each CELL in your battery to 3.65.

Will that give you back your list AH?
Maybe but it will balance it.

I don’t think that EQ or balancer is going to do anything for you. I would shelve it.

Thanks for all your input to give u some history I purchased this from a guy that bought a Palat of them brand new... I took it brand new out of the box I felt I got a good deal as a 200amp hour 48v for 1500.00 so some lose of the amp hour I can live with as long as it doesn't keep going down but if there is something I could do affordable to add to the battery I would do as long as I don't have to repeat every 6 months... hope that makes sense

 

[WindWizard]

Not sure when you say high cells but I have a load tester for 12vdc that would make quick work of draining a 12v set of battery's that I use on testing my golf cart battery's to test load . My original thought was that the BMS should balance the battery's my early voltage checks had 3.5 to some 3.6v battery levels I had found that if I discharge to low I had issues with my MPPT coming on to charge the battery backup

When I assembled my battery pack I did not top balance them because to me it just was a waste of time. I know a lot of people believe in top balancing and that is fine but I saw in the Overkill BMS manual a little blurb about how to do it with the 16 Cells all in series and I thought that would be perfect for me so I could put my Cells to work and not have to wait weeks and invest in a charger, so I purchased the two 12v lights for $8 from Amazon and then took an alligator lead clip and cut it in half and soldered it onto each end of the light I found that once a Cell gets to 3.4 volts then it needs to be discharged. Just connect the alligator clips onto the Cell and the light will light up. Watch the Cell voltage and discharge it to the lowest Cell voltage. Just keep doing this with the Cell voltages above 3.4 volts starting with the highest ones. The Cell packs work very well for me now. I can get full Amperage out of my packs. Looking at your data, Cell 6 and Cell 13 both need to be discharged. Do this and it should increase your battery amperage. It is pretty easy to do. Just hook the light onto Cell 6 for a while and then onto Cell 13 for a while.

https://www.amazon.com/gp/product/B076MKZS35/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

 

[Nobodybusiness]

Thanks for all your input to give u some history I purchased this from a guy that bought a Palat of them brand new... I took it brand new out of the box I felt I got a good deal as a 200amp hour 48v for 1500.00 so some lose of the amp hour I can live with as long as it doesn't keep going down but if there is something I could do affordable to add to the battery I would do as long as I don't have to repeat every 6 months... hope that makes sense

That was a good deal for a 10Kw battery.

I’m not sure what BMS they put in there and whether it has a balance function or not.

There is certainly some total loss from the 2 cells shooting up in voltage turning off your charging.

Honestly I wouldn’t worry about it Unless it gets extreme.

If so you can open the battery and charge each individual cell to 3.65 volts to balance it so you get a full charge.

Will that be permanent? Probably not but will Last for a while.

You losing about 1 kWh at 19ah.

 

[Buick39]

When I assembled my battery pack I did not top balance them because to me it just was a waste of time. I know a lot of people believe in top balancing and that is fine but I saw in the Overkill BMS manual a little blurb about how to do it with the 16 Cells all in series and I thought that would be perfect for me so I could put my Cells to work and not have to wait weeks and invest in a charger, so I purchased the two 12v lights for $8 from Amazon and then took an alligator lead clip and cut it in half and soldered it onto each end of the light I found that once a Cell gets to 3.4 volts then it needs to be discharged. Just connect the alligator clips onto the Cell and the light will light up. Watch the Cell voltage and discharge it to the lowest Cell voltage. Just keep doing this with the Cell voltages above 3.4 volts starting with the highest ones. The Cell packs work very well for me now. I can get full Amperage out of my packs.

https://www.amazon.com/gp/product/B076MKZS35/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Thanks for sharing and very interesting on your concept of doing it.

 

[Buick39]

That was a good deal for a 10Kw battery.

I’m not sure what BMS they put in there and whether it has a balance function or not.

There is certainly some total loss from the 2 cells shooting up in voltage turning off your charging.

Honestly I wouldn’t worry about it Unless it gets extreme.

If so you can open the battery and charge each individual cell to 3.65 volts to balance it so you get a full charge.

Will that be permanent? Probably not but will Last for a while.

You losing about 1 kWh at 19ah.

Thanks for your reply and that was the down fall not much support or information on the battery. I currently have the top off it in the event If I purchase a power supply and charge each battery would I need to remove the buss bars to charge separately? or can you go across each battery in circuit?

 

[WindWizard]

Thanks for your reply and that was the down fall not much support or information on the battery. I currently have the top off it in the event If I purchase a power supply and charge each battery would I need to remove the buss bars to charge separately? or can you go across each battery in circuit?

The beauty of the way to balance your pack is that you don't have to take off the bus bars wires bms or anything. Just discharge Cell 13 and Cell 6 using the HomeAid light clip. It works perfect and does a quick job of bringing the Cells in line again. I highly recommend you do it. Just make sure that your light doesn't fall on some other posts or wires and short out. As long as it is only across Cell 13 for example then it will work perfect.

 

[Nobodybusiness]

Thanks for your reply and that was the down fall not much support or information on the battery. I currently have the top off it in the event If I purchase a power supply and charge each battery would I need to remove the buss bars to charge separately? or can you go across each battery in circuit?

Charge each cell.
I know it seems trivial but a battery is made from individual cells.

Just connect to each cell positive and negative on the bus bar of each cell.

 

[Buick39]

The beauty of the way to balance your pack is that you don't have to take off the bus bars wires bms or anything. Just discharge Cell 13 and Cell 6 using the HomeAid light clip. It works perfect and does a quick job of bringing the Cells in line again. I highly recommend you do it. Just make sure that your light doesn't fall on some other posts or wires and short out. As long as it is only across Cell 13 for example then it will work perfect.

what would be your thought on this battery load test I have one already in the garage which it acts like a heat on the load and do your process instead of purchasing the light bulbs? https://www.screencast.com/t/ftblxFeiqHh

 

[WindWizard]

what would be your thought on this battery load test I have one already in the garage which it acts like a heat on the load and do your process instead of purchasing the light bulbs? https://www.screencast.com/t/ftblxFe

No. Placing a 100 amp load on an individual cell would be not a good idea. The light is okay because it discharges the Cell at around 2.5 amps. That way you can watch the Cell discharge and then control it appropriately. Another thing I did was to put a sticky number on each of my Cells so I could identify the Cells quickly. With your pack just start with the negative terminal and the first Cell is 1. The last one should be 16 and should go the to positive terminal.

 

[Buick39]

No. Placing a 100 amp load on an individual cell would be not a good idea. The light is okay because it discharges the Cell at around 2.5 amps. That way you can watch the Cell discharge and then control it appropriately. Another thing I did was to put a sticky number on each of my Cells so I could identify the Cells quickly. With your pack just start with the negative terminal and the first Cell is 1. The last one should be 16 and should go the to positive terminal.

Got will do thanks again to all for there help this has been a good learning curve.

 

[WindWizard]

No. Placing a 100 amp load on an individual cell would be not a good idea. The light is okay because it discharges the Cell at around 2.5 amps. That way you can watch the Cell discharge and then control it appropriately. Another thing I did was to put a sticky number on each of my Cells so I could identify the Cells quickly. With your pack just start with the negative terminal and the first Cell is 1. The last one should be 16 and should go the to positive terminal.

If it is a passive load then it would be around 26 amps. That is roughly a ten time amperage increase over the light which would balance them super quick. It may work but I would use caution.

 

[sunshine_eggo]

Let's keep in mind that even Battleborn batteries can lose 50% of their capacity if they are not regularly charged to full and allowed to balance there. As I recall, they recommend two hours of absorption above 14.2V/month.

If these batteries were being cycled to a lower peak voltage and not held at a sufficiently high float or at absorption long enough, balance can easily drift over time. I've seen fully top balanced packs go out of balance from just sitting for two weeks before the batteries are built. A 0.1% variation in SoC of cells will trigger a runner.

The minimum effort solution here is to alter charge characteristics with a longer absorption time and/or a higher float voltage so the batteries can balance themselves.

 

[Buick39]

Let's keep in mind that even Battleborn batteries can lose 50% of their capacity if they are not regularly charged to full and allowed to balance there. As I recall, they recommend two hours of absorption above 14.2V/month.

If these batteries were being cycled to a lower peak voltage and not held at a sufficiently high float or at absorption long enough, balance can easily drift over time. I've seen fully top balanced packs go out of balance from just sitting for two weeks before the batteries are built. A 0.1% variation in SoC of cells will trigger a runner.

The minimum effort solution here is to alter charge characteristics with a longer absorption time and/or a higher float voltage so the batteries can balance themselves.

Just took that shot of some of the settings although I think the BMS controls all that not the mppt. Now in most cases I use my solar which is a very slow charging typically no more than 18 amps and that will only be an 1 to 2 hours a time at this time of year otherwise if I want to quickly charge it I do it through the utility and always charge to 100%.

 

[sunshine_eggo]

Just took that shot of some of the settings although I think the BMS controls all that not the mppt.

If the BMS is in communication with the MPPT/Inverter, then yeah. 56.0 bulk and float shown are enough to get balancing.

Now in most cases I use my solar which is a very slow charging typically no more than 18 amps and that will only be an 1 to 2 hours a time at this time of year otherwise if I want to quickly charge it I do it through the utility and always charge to 100%.

If you've just said that you don't regularly charge to 100%, that's the likely cause of your capacity loss. The BMS doesn't get enough time to top balance.

 

[Buick39]

If the BMS is in communication with the MPPT/Inverter, then yeah. 56.0 bulk and float shown are enough to get balancing.



If you've just said that you don't regularly charge to 100%, that's the likely cause of your capacity loss. The BMS doesn't get enough time to top balance.

Unfourtanaly it doesn't communicate with the mppt never has worked and support wasn't any help as they wasn't familiar with the battery so it just reads the voltage. And I always charge to 100% and will normally turn battery off.

 

[sunshine_eggo]

Unfourtanaly it doesn't communicate with the mppt never has worked and support wasn't any help as they wasn't familiar with the battery so it just reads the voltage. And I always charge to 100% and will normally turn battery off.

Then you have the option of setting the bulk and float values in the MPPT. Find the highest bulk voltage that doesn't trigger over-voltage protection. Set float to 0.1V below bulk. hold it there for 24 hours. You should see the high cell voltage come down and at least 1 of the others increase.