Help with 128 batteries each one is 280ah, and want to configure for 48v system.

[kromc5]

Pulled the busbars and group 9 were all at the same voltage, slowly removing busbars all the others so far are 3.38 - 3.39.

 

[Shawn Hayes]

Pulled the busbars and group 9 were all at the same voltage, slowly removing busbars all the others so far are 3.38 - 3.39.

A crazy thought....since #9 is a constant problem, any chance the 3” bus bar from #8 going to #9 is carrying some voltage causing it to keep varying? Don’t seem like it but just a thought? It’s my understanding all bus bars should be similar in size etc?

 

[kromc5]

A crazy thought....since #9 is a constant problem, any chance the 3” bus bar from #8 going to #9 is carrying some voltage causing it to keep varying? Don’t seem like it but just a thought? It’s my understanding all bus bars should be similar in size etc?

I can try this, I went with 3 worrying about voltage drop across the back side but I can test that.

Update: I keep forgetting, they did charge fine for 4 days then this started occuring. But I will test that shortly and report back.

Update: Wanted to check and see how it would look. I can use 3 of the 11 inch and two of the 4.5.

 

[Sanwizard]

I can try this, I went with 3 worrying about voltage drop across the back side but I can test that.

Update: I keep forgetting, they did charge fine for 4 days then this started occuring. But I will test that shortly and report back.

Update: Wanted to check and see how it would look. I can use 3 of the 11 inch and two of the 4.5.

NICE Big fat busbars, but small contact area. Probably would not hurt to clean and polish the terminals, or perhaps some de-oxidizer like no-oxID special on the aluminum.

 

[kromc5]

NICE Big fat busbars, but small contact area. Probably would not hurt to clean and polish the terminals, or perhaps some de-oxidizer like no-oxID special on the aluminum.

I have done that twice now and ox on all them and full deburred all the holes with cnc tool. That is why I do not undestand why it would start doing this after 4 days.

 

[kromc5]

Sadly putting the small busbar on did not change anything. Time is on the right just climbs like crazy. I'm thinking of pulling it apart, marking all the batteries and change them around to see if the it stays the same or do we see 9 charge normal and another cell group run away.

 

[kromc5]

Thinking this evening of swapping the cell banks, technically 9 would become 8 and so forth. Unless anyone has suggestion on how to proceed.

 

[rhino]

Just wanted to double check that you did verify the voltage was accurate with a volt meter on group 9 when it shows it that much higher? Have you also swapped the blockmon on group 9 with another group?

 

[kromc5]

Just wanted to double check that you did verify the voltage was accurate with a volt meter on group 9 when it shows it that much higher? Have you also swapped the blockmon on group 9 with another group?

I dissembled the pack twice and checked each cell individually and the voltages were correct. I changed blockmons on 8,9 but no difference.

 

[Shawn Hayes]

The M8s only passive balance at 1.75a I believe per cell block so if you have 4 in parallel then that is 1120ah for that Little M8 to manage. I would look to active balancer if you want to use the upper end of the curve with these cells.
Here is a Very good review of a cheap active 5a balancer. I would use them in conjunction to the Batrium.

I watched the video. Got me thinking about adding active to my setup. With Batrium BMS is there a setting that needs to be turned off when using active balancers?
Correct me if I’m wrong, but I’m doing a 4p16s so I would only need a 16s active balancing setup? Only one balancer per pack of 4, being they’re 1120ah packs? If I read what you wrote Correctly?
I did look up the QNBBM from Deli-Green today because I’ve seen people say good things about them. Just thinking that maybe I should have them here and on hand “if” needed. I will not put a full load on my system until maybe the first of 2022 as we are still under construction.
Thanks

 

[kromc5]

I watched the video. Got me thinking about adding active to my setup. With Batrium BMS is there a setting that needs to be turned off when using active balancers?
Correct me if I’m wrong, but I’m doing a 4p16s so I would only need a 16s active balancing setup? Only one balancer per pack of 4, being they’re 1120ah packs? If I read what you wrote Correctly?
I did look up the QNBBM from Deli-Green today because I’ve seen people say good things about them. Just thinking that maybe I should have them here and on hand “if” needed. I will not put a full load on my system until maybe the first of 2022 as we are still under construction.
Thanks

You will need 16, in hardware - cellmon - you can manage the passive balancing.

 

[kromc5]

I thought about how to approach the next test: I still believe that another cell group is the issue but they charge together and resistances are the same. I’m really trying to avoid data logging them all.

Cell Group 9 started to run after 4 days during that time no issues they balanced each day near perfect:
Everything tried but failed:

Checked the cells individually higher voltage was correct.
Changed to a smaller back busbar.
Changed out all 4 batteries in cell group 9.
Changed cellmons should have zero effect but why not.


Interesting part: Decided to move 4 last cell groups both sides forward and 3 both groups backward.
Pulled the pack completely apart, moved the last 4 cells groups both sides forward, moved 3 cell groups both sides backwards.

Exhibited the same behavior, cell group 9 was the runner again and which was now in cell group cell group 12 and the behavior followed.


My two thoughts are:
Moved cell group 9 that is cell group 12 position forward to cell group 15. I will move moved 15, 14, 13, backward. I would be very happy if cell group 13 which will be now be cell group 12 exhibit the behavior.

My other idea was to replace group 9 again but keep the same move order.

Always open for any suggestion but wil get to work this evening to retry tomorrow.

 

[Shawn Hayes]

I thought about how to approach the next test: I still believe that another cell group is the issue but they charge together and resistances are the same. I’m really trying to avoid data logging them all.

Cell Group 9 started to run after 4 days during that time no issues they balanced each day near perfect:
Everything tried but failed:

Checked the cells individually higher voltage was correct.
Changed to a smaller back busbar.
Changed out all 4 batteries in cell group 9.
Changed cellmons should have zero effect but why not.


Interesting part: Decided to move 4 last cell groups both sides forward and 3 both groups backward.
Pulled the pack completely apart, moved the last 4 cells groups both sides forward, moved 3 cell groups both sides backwards.

Exhibited the same behavior, cell group 9 was the runner again and which was now in cell group cell group 12 and the behavior followed.


My two thoughts are:
Moved cell group 9 that is cell group 12 position forward to cell group 15. I will move moved 15, 14, 13, backward. I would be very happy if cell group 13 which will be now be cell group 12 exhibit the behavior.

My other idea was to replace group 9 again but keep the same move order.

Always open for any suggestion but wil get to work this evening to retry tomorrow.

So are you saying group 9 is the runner NO MATTER which group of batteries occupies the space #9?

 

[kromc5]

So are you saying group 9 is the runner NO MATTER which group of batteries occupies the space #9?

I'm sure it’s hard to follow with the moving, in the process of moving the groups - 9 is now in slot 12 which still continued to run up. But also remember I swapped out all 4 from group 9 earlier and the issue stayed. I was hoping cells moved to group 9 would run up but it did not to my great disappointment. If it, had I could have started looking at packs 8 to 1. So, for tomorrows test, group 9 has now been moved to cell group 15 and will see how it goes.

 

[Shawn Hayes]

I'm sure it’s hard to follow with the moving, in the process of moving the groups - 9 is now in slot 12 which still continued to run up. But also remember I swapped out all 4 from group 9 earlier and the issue stayed. I was hoping cells moved to group 9 would run up but it did not to my great disappointment. If it, had I could have started looking at packs 8 to 1. So, for tomorrows test, group 9 has now been moved to cell group 15 and will see how it goes.

How did you balance your cells before you built this battery originally? Balance in groupings of 4, 8, etc?
Just curious if that runner group was balanced together, packed together and for some reason runs differently? I k me you’ve swapped batteries but lost now on if you changed out cells within packs.

 

[Sanwizard]

How did you balance your cells before you built this battery originally? Balance in groupings of 4, 8, etc?
Just curious if that runner group was balanced together, packed together and for some reason runs differently? I k me you’ve swapped batteries but lost now on if you changed out cells within packs.

Perhaps add a 5 amp active balancer? I use a BMS on every cell, and they seem to stay around .008 mv deviation. Without the active balance( mine is 2 amp in the Heltec BMS) it would vary much higher.
I like active vs resistive, as active can send power to the lower cells from the higher cells, so a bit more efficent and less heat. Thats just my personal preference. I am sure each method has its advantages and disadvantages.

 

[kromc5]

How did you balance your cells before you built this battery originally? Balance in groupings of 4, 8, etc?
Just curious if that runner group was balanced together, packed together and for some reason runs differently? I k me you’ve swapped batteries but lost now on if you changed out cells within packs.

I did them in groups of 32, for a total of 128 batteries.

 

[kromc5]

Perhaps add a 5 amp active balancer? I use a BMS on every cell, and they seem to stay around .008 mv deviation. Without the active balance( mine is 2 amp in the Heltec BMS) it would vary much higher.
I like active vs resistive, as active can send power to the lower cells from the higher cells, so a bit more efficent and less heat. Thats just my personal preference. I am sure each method has its advantages and disadvantages.

Do you have a link for active balancer that can do a 4p16s?

 

[Sanwizard]

Do you have a link for active balancer that can do a 4p16s?

I dont think it would work as well on banks vs cells, but you can give it a shot.

Amazon.com: Heltec 16S 5A Capacitor Active Equalizer Balancer Lifepo4 Lithium Lipo/Titanate LTO for Battery Group Balancer 12S 13S 15S : Electronics

Buy Heltec 16S 5A Capacitor Active Equalizer Balancer Lifepo4 Lithium Lipo/Titanate LTO for Battery Group Balancer 12S 13S 15S: Battery Chargers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[Sanwizard]

I dont think it would work as well on banks vs cells, but you can give it a shot.

Amazon.com: Heltec 16S 5A Capacitor Active Equalizer Balancer Lifepo4 Lithium Lipo/Titanate LTO for Battery Group Balancer 12S 13S 15S : Electronics

Buy Heltec 16S 5A Capacitor Active Equalizer Balancer Lifepo4 Lithium Lipo/Titanate LTO for Battery Group Balancer 12S 13S 15S: Battery Chargers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

I just noticed they went way up in price from last year! I think I paid $28 for mine on Alibaba.