diy solar

diy solar

48V 16cell 105AH Eve Battery Xiaoxiang BMS Settings

psnlk

New Member
Joined
May 15, 2022
Messages
10
HI i got Eve 16Cells with Xiaoxiang BMS have some issues

1) everytime when i charge batteries, the pack don't charge to 3.4 or over. but sometime single cells go over 3.4V. i'm sure this has to do with my BMS settings.

2) or do i have to charge over 3.4V and go up to 3.6V to get the maximum from battery pack? ( i know the safe charging/discharging areas are stay between 2.5-3.6V)

can someone please check my images and help me with proper settings.
when i got the 16cells i checked all had 3.2V and after connecting the BMS total voltage was showing 51.2V

by the way this is connected to Growatt 5000es
Thank you.
 

Attachments

  • WhatsApp Image 2022-05-18 at 8.59.27 AM-2.jpeg
    WhatsApp Image 2022-05-18 at 8.59.27 AM-2.jpeg
    59 KB · Views: 33
  • WhatsApp Image 2022-05-18 at 8.59.28 AM.jpeg
    WhatsApp Image 2022-05-18 at 8.59.28 AM.jpeg
    56.9 KB · Views: 35
  • WhatsApp Image 2022-05-18 at 8.59.28 AM-2.jpeg
    WhatsApp Image 2022-05-18 at 8.59.28 AM-2.jpeg
    56.8 KB · Views: 31
  • WhatsApp Image 2022-05-18 at 8.59.28 AM-3.jpeg
    WhatsApp Image 2022-05-18 at 8.59.28 AM-3.jpeg
    55.4 KB · Views: 49
  • WhatsApp Image 2022-05-18 at 8.59.28 AM-4.jpeg
    WhatsApp Image 2022-05-18 at 8.59.28 AM-4.jpeg
    52.9 KB · Views: 45
  • WhatsApp Image 2022-05-18 at 8.59.27 AM.jpeg
    WhatsApp Image 2022-05-18 at 8.59.27 AM.jpeg
    53.5 KB · Views: 36
In the last picture cell 9 looks high and probably went over volt causing the BMS to protect. The bleed resistors are very small and may not ever really knock #9 down to the other cells. Need to bleed this one down manually to match the others. Otherwise need to reduce charging voltage to 53.80 to avoid over volt. Once in balance increase the charging voltage to 55.20 and see if it goes.

Settings look fine although usually the balance start voltage would be 3400 so that balancing takes place in the top voltage area.
 
In the last picture cell 9 looks high and probably went over volt causing the BMS to protect. The bleed resistors are very small and may not ever really knock #9 down to the other cells. Need to bleed this one down manually to match the others. Otherwise need to reduce charging voltage to 53.80 to avoid over volt. Once in balance increase the charging voltage to 55.20 and see if it goes.

Settings look fine although usually the balance start voltage would be 3400 so that balancing takes place in the top voltage area.
thank you for the reply
on the app where to reduce charging voltage to 53.80 ?
 
thank you for the reply
on the app where to reduce charging voltage to 53.80 ?
You need to do this on the Growatt , Settings 19 & 20 , but bleed down the high cell first. I made up a special resistor pack with leads and croc clips for this purpose. You have to get your top balance sorted first. I use the same inverter and BMS and my setting for 19 & 20 is 54v. You can increase this setting later once all the cells track properly to within say 20mV.
I added a Heltec 5amp balancer and can now maintain 5 - 8mV cell delta. I turned the balancing on the BMS off and leave the Heltec connected permanently.
 
Ok, right now my Growatt settings are
19 = 57.60V
20 = 57.60
21 = 42V

i will change this to above ratings and see.
bleed down the high cell i can use a 12V car light with some croc clips.
do you have a product link to the 16Cell 48V balancer?

Thanks
 
Hi
Didn’t have to bleed the cell down. After changing the voltage to 53.80 all settled.

Now settings are
19 - 55.2v
20- 55.2v

Question remain same
Why the batteries are not charging up to 3.6v
 

Attachments

  • 9EBF688B-EA32-4FE8-99B9-0B3BB453194A.png
    9EBF688B-EA32-4FE8-99B9-0B3BB453194A.png
    624.6 KB · Views: 10
Very odd. Maybe it was a bad connection.
Although the picture shows cells well below the top charge and will tend to diverge above 3.40 if not closely balanced.


Going to 3.60 on a regular basis is a bit overrated. 55.2 / 16 = 3.45 and to get 3.60 need 3.60 x 16 = 57.6
 
Thank you, now I know if I increased the charging voltage from Growatt then cells should charge high. I’ll test that

If you see the above image, it’s showing pack is discharging at the rate of 1.0A or below

So why is that?
Why can’t the battery pack stay 100% after full charge ?
 

Attachments

  • 37AAC2B2-FC6C-421A-B290-1C4454084C64.png
    37AAC2B2-FC6C-421A-B290-1C4454084C64.png
    728.5 KB · Views: 4
3.45 is not really full full charge unless the voltage is held there for an extended absorption period. Voltage will always settle a bit once resting or slight discharge. Charging a battery is not the same as filling a tank of gasoline to the "full" mark. I expect the battery is close to 95% and I call that full.
 
You are almost there. You do not gain much by charging all the way to 3,65v . Also , there can be voltage measurement discrepancies between the Growatt and the BMS. It took me quite a while to fine tune my setup as I had one or two cells peaking before the others. What you can experiment with is to increase the settings of 19 & 29 by 0,2v at a time and observe. With no load on the battery bank other than the inverter , the BMS will show a discharge of the inverter idle current. Try and cycle the setup a few time between full and say 10% SOC and observe. After that you can make any adjustments if required.
BTW , your cell delta looks good ? . You may not need a balancer after all. I was not that lucky as the factory in China sent me 8 out of 28 duff cells.
You can also check the total battery voltage with a DMM and compare it to what is displayed by the Growatt and adjust
19 & 20 accordingly. I found an error of up to 0,6v and had to compensate.
 
Last edited:
Attached image for discharging- Is this mean need bottom balance
Current status
19 - 56.2
20 - 56.2
 

Attachments

  • 1F33DF2D-72C8-4F22-BA87-5C2C318132EB.png
    1F33DF2D-72C8-4F22-BA87-5C2C318132EB.png
    710.4 KB · Views: 10
Attached image for discharging- Is this mean need bottom balance
Current status
19 - 56.2
20 - 56.2
I would suggest a few charge / discharge cycles to see if the cells will stabilise and report results back here.
 
Attached image for discharging- Is this mean need bottom balance
Current status
19 - 56.2
20 - 56.2
Cannot have both a top and bottom balance. One will always throw the other off balance. Generally keeping the top balance is better.

OK to run the cells down to discover the minimum voltage and total capacity available with minimum risk of low voltage protection from the BMS. Adjust the charging and usage pattern to avoid going too low.
 
Completely different question

I have 2 Growatt 5000es with 5kw (105ah x16) and 8Kw (16x 166ah) battery pack

What’s the best way to connect in single phase ?
Remember it’s different capacity batteries
 
I think it is possible to connect a battery to one Growatt and the other to the 2nd Growatt and then parallel the two inverters with the linking cable.
 
Cannot have both a top and bottom balance. One will always throw the other off balance. Generally keeping the top balance is better.

OK to run the cells down to discover the minimum voltage and total capacity available with minimum risk of low voltage protection from the BMS. Adjust the charging and usage pattern to avoid going too low.
Due to couple of cells low voltage complete battery pack can not use hitting the low voltage trigger from BMS

What should I do to balance this
 

Attachments

  • 29F962B4-D667-4233-8311-A123C2E6BDC8.png
    29F962B4-D667-4233-8311-A123C2E6BDC8.png
    631.8 KB · Views: 7
Due to couple of cells low voltage complete battery pack can not use hitting the low voltage trigger from BMS

What should I do to balance this
This is the PITA bit. What I would do is to get all the cells at the same potential i.e. connect all the cells in parallel and leave for a couple of days. Then build the 16 cell battery again and charge to full and top balance.
Unless you want to charge the individual cells until they are all at the same SOC. After that you will have to do a discharge cycle again to see if you have any wayward cells.
 
This is the PITA bit. What I would do is to get all the cells at the same potential i.e. connect all the cells in parallel and leave for a couple of days. Then build the 16 cell battery again and charge to full and top balance.
Unless you want to charge the individual cells until they are all at the same SOC. After that you will have to do a discharge cycle again to see if you have any wayward cells.
Or buy one of those active balances would do the trick? Since the pack is assembled now
 
I also did not want to dismantle my 48v battery , so I used my Victron 30A 12v battery charger and recharged the cells in batches of 4. No need to disconnect anything ( only the load ) , just connect charger. Let the charger charge each batch until ‘float’ level is reached ( almost zero current ) . You can monitor the progress on your BMS display and detect any wayward cells.
Very important : Each person building / assembling batteries should have a decent bench power supply / charger rated at 15 - 30A and preferably with a LiFePO charge profile. I have always used Victron ( as I am a reseller here ) as you can set up custom charge profiles etc. and because I like their products.
I would only connect an active balancer once your cells delta is below 100mV.
 
Back
Top