JBD-120A 12V BMS, perfect settings?

[MrSteve]

Hi all.

A couple days ago my JBD BMS (from aliexpress) arrived and i have build and top balanced a 12V pack with 4 105AH aluminum cased cells.
I will be using a Victron Smart Mppt 75-15 to charge it most of the time and use the "5000+cycle" settings as recommended by Will.

I have been playing around with the BMS and settings a bit.

My question.. what are the best settings on my BMS to work best with the Victron settings?
Just set the total AH to 105AH and usable AH to say a 90%/ 95AH?
I use a cheaper copy of the Victron BMV battery monitor to see the state of charge in %
but would love to have a fairly accurate SOC reading via the JBD Bluetooth app.

Or don't adjust settings at all, just let the BMS do it's work, cut off at 2.5V and stop charge at max 3.65V,
the Victron Mppt should stop charging at 14.2V - 3.55V per cell if cells are nicely balanced.

Btw,
I have noticed that when i was discharging the pack for the first time and go back and forward in the settings menu
that when say the battery was at 70% and a 13.30V in the app the app jumped back to 100% even at this lower voltage..
I guess i just need to get a few cycles up and down to get a better SOC reading in the app?

Like to hear your input on this guys!

Thanks much,
Steve.

 

[Gazoo]

The BMS is used as the last line of defense to protect the cells so the HVD and LVD should be set to 3.65 volts and 2.50 volts.

Just set the total AH to 105AH and usable AH to say a 90%/ 95AH?

Set the capacity to 105ah and the usable capacity to 70%. When the BMS uses 70% or more it will count as 1 cycle.

have noticed that when i was discharging the pack for the first time and go back and forward in the settings menu
that when say the battery was at 70% and a 13.30V in the app the app jumped back to 100% even at this lower voltage..
I guess i just need to get a few cycles up and down to get a better SOC reading in the app?

Yes. Whenever any of the parameters are changed you will need to cycle the battery at least once to get accurate readings. This means charging to 14.60 volts and discharging to 10 volts. This will also give you the opportunity to test the BMS's HVD and LVD to make sure they work.

 

[MrSteve]

The BMS is used as the last line of defense to protect the cells so the HVD and LVD should be set to 3.65 volts and 2.50 volts.


Set the capacity to 105ah and the usable capacity to 70%. When the BMS uses 70% or more it will count as 1 cycle.


Yes. Whenever any of the parameters are changed you will need to cycle the battery at least once to get accurate readings. This means charging to 14.60 volts and discharging to 10 volts. This will also give you the opportunity to test the BMS's HVD and LVD to make sure they work.

Thanks much for your reply!

Is setting the usable capacity only for the cycle count? Or does it influence the battery’s SOC % reading as well?
I guess not, but just curious.

I will put the battery pack tru a couple of cycles like you said and see how the BMS performs.

Thanks again.

 

[Gazoo]

Is setting the usable capacity only for the cycle count? Or does it influence the battery’s SOC % reading as well?
I guess not, but just curious.

As far as I know...no. There are separate settings for the SOC. I haven't messed with the SOC settings.

I will put the battery pack tru a couple of cycles like you said and see how the BMS performs.

This's the best thing you can do and is what I did to become familiar with the BMS and it's settings. Keep an eye on the delta especially at the top and the bottom. The delta will let you know how well your cells are capacity matched. If you parallel top balanced your cells then the delta will most likely be better at the top than at the bottom.

 

[MrSteve]

As far as I know...no. There are separate settings for the SOC. I haven't messed with the SOC settings.


This's the best thing you can do and is what I did to become familiar with the BMS and it's settings. Keep an eye on the delta especially at the top and the bottom. The delta will let you know how well your cells are capacity matched. If you parallel top balanced your cells then the delta will most likely be better at the top than at the bottom.

So far they seem well matched, very small delta.. I only charge at 10-15Amps, I can imagine charging or discharge with higher amps they start to drift a little but settle and get closer together again after that.

I will have a better look at the BMS manual, should have done that before asking noob questions lol..