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Discussion Starter #1
I found this on AliExpress. I am hoping it is a simple BMS. I have found no product manuel on-line
Would someone take a look at product and let me know if it is indead a BMS, how it works.and how to hook it up.
I am building a 48volt off grid solar energy pack with CALB 180ah.
Thanks, James

 

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this is just a guess on my part, but it looks like just a very simple cell balancing board using DW01x circuits. There is no communication, adjustment or control of this board--the voltage level of each cell is determined by whichever "x letter" was selected for the "DW01x". All the cells will be continuous balancing without regard to their neighbor, to the pack, or to any target that you might desire.

You might want to investigate your options for battery management systems that allow you to monitor, adjust and control the balancing function, in addition to managing the charging and discharge functions. You might want a "smart" top level controller with dumb balancers that only turn on/off when commanded. For example you might want Pack level voltage monitoring and Pack level current control.

Here is an example of a dw01 individual circuit, it is modified for use as balancer on the board you found, then it is repeated 16 times.
 

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Discussion Starter #5
I found this on AliExpress. I am hoping it is a simple BMS. I have found no product manuel on-line
Would someone take a look at product and let me know if it is indead a BMS, how it works.and how to hook it up.
I am building a 48volt off grid solar energy pack with CALB 180ah.
Thanks, James

 

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Discussion Starter #6
Hi Everyone..

Thank you all your response.

I am trying to get multi use out of my EV conversion battery pack by dividing the pack into thirds.
Use all three packs on my EV, use single pack for my 45 volt Ebike and a 45 volt solar array on my camper
while on vacation.

Some of my insanity comes from watching a youtube titled “Milk Crate Projest”
He has a sequel video “BMS to Milk Crate Project” (Not impressed with his pick for
BMS)

I am dealing with mix voltage for between usage.

My first concern is: 16 cell build is not 45 volts. It is 51.2
51.2 times 3 is not 144 volts, It is 153.3

Question:
Will 153.3 damage my 144 volt EV motor?
All 144 EV conversions I have seen use 45 cell, not 48 cells.

Question:
Will my 45 volt camper solar array charge the 51.2volt pack.

Question:
Will 51.2 damage my 45 volt bike motor.

Thanks James
 

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Discussion Starter #7
Hi again with another catch 22 on split pack maybe you can help me with.

I now remember why I was more interested in a Balancer rather than BMS.

A Balancer needs no power source. Again, I’m not sure?

48 volt BMS use 48 volts off pack to functions and monitor pack voltage. Placing three packs in series will probably burn up the BMSs.

Question:
Can you run a BMS with an external power source, in parallel, to power all three BMSs?
I will not indicate total pack voltage of EV pack but will it still function in other aspects.
EV has pack voltage monitoring with 144v shunt and meter.

James
 

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Youtube is a terrible primary learning source way too much incorrect information.

All those questions requires the precise data for each device involved, ideally from the mfg's data sheet.

And precise pack voltages for A. midpoint nominal, B. usage LVC, C. charging HVC and what SoC / voltage point you plan for balancing.

The usual EV chemistries at nominal 3.6-3.7Vpc have nothing to do with LFP's unique curve, so stop thinking in general terms like "45S"

With LFP 16S is indeed called 48V nominal. Note even with lead batteries that label really means 57-58V charging, down to fully depleted at 42V.

Actual LFP 50% midpoint will be 51-53V, charge termination for normal cycling should be 55-56V

only go to 57+V for occasional testing /maintenance.

Multiply these voltage ranges above by three to get your 48S voltages for EV scenario.

Never let such cells drop below 3.0V at rest, so for 16S your 45V is out of the question, more like 14S

which 42S may be better for your EV gear as well.

Note that 7S works well with inexpensive standard hobby gear, full-featured balance charging, capacity load testing, other maintenance protocols etc.
 

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Note that "a BMS" is just a collection of functionality:

Maybe balancing, depends what you want, make sure high balancing current and all setpoints fully adjustable

HVC, LVC

might be based on per-cell or whole-pack voltage

maybe OCP but fuses are better IMO, no need for current to flow through the voltage-only monitoring circuits, use external contactors.

Temperature?

No need to seek everything in one device so long as longevity & reliability are top priorities.

And build the packs so each voltage-configuration gets their own, not putting 3 BMS in series

all such circuitry easily tested / replaced and removed when not in use.

Extra easy access to the balance leads to cross-verify against known good DMMs and ammeters, never trust built-in sensors and displays.
 

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Discussion Starter #10
OMG. Let me re-phrase..

If a 154.3 volt lihjtning bolt came right ouf my ass and went into my 144 volt EV motor will it blow? it up.
 

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No, there is a motor controller between the pack and the motor that regulates the current and voltage to the motor.

you don't say what kind of motor you have, but assuming a brush type DC motor, it you put 144V directly to your motor on the bench, then it will jump off your bench onto the floor and smash your foot. so don't try that, only use 12V on the bench to run in your brushes.
 
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