# BMS123 real user experiences



## evpower (Aug 9, 2013)

If someone has the BMS123 system on the battery pack, I would like to hear the real user experiences. 

BMS123 is this BMS system










Available in Europe here: http://www.ev-power.eu/BMS123-System/

Support pages here: http://gwl-power.tumblr.com/tagged/BMS123

Thanks for your comments!


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## mora (Nov 11, 2009)

I don't have one but I've installed one system for my friend. I'll throw in my comments. It seems to work as advertised. Very useful for people who use TCCharger. Price for full system isn't bad either.

I didn't like accuracy of amp meter calibration. Though it might not be relevant for driver to see exact amps drawn. Like if it was 200A or 210A. Percentage there is enough. But I could never get needles to the middle point, even though software had accurate enough steps for calibration. Needle always jumped over the point I wanted it to stay on. It took some time to figure out how meter positions should be calibrated but luckily it was simple. First meter just kept jumping around when I kept clicking different calibration boxes.

I didn't also install it on top of bolts but soldered flattened ring terminal to every single board. Then added single wire from board to another terminal.

Wire terminals inside the main control box are hard to reach and requires lots of precision when connecting signal wires. I was able to do it, my friend couldn't have managed it. It was also a bit of pain to fit all the required wires through the plastic nut that goes through the box front wall.

Cell in/out was a bit confusing. Manual had nice pictures about connections that made things clear. I read the whole manual through before starting installation.

My friend has wired his 12V system so that he cuts loads at negative side instead of positive side. BMS control board is wired "always on" as suggested in manual. All the negative leads coming from control board are directly connected to the ground. This causes some leakage but I don't think this is BMS problem. I would have wired entire 12V system differently so I wouldn't have faced any leakage problems.

We liked its ability to control charger other than on/off too. Light show on top of batteries is cool. It has also already indicated one weaker cell that was removed from the pack. Control software looks cool too. It would be cool to have it also on android so one could mount a small android device on dashboard and see what BMS wants to show you. If software could show every single cell voltage in bar-style graph in full screen I'd be very tempted to install this system on my EV. Or the next one I'm going to build some day.


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## mira9_cz (Feb 27, 2013)

For those who want to see how BMS123 looks like when installed in the vehicle, please watch my thread Mazda RX-8 conversion

http://www.diyelectriccar.com/forums/showthread.php/czech-mazda-rx-8-dc-conversion-88587p12.html

I'm using 98 Wina cells (http://www.ev-power.eu/WINA-30Ah-100Ah/WINA-LiFePO4-Power-3-2V-100Ah-aluminium-case.html) and as a BMS I had chosen BMS123, mainly because of it is able to control TC-Charger, simple installation and reasonable price. 

My installation is not ready yet, 15 cells with balancing modules is yet not connected. I will keep this thread updated when I will got some real experience.


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## evpower (Aug 9, 2013)

External logger has been developed for BMS123. It can store all the values that BMS123 monitors:

- time
- charge level
- voltage
- current
- minimum cell voltage [V]
- minimum cell voltage index
- maximum cell voltage [V]
- maximum cell voltage index
- minimum cell temperature [C]
- minimum cell temperature index
- maximum cell temperature [C]
- maximum cell temperature index
- error bit
- charger connected bit

It is based on platform of Linux Micro PC. Web interface is available as well.


http://www.ev-power.eu/BMS123-System/BMS123-BMS-Data-Logger.html

This device is very good:

- If you are interested in data of your battery pack from time when you could not check the BMS in realtime.
- If you need to prove how were your cells treated.
- If you want to find our minimum or maximum values.
- To create graphs of voltage and current and tune your E.V. further.


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## evpower (Aug 9, 2013)

Support articles for the BMS123 system

http://gwl-power.tumblr.com/tagged/BMS123


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## JonasFilipe9 (Jan 9, 2015)

evpower said:


> Support articles for the BMS123 system
> 
> http://gwl-power.tumblr.com/tagged/BMS123


Thank you guys for the information about the communication protocol!

I would also ask you for a diagram with the different block of the system... Something like this: http://www.mpoweruk.com/images/bms.gif

Most of the blocks are the same for what I understand.


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## JonasFilipe9 (Jan 9, 2015)

I'm using and still testing BMS123 with Elcon Charger and I think it works fine and has a good way of charging cells, a little different from usual I think.
I've also noticed some details that might not be clear when you buy it or you are figuring out how it works before buying, because are not in the manual.

The module, even offline, stores the by-pass voltage and dissipate energy in the transistor if the cell voltage is over the value set before in the software.

This means if we set by-pass voltage to 3.4V, charge the cells separatly to 3.6V and the resting voltage stays over 3.4V, when you install the cell module on the cell the module, it will dissipate cell energy until you have 3.4V, although you have no communication with BMS main controller.

The transistor may be very hot and as it is not connected to the main board I think this might result in the damaging of the transistor due to over-heating. So this is a situation users may have in mind.


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## mira9_cz (Feb 27, 2013)

JonasFilipe9 said:


> The transistor may be very hot and as it is not connected to the main board I think this might result in the damaging of the transistor due to over-heating. So this is a situation users may have in mind.


I asked the manufacturer about this issue specifically. I was also worried about transistors lifetime and I asked if the Tmax setting has something to do with protecting the transistors. I was told to not to be worry about the transistors and that the temperature meter is there for cells only. Plus that balancing modules acts like this in purpose to do their job even when communication with Main Controller is lost (malfunctioning DC-DC, discharged 12V board bat., etc.).

My observation is that Tmax is useful only when discharging. During the charging you can trust only to Tmin. As soon as balancing starts, Tmax is influenced by heat from transistors. It makes sense since the temp sensor is at the balancing board, not externally mounted. In my case Tmax is reached by cells in front battery box which is sealed tight from dirt from the road and so not very much ventilated.


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## mira9_cz (Feb 27, 2013)

JonasFilipe9 said:


> Thank you guys for the information about the communication protocol!
> 
> I would also ask you for a diagram with the different block of the system... Something like this: http://www.mpoweruk.com/images/bms.gif
> 
> Most of the blocks are the same for what I understand.


The most explaining scheme I think is this:


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## JonasFilipe9 (Jan 9, 2015)

mira9_cz said:


> I asked the manufacturer about this issue specifically. I was also worried about transistors lifetime and I asked if the Tmax setting has something to do with protecting the transistors. I was told to not to be worry about the transistors and that the temperature meter is there for cells only. Plus that balancing modules acts like this in purpose to do their job even when communication with Main Controller is lost (malfunctioning DC-DC, discharged 12V board bat., etc.).
> 
> 
> 
> My observation is that Tmax is useful only when discharging. During the charging you can trust only to Tmin. As soon as balancing starts, Tmax is influenced by heat from transistors. It makes sense since the temp sensor is at the balancing board, not externally mounted. In my case Tmax is reached by cells in front battery box which is sealed tight from dirt from the road and so not very much ventilated.




OK, so although they get hot, the current is limitated so the transistors won't fry. I had that doubt too, I've noticed also that the temperature rises when the transistors start doing by pass. But the cell was not 20ºC hotter...



I think there's a thermistor on board, which varies its resistance approximately linearly accordingly to temperature variation. But I would like some help to identify it:








This is Albertronic property must refer.


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## JonasFilipe9 (Jan 9, 2015)

I'm building a block representation of it (is still incomplete) and I would like your opinion to see if there is no big mistake or what could be done to make it more precise...


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## evpower (Aug 9, 2013)

*Latest support updates for the BMS123 system:*

* FAQ: How does the balancing of the BMS or SBM work? 
http://gwl-power.tumblr.com/post/116372109646/

* BMS123 Data Logger connections
http://gwl-power.tumblr.com/post/107927645426/

* FAQ: The BMS123 – showing the “L” indicator
http://gwl-power.tumblr.com/post/107143391136/

Check more articles at: http://gwl-power.tumblr.com/tagged/BMS123


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