[Citystromer]

Hi,
I`m planning to build a BMS using innexpensive zener type ballancer, (3A max, conducting at 3.6V) and celllogs8 from SHENZHEN JUNSI.
I`ve read some threads about the device being inherently solid, except it can`t be connected to the laptop while on the battery- which I`m not planning on doing.
I`ll be using one cellog for every 8 cells, and a master contactor, that takes the battery of the charger OR the controller when either ANY cell activates HV or LV.
Any reason why I shouldn`t do this? Except for building solid harnesses.

[madmike8]

Honn1002 used cellogs to make a bms...

http://www.diyelectriccar.com/forums...ghlight=cellog

[frodus]

I think they're great. IMHO monitoring is an absolute must with lithium batteries. Having an LVC and HVC is important to keep a healthy pack.

If I was going without a balancing BMS, the Celllogs is exactly what I'd use for a cheap robust system.

Just one thing though, they can cause unbalance on the pack because they tap power off of the first cell or two. Just something to keep in mind. I think there are mods out there to fix this, but I'm not sure.

[major]

Originally Posted by frodus

Just one thing though, they can cause unbalance on the pack because they tap power off of the first cell or two. Just something to keep in mind. I think there are mods out there to fix this, but I'm not sure.

Actually off the first 6 cells. It takes a while, but it will cause cells 7 & 8 to drift to higher voltage than the first six. There is a simple fix....jumper soldered inside the cover of the celllogger. I haven't tried it yet. It is shown on a thread in this forum somewhere.





Here it is. From the thread http://www.diyelectriccar.com/forums...ghlight=cellog

And if interested, I can supply the JST connectors with wires assembled.

Anybody know if bblocher is still around? He had a nice circuit board design for this. Photo of his solution attached.

[frodus]

Thanks Major!

[madmike8]

Yeah, I wish someone had a good circuit board for this... even the files so, we could order some...

[madmike8]

Doh, double post sorry...

[rwaudio]

Originally Posted by madmike8

Doh, double post sorry...

I'm actually working on one. 12 un-cased Cell log 8's that can be used to monitor up to 96 cells, with alarm outputs connected to relays that form a NO or NC loop depending on how you want it to work. Cell logs plug into connectors on the PCB and if you used one or more logging versions they could be removed easily to download the data. Along with relays on the most negative wire since you can basically turn them off (and remove parasitic load) by disconnecting the ground wire.

[madmike8]

Originally Posted by rwaudio

I'm actually working on one. 12 un-cased Cell log 8's that can be used to monitor up to 96 cells, with alarm outputs connected to relays that form a NO or NC loop depending on how you want it to work. Cell logs plug into connectors on the PCB and if you used one or more logging versions they could be removed easily to download the data. Along with relays on the most negative wire since you can basically turn them off (and remove parasitic load) by disconnecting the ground wire.

Sign me up...

[major]

Originally Posted by rwaudio

I'm actually working on one. 12 un-cased Cell log 8's that can be used to monitor up to 96 cells, with alarm outputs connected to relays that form a NO or NC loop depending on how you want it to work. Cell logs plug into connectors on the PCB and if you used one or more logging versions they could be removed easily to download the data. Along with relays on the most negative wire since you can basically turn them off (and remove parasitic load) by disconnecting the ground wire.

Kool I'm interested. Any thoughts to making the board modular? I have different applications where I need 2, 4, 6 or 12 of the little buggers for the installation in particular.

On the data side of the gizmos, has anybody opto isolated the USB to computer connect so you can monitor multiple cellloggers (or even a single) without blowing sh!t up? Or download without disconnecting the unit from the battery. They aren't perfect devices, but pretty nice for $29