Low cost BMS

[harlequin2]

If anyone wants to build some of these BMS modules, drop me a PM and I'll send you the pcb files and the software.
I'm presently using a terminal program in my laptop (running a script) to do the polling and that proves that it all works OK.
Once the master is finished, it will provide a dedicated lcd and alarm outputs, but if you don't mind craning to look at a laptop on the seat and a bit of mental arithmetic, its quite usable!

[ianbartie]

jackbauer
I used Omron G5N-1A miniature PCB relays. They can switch 3A@30VDC & the coil draws only 16.7mA - next to nothing.
I got them from a guy in Hong Kong for about $1.50 each.

[harlequin2]

Fairly cheap for a relay.
I don't see the need for one though. My board draws less than a milliamp and I have no problem with leaving it powered up continuously which gives you 24 hour monitoring for a parts cost per cell of around $US4.

[harlequin2]

Here's a picture of my prototype board connected to a TS40 cell. Its a combination of SMDs and TH parts but the production version will be all SMD with the parts mounted on the top side. I've used 1205 parts to make assembly easy and if you've never tried a surface mount board, this is the one to cut your teeth on! Large parts, plenty of space, you can hand solder it without any trouble.
My pcbs should be here pretty soon and I'll build a whole heap for the car, plus a few over.
The pcbs from China cost .85c each, plus initial tooling and freight makes my first 100 come out at about $1.65 each. All the other parts add another $3.30 per board, so its still under $5. Not bad if you have to make a hundred or two.

[harlequin2]

Originally Posted by harlequin2

Here's a picture of my prototype board connected to a TS40 cell. Its a combination of SMDs and TH parts but the production version will be all SMD with the parts mounted on the top side. I've used 1205 parts to make assembly easy and if you've never tried a surface mount board, this is the one to cut your teeth on! Large parts, plenty of space, you can hand solder it without any trouble.
My pcbs should be here pretty soon and I'll build a whole heap for the car, plus a few over.
The pcbs from China cost .85c each, plus initial tooling and freight makes my first 100 come out at about $1.65 each. All the other parts add another $3.30 per board, so its still under $5. Not bad if you have to make a hundred or two.

Forgot the picture!

[Simy]

Very nice! I may just take your idea and re program the brain to do what I want, but I'm not sure yet... I am still learning how to use the PIC

[harlequin2]

Since there doesn't seem to be much interest in this, I am going on holiday for a month! Be back lat August and I might then publish the rest of the details - if anyone is actually interested. (-

[ianbartie]

Well, I am certainly interested for sure.
Just have a heap of other things on my plate at the moment too, like most of us.
If you wouldn't mind, send me a copy of the files so I can have a bit of a play around with it (in my copious spare time)

[harlequin2]

Originally Posted by ianbartie

Well, I am certainly interested for sure.
Just have a heap of other things on my plate at the moment too, like most of us.
If you wouldn't mind, send me a copy of the files so I can have a bit of a play around with it (in my copious spare time)

I'll put all the files up here when I get back home. Can't do it now because Iam on holiday in France and didn't bring the computer with allthe files with me. This is just a wee Netbook. Sorry I can't do it sooner!
Bright side is that the master should be finished by then.

[ianbartie]

No problem. Have a good holiday.
Look forward to seeing all the info.