Arduino BMS Shield using TI BQ76PL536A (Update 9/16)

[grindz145]

Did you end up populating the balance resistors? That would be REALLY helpful

 

[matterrr]

I haven't gotten the boards back yet - they estimated that they will be shipped September 15th. I haven't placed the balance resistors - they wouldn't fit on the Uno board, but it's a possibility for the future Mega board.

In the meantime, I have ordered some equipment to build these, and I'm working on the software side with the old boards.

Thanks for the feedback and look for some more updates soon. Feel free to discuss and add suggestions.

 

[grindz145]

Excellent. Sorry to nag on that front. It's just the one missing piece that I've been too lazy to implement myself Otherwise the board is still very exciting.

 

[matterrr]

Hey everyone,

Just got the PCBs back from OSH Park and they look great. Here are some pictures:

http://imgur.com/a/TdqGv#6KqZs40

Tonight I will be ordering the parts I need and trying to make a solder stencil. Wish me luck!

 

[dmwahl]

Tonight I will be ordering the parts I need and trying to make a solder stencil. Wish me luck!

Boards are looking good, nice work. Solder stencils aren't bad once you get the hang of it. I make mine out of aluminum cans and they work great. Only tip I would share is to use a timer so your etch times are consistent, it's kind of tough to tell if you over or under do it and having the time helps a lot.

 

[matterrr]

Thanks! I finished the solder stencil and I think it turned out well:

I used a Silhouette Portrait craft cutter, which I got for $80 on Craigslist, and a custom script I found online - it converts paste gerbers to special cut files. All you need is a few mylar overhead transparencies ($20 for 100) and you're good to go. I think it will be cheaper in the long run than some other options - it costs $25 - $30 per mylar stencil if you order through Pololu.

 

[dmwahl]

Nice, that stencil looks great. Curious, did you undersize the stencil openings relative to pad size? I had trouble with bridging on the TI chip since I forgot to do that.

 

[matterrr]

I shrunk the cream layer by 2 mil, so the openings are slightly smaller than the pads.

 

[kfong]

Nice, I didn't think it was possible to cut such fine detail without a laser. Where did you find the script file? Did you do just one cut pass? I have a similar machine I would like to try it on.

 

[matterrr]

I used the tutorial found here:

http://adamfeuer.com/notes/2013/08/...-solder-paste-stencils-using-gerber2graphtec/

I used the settings below with two passes, and a blade setting of 2:

--speed 1,1
--force 8,15

The reason it is so precise is because the script separates the X and Y cuts, so instead of drawing a rectangle, it will draw all the horizontal lines and then all the vertical lines. This way, the momentum of the cutting head doesn't cause rounded or sloppy corners.

 

[ShreddinPB]

This looks great! I am still excited, and I learned something new.. stencil cutter, never even heard of one

 

[Alan B]

Nice Project, and good info on the stencil cutting.

 

[techmind]

Hey everyone,

Just got the PCBs back from OSH Park and they look great. Here are some pictures:

http://imgur.com/a/TdqGv#6KqZs40

Tonight I will be ordering the parts I need and trying to make a solder stencil. Wish me luck!

This is a really great project

I am very interested in getting hands on one of your pcb, as i also working with a bms for arduino. Can i buy a pcb from you? Is your project open source?

thanks

 

[jumpjack]

Looks vary good, I pulled an Arduino mega (atmega2560) out of my drawer and thought it would do nicely.
Then found this thread, looks like it'll save me a lot of work
Edit: Though I em looking at the Atmel ATA6870 as it's a cheaper chip and requires less external components.

Did you succeed with your project?
I just discovered this chip, and as far as I can understand, it requires no components at all to just read cells values: is this correct? I'd like to build just a logger for a 20 cells battery pack.

 

[dmwahl]

I think he's no longer checking the thread, I'm working on a similar project (see signature link) but it's not complete yet. Will be 12-24S and include the option for balancing as well as monitoring.