Old BMS Hardware Thread

[GregsGarage]

On my last schematic I think I should swap pins 2 and 3 on the pic because pin3 is an analog input which might be useful if checking the state of the load resistor if it is being driven by a pwm signal.

Seperate question, do these optos look suitable, don't know what the difference is other than the price?
http://uk.farnell.com/vishay/tclt1000/optocoupler-smd-transistor-o-p/dp/8310688
http://uk.farnell.com/vishay-semiconductor/tclt1000/optocoupler-transistor-o-p/dp/1469548

[isaac_alaska1]

i don't see any difference between those optos. the downside with both of them is the current transfer ratio (CTR) is really variable, 50-600%. so they could have extremely varying results, depending on which batch you got (like happened to me.)

these might be better:
http://uk.farnell.com/vishay/tclt1009/o ... dp/8310750

CTR is 200-400, like the ones on the board that peter sent. they worked good even with 360 ohm drive resistors, and should work even better with 180 ohm or so.

they're more expensive, but much tighter tolerances.


Also, the speed sensor is working extremely well now. There was an issue with the line that configures the settings for the pin that is being used for the VSS input. One of the bits was set that essentially turned the pin into an oscillator instead of an input. If anyone is having problems with the speed sensor input not working, this is likely the problem. i don't have the line in front of me right now but if anyone wants it i can get it and post the new change.

[retepsnikrep]

Issac please post the osc bit change data that's very important.

[isaac_alaska1]

posting the code changes in the software thread

[GregsGarage]

I've not got much time for the next couple of weeks, but did this last night sitting in Newcastle while my daughter and her friends where at a concert. I've changed some pin assignments again and will breadboard it to check ICSP works when I get time.

EDIT: Just spotted Q1 is connected wrong way round.

[isaac_alaska1]

a few pics of what i've been working on:

on-screen display. changed it up a little bit. there is also a submenu where you can read maximum amps



this is the lid of my battery box



this is the lid, wired to the batteries and connected to the box



this is looking down through the top of the lid, right behind the bms slave boards. there's lexan on top but it's so clear it's hard to see



the fuse block i designed. it should work quite well. holds the nine fuses you can see, plus a main fuse. the main fuse will be either 250 or 400 amp, depending on how easily i can blow the 250 amp one



the box, with all the battery leads, before i zip tied them together and put the lid on top

[retepsnikrep]

Looks cool Issac! Hope it works!!

[isaac_alaska1]

i am hoping the same thing! right now i am trying to figure out how to wire up an "insulation monitoring device" (sometimes known as a "bender" because of the company that makes them). we have two that are really simple to interface with, but sometimes give false signals, and then we have one that is much more complicated and requires a lot of external circuitry, but is supposed to be better. emailing the company to ask their advice haha.

[GregsGarage]

I've not got much time for the next couple of weeks, but did this last night sitting in Newcastle while my daughter and her friends where at a concert. I've changed some pin assignments again and will breadboard it to check ICSP works when I get time.

EDIT: Just spotted Q1 is connected wrong way round.

I've breadboarded the circuit to test the ICSP and it seems to work fine. I can read, write and verify the pic fine. I did do a couple of cheats. I used a 12f683 and also some leds in place of optos, but I am happy that the ICSP works as drawn. I am working on updating the schematic and have fixed Q1. Hopefully have a new schematic by the end of the week, time permiting.

[isaac_alaska1]

not done yet, but most of the hardware is finished for the BMS. now it's all software touch-ups and actually mounting the pieces where they belong, but as-is they have all the correct wires on them and come on when the machine comes on.

http://www.youtube.com/watch?v=p2KCN3Eu ... AAAAAAAAAA