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by dillond666
Sat Aug 11, 2012 5:37 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

I got my first delivery of components from Farnell. The 0805 package looks miniscule when you see it! I had a little trial run soldering 0805 resistors to a bit of stripboard, it's actually piss easy :D I gave the board "pads" a little wipe from the flux pen first and then put a little spo...
by dillond666
Tue Aug 07, 2012 9:32 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

I've modified the silkscreen to start at GND and let the numbers represent the +ve cell terminals. I suppose it does make a little more sense :) Sent the files off to Iteadstudio, cheaper than PCB Cart but still ended up 3 and a half times the headline price :x Really hope I haven't messed this up o...
by dillond666
Mon Aug 06, 2012 8:12 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

Hopefully you're missing something :wink: The cell numbers represent the connection to the negative terminal of the cell hence 48 and 48+ at the other end. I've added some ground planes on the bottom layer, one for each group of 12 cells and one for the MCU bit. Board is 160 x 160. I did get the tex...
by dillond666
Sun Aug 05, 2012 6:36 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

Nearly there! Just a little more worrying, checking and double checking.
I feel the scope for cock ups on this board are immense.
My cells are on the boat from China though so I'd better get a move on :shock:
by dillond666
Sat Aug 04, 2012 3:24 pm
Forum: BMS thread
Topic: LTC6802 based 12 cell slave.
Replies: 75
Views: 82568

Re: LTC6802 based 12 cell slave.

Nice and tidy work Greg, I'm salivating :lol: . What width did you make the traces going to the LTC6802? I'm using 0.2mm but I've never done them as narrow before and I'm flapping a little about it. Are you hand soldering? Are your caps and resistors etc 0805 packages? Hope you've bought a flux pen!...
by dillond666
Sun Jun 17, 2012 10:08 am
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

Spotted a few errors, Error on startup/shutdown circuit on left hand MAX11080 chip. Changed the alarm output to a switched relay, I think this will be less troublesome. Put in a link trace between the MAX11080 chip connectors and reduced three of them from 13 to 12 pin, this should help eliminate wi...
by dillond666
Sat Jun 16, 2012 7:57 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

I found a newer revision of the datasheet which had clearer information. :) I have linked to my schematic. Most component values have yet to be filled in. The functionality is barebones. The MCU listens to the heartbeat of the BMS and if it is absent the alarm output will be enabled. Hi and Low volt...
by dillond666
Mon Jun 11, 2012 5:14 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

Hijacking in a good way :lol: I'll be looking in on your thread and I hope you'll have a look at mine. More options are always better :wink: I have hit a snag as I do my schematic. If I use the shutdown pin, it also shuts down the vreg power (Vaa)so how do I wake the bugger up again? It's probably d...
by dillond666
Sat Jun 09, 2012 10:10 am
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

Doesn't this mean that when you pull the master bus low, you also pull the PIC power supply low? Maybe you could utilise the (unused?) fourth wire on the bus as the master bus signal wire and leave wire one to be the common pic supply. On your schematic it seems as if the supply decoupling (C18, 19 ...
by dillond666
Thu Jun 07, 2012 11:32 pm
Forum: BMS thread
Topic: Lithium Battery Monitor 48 cell
Replies: 57
Views: 66324

Re: Lithium Battery Monitor 48 cell

I had looked at the Linear part too because it has the option to balance but balked at the £22 cost :shock: The Maxim part seems cheap and does the basics. I'm using Kicad too and think it's pretty good. Greg, check out the isolator I'm talking about, it might solve your 4mA to opto problem, Farnell...

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