Lithium Battery Monitor 48 cell

Threads relating to the BMS system begun by Peter Perkins

Moderators: GregsGarage, retepsnikrep

GregsGarage
Posts: 870
Joined: Tue Apr 01, 2008 5:27 pm
Location: Galashiels, Scottish Borders
Contact:

Re: Lithium Battery Monitor 48 cell

Postby GregsGarage » Mon Jun 11, 2012 7:28 pm

See if Maxim did a demo board for the chip. That may have the answer you need in the documentation/schematic for it.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Lithium Battery Monitor 48 cell

Postby dillond666 » Sat Jun 16, 2012 7:57 pm

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 voltage thresholds are set on the pin headers next to the Maxim chips.
The MCU will also switch the charger on and off. MCU knows charger is plugged in because it gets its power on pin 2 of the power connector
and powers an opto on the MCU pin.
http://dillond1.pwp.blueyonder.co.uk/MaximBMS.pdf

Comments?

Derek

Edit : spelling
Last edited by dillond666 on Sat Jun 16, 2012 11:29 pm, edited 1 time in total.

GregsGarage
Posts: 870
Joined: Tue Apr 01, 2008 5:27 pm
Location: Galashiels, Scottish Borders
Contact:

Re: Lithium Battery Monitor 48 cell

Postby GregsGarage » Sat Jun 16, 2012 9:23 pm

The fuses connected to pin 13 will need to be rated at full pack voltage in the case of a open in the pack wiring. Or you can fuse at all the cell connections, right at the cells, which you should do anyway. On my Matiz, I can easily isolate all 4 of my battery packs using a combination of contactors, big red button and removable fuse on a anderson connector. With your system I would have to disconnect the bms from all the cells first before isolating any of my battery boxes. But if you have a single battery box then this is not much of a problem.

Looks good though.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Lithium Battery Monitor 48 cell

Postby dillond666 » Sun Jun 17, 2012 10:08 am

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 wiring errors.

Thinking of a cell connector solution but can't find much other than D connectors :?

revised schematic: http://dillond1.pwp.blueyonder.co.uk/MaximBMS-V0.1.pdf

Derek

GregsGarage
Posts: 870
Joined: Tue Apr 01, 2008 5:27 pm
Location: Galashiels, Scottish Borders
Contact:

Re: Lithium Battery Monitor 48 cell

Postby GregsGarage » Sun Jun 17, 2012 10:50 pm

How about the Mini-fit connectors by Molex and others. Maybe reduce the number of cell connectors to just 2, a male and female so you can't mix them up.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Lithium Battery Monitor 48 cell

Postby dillond666 » Sun Aug 05, 2012 6:36 pm

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:
Attachments
maximpic.png
maximpic.png (49.93 KiB) Viewed 14001 times

User avatar
retepsnikrep
Posts: 1387
Joined: Sat May 26, 2007 4:50 pm
Location: North Yorkshire England
Contact:

Re: Lithium Battery Monitor 48 cell

Postby retepsnikrep » Mon Aug 06, 2012 6:24 pm

That's impressive.

You don't seem to have a GND for cell1 or am i missing something?
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Lithium Battery Monitor 48 cell

Postby dillond666 » Mon Aug 06, 2012 8:12 pm

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 text on the silkscreen back to front on the prog/run jumper though :oops: .Final checks then it'll be beyond my control :shock:

GregsGarage
Posts: 870
Joined: Tue Apr 01, 2008 5:27 pm
Location: Galashiels, Scottish Borders
Contact:

Re: Lithium Battery Monitor 48 cell

Postby GregsGarage » Mon Aug 06, 2012 9:33 pm

dillond666 wrote:The cell numbers represent the connection to the negative terminal of the cell hence 48 and 48+ at the other end.


Interesting numbering scheme, Peter and I have always done it the other way round, label cell 1 neg, cell 1 +, cell 2 +, etc. but there's nothing to say we are doing it right. :lol: Glad to see it coming along.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Lithium Battery Monitor 48 cell

Postby dillond666 » Tue Aug 07, 2012 9:32 pm

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 or It'll be the most expensive beermats I've ever owned :D


Return to “BMS thread”

Who is online

Users browsing this forum: No registered users and 4 guests