Old BMS Hardware Thread

Threads relating to the BMS system begun by Peter Perkins

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Re: BMS Hardware

Postby retepsnikrep » Sat Jun 19, 2010 5:23 pm

I would lke to start a list of hardware features for bms master board v3. Please quote this post and add your stuff at the bottom of the post. I'll start it off. The board will have all the features of V2 in addition to the below list.

1) Picbasic pro based 16F886 Master Chip with icsp
2) Picbasic pro based 12F683 Watchdog chip with icsp
3) Tellymate Video chip 38x25 Display with icsp
4) I2C Eeprom chip 64kbyte

5) Auto power off option once charging complete. BMS powers down after charge end. Save aux battery power. Possibly power BMS from main pack? Once BMS has turned itself off can't restart without operator input.

6) Two seperate charging relay outputs to control a home made two stage charger using 48v open frame power supplies.

7) 19200 baud in/out ports/feature for the home made controller interface. Greg

8) Possible delayed charge start to allow use of off peak electricity. Not sure hiw that will work with option 5

9) Remote display tx port

10) ?
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.

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Re: BMS Hardware

Postby GregsGarage » Sat Jun 19, 2010 6:44 pm

If you look back to page 17, I have a diagram for a auto power down of the master after charging has finished. This uses the auxilliary contacts on the zivan charger which when the charging finishes the contacts open and this cuts power to the master. Or if the master switches off the charger relay, this will also cause the auxiliary contacts to switch as well, also cutting power to the BMS. It just requires the ignition to be switched on to start the charging, but you have to remember to switch it off or none of it will work. Still you aren't likely to leave the keys in the ignition while the car is charging, so shouldn't be a problem. Still a DIY battery charger does appeal. Maybe bring back the controller relay output that we used to have, I think on version 1 of the master.

The delayed charge idea is nice, how about replacing the watchdog chip with some sort of real time clock chip that can also do the watchdog functions. I don't know much about them, but something must exist that will do this.

I don't like the idea of powering the master from the traction pack. It means that you then need an isolated supply which seems an unnecessary expense when your ev already has an isolated supply. By using the vehicles 12v supply you don't have to worry about what voltage the traction pack is, after all this system could be used on 36 volt or 360 volt systems. This means different isolated supplies depending on the voltage of the traction pack.
Greg Fordyce

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http://www.evalbum.com/4191

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Re: BMS Hardware

Postby retepsnikrep » Sun Jun 20, 2010 3:14 pm

I agree BMS powered by 12v supply is better.

My BMS is not wired via the ignition at all, it is totally independant and has seperate on/off switch allowing it to run when car is off to control charging. The zivan relay contacts may be a good idea and perhaps we can just use the contacts via the bms interlocks so it can detect when the zivan has turned off.

I also think a simple press to make button which allows a transistor switch to be activated which powers the bms, the transistor switch is then fed/kept alive by the bms which can cut the drive to the transistor when reqd killing it's own power supply.

I agree a RTC may be a good idea there are a few used with picaxe etc that we can use with pbpro http://www.rev-ed.co.uk/docs/DS1307.pdf this can be on the same bus as the I2C temp sensors which saves pic pins. The more I2C stuff the better.

The I2C tempsensor serial numbers may be able to be stored several places.

1) In the master pic eeprom. But if you upgrade the software you would have to modify it to incorporate the temp sensor serial number data each time.

2) In the eeprom chip, this is then available even if master program updated.

3) In the RTC SRAM as above

Some other thoughts I had about Master Board V3. Some of these are Insight specific.

An ODBII connection so that data from the car can be displayed on BMS screen.

A BCM Interceptor (This is an RS485 interface specifically for the Honda Insight)

Return the last slave bus in the strings data to the Master, this gives us an easy check to see if the commands have been received correctly. So we have a loop. Out of Master to first slave, passed along slaves until out of last one and back into Master.
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.

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Re: BMS Hardware

Postby GregsGarage » Sun Jun 20, 2010 6:08 pm

The RTC ideas sound good.

retepsnikrep wrote:Some other thoughts I had about Master Board V3. Some of these are Insight specific.

An ODBII connection so that data from the car can be displayed on BMS screen.

A BCM Interceptor (This is an RS485 interface specifically for the Honda Insight)

Return the last slave bus in the strings data to the Master, this gives us an easy check to see if the commands have been received correctly. So we have a loop. Out of Master to first slave, passed along slaves until out of last one and back into Master.


The OBD connection could be the same port I am using for my controller. Eventually I would like to be able to read the full data stream from the controller on the BMS display if required. So really we need the same things, just have to come up with a hardware design that fits both of us. If we can do that it should fit most people. The RS485 could be useful and its very similar to the can bus used on cars, so again we should try and come up with a hardware design that could accommodate either protocols. I don't have any use for RS485 or CAN, one of the reasins I chose the Matiz, but for newer conversions it could be a benifit.

Another thought is are we going to stick with the 16F886 or chose a different pic for version 3? Maybe something with multiple hardware comm ports might make things a bit easier.
Greg Fordyce

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Re: BMS Hardware

Postby retepsnikrep » Sun Jun 20, 2010 7:42 pm

I think we need to stick with the pic we know for now, as at least we/I have a chance of working out something if it doesnt work. If it worked on the picaxe it will work on the pic mentality. There are a number of pin compatible 28 pin pics with more than one usart so we may just be able to drop one in later. V3 is of course just a stepping stone to V4 :wink:

I'll need to concentrate on getting the pbpro software working on V2 for now.
I will store the temp sensor data once gathered in the eeprom chip for now.

Just looking at the pinout and it might be possible to hack the RTC clock chip into the eeprom socket on the V2 board.
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.

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Re: Old BMS Hardware Thread

Postby martinwinlow » Thu Jun 24, 2010 7:29 pm

Hi Peter & Others,

A couple more questions...
Current Sensors... is it possible to use one of these... http://www.tamura-ss.co.jp/en/electroni ... /l01z.html ? Only it has but 3 connections:- Out Gnd 5V. How do they (even a 4 terminal one) connect correctly (Gnd and +5V obvious - others not so)?

Next, not getting anything out of the watchdog but I note the earlier comment about floating inputs and will try again.

How many of the peripherals need to be attached to the Master PCB for it to function normally? Dash butttons and lights?

Regards, Martin.
Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk

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Re: Old BMS Hardware Thread

Postby retepsnikrep » Fri Jun 25, 2010 4:23 am

Martin

I think there was a suggested higher current sensor some while back. I've no idea if the one you have picked would work.

It may well do but is it bi-directional? Does the output float at 2.5v at 0A that's what you need.

As you mention power and GND are obvious the other two connections are for the different sensor types.

You should only need one of the other connections anyway. Remember I use Allegro current sensors -100 to +100A.

Pin 2 is for sensors that require an offset voltage.

Pin 3 is for sensors that float at 2.5V at 0A.

Re Watchdog

http://www.solarvan.co.uk/bms/Watchdog1 ... 10_V02.txt

http://www.solarvan.co.uk/bms/Watchdog1 ... 10_V02.hex

Alarm should sound after about 65 seconds.

This works OK tested 230610

You need the buttons, & temp sensiors connected as a minimum. The slaves connected as well also helps.

Obviously if things are missing like slaves, temp sensors etc then you will get continious error reports from the Master.

I assume you have succesfully programmed your new picaxe chip?

Do not load the plain pic variant software into your picaxe or it will be wiped. Use only the picaxe editor software and the 3.5mm socket for programming the Master at present.

This is the latest picaxe master software it is untested at present.

http://www.solarvan.co.uk/bms/MASTER_8M ... UD_I2C.txt

I'll confirm it works later today hopefully when my spare picaxes arrives!
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.

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Re: Old BMS Hardware Thread

Postby martinwinlow » Sat Jun 26, 2010 9:53 pm

Peter,

Re the dash buttons/LEDs - I've had a look thru the threads and can't find any info on what they all do exactly.

I found the schematic for them ... BMSKeyMatrixLeds.jpg (?) So...

J1/Pin 1 - +5V
J1/Pin 2 - D4 - Watchdog LED - Tells you watchdog is working by flashing (at what rate?)
J1/Pin 3 - D3 - Pulse LED - Tells you Master is working? How?
J1/Pin 4 - D2 - Dash LED - Doesn't do anything yet?
J1/Pin 5 - D1 - Dash LED - Ditto
J1/Pin 6 - Switch Common rail(?) What do all these switches do?
J1/Pin 7 - Master Reset Switch(?) Resets whole caboodle?
J1/Pin 8 - Gnd

Regards, martin
Regards, Martin Winlow
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www.winlow.co.uk

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Re: Old BMS Hardware Thread

Postby martinwinlow » Sat Jun 26, 2010 11:02 pm

Peter,

JP1 - Master Reset Enable on the Master PCB - is this supposed to be shorted for normal operation or open?

WRT... 'because without an active master chip plugged in, the input to the watchdog pin floats and detects static and stray emi as pulses reseting the watchdog timer'... can I confirm that the input pin is 4? And that it needs to be 'pulled down' to gnd with a 1k resistor?

I take it that the dash buttons and leds do not need to be installed to test the Watchdog on its own? And the temp sensors? Both of them?

Sorry for all the daft questions.

Regards, Martin
Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk

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Re: Old BMS Hardware Thread

Postby martinwinlow » Sun Jun 27, 2010 12:31 am

Peter,

For bench testing the system, I thought about using 3 x AA rechargeable cells (in series, obviously) to simulate one lithium cell and then rig 2 or more of these to the same number of slaves. Can you see any issues with this?

Will I have to remove the PICs from the unused slaves to avoid errors etc?

Connecting the 16 slaves PCBs to the master... I assume Master PCB 'Master Bus', J11 connects to Slave PCB 'Master Data Bus', Conn3 and the other end of the SlavePCB 'Master Data Bus', Conn 4, connects to the Conn3 of the next slave board and so on?

Further, the Master PCB 'Slave Bus', J8 connects to the Slave PCB 'Slave Data Bus In', Conn1 and the Slave PCB 'Slave Data Bus Out', Conn2 daisy chains to the next Slave PCB 'Slave Data Bus In', Conn1 etc...? Will a simple twisted pair of 1/4 of a bit of Cat5 cable do for these connections?

Lastly, the Slave to cell connections... We already discussed fusing these with a 1A, suitably rated, in-line fuse and I gather each slave connects across the cell it is monitoring with adjacent cells sharing the connection thus saving a wired connection per cell?

Again, apologies for all the questions. I'll put it all on my blog once I have digested your replies to all the above - and no doubt there will be one or 2 follow-up questions!

Regards, MW.
Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk


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