BMS System

[mattcarr]

I have been trying to establish a comm link to the C1 Ev'ie BMS system as it has got a 9 pin serial connection. I have used both a normal serial cable and a null cable as well. I have gone through as many variances of port configurations but not managed to get a link up to receive data.

Does anyone know anything about the BMS system on these cars? I would like to get the data out of this system if it is possible..

Cheers

Matt

[retepsnikrep]

What is supposed to plug into the port?

Is there any info on the port at all anywhere?

Is it really a serial port or just a handy 9 pin connector?

If you can't get any info on it you really are struggling.

I suppose a scope on some of the pins to see if there is a data stream emerging or varying voltages etc would be a start.

[GregsGarage]

I don't have any info on these, but an oscilloscope would tell you if any pins are transmitting data. Of course it may not transmit anything by default, but might need to receive some commands before transmitting anything. You might want to look at the 16 pin OBDII conector. If the car has one, it will be transmitting a live data stream.

[mattcarr]

Thanks for the replys. The person I got the car from told me that a when he called the conversion company out a technition connected up a laptop to the port to check the BMS out and monitor the batteries. It might well be waiting for a transmit command before it sends anything. I dont have an oscilloscope but I will try my volt meter to see if anything is there.

[retepsnikrep]

You might want to look at the 16 pin OBDII conector. If the car has one, it will be transmitting a live data stream.

RU Sure it transmits by default? Not on my cars it doesn't you have to request data using pids and a scantool.

http://en.wikipedia.org/wiki/OBD-II_PIDs

[GregsGarage]

RU Sure it transmits by default?

No, I guess what I should have said is that the OBDII plug would be the most likely place to find data.

[mattcarr]

I used to connect up hyperterminal to my G-Wiz and that was always transmitting over the serial port. You just had to match the connection settings on the PC to get the data stream. This serial connection does trace back to the BMS box. Now the previous owner said a technition connected it to a laptop - that makes me think they used a standard comm port connection type. Normally these type of devices stream data out - but this may well be waiting for a transmit command. I checked the pins with my volt meter and it did jump around a bit but did not settle on register any voltage readings.

[ChrisB]

I suspect there wont be any data BMS'wise coming from the ODB port, it looks like it will be all on the 9pin serial connection.

I doubt its anything special and just an off the shelf BMS, find out who makes it and I suspect you'll be there

ChrisB

[mattcarr]

Well, I have had my BMS replaced by ECCplc and my car is in good working order again. The chap in the workshop was very helpful and gave me plenty of information on the cars, as well as the BMS. The BMS lets the charger run at full power until the pack gets to 102 volts - thats 4.08 volts per cell, it then throttles back the charge rate and lets it run at reduced power until the first battery hits 4.35 volts. It will then terminate the charge until the pack drops back to 102 volts, then it will start charging again at reduced power again until a battery hits 4.35 volts. I got to watch this cycle happening on a laptop that they had connected to my car and it is interesting to see the batteries get much closer in voltage as this charging cycle continues to happen. All the while the BMS is bleeding off 1amp from the cells with the highest voltage in the pack to keep them as close as possible to the rest.

I did get one word of warning that I may have a cell in my car battery pack that is slightly weaker than the rest of them as when they were road testing it the BMS reduced the drive power. I was told that the car was at about 46% soc and he was driving flat out up a hill drawing about 200+amps and the charger recorded a cell triggering a low voltage warning of 2.6 volts, this triggers the BMS to reduce the power the controller can draw until the voltage goes back above 2.6 volts. I was told the car was surging gently as the BMS did this until he got to the top of the hill and the load on the batteries was reduced. I know that the cold weather has not helped as the cold does affect the battery to have a bigger voltage sag in the car than in the warmer weather. One thing for me to watch out for in this cold weather.

I had a mooch around the workshop as there was lots of things out. They have got the complete electrical setup of the car on a bench, Batteries, charger, controller, and a motor hooked up to what appears to be a big loading motor. I did grab some pictures - with permission - and once I have them off my phone I will post them here.

They had a converted smart car in the garage that has got the same innards as the C1's except that it is a 24 cell version and not 25 cells. I had been told that this car does not have a BMS in it so it does not get much use.

I was told that they made around 150 cars before citroen put a stop to supplying them more cars. They made a few versions of the C1 car, including one that had an extra 7 cells in it making it a 32 cell version. The cost to upgrade my car - 3.5k and this would give about an extra 15 miles range, but it would also offer alot more power has the car would have a higher nominal voltage pack in it. I may well onsider this option, if they still offer it when the time comes to renew my battery.

I am just pleased to get my car back in a state where I can now leave it plugged in safe in the knowledge that the BMS is doing it's job.

We have used the car loads since having it back and we have now rolled past the 9000 mile mark.

[GregsGarage]

Thanks for posting the update, glad the car is working well. I was surprised at the voltages they where charging to, seemed a bit high but they must be a Lipo cell and not Lifepo4.