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Battery Voltages

Posted: Tue Nov 13, 2007 5:21 pm
by Graham Hudson
Good Evening to you all. This is my first technical posting and I wondered if you could help me. I have been experimenting with getting information out of the RS232 Port on my g-Wiz. I have been using HyperTerminal which is in Windows XP. A section of the readings I got out are pasted below. I can recognize the eight battery voltages and the total pack voltage, but does anyone know what all the other figures mean?


Posted: Fri Nov 16, 2007 3:39 pm
by anachrocomputer
Just wondering what state the vehicle was in when you took that log of the serial data. Was it charging? Or discharging (i.e. running)? Or idle? Thing is, I can see some negative numbers there, and that reminds me of Nikki's BMS on the City-El where current is negative or positive according to charge or discharge.

It's great to see actual data from a G-Wiz, too! Reminds me a bit (if you squint) of NMEA data from a GPS.

Posted: Fri Nov 16, 2007 5:42 pm
by Graham Hudson
The vehicle had been used in the morning for about 5 miles and had subsequently finished re-charging. The readings were taken about two hours after the charging had finished with the charger cable disconnected and everything turned off.

Posted: Sun Nov 18, 2007 10:05 am
by aminorjourney
Hi there Graham,

Interesting output. Are you able to interact with it at all?

I would concur with you on the battery voltages and the total pack voltage, but I'm a little stumped at the last ones.

I would agree though with John too - I suspect some of those figures will be diagnostic based with perhaps some binary or decimal bit flags. I would also try turning on the heater with the laptop on and data logging enabled (unless there's a safety interlock prohibiting this). The current drain should show up on the diagnostic quite happily.

The final suggestion would be that you actually keep the laptop attached and take the car out for a quick drive (maybe 15 miles or so) and then charge it up. You'll be able to deduce quite a lot there from the data you obtain, especially if you keep track of what's going on during that drive.

My car's BMS (which is the excellent BMS rev B for Lithium Ion cells) can output a heartbeat status every second, giving me individual cell voltages, temperatures, etcetc.

One of the things I'm currently trying to do is to interface an old Zaurus PDA (linux based, so I can put pretty much anything on there I can find a port for) to give me a really comprehensive datalogging ability when I'm driving around.

Shortly after installing the system I was able to use an old Mac in my garage to link to my car and was able to data log quite a bit. I'll have a look to see if I can find any of my output for you to compare with. Obviously it's a different system so I don't know how much use it will be.

Good luck!


P.S. Below is a screenshot from my computer showing the car's BMS. The second column is the battery voltages; the third column (top three rows) is the current drain/charge; and the fourth column is battery temperature (first 7 rows)

If you click on it you'll get the larger version at my Flickr page.


Posted: Sun Nov 18, 2007 10:27 am
by Teslas fag packet
Ey up,

that looks grand nikki, i think if it were me i would write a simple dash board type form displaying the elements i do understand, batt volts and so on. I would also put the values i didn't understand in a big font. you may as well wright a parser now coz you have to do it anyway

also i would get one of these

just in case a keen member of the constabulary takes a dislike to what you are doing also having a blue tooth connection may be of use later

ace project BTW

Posted: Sun Nov 18, 2007 10:40 am
by MalcolmB
Good link Tesla! Looks like I could use that to give a real time dashboard display of info from my Alltrax controller on my handlebars. Cool!

Posted: Sun Nov 18, 2007 10:49 am
by Teslas fag packet
Ey up Malc,

Thanks, and I'm glad to see you ARE COMING TO THE LEEDS GET TOGETHER.

POSTED HERE ... .php?t=636


i found them when i built my OBD scan tool for clearing fault codes and getting real time info out of my Prius.


Posted: Sun Nov 18, 2007 10:51 am
by aminorjourney
You know, I was contemplating the bluetooth dongle as I'm getting sick and tired of switching the RS232 connections out every time I want to interface with the thing. In daily operation I just have a simple bar-graph showing me remaining AH as a 'fuel gauge'. Of course, when I need to program the BMS I have to switch that for a null modem.

Anyway - back to the G-Wiz thing. How old is the car? Are you thinking of changing out the batteries for something more fun? ;)

Posted: Sun Nov 18, 2007 1:15 pm
by Graham Hudson
Hi Nikki
The cars 18 months old, and until the warranty runs out in 6 months time I am not intending to change anything. I would seriously like to get rid of the lead/acids when they finally pack up but as with everything it depends on the cost. I like your idea of connecting up the laptop and turning on the heater, and/or taking the car for a run - the only problem I foresee will be the mountain of information that will come out. Do you know if there is a setting to limit this output in "Terminal"

tesla's battery pack

Posted: Wed Apr 08, 2009 1:09 pm
by phil shepherdson
[looking at that battery pack: is it dc or ac motor youre running?
if the former the connecting wires surely need to be thicker than what i can see especially regarding the length to the engine at the front?