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Thread: Scangauge II - how does it find the battery charge?

  1. #1
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    Arrow Scangauge II - how does it find the battery charge?

    Hi there

    I'm writing a windows mobile program to show diagnostics info using the OBDKey bluetooth dongle. Most of the sensors I can get values for, tried it on two types of car now.

    For my car, an MG ZS 180, I know that Scangauge II can show the battery charge level, but I'm not able to find the correct PID myself. I've done plenty of googling about but not found anything yet.

    Does anyone know what the command sequence is that Scangauge uses to obtain the battery charge?

    Thanks

    Simon

  2. #2
    North of the land of Hey Huns
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    It's likely using the ATRV command, which reads the input voltage as the ELM chip see's it, it's not actually talking to the ECU to get that value

  3. #3
    Variable Bitrate
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    You can find some info here: http://en.wikipedia.org/wiki/OBD-II_PIDs
    However, this in incomplete and out of date. All info can be found if you buy a copy of J1979, see: http://engineers.ihs.com/document/ab...QIACAAAAAAAAAA
    Control module voltage: pid 0x42

  4. #4
    VENDOR - ScanTool Vitaliy's Avatar
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    p2psmurf is right, although "Battery Voltage" and "ECU Voltage" are theoretically not the same, they are for most purposes, and that is how ScanGauge is determining the battery voltage.

    When you issue 01 42, you will get a 16-bit value. Multiply it by 1 millivolt to get the actual voltage.

    If you want to see exactly what ScanGauge is sending on OBD-II, you can use a Y-splitter and the ATMA (monitor all) command on the OBDKey to observe the communication.

    I not 100% sure whether OBDKey supports the ATMA command, as it is not based on the ELM327, but I think it does (it's been a while since I played with it).

    Vitaliy
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
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  5. #5
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    The ATRV command does return 12.0v but it remains constant even when the engine is running, unless my alternator has packed in :-o

    I don't actually have a Scangauge, but I've been told that the voltage it shows is different engine off and engine on.

    Sending a 0140 shows that the PID $42 isn't supported by my ecu, so I can't get it from the Control Module Voltage either.

    Anyway, my windows mobile dashboard program looks pretty sweet so far!
    Attached Images Attached Images  

  6. #6
    VENDOR - ScanTool Vitaliy's Avatar
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    Sonicmule, it sounds like OBDKey is just faking ATRV. There is no way the battery voltage can remain constant at exactly 12V. You might want to give ElmScan 5 Bluetooth a try:

    http://store.mp3car.com/category_s/152.htm

    I can guarantee that ATRV will work properly.

    Vitaliy
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  7. #7
    VENDOR - ScanTool Vitaliy's Avatar
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    Quote Originally Posted by sonicmule View Post
    Anyway, my windows mobile dashboard program looks pretty sweet so far!
    It does. What are your plans for it?
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  8. #8
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    Thanks for your help Vitaliy, I will give the makers of OBDKey a shout and see what they say.

    My app allows you to design your own custom gauges and add them to different screens which you can cycle through. If I can get it looking like Dashdaq, that will be cool.

    Hopefully I'll be releasing it soon for a small fee / donation

  9. #9
    Variable Bitrate quantum's Avatar
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    That looks sweet sonicmule!

    Will your app also send info / work with a PC vs a WM device?

    I was thinking about having something similar in my car (OBDII - Cadillac). Only, I would LOVE to have gauges like this: http://blog.everythingflex.com/2008/...uge-component/

    My goal would be to use a USB OBDII tool (Elm, OBDPros, etc), hook it up to a dedicated PC, and then display the info on my 3.5" LCD VGA.

    Since the LCD also has a touch screen, I thought I could have a simple skin with one gauge on each screen, and when touched, it would cycle to the next gauge. Maybe 10-12 gauges in all.

    I am not sure the OBD software packages that are out there have this capability. Most of the ones I have seen have complete gauge clusters, and on a 3.5" screen, it would be way too small to read a cluster.

    Is this possible with your setup, or does anyone know a different / better way to accomplish this? I am open to ideas.

    Thanks in advance!

  10. #10
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    Hi Quantum

    I like that gauge, thats sex on a stick.

    Once I've got my windows mobile version running I will be looking at developing it for normal windows with more bells and whistles stuck in it. You can't do too much with a 200Mhz processor.

    I've had my little app running on a window's ce device with 1024x768 screen and that's a nice size for a cluster. The screen is configurable so you can have 1 gauge on there if you need it.

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