LED battery monitor

Discussion in 'Technical' started by gobs, Nov 14, 2009.

  1. Hi all,

    Several times we spoke here about batteries... The best and the worst it happened...
    As BMW F650GS (single) are known to get some troubles with their lead/acid battery (settled just upon engine head, close to engine oil tank and with not any realy good ventilation: what a hot area just there, and batteries don't like that for sure), I decided to install a "LEDs battery monitor" on my bike.
    Obviously this device doesn't care the level of acid or maintain it in any way instead of you. It "only" gives you in real time the battery state of health it is connected to. Up to you to react in the right way...
    Could be useful for some other BMW models or Honda Africa Twin or some others models/brands renown for their "battery troubles"...
    I found a excellent (IMHO) diagram on the web (thanks to M. Sam from Greece), modified it a little bit and did the job by myself (one IC, one zener diode and a bunch of resistors plus the 4 LEDs), then found some place to add it to the dashboard...
    It's a sort of voltmeter. Not accurate, but explicit for the use expected. Something like: warning, passable, good, alert!

    Here are the two parts: the unit and the four 3mm LEDs display ready to install on the bike:


    Not so big to be easily hiden somewhere though a smallest box could be used for the unit... Total cost less than 100 Bahts...
    The fifth bigger "crystal" LED is a flashing red one that will be connected to a future alarm system I'm building too... Model tested with success yet, but has to be improved a bit...

    So, four coloured LEDs display the efficiency of the charging system (when engine is running) AND/OR the condition of the battery (when engine is not running or stopped) as follows:
    1) Yellow: 10.60 Volts to 12 Volts
    - Engine running: no charge (loosen connexions/cables or problem with altenator)
    - Engine stopped: very bad battery (please, for your comfort, check, charge or change it asap!)
    2) Green ≠1: 12 Volts to 13.40 Volts
    - Engine running: low charge in "normal condition" (check cables and alternator) or heavy load being used (many high power electric devices running at the moment: please be aware about this)
    - Engine stopped: battery in good condition (please enjoy and cherish it!)
    3) Green ≠2: 13.40 Volts to 14.80 Volts
    - Engine running: good charge in "normal use" (happy biker!)
    - Engine stopped: no matter...
    4) Red: 14.80 Volts and up
    - Engine running: alert! (you are toasting the battery), too high charge (usually rec/reg blown), please stop and check/replace the component asap!
    - Engine stopped: no matter...

    So, when riding, in "normal electric condition" we get 3 LEDs glittering: yellow+ green ≠1 + green ≠2. And if engine not running in same "normal electric condition" we get 2 LEDs glittering: yellow + green≠1.
    If not so, see upper...

    The dashboard as it is now on my F650GS:


    On the right hand side in the black area under the clocks, the four coloured LEDs and the future "alarm warning" as a whole...
    On the left hand side, two switches, the left one commanding the "LEDs monitor" on/off, the right one with its small LED ready here for a future use: maybe a manual command for the cooler fan or, through a relay, additional front lamps... don't know yet. But doing the job I did it "fully"...
    To be automatic, the device can be connected to a + running after the "on" key-contact (sidelight on recent bikes for example). For my part, I don't need to have a "Christmas Tree" flashing all along the ride. So I choose to connect the device directly to the battery through a spare harness and fuse I already drew for different uses, and put a switch on its way to only check from time to time...

    I have used the "thing" for some weeks now, and all seems OK with it. Meaning no failing or strange behavior... So I decided to install it a next time on my Fazer 600...

    I don't know if all this is interesting, but as a "technique addict" I wanted to share... if sometime useful...

    Cheers to all,
  2. Nice one Gbs

    I have seen many LT riders has added that to they dash board, i'm also adding that bit i'm looking Sqeer one max 2cm tall and 5cm lenght
  3. Sorry, I forgot to share the diagram...
    Here it is, in its original shape from M. Sam:


    R1: 1.2K
    R2-3-4: 680R
    R5: 15K
    R6: 10K
    R7-8-9-10: 1K
    RV1: 10K trimpot
    D1: Zener diode 5.6V/0.5W
    D2-3-4-5: coloured LEDs
    IC: LM324

    To reach the figures I expected as described previously, I modified it a very little bit, as follows:
    R6: 10K trimpot + one 4.7K resistor in serie
    D1: Zener diode 6.2V/1W
    - the 14V alert is a bit low. Some charging systems can "normally" deliver more than that (14.2V / 14.4V if needed). So no need to see the red alert flashing from time to time...
    - then, a good running charging system will deliver much more than 13V in any case. So the 13.4V I wished to get on the third LED.

    Before install it you have to adjust it with a independant DC power supply with RV1 trimpot (more the R6 10K trimpot I add if used)...

    The link to the original diagram by M. Sam:
    http://users.otenet.gr/~athsam/voltmete ... attery.htm
    Thanks to him.

  4. Hi Marco,

    Sorry I don't understand what you mean by " Sqeer one max 2cm tall and 5cm lenght "... Is it about the box/unit or the display?
    In any case, doing it yourself, you can nearly choose the size you expected...
    Display 2x5 is easily doable with 3mm LEDs.
    About the unit, you can use 1/4W resistors and "play" with the "wiring tracks" to get it in a 2x5 box... I guess it is doable too...

    And yes I heard of many BMW riders adding this thingy to their dashboard... Mmmmmmmh!.. :roll:

  5. Sorry matey

    i noticed that just now,, my "Typo" yes Squeer, display,and i look ready made as there is some but so far not found in thailand

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