Carbon Monoxide alarm mystery

Discussion in 'Tech/Mech General' started by Goforit, Feb 21, 2013.

  1. Goforit

    Goforit Funster

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    I am a relative newcomer to motorhoming (1st van bought July 2012). I have recently come across a problem that has me fooled. My CO detector is repeatedly activated when the van is connected via EHU to the domestic mains supply. This started when I hooked up at the start of winter and started to occasionally run a oil heater during old spells. At first I assumed it was the heater so removed it. The problem persisted so by a process of elimination (including shutting off all gas appliances at both the bottles and isolation valves and replacing the detector) I have now discovered it only occurs when on EHU and the leisure (not vehicle) battery is charging. I have 2 x 100ah batteries in tandem fitted. My control unit display is showing the leisure batteries at "poor" level and less than 11v despite charging, so I assume I have at least one knackered battery. I am resigned to buying 2 new batteries as I read in the forum that once one goes it is better to replace both. What does puzzle me is why is the CO alarm activated when the issue appears to be unrelated to non efficient combustion (unless the battery is cooking). Has anyone else come across this problem or have any ideas?
     
  2. pappajohn

    pappajohn Funster Life Member

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    are you sure it isnt a 'low battery' warning for the co alarm's internal battery.

    or if the alarm is powered from the leisure batteries it could be indicating the same thing if the batteries are really down to 11v.
     
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  3. Goforit

    Goforit Funster

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    Thought of that so fitted a new detector with a new battery and got the same response
     
  4. pappajohn

    pappajohn Funster Life Member

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    then if one battery is well knackered it could be gassing on charge and the detector is picking up the hydrogen gas.
     
  5. FULL TIMER

    FULL TIMER Read Only Funster

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    Some of these alarms also sense other gases could the alarm be picking up the gases from the knacked batteries, try switching the charger off and see if it still happens, also check that the space where your batteries are is vented through the floor etc, and don't go in there with a fag until you know, that gas is mighty explosive.
     
  6. JeanLuc

    JeanLuc Funster

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    I suspect the problem is with one of your batteries. I had exactly the same effect with my CO alarm when one of my original gel batteries failed; they gas when that happens. Be very careful and stop plugging in to EHU with immediate effect; a gassing battery gives off hydrogen and sometimes hydrogen sulphide. The former, as you know, is highly explosive.
    Another thing to be careful of is to ensure that the charger is set to operate with the kind of battery you have fitted. Most have selector switches to suit flooded lead acid or gel: they need different charging regimes. It is possible that an incorrect setting could lead to over-charging.

    When you get your batteries replaced, I would recommend fitting venting tubes to carry any gas to the outside. Although many batteries are described as 'sealed', they can still give off gas when they fail - as they surely will in time.

    p.s. sorry for repetition - I have just noticed that Fulltimer has said much the same as me.
     
    Last edited: Feb 22, 2013
  7. hilldweller

    hilldweller Funster Life Member

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    Once you have new batteries make sure you monitor them well for a day or two with a good voltmeter to make sure your charger is not cooking them.
     
  8. Goforit

    Goforit Funster

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    Thanks all, it is almost certainly being triggered by hydrogen, others beware. I will take on board your advice re venting, voltage check etc. Lucky I packed up smoking 8 years ago!!
    What surprises me is that the vehicle user manual etc. has a large section on the fitted CO monitor and what you should do, but gives no warning on alternative substance triggers, and neither do I recall seeing it on monitor instructions. I had to work out for myself what was happening, and rely on funsters to help:thumb: me.
     
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  9. Don Quixote

    Don Quixote Funster

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    Well you learn something every day here. Thought I would go round to our MH and check so what ours did!!! I sprayed some "underarm" deodorant and would you believe it the alarm went mad.... then got old battery that I know gives off smell when put on a charger and again alarm went mad.
    Thing is we have a switch on ours to allow it to be on/off and we always had it to off. Think now I will have it switched on from now on. Of course I thought it only detected Carbon Monoxide.................

    John
     
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