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Thread: Battery removal question

  1. #11
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    Quote Originally Posted by thepalmtrees View Post
    I used to disconnect my battery to charge it without any problems----I don't bother these days. Glyn
    Depends on the charger. Older chargers in particular can damage the cars electronics. Personally I would on charge a battery in situ if the charger explicitly says its designed to do so.

    In addition, always leave the bonnet (well, boot on XJ and many BMWs) open, as the gas the battery gives off is hydrogen, and gets "interesting" if it is ignited by sparks...
    2010 XJ Portfolio running on lorry fuel. I know, Jag Diesel is just wrong!

  2. #12
    Senior Member Ice Cube's Avatar
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    The battery should be vented by a pipe that goes down to the underside of the boot. It doesn't vent into the boot. Check that it's in place.
    2008 XJR + sun roof + soft leather + ACC + retrofit: burr walnut interior trim
    ++++++++++++++++++++++++++++++++++++++++++++++++++
    2007 X-Type 3.0 SP Auto + retrofit: walnut dash & gear knob + rear sill protectors + mudflaps + Al powerwash crucifers + memory powerfolds

    "Life's too short for touchscreens - give me lots of nice buttons to press"

  3. #13
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    Quote Originally Posted by Ice Cube View Post
    The battery should be vented by a pipe that goes down to the underside of the boot. It doesn't vent into the boot. Check that it's in place.
    Indeed, but when charging, you may get more hydrogen build up than that simple vent pipe is really good for dispersing, hence keeping boot open.
    2010 XJ Portfolio running on lorry fuel. I know, Jag Diesel is just wrong!

  4. #14
    Senior Member Ice Cube's Avatar
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    Hate to get too deep into chemistry, but, provided the battery is in normal condition, no gases should be released during the charging process. This may appear surprising, but hydrogen is only given off at the negative plate and oxygen at the positive plate when the charging rate exceeds the availability of lead sulphate or the rate at which it can be broken down into its constituent parts. This occurs at the end of the charging process, and is manifested by the charging current failing to reduce and the charge voltage across the terminals failing to increase any further. At this point gassing occurs with a liberation of both hydrogen and oxygen, and the plates will eventually begin to break down. It's the point where you need to turn the charger off. Meanwhile, the vent pipe is quite capable of dealing with the situation, but I would also keep the boot separately vented in case the vent pipe is not an airtight fit into the battery.
    2008 XJR + sun roof + soft leather + ACC + retrofit: burr walnut interior trim
    ++++++++++++++++++++++++++++++++++++++++++++++++++
    2007 X-Type 3.0 SP Auto + retrofit: walnut dash & gear knob + rear sill protectors + mudflaps + Al powerwash crucifers + memory powerfolds

    "Life's too short for touchscreens - give me lots of nice buttons to press"

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