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Tec Mod battery question

Discussion in 'Ask The Veterans' started by _more_, Dec 20, 2012.

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  1. _more_

    _more_ Moved On ECF Veteran

    May 22, 2012
    Here is the link: ********************************************************************************************************************

    3rd one down, TEC MOD - Mechanical Telescopic Mod

    I wonder if it is ok to have my battery like Eric says. I do know the negative end should be with the spring so that is the way I have mine like Eric says. It is just strange to me that it is backwards. Will it be okay/not dangerous. On other bottom switch telescope tube mods the spring is on the bottom where you push it. I get so confused and worry a lot :(

    sorry i can't write very good...

    btw I love this mod :)
  2. Kent C

    Kent C ECF Guru Verified Member ECF Veteran

    Jun 12, 2009
    NW Ohio US
    Eric says:

    You can put the battery in either way but I prefer (and recommend) you put it in with the bottom of the battery facing the spring.

    'Either way' means that there is a reverse polarity protection circuit - good idea these days - so you shouldn't have a problem but just go with his recommendations. 'Bottom of the battery against the spring' is standard.... just odd because the battery is 'upside down'. So no problem....
  3. rolygate

    rolygate Forum Manager Admin Verified Member ECF Veteran

    Supporting member
    Sep 24, 2009
    ECF Towers
    Please read this article in The Library. It explains the various issues.

    The rule of thumb is: never insert a battery in reverse even if it works. It's possible that there may be reasons why a specific APV may be safe with this reverse polarity arrangement though I haven't yet seen one that this would apply to.

    The general principle in electrical engineering is that you don't make the machine casing the positive line, and there are multiple good reasons for this - imagine your fridge wired like that. In an APV you can probably see that since the whole of the battery can (the metal case of the battery) is negative, when the label wears or tears you'll have a direct neg to pos short-circuit that may bypass a fuse. There are no good reasons to design a device like this, only shortcuts and bodge-ups designed to save money.

    It screams at you: designed by someone who doesn't have a clue about engineering and/or who couldn't care less about safety issues. There are too many people like that making lithium cell powered devices pulling several amps used in direct proximity to the face.
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