Tester Battery | Ford Escort Owners Association (FEOA)
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Tester Battery

Discussion in 'Electrical' started by novanutcase, Nov 6, 2020.

  1. novanutcase

    novanutcase FEOA Member

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    One of the issues I tend to run into when I'm at the junkyard is testing electrical parts. I don't want to have to lug around a car battery. How much power do I need to have to be able to run car electronics? I'd like to find a portable small form factor battery that I can carry around with me to be able to test electronics at a reasonable price.

    Would a 9v block battery and some alligator clips work?

    Suggestions?

    John
  2. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    A 9 volt will check injectors, and if alkaline, a fuel pump. A plain (carbon zinc, heavy duty etc.) will not run the fuel pump.

    I have a 12 volt and a 14.4volt battery from a cordless Dewalt tool that work great to check pumps etc. You obviously have to make leads for it. I have an alligator clip on one of the leads.

    I have used an 18 volt battery to free up a fuel pump in an old car that was sitting for years. I touched the leads to the pump wiring harness one way then the other repeatedly until the pump started to twitch, then groan, then spin freely.
    That pump lasted years afterwards.
  3. novanutcase

    novanutcase FEOA Member

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    AHA! I didn't think about that. I have a DeWalt 18v battery I think is still good.

    Thanks!

    John
  4. denisond3

    denisond3 Moderator Staff Member

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    I see small 12 volt lead-acid batteries at hardware stores; ones about half the size of a carton of cigarettes. They might weigh a pound or two, and would have a lot more umpfh than a 9V battery would. I have had them work for 4 or 5 years before they get too sulfated from sitting around. I used to use them when checking out the operation of a salvaged car radio I was going to install.
    The 18 volt DeWalt kind of battery would also be good - with the small risk of the 18 volts burning out 12 volt bulbs in a car. Mine are at least 5 years old, and still seem to work the drill very well for the same amount of time after charging. Being Li-Ion they might have some kind of an internal fuse to prevent disaster if the little contacts saw too much load.

    Thanks for the idea of using the 18 volt battery to try freeing up a fuel pump. I have an 86 Comanche whose fuel pump isnt working (the vehicle 'sits' for long periods), and its not convenient to get the pump out for testing.....but the leads come up to an underhood relay.
    zzyzzx and novanutcase like this.
  5. novanutcase

    novanutcase FEOA Member

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    Great ideas also! I like the lead acid battery idea since, as you pointed out, the 18v may overvolt the electronics.

    Got any links to the battery? I was thinking even one of those cell phone batteries and cut off one of the ends on a USB cable and solder on some alligator clips but I think the wire gauge would be too small to pass the required voltage needed,

    John
  6. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    zzyzzx likes this.
  7. denisond3

    denisond3 Moderator Staff Member

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    Do an eaby search for "battery 12 volt amp hours" to see a selection of them.
  8. marclar

    marclar Administrator Staff Member

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    do you have a 12v dewalt or milwaukee tool? can use a batt from one of them
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  9. novanutcase

    novanutcase FEOA Member

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  10. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    18 volts would be hard on most things, but that's what I used to free up the stuck fuel pump.

    Of course under load and if it hasn't just been charged, the 18V battery voltage might be a little less than 18 volts, and a running car can easily have 14 volts. So they aren't that far apart.

    Probably a 14.4 volt battery would be ideal for testing.
  11. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    18 volts would be hard on most things, but that's what I used to free up the stuck fuel pump.

    Of course under load and if it hasn't just been charged, the 18V battery voltage might be a little less than 18 volts, and a running car can easily have 14 volts. So they aren't that far apart.

    Probably a 14.4 volt battery would be ideal for testing.
  12. denisond3

    denisond3 Moderator Staff Member

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    That is the kind I used to use - was very handy for lots of small electronics products.
  13. zzyzzx

    zzyzzx FEOA Member

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    Don't know about Lithium battery packs, but have rebuilt a few Nicad battery packs. The individual cells on old ones are often shot, so on an old 18V battery pack that's unusable for a tool is going to be perfectly good for testing 12V stuff once at least one cell has gone bad.

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