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When replacing battery in a pack

Discussion in 'General Electronics Discussion' started by mrel, Dec 2, 2019 at 1:12 AM.

  1. mrel


    Jul 2, 2008

    (1) Most cordless tools use the 18650 battery in there battery pack.

    12 volts battery pack have three 18650 battery in pack when replacing the battery ,do person buy battery with out circuits protection in the battery.

    Do cordless tools battery have protection build in for each individual battery in the pack ?

    Don't know what kind battery to get with circuit protection build in the battery or no circuit protection.

    (2) when looking at e Bay on the 18650 battery ,there so many different ampere hour listed for the 18650 battery ,is there way testing to find how true the ampere hour list on the battery.

  2. Bluejets


    Oct 5, 2014
    Show which one you are trying to refit.
    It is normal for replacement assemblies to be available, therefore negating the need to "attack" the old casings.
    Usually cheaper than one can buy the individual cells.
    As with many batteries but more-so with 18650, a lot of cheap knock offs out there that are not worth a cracker.
  3. dave9


    Mar 5, 2017
    The pack will either have all the protection on a separate PCB in it, or a portion and the rest is in the tool itself.

    You do not need and should not use protected cells nor try to add your own PCB for that. Reuse the one already in the battery and/or tool.

    You should buy major brand cells rated for high current. There are many tool battery reviews on youtube where they tear down the battery to show what cells were used as examples of what you could buy, but when buying only a few cells at a time as a consumer, it may be no more expensive to buy the ready made OEM battery pack.

    There are exceptions, mostly professional grade tools may charge a premium for their battery packs. Buy individual cells (or packs too) from a trusted seller as there are counterfeit major brand batteries out there.

    Better standalone battery chargers (for individual 18650 cells before you put them in the pack, not the tool battery charger) can do a discharge test to tell you the true capacity, at least under the cahrger's test drain rate. Cordless tool use tends to drain batteries much faster than that so the realized capacity in use will be lower, but it helps a lot to get batteries rated for higher current. If you get factory fresh major brand cells you should not have to worry about the capacity being as labeled.
    davenn likes this.
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