Converting a screwdriver to Li-ion without BMS

Many craftsmen have a cordless screwdriver in their service. Over time, the battery degrades and holds a charge less and less. Battery wear greatly affects battery life. Constant recharging doesn't help. In this situation, “repacking” the battery with the same elements helps. The most commonly used elements in screwdriver batteries are the “SC” size type. But the most valuable thing a master has is repairing things with his own hands.

Let's remake a screwdriver with a 14.4 volt battery. Screwdrivers often use a motor for a wide range of supply voltage. So in this case, you can use only three Li-ion cells of the 18650 format. I will not use control boards. The discharge of elements will be visible in operation. As soon as the self-tapping screw does not tighten, for example, it’s time to put it on charge.

Converting a screwdriver to Li-ion without a BMS board

First, let's disassemble our battery. There are 12 elements inside it. 10 pieces in one row and 2 in the second row. A contact group is welded to the second row of elements.We leave a couple of elements with a contact group, and dispose of the rest.

Now you need to solder the wires for further work. The contacts turned out to be made of a material that cannot be tinned, so we soldered the wires to the elements. Minus to the body of the element, and plus directly to the positive patch. The old elements act as a support and do not participate in the work.

I will use lithium-ion batteries of the 18650 format. The elements are used. High-current elements are needed for modification. I “changed” my elements into heat-shrink from Sanyo, the old one was pretty shabby. I checked the residual capacity Imax.

We connect the batteries in series and solder the head elements. The battery is almost ready.

Now let's ensure comfortable charging. You need to install a four-pin connector. I used a connector from an old motherboard for the number of pins I needed. I took the mating part from an old computer power supply.

Cut a hole for the connector. Fill the connector with epoxy glue or super glue with soda. We also solder the wires.

Solder the wires to the elements. Wire from the first contact of the connector to the battery positive. A wire from the second contact of the connector to the plus of the second element, which is also the minus of the first element, and so on. Since I will be charging with a “smart” charger, I need to make a balancing wire.

As a connector for connecting to the charger, I will use the wire from the computer's power supply. The wire through which the floppy drive was powered. We cut off all the keys from the connector and it fits perfectly into the charger. It unsolders easily. Red wire to the first contact of the battery connector. Black wire to the second pin of the battery connector, etc.

We connect to the charger and do not forget about the power wires. Our wiring is a balancing one. We set the balance on the charger and wait for a full charge.

In this simple way you can modify a shooter battery for your home.

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Comments (20)
  1. poor collective farm
    #1 poor collective farm Guests May 10, 2018 07:34
    6
    ahaha incredibly simple. collective farm!
  2. Guest ANDREY
    #2 Guest ANDREY Guests 10 May 2018 14:00
    5
    WITHOUT PROTECTION, THE BATTERY CAN VERY EASILY FAILURE.
    1. popvovka
      #3 popvovka Guests 10 May 2018 18:05
      2
      Tell me, without protection from what?
  3. Guest Fedor
    #4 Guest Fedor Guests 10 May 2018 16:18
    0
    What kind of current do they give out?
    1. popvovka
      #5 popvovka Guests 11 May 2018 13:42
      0
      About 25 amps I think.
  4. Builder
    #6 Builder Guests 10 May 2018 18:58
    3
    Without protection against discharge current - if the current consumption is higher than that which the battery can supply, the latter may simply fail! I agree with the commentator, the collective farm is a collective farm! Well, if you are lucky with the discharge currents, you can easily just drop the battery to zero and not restore it.
    1. popvovka
      #7 popvovka Guests 11 May 2018 13:41
      2
      You can’t set it to zero, you need to be careful and not press the button until you lose power.
    2. Guest Victor
      #8 Guest Victor Guests 11 May 2018 14:19
      2
      You've probably never mocked these elements. She is surprisingly tenacious.
  5. Zayas
    #9 Zayas Guests 10 May 2018 20:40
    3
    The author doesn’t even seem to know what the protection board is used for in lithium-ion or lithium polymer batteries, without this board the battery becomes explosive and fire hazardous (when charging and excessive load on the screwdriver), it’s not for nothing that screwdrivers have Nickel-cadmium batteries installed! DON'T DO THIS EVER PEOPLE!!!
    1. popvovka
      #10 popvovka Guests 11 May 2018 13:50
      4
      The standard board in batteries is not in this situation.
      BMS from China is also not reliable. It has been tested more than once, experiments show. If you use low current ones, they are dangerous. Hypover is immediately applied.
      Nickel-cadmium has a memory effect. Although it is capable of delivering large currents.
      Repacking is not a problem at all, since I work with a “point” and repack several batteries a day (cadmium, hydrite, lithium).
      This method is applicable for home. There is no need to press the button into a frenzy. The battery converted using this method has paid off. We covered two ceilings with plaster; no heat was generated. There has not been an explosion and there will not be one if you follow basic operating precautions.
    2. Guest Victor
      #11 Guest Victor Guests 11 May 2018 14:17
      0
      A friend of mine did this on laptops back in 2010, and they still work for him. It only charges one at a time and you have to open it every time.
  6. astravit
    #12 astravit Guests 11 May 2018 09:27
    1
    Instructive article
  7. Guest Alex
    #13 Guest Alex Guests 15 May 2018 20:53
    0
    Nickel-cadmium, by the way, also explodes. Recently the 18-volt battery died, now I’m using one battery, I’m thinking of switching to a lithium-ion battery.
    1. popvovka
      #14 popvovka Guests 16 May 2018 23:30
      0
      As long as I’ve been working with them, they’ve never failed. But they squealed, yes.
  8. Rudik
    #15 Rudik Guests 17 May 2018 09:35
    0
    If you indulge yourself, it’s an option. But from the point of view of economic and practical considerations it is not interesting. For example, repackaging this 2Ah, 1t.r. battery with new batteries, what the author suggests, will cost at least 3.5t.r. with a bms board of 4 tr... and such a charger is not practical at a construction site.
    1. Guest Victor
      #16 Guest Victor Guests 17 May 2018 10:35
      0
      Maybe 1000 rubles on trash. 12 elements with work for 1000 rubles. Rubbish no less. On the market, new junk costs 1000 rubles and will last for a couple of months. Before you speak, estimate the price and what kind of quality there is for that kind of money. Such elements, I asked at a regular radio store, cost about 400 rubles each. So don't be Andersen.
  9. Guest Andrey
    #17 Guest Andrey Guests May 18, 2018 00:07
    0
    Why bother with nonsense? I ordered new ones from Ali for 2000 thousand mil amp hour and that’s it.
    1. popvovka
      #18 popvovka Guests 18 May 2018 21:01
      1
      Damn it))
      All the best things are made with your own hands.
      A person ordered from Ali, but they didn’t work very well. I decided to make it simpler.
    2. Yuri
      #19 Yuri Guests 22 October 2018 10:35
      2
      2000 thousand mil amp hour = 2000 amp/hour. This is a diesel battery, cool!
      1. popvovka
        #20 popvovka Guests 3 February 2019 18:12
        3
        What? 2000mAh-2Ah, which diesel one?