How to Repair a Cordless Screwdriver Battery at Home

The main element of almost all categories of portable power tools is a battery. At the same time, this is the most expensive part. For example, a battery of average characteristics of a screwdriver costs 60-70% of the total. Therefore, every home craftsman or professional craftsman should know how to repair the batteries for a screwdriver on their own. And save money and give the instrument a second life.

Varieties of batteries for a screwdriver

Before proceeding with the repair, it is necessary to make a diagnosis, and for this, find out what types of batteries are used in screwdrivers. Such knowledge will help to quickly determine the type of power source, respectively, to choose the right approach.

Nickel cadmium batteries

How to Repair a Cordless Screwdriver Battery at Home

Nickel-cadmium battery is a popular power source for screwdrivers of various capacities. Its main advantage is its low price, which is why such batteries are widely used: from hand tools to electric cars carrying large loads. An interesting fact is that nickel-cadmium power sources are installed even in trolleybuses.

  • When used correctly, they have a long service life and a large number of charge / discharge cycles.
  • May be in storage mode for a long time. It is important to know that nickel-cadmium batteries can only be stored discharged.
  • Low ambient temperatures do not affect longevity.
  • Available at their pricing.
  • If used improperly, the self-discharge current increases.
  • It is not recommended to open batteries. nickel and cadmium are toxic and very harmful to the human body elements.

Nickel Metal Hydride Batteries

  • Large capacity. Such power sources can last 20% longer in one cycle than nickel-cadmium batteries.
  • Long service life. With proper handling. at least 300 charge / discharge cycles.
  • Do not require a complete discharge.
  • Recovery of nickel-metal hydride power sources is not possible, only replacement.
  • High pricing policy.
  • Immunity to low ambient temperatures.

The nickel metal hydride element, which can be very important for some users, is environmentally friendly. But still, one should not forget about the correct disposal of spent power sources.

Lithium ion batteries

Replacing the batteries in a screwdriver, if they are lithium-ion type, occurs within a few minutes. But such power supplies as nickel-metal hydride batteries are not repairable.

  • The largest number of charge / discharge cycles among other batteries.
  • High capacity.
  • Lighter weight, respectively, greater convenience when handling a power tool.
  • High pricing policy. It is not always important to buy a new lithium-ion battery. it is more profitable to purchase a complete power tool.
  • If stored improperly and without additional charge, they quickly become unusable.

Tool List

Repair or diagnostics of the battery of a screwdriver is impossible without a specific tool and measuring instruments. To restore the battery, it is not necessary to buy expensive tools, budget manufacturers are quite suitable.

The list of tools required to repair the battery of a screwdriver:

  • Multimeter. A measuring device that allows you to determine direct and alternating voltage, resistance, current, or ring the circuit for an open. expensive models are able to measure the capacity of the elements, but they will not be useful to the home master.
  • Flat and figured screwdrivers. An indispensable tool that will help out more than once in the future.
  • Montersky knife with interchangeable blades.
  • Soldering iron. A power of 40 watts will be enough. powerful models are more expensive, and if improperly handled, they can damage the element.
  • Tin and solder. Inexpensive supplies.

Consumables, for example, insulating tape or a heat shrink tube, household glue, small pieces of wire, will also be useful.

Diagnosing a faulty battery

Before you repair a screwdriver battery at home, you need to find out the cause of its failure. Correct diagnosis is 80% of the work done. And this process is not always simple and clear.

Diagnosing battery malfunctions involves identifying one or more cans that are out of order. The simultaneous failure of all batteries is nonsense that occurs once a century.

Fault Detection Sequence:

  • Fully charge the battery pack of the screwdriver. A special charging socket is always included with a portable power tool. In which it is necessary to install the removed battery and give several hours for a full charge. The end of the charge cycle is a lit green indicator on the case.

Video: How to Repair a Cordless Screwdriver Battery at Home

  • Remove the battery cover. There are no non-separable cases: some manufacturers make bolt fasteners, others. glue. It’s easier with bolts. just unscrew them and remove the cover. The glued surface can be carefully cut with a construction knife.
  • Conduct a visual inspection. In the event of failure, the battery jar usually swells up. this is clearly visible with the naked eye. The cause of the low capacity may be a burnt wire or a jumper between the elements.
  • Measure the voltage at each bank. Before starting measurements, the multimeter should be switched on in the “Constant voltage” mode and touch the probes of the terminals of each element. It is not necessary to solder each element.
  • Using small wires, connect a simple automotive lamp for 12 V or 24 V to the power source of the screwdriver (depending on the rated voltage of the battery of the screwdriver). Leave the lamp on for 30-40 seconds.
  • Disconnect the car lamp from the battery and re-measure the potential difference of each element.
  • Identify the element with the maximum drop in capacity and replace it.
  • Reassemble the battery in the reverse order.

Repair or diagnostics of batteries for a screwdriver can be done by yourself without any difficulties. This is clearly seen from the above sequence. You only need to have a tool, a minimum amount of knowledge, free time and the desire to do something with your own hands.

Nickel Cadmium Battery Recovery

Repair of the battery of a screwdriver can be considered budgetary only when the batteries are not disposed of but restored. To restore the batteries nickel-cadmium type, you should know the features of their operation. For example, when the electrolyte dries, the only way for such batteries is to go to a recycling station.

How to restore a nickel-cadmium battery yourself:

  • Disassemble the battery, solder and charge each jar. In the general battery, it will not be possible to charge all the cells normally. certain current losses will still be present.
  • Apply voltage of 3.6 V to each bank for no more than 3-5 seconds. To do this, you can use regulated power sources: laboratory transformers or car chargers.
  • Measure the voltage at the terminals of each jar. If all the elements show a voltage of 1.2-1.4 V. this means that the "flashing" of nickel-cadmium batteries was successful. If the voltage is low or absent, the battery is damaged or there is no electrolyte in it.

If after several cycles the nickel-cadmium battery does not want to charge, then the only way out is to replace it. It will still be cheaper than buying a new battery.

Is distilled water recovery true or fiction?

Many craftsmen who are able to restore power tools claim that dried up power supplies cannot be “reincarnated”. Others say that you can restore the batteries, you need only distilled water, a tool and 30-40 minutes of free time.

Sequence of battery recovery with distilled water:

  • Using a thin drill and drill, make a small hole in the top of the battery jar. If you drill the middle of the element or the lower part, you can damage the power source. It will be impossible to restore it later.
  • Using a syringe, pour distilled water into the battery to the maximum.
  • Leave the battery in a clean and warm place for 1-2 days, do not close the hole.
  • Combine the elements with distilled water in one battery.
  • Put the battery on charge until the capacity is fully restored. After charging, check the voltage at each bank and add distilled water if necessary.
  • After checking, close the holes with a glue gun. It is strictly forbidden to solder holes. this can damage the battery cell.
  • Install the battery back into the case, close the lid and recharge.

Easy recovery: replace multiple items

If operations with distilled water and the “flashing” of nickel-cadmium batteries require time and dexterity, then to replace your used cells you only need a multimeter, a soldering iron and new battery banks.

Before replacing, it is necessary to diagnose the battery and how to do it correctly is described above. The battery consists of individual elements that need to be soldered. For soldering, low-power soldering irons are used, otherwise high temperatures can damage power sources. Low voltage components should be set aside or marked.

Advice! If possible, it is better to use a soldering station with power control or spot welding.

After identifying faulty power supplies, they simply need to be replaced with new ones that are re-soldered into the common battery. The cost of individual cans is much lower than the entire assembly assembly, so there will be savings. After all the elements are collected in the battery, it is necessary to carry out several charge / discharge cycles of the battery.

Complete replacement and erasing of the “memory” of batteries

There is a little secret to extending the life of new power supplies. To do this, remove the factory settings from the cans that are set in several charge / discharge cycles. The operation to extend the durability should only be on new elements, and in the future they should be charged correctly.

A new battery jar is discharged to a voltage of 1 V. It is important to monitor this parameter, since below one volt the battery may become unusable, after which its restoration will be impossible. For a discharge, it is best to use an adjustable load at which a current of 1 A.

After a complete discharge, all elements must be recharged using the rated current and voltage indicators. After a full charge, you can solder the power sources into the battery and install it on a screwdriver.

Self-tuning battery for lithium-ion banks

A lithium power supply has many advantages:

  • Less weight.
  • Reduced charge time.
  • The lack of factory "memory".

Therefore, some craftsmen are trying to buy an inexpensive screwdriver with a nickel-cadmium battery and remake it for lithium batteries. It should be clarified right away that lithium-ion batteries are much more expensive than all other power supplies and their disadvantages.

  • Calculate the required number of lithium cans for the battery. You can pick up more power and thus reduce the number of elements.
  • Use the jumpers to connect all the batteries into a single battery.
  • Solder the battery to the controller board, designed for the working current of the screwdriver.
  • Disassemble the screwdriver battery and remove all nickel-cadmium batteries.
  • Solder together the output contacts of the controller board and the terminals of the battery case. Fully assemble the housing.

Keep in mind that after replacing the power sources, you may need a new charge unit. Otherwise, the old power simply will not be enough to restore the full capacity of the battery.


From the article, you learned how to repair a battery for a screwdriver with a small number of tools and measuring instruments.