Replacing Nickel Batteries With Lithium In A Screwdriver

Replacing batteries in a screwdriver

Replacing Nickel Batteries With Lithium In A Screwdriver

This article will discuss in detail how batteries are replaced in a screwdriver. The best option would be to remake existing bad nickel cadmium batteries to more modern and reliable.

Replacing the battery in a screwdriver

So, nickel cadmium batteries are bad because they have a memory effect. That is, if the battery is not fully discharged and immediately charged, then it undercharged capacity will be lost. So, over time, the battery capacity will decrease more and more. Accordingly, the screwdriver will work worse and worse, it will be enough for a couple of minutes maximum.

So after hours spent You can get a working screwdriver again. Two branded batteries would cost the owner of a power tool a tidy amount, and it turned out to save, because Chinese elements were bought.

How do I do a screwdriver battery repair?

  • Design Features
  • Battery Check
  • Measurement under load
  • Checking individual items
  • Resistance Quality Assessment
  • Necessary tools

Screwdriver # 8211 is a necessary and useful tool in the household. When a person gets used to such an instrument, it is difficult to do without it. What to do if a screwdriver fails? I don’t want to go to the workshop if you just need to repair the batteries of a screwdriver!

The scheme of the device cordless screwdriver.

Despite the reliability of modern designs, batteries are often the cause of a tool malfunction. In order to repair the battery of a screwdriver does not bring a lot of difficulties, you need to get acquainted with the design, the principles of inspection and repair.

Design Features

The screwdriver’s battery is a direct current source that is produced during electrolysis. Each element has two electrodes (cathode and anode). The electric voltage generated by it is determined by the potential difference between the electrodes (poles). The main characteristic (along with voltage) of the cells and the battery as a whole is capacity. When connecting the elements in series, the voltage of each is added. As a result, the voltage at the output of the battery is defined as the sum of the voltages of all components. The voltage of 12 V is achieved by a battery of 10 cells, each of which has 1.2 V.

Schematic of a lithium screwdriver battery.

Many screwdriver batteries have nickel-cadmium cells. The anode is made of a nickel compound, and the cathode # 8211 is based on cadmium or its compound. A solution of potassium and lithium hydroxides was used as an electrolyte. Nickel-cadmium elements have a high capacity with small sizes and an extended validity period (more than 3000 cycles). Voltage can reach 1.37 V.

Find the use of Nickel-metal hydride elements, which consist of the same anode and cathode of an alloy of Nickel. They are environmentally friendly, but they have a tendency to self-discharge when not in use. Most imported screwdrivers are equipped with lithium-ion and lithium-polymer batteries. They have high values ​​of capacity in a compact design. In both types, the cathode is made of coal, and the anode # 8211 of lithium and cobalt compounds. As electrolytes, a salt composition saturated with lithium ions and a liquefied polymer composition, respectively, are used.

Battery Check

A check of the battery of the screwdriver is aimed at clarifying the performance in order to determine the need for repair or identify the cause of the malfunction. Most accurately, the performance of the cells and the battery as a whole can be determined by the capacity, which can be measured by a special tester of the “Coulomb” type. However, this professional device is not available to everyone.

Diagram of a device for checking batteries.

It remains to assess the condition and capacity by indirect indicators, namely by current and voltage at the output terminals, which can be measured directly (by ammeter and voltmeter).

Do you really need to repair a screwdriver because of the battery? This can only be set after fully charged. Already at the stage of charging the battery, you can conduct a preliminary assessment of its condition. To do this, when the charger is turned on, the recovery rate of the current and voltage at the battery output is determined.

Such verification is carried out in the following order. After 30 minutes of charging the cells, the voltage value at the output terminals of the battery is measured. It is normal to reach a value of 13 V. Measurements continue every 30 minutes. If the second measurement shows 13.5 V, and after another 2 hours the voltage reaches 14 V and does not increase anymore, then charging has reached a maximum. The nominal voltage value is 17 V. In this case, you need to think about how to repair the battery of a screwdriver. At the same time, it is too early to draw a final conclusion, since the manifestation of a “memory effect” is possible. This phenomenon is characteristic of NiCd cells and is due to residual processes in partial discharges and charge the battery before.

Similarly, you can assess the state of the battery by the current value. Good elements show a constant increase in current during the first 60 minutes of charging to a value of at least 1 A. Such a process is characteristic of intact cells.

Measurement under load

Screwdriver battery connection diagram.

If there are no obvious manifestations of battery failure during charging, it is too early to talk about its normal operation. It is possible to more accurately determine whether a screwdriver battery repair is needed when carrying out measurements under load. Such tool tests can be performed independently when an artificial load is connected to the battery. Such a load should be about 35-40 watts. As a load, you can use a car lamp for a headlight with a power of 35 W or a spot lamp with a power of 35-40 W for a voltage of 12 V.

To conduct the test, an elementary electrical circuit is assembled in which the elements are discharged to the load. In this case, the current and voltage are measured by appropriate devices. Discharge time # 8211 3-5 minutes. Using the lamp as a load makes it possible to visually assess the state of the battery: if the brightness of the lamp does not change, then the battery capacity is normal. This conclusion, of course, is preliminary. Another thing, if the light dimmed, then this is a clear manifestation of the malfunction of the elements. So, battery repair is required. The result is better clarified by measuring the voltage at the output terminals. After discharging for 5 minutes, the voltage should be within 12-12.4 V (at a nominal value of 12.4 V). If the voltage drops below 12 V, then we can talk about the need for repair.

Checking individual items

If preliminary measurements indicate the need to repair the battery of the screwdriver, you should open the tool body and remove the battery. Typically, a battery pack contains 10-12 cells (cans) with a nominal voltage of 12-14 V. Repair the battery of a screwdriver with your own hands # 8211 to find and replace the faulty part.

Table of varieties of the battery.

After removing the battery, inspection is carried out, first of all, of rations. Vibration of the instrument during operation could result in poor contact. Therefore, the first repair of batteries for screwdrivers with their own hands is done by soldering damaged contacts.

If everything is OK with the contacts, then each bank is disconnected in turn, the voltage at the electrodes is measured. The voltage value should not be lower than 1.2 V. When conducting measurements, disconnect all additional elements, in particular, charge control sensors. The measurements are carried out with a DC voltmeter with a scale of up to 1.5-2 V. If the voltage value does not correspond to the nominal value, then the screwdriver’s battery is repaired by replacing the unusable can with a new element of the same rating.

The new can must match the previous one in nominal capacity (the value is indicated on the case).

A situation may arise when all banks show a normal voltage, and a preliminary assessment indicated a malfunction of the screwdriver battery. In this case, you will have to measure the parameters of each can under load. The tests are carried out similarly to the battery tests, but the light from the flashlight will serve as the load.

Resistance Quality Assessment

Repair of the screwdriver battery by replacing the elements should be made if significant self-discharge of the battery without a workload is noticed. Such an assessment is carried out by measuring the voltage at the output terminals every 24 hours for 30 days. For nickel-cadmium cells, self-discharge during this time should not exceed 20%, and for lithium-ion # 8211 no more than 8%.

Necessary tools

To repair the battery of a screwdriver with your own hands, you should have the tools:

Alteration of the screwdriver on lithium batteries.

Alteration of the screwdriver on lithium batteries.

Sobsno once the conversation came, then let it lie down Temko.

I have a dead battery for a 14.4 volt screwdriver

Inside there were 12 cans of nickel batteries.

An idea arose to shove some lithium there and make an uber screwdriver.

Re: Alteration of a screwdriver on lithium batteries.

And I was able to answer my questions

Lithium-ion (notebook) or polymer (flat)?

Where payment cutoff, I ask you to die Accum.

Maybe you should think about brushless and a hobby regulator?

There is a cut-off / protection, for the hobby regulator.

Such a long time charging suggested:

All parameters are set by jumpers. Charging on avr, if you can finish it later.

We integrate the balancer into the battery, PCMPRO:

The question is in the self-discharge of the battery through this balancer. I’m checking it now. I charged the battery and hung the balancer on it. During the night, the charge fell by 0.02 volts

In the first alteration, do not suffer with the optimization of batteries. As the saying goes: when it comes to family honor, the question of money is not appropriate:

Polymer battery dualsky 1300mah 11.1v 30c / 5c

Banks are selected by the manufacturer, 2 or 3 pcs will enter the standard battery case. The capacity will be 2 times higher than the regular one, the mass is less. I disassembled my screwdriver, killed the electromechanical regulator, but there is an operational amplifier there. In general, you can finish the cutoff.