How to repair the battery for an electric screwdriver: fault detection and recovery
How to repair the battery for an electric screwdriver. this is a frequently asked question among home masters, because this device is in the arsenal of almost every owner. The main advantages of the tool, functioning from the battery, consider compactness, the ability to work with it even at height (due to the lack of power wires). Nevertheless, the battery of this device can fail, and it is not profitable to buy a new one, because its price sometimes reaches up to 60% of the cost of the tool. Therefore, it is recommended to try to repair the battery. how exactly, we will tell you today.
Despite the variety of models of these tools, the battery in all screwdrivers has a similar appearance. It is a box made of plastic, where there are many compound batteries. They are fastened to each other in a single circuit so that the wires of the “cans” on both sides are shorted to the contacts that provide power to the screwdriver.
All batteries have a primitive structure, which can be sorted out even by an inexperienced technician, little familiar with electrical engineering. In addition to power parts in the box of the unit is often located:
- thermistor. allows you to control the temperature of the cans during charging;
- The thermal switch. automatically opens parts of the circuit if the battery overheats;
- control and monitoring board (only lithium-ion batteries have one).
Changing the cells in the battery screwdriver with their own hands
Hello! Here’s an overview with step-by-step instructions for replacing the cells in a screwdriver battery pack. In the review a little text, a little more photo material, as well as the answer to the question: “What is the capacity of Chinese batteries at 2500 mA/h?”.
Those interested, please come in I have such an inexpensive screwdriver Roteri RCD-14.4, which has been in service for several years, but over time the battery charge has become less and less. Search for a suitable battery in stores led to nothing. So it was decided to order battery cells and replace them myself. Dismantling the battery presented a review of the following: The battery consists of 12 cells SC Ni-Cd. It was decided, ordered, received: To check the performance of all cells, as well as to check the capacity, was used La Crosse RS-700 charger, which I already reviewed here. Because of their size these batteries can not be installed in the charger normally, so to ensure contact with the unit were used AA batteries with duct tape on one end, and to the reviewed battery cells were soldered wires: The charger itself was switched to TEST mode, and so 3 times, that’s what came out of it: So, out of 12 batteries 3 were defective (real capacity about 100 mA/h), the rest had a capacity in the range of 900mAh to 1500 mAh, not 2500 mAh. This is an answer to the question posed in the “topic”. I had to write a complaint to the seller, in response the seller offered to send me four of the same batteries for free. I agreed. The package arrived. This time all 4 batteries turned out to be functional with similar capacity to the others. Let’s proceed to replacement of elements:For tinning of petals flux LTI-120 was used, usual rosin was not tinned. Solder better on the “minus” side of the battery, t.к. The battery case is a “minus” and if there is a violation of the insulation at the soldering point, it will not lead to anything. At the end the whole battery was firmly fastened with scotch tape and set in the case: A test of the screwdriver showed that 600 was not wasted!
10 Min tool repair: Replacing the battery in a Parkside / Lidl electric screwdriver
Hereby I bid farewell, and yes, please don’t be stingy in clicking on “liked the review”, t.к. This is an incentive to write more reviews 🙂
A common method of Ni─Cd battery recovery?
On the subject of Ni─Cd battery recovery there are many articles and videos on the Internet. Most of them are concerned with the recovery of batteries from screwdrivers and other hand-held tools. This is not surprising since such batteries are quite expensive and often hard to find. Basically when recovering nickel─cadmium batteries one method is used, which we will now describe.
The picture below shows a complete screwdriver battery and its contents.
And the following photo shows one battery of this assembly.
In brief, the method of restoration consists of a Ni─Cd battery with a high current in short pulses for a few seconds. And the current should be much higher than the battery capacity (tens of times higher).
How To. Electric screwdriver repair
The method of restoration is suitable for nickel─cadmium batteries. Not to be confused with nickel─metal hydride batteries. It has been tested on roll-on-roll-off models. Basically suitable for batteries of any age and even leaky ones. Of course, the older the battery, the less likely it will be to be repairable. What you will need when carrying out the recovery procedure:
- Another working battery with a strong current. It can be a battery from an uninterruptible power supply, a car battery, etc. п.;
- alligators, pieces of wire. Wire pieces should be about 10 centimeters long and have a cross section of at least 1.5 mm2 ;
- a multimeter to check the voltage;
- Protective equipment (gloves, goggles).
Warning! Do not wear protective equipment. Be sure to wear eye protection and gloves to protect your eyes and hands.
Ideally this should be done on each battery individually (1.2 volts) and not all at once. In this case the recovery procedure will be more efficient and a second battery can be used with less capacity (a standard car battery or a battery from an uninterruptible power supply will be quite enough).
- Find plus and minus of the battery you are going to restore (or of the whole screwdriver, if you are going to restore it);
- Then use a piece of wire and alligators to connect the minuses;
- Then a second piece of wire is attached to one of the plus pins;
- Then the free end of the wire should quickly touch the remaining free positive contact. Here it is important to touch quickly and briefly (2─3 touches per second). This procedure lasts for 3─4 seconds. It is important not to weld the wire at the point of contact.
In general, it is recommended that the wire should not touch the battery lead itself, but first attach an alligator clip or plate to it. And already touch them.
After one cycle of these touches the voltage of the battery to be regenerated is measured. If it does not appear, then do another cycle. After the battery shows voltage, it is placed on charge until its capacity is reached. It will most likely be less than the rating. It is recommended to do some more charge-discharge cycles to train the battery. For details on how to charge Ni-Cd batteries see this link.
After reading the reviews about this method of restoration, it became clear that it gives only a short-term improvement of the battery. The battery really started working, charging, discharging, gaining capacity, but fell into a “coma” for a while. I understand that this is because the source of the problem was not eliminated. The burn-in eliminated the dendrites that caused the microcircuits and made the battery come back to life. But since the composition and volume of the electrolyte is disturbed, everything returned to its original state.
After searching on the internet I found another, more perfect method of Ni─Cd battery recovery. You should also read the material about how to reset the Ni─MH batteries.
Replacing the cans in the battery
How to repair the battery for an electric screwdriver? The easiest way to revive the battery is to replace one of the cans.
Find the defective element with low voltage. To do this you need to use a tester.
Instructions on how to check the battery of an electric screwdriver with a multimeter:
- An ordinary multimeter has two probes. red and black. There are two contacts (plus and minus) at the opposite ends of the can.
- The tester selection lever is set to “constant voltage” mode. If the multimeter has an automatic value selection, this is enough. If there is no sign, you need to put the lever in position “20”.
- The styli are attached to the contact pads and the voltage is measured. The screen shows the real voltage. If there is a “-” sign in front of the numbers, then the probes need to swap with each other.
- Each bank is checked according to this algorithm.
When a broken cell has been found, it is simply unsoldered and replaced. It is necessary to use a powerful soldering iron not to overheat the can.
Types of batteries
According to their design features, a distinction is made between batteries in the form of a slider and a cage.
Slider shaped screwdriver battery
But these are insignificant differences compared to the battery types. Both slider and cage are used in different types of batteries.
There are three types of screwdriver batteries:
Lithium. polymer batteries (Li-Pol) are not made for screwdrivers. Their main applications: smartphones, cell phones, tablets, laptops, radio-controlled devices, electric cars.
Nickel-cadmium batteries are the cheapest, fastest to charge, have more than a thousand charging cycles. Batteries are resistant to low temperatures. But they have a memory effect. That is, you can charge them only when they are fully discharged, otherwise the capacity will drop. They have a high self-discharge current. They are made of toxic materials and are difficult to dispose of. These batteries are the most in demand.
Nickel metal hydride batteries are more expensive, non-toxic, have low memory effect. Self-discharge current is greater than that of nickel-cadmium batteries. The capacity is higher, the charge cycle is more than five hundred. These batteries can not withstand a high rate of discharge. They are less suitable for maximal use of the tool’s power. They must be constantly recharged.
Lithium ion batteries are more expensive, powerful, recharge quickly. They have no memory effect. Low self-discharge current. Battery cell voltages are higher, so there are fewer cells. Therefore dimensions and weight of such batteries are smaller than those of nickel batteries. But they should not be fully discharged, otherwise after some such cycles you have to buy a new one. To improve the quality of lithium-ion batteries, manufacturers install a chip in the battery case or screwdriver that monitors the battery‘s performance. A multi-level, multi-stage protection is formed:
- From high temperatures.
- From complete discharge. These batteries fear complete discharge and cannot recover from a lower permitted level of discharge.
- From short circuits.
- From overcharging, as it may cause an explosion.
- From overload currents.
A control board installed in the battery case is more effective. When the battery is not in use and lying away from the screwdriver, the chip monitors the battery and opens the circuit if there is a problem. The battery is fully protected.
Electrical circuit diagram for converting an electric screwdriver for Li-Ion batteries
Before replacing the batteries in an electric screwdriver, it is advisable to prepare a proper assembly diagram. To avoid failure of any components, the polarity of the connection must be precisely observed.
Important! When making a diagram, it is recommended to mark the positive polarity in red and the negative polarity in blue.
List of necessary tools
The following tools may be needed for repair work:
- Multimeter. This tool is needed for measuring AC and DC voltages.
- Screwdrivers and flathead screwdrivers. Useful for disassembling the body of an electric screwdriver.
- Soldering iron. Inexpensive models with a power of about 40 watts are suitable for repair.
Additional information! Consumables like solder and tin are needed to use the soldering iron.
Finding a problem
Finding the source of the faults that occurred involves the use of several methods:
- Using a multimeter. helps diagnose the condition of the devices put on the charge;
- To use a 12-volt car light bulb with 35 watts of power.
These methods allow you to diagnose the problem without opening the battery. An additional method of testing is considered the release of gas from the devices, with the opening of the housing. The last method restores functionality for a short time.
Causes of complete discharge
Zeroing of elements is connected with the peculiarities of storage:
Important! The problem with new instruments is due to storage violations by the retailer using unheated storage facilities.
Replacing Ni─MH, Li─Ion, Ni─Cd cells in a screwdriver battery
After you have restored the elements, they should be soldered back in. If you decide not to restore but to replace the battery cells, you can search for them in appropriate online stores. Either way they will need to be replaced in the assembly, which means you will have to solder.
First you bite off or unsolder the element from the connection plate. Then rebuild or just replace. Then solder the work cell to the plate to combine it into a daisy chain. It is advised to solder quickly so that the battery insides are not damaged by the heat of the case.
Ideally keep all the connection plates and solder the cells to them. If this does not work, replace them with copper plates with the appropriate cross section. This is important because if the cross section is not the same as the standard one, these places will heat up when charging. The thermistor may trip as a result. It goes without saying that you have to solder the cells in the correct polarity.
If you have a screwdriver with metal hydride batteries, read how to repair Ni─MH batteries.
After reassembling the entire battery you should put it on charge, after which you should measure the voltage of all the cells. After charging it should be about the same for all cells (about 1.3 volts). Then do a battery discharge. You can do this by turning on the screwdriver or you can do it with a light bulb, as shown above. It is advisable to do this procedure once every three months. This is the so-called memory wipe of Ni─Cd batteries. How to properly charge Ni-Cd batteries is explained in detail at the above link. Return