Li-ion battery charger. Charger for Li-ion for free How to make a charger for li ion

Modern electronic devices(type cell phones, laptop computers or tablets) are powered by lithium-ion batteries, which replaced alkaline analogues. Nickel-cadmium and nickel-metal hydride batteries have given way to Li─Ion batteries due to the better technical and consumer qualities of the latter. The available charge in such batteries from the moment of production ranges from four to six percent, after which it begins to decrease with use. During the first 12 months, battery capacity decreases by 10 to 20%.

Original chargers

Chargers for ion batteries are very similar to similar devices for lead-acid batteries, however, their batteries, called “banks” for their external similarity, have a higher voltage, so there are more stringent tolerance requirements (for example, the permissible voltage difference is only 0. 05 c). The most common format of a 18650 ion battery bank is that it has a diameter of 1.8 cm and a height of 6.5 cm.

Just a note. A standard lithium-ion battery requires up to three hours to charge, and the more precise time is determined by its original capacity.

Manufacturers Li- ion batteries It is recommended to use only original chargers for charging, which are guaranteed to provide the required voltage for the battery and will not destroy part of its capacity by overcharging the element and disrupting the chemical system; it is also undesirable to fully charge the battery.

Pay attention! During long-term storage, lithium batteries should optimally have a small (no more than 50%) charge, and it is also necessary to remove them from the units.

If lithium batteries have a protection board, then they are not in danger of being overcharged.

The built-in protection board cuts off excessive voltage (more than 3.7 volts per cell) during charging and turns off the battery if the charge level drops to a minimum, usually 2.4 volts. The charge controller detects the moment when the voltage on the bank reaches 3.7 volts and disconnects the charger from the battery. This essential device also monitors the temperature of the battery to prevent overheating and overcurrent. The protection is based on the DV01-P microcircuit. After the circuit is interrupted by the controller, its restoration is carried out automatically when the parameters are normalized.

On the chip, a red indicator means charge, and green or blue indicates that the battery is charged.

How to properly charge lithium batteries

Well-known manufacturers of li-ion batteries (for example, Sony) use a two- or three-stage charging principle in their chargers, which can significantly extend the battery life.

At the output, the charger has a voltage of five volts, and the current value ranges from 0.5 to 1.0 of the nominal capacity of the battery (for example, for an element with a capacity of 2200 milliamp-hours, the charger current should be from 1.1 amperes.)

At the initial stage, after connecting the charger for lithium batteries, the current value is from 0.2 to 1.0 of the nominal capacity, while the voltage is 4.1 volts (per cell). Under these conditions, the batteries charge in 40 to 50 minutes.

To achieve constant current, the charger circuit must be able to raise the voltage at the battery terminals, at which time the charger for most lithium-ion batteries acts as a conventional voltage regulator.

Important! If charging is needed lithium ion batteries, which have a built-in protection board, then the open circuit voltage should not be more than six to seven volts, otherwise it will deteriorate.

When the voltage reaches 4.2 volts, the battery capacity will be between 70 and 80 percent capacity, which will signal the end of the initial charging phase.

The next stage is carried out in the presence of constant voltage.

Additional information. Some units use a pulse method for faster charging. If the lithium-ion battery has a graphite system, then they must comply with the voltage limit of 4.1 volts per cell. If this parameter is exceeded, the energy density of the battery will increase and trigger oxidation reactions, shortening the life of the battery. IN modern models batteries use special additives that allow you to increase the voltage when connecting a charger for li ion batteries to 4.2 volts plus/minus 0.05 volts.

In simple lithium batteries chargers maintain a voltage level of 3.9 volts, which is a reliable guarantee of long service life for them.

When delivering a current of 1 battery capacity, the time to obtain an optimally charged battery will be from 2 to 3 hours. As soon as the charge becomes full, the voltage reaches the cutoff norm, the current value rapidly drops and remains at the level of a couple of percent of the initial value.

If the charging current is artificially increased, the time of use of the charger to power lithium-ion batteries will hardly decrease. In this case, the voltage initially increases faster, but at the same time the duration of the second stage increases.

Some chargers can fully charge the battery in 60-70 minutes; during such charging, the second stage is eliminated, and the battery can be used after the initial stage (the charging level will also be at 70 percent capacity).

At the third and final charging stage, a compensating charge is carried out. It is not carried out every time, but only once every 3 weeks, when storing (not using) batteries. In battery storage conditions, it is impossible to use jet charging, because in this case lithium metallization occurs. However, short-term recharging with constant voltage current helps to avoid charge losses. Charging stops when the voltage reaches 4.2 volts.

Lithium metallization is dangerous due to the release of oxygen and a sudden increase in pressure, which can lead to ignition and even explosion.

DIY battery charger

Charger for lithium-ion batteries is inexpensive, but if you have a little knowledge of electronics, you can make it yourself. If there is no accurate information about the origin of the battery elements, and there are doubts about the accuracy of the work measuring instruments, you should set the charge threshold in the region from 4.1 to 4.15 volts. This is especially true if the battery does not have a protective board.

To assemble a charger for lithium batteries with your own hands, one simplified circuit is enough, of which there are many freely available on the Internet.

You can use an LED for the indicator charging type, which lights up when the battery charge is significantly reduced, and goes out when discharged to “zero”.

The charger is assembled in the following order:

• a suitable housing is located;
• a five-volt power supply and other circuit parts are mounted (strictly follow the sequence!);
• a pair of brass strips is cut out and attached to the socket holes;
• using a nut, the distance between the contacts and the connected battery is determined;
• A switch is installed to change the polarity (optional).

If the task is to assemble a charger for 18650 batteries with your own hands, then a more complex circuit and more technical skills will be required.

All lithium-ion batteries require recharging from time to time, however, overcharging as well as completely discharging should be avoided. Maintaining the functionality of batteries and maintaining their working capacity for a long time is possible with the help of special chargers. It is advisable to use original chargers, but you can assemble them yourself.

Video

The invention and use of tools with autonomous power sources has become one of the hallmarks of our time. New active components are being developed and introduced to improve the performance of battery assemblies. Unfortunately, batteries cannot work without recharging. And if on devices that have constant access to the power grid, the issue is solved by built-in sources, then for powerful power sources, for example, a screwdriver, separate chargers for lithium batteries are necessary, taking into account the peculiarities various types batteries.

In recent years, products based on lithium-ion active components have been increasingly used. And this is quite understandable, since these power supplies have proven themselves to be very good:

• they have no memory effect;
• Self-discharge has been almost completely eliminated;
• can work at sub-zero temperatures;
• hold the discharge well.
• the number was increased to 700 cycles.

But, each type of battery has its own characteristics. Thus, the lithium-ion component requires the design of elementary batteries with a voltage of 3.6V, which requires some individual features for such products.

Recovery Features

With all the advantages of lithium-ion batteries, they have their drawbacks - this is the possibility of internal short-circuiting of elements during charging overvoltage due to active crystallization of lithium in the active component. There is also a limitation on the minimum voltage value, which makes it impossible for the active component to accept electrons. To eliminate the consequences, the battery is equipped with an internal controller that breaks the circuit of elements with the load when critical values ​​are reached. Such elements are stored best when charged to 50% at +5 - 15 ° C. Another feature of lithium-ion batteries is that the operating time of the battery depends on the time of its manufacture, regardless of whether it has been in use or not, or in other words, it is subject to the “aging effect”, which limits its service life to five years.

Charging lithium-ion batteries

The simplest single cell charging device

In order to understand more complex charging schemes for lithium-ion batteries, let's consider a simple charger for lithium batteries, more precisely for one battery.

The basis of the circuit is control: a TL 431 microcircuit (acts as an adjustable zener diode) and one reverse conduction transistor.
As can be seen from the diagram, the control electrode TL431 is included in the base of the transistor. Setting up the device comes down to the following: you need to set the voltage at the output of the device to 4.2V - this is set by adjusting the zener diode by connecting resistance R4 - R3 with a nominal value of 2.2 kOhm and 3 kOhm to the first leg. This circuit is responsible for adjusting the output voltage, the voltage adjustment is only set once and is stable.

Next, the charge current is regulated, the adjustment is made by resistance R1 (in the diagram with a nominal value of 3 Ohms) if the emitter of the transistor is turned on without resistance, then the input voltage will also be at the charging terminals, that is, it is 5V, which may not meet the requirements.

Also, in this case, the LED will not light up, but it signals the current saturation process. The resistor can be rated from 3 to 8 ohms.
To quickly adjust the load voltage, resistance R3 can be set adjustable (potentiometer). The voltage is adjusted without load, that is, without element resistance, with a nominal value of 4.2 - 4.5V. After reaching the required value, it is enough to measure the resistance value of the variable resistor and replace it with the main part of the required value. If the required value is not available, it can be assembled from several pieces using a parallel or serial connection.

Resistance R4 is designed to open the base of the transistor, its nominal value should be 220 Ohms. As the battery charge increases, the voltage will increase, the control electrode of the transistor base will increase the emitter-collector contact resistance, reducing the charging current.

The transistor can be used KT819, KT817 or KT815, but then you will have to install a radiator for cooling. Also, a radiator will be required if currents exceed 1000mA. In general, this classic charging scheme is the simplest.

Improvement of the charger for lithium li-ion batteries

When it becomes necessary to charge lithium-ion batteries connected from several soldered unit cells, it is best to charge the cells separately using a monitoring circuit that will monitor the charging of each individual battery individually. Without this circuit, a significant deviation in the characteristics of one element in a series-soldered battery will lead to a malfunction of all batteries, and the unit itself will even be dangerous due to its possible overheating or even ignition.

Charger for 12 volt lithium batteries. Balancer device

The term balancing in electrical engineering means a charging mode that controls each separate element participating in the process, not allowing an increase or decrease in voltage less than required level. The need for such solutions arises from the features of assemblies with li-ion. If, due to the internal design, one of the elements charges faster than the others, which is very dangerous for the condition of the remaining elements, and as a result of the entire battery. The circuit design of the balancer is designed in such a way that the circuit elements absorb excess energy, thereby regulating the charging process of an individual cell.

If we compare the principles of charging nickel-cadmium batteries, they differ from lithium-ion batteries, primarily for Ca - Ni, the end of the process is indicated by an increase in the voltage of the polar electrodes and a decrease in the current to 0.01 mA. Also, before charging, this source must be discharged to at least 30% of the original capacity; if this condition is not maintained, a “memory effect” occurs in the battery, which reduces the battery capacity.

With the Li-Ion active component the opposite is true. Completely discharging these cells can lead to irreversible consequences and dramatically reduce the ability to charge. Often, low-quality controllers may not provide control over the level of battery discharge, which can lead to malfunctions of the entire assembly due to one cell.

A way out of the situation may be to use the above discussed scheme on adjustable zener diode TL431. A load of 1000 mA or more can be achieved by installing more powerful transistor. Such cells connected directly to each cell will protect against incorrect charging.

The transistor should be selected based on power. Power is calculated using the formula P = U*I, where U is voltage, I is charging current.

For example, with a charging current of 0.45 A, the transistor must have a power dissipation of at least 3.65 V * 0.45 A = 1.8 W. and this is a large current load for internal transitions, so it is better to install the output transistors in radiators.

Below is an approximate calculation of the values ​​of resistors R1 and R2 on different voltage charge:

22.1k + 33k => 4.16 V

15.1k + 22k => 4.20 V

47.1k + 68k => 4.22 V

27.1k + 39k => 4.23 V

39.1k + 56k => 4.24 V

33k + 47k => 4.25 V

Resistance R3 is the load based on the transistor. Its resistance can be 471 Ohm - 1.1 kOhm.

But, when implementing these circuit solutions, a problem arose: how to charge a separate cell in a battery pack? And such a solution was found. If you look at the contacts on the charging leg, then on the recently produced cases with lithium-ion batteries there are as many contacts as there are individual cells in the battery; naturally, on the charger, each such element is connected to a separate controller circuit.

In terms of cost, such a charger is slightly more expensive than a linear device with two contacts, but it is worth it, especially when you consider that assemblies with high-quality lithium-ion components cost up to half the cost of the product itself.

Pulse charger for lithium li-ion batteries

Lately, many leading manufacturers of self-powered hand tools have been widely advertising fast chargers. For these purposes, pulse converters based on pulse-width modulated signals (PWM) were developed to restore power supplies for screwdrivers based on a PWM generator on a UC3842 chip; a flyback AS-DS converter was assembled with a load on a pulse transformer.

Next, we will consider the operation of the circuit of the most common source (see the attached circuit): mains voltage 220V is supplied to the diode assembly D1-D4, for these purposes any diodes with a power of up to 2A are used. Ripple smoothing occurs on capacitor C1, where a voltage of about 300V is concentrated. This voltage is the power supply for pulse generator with transformer T1 at the output.

Initial startup power integrated circuit A1 enters through resistor R1, after which the pulse generator of the microcircuit is turned on, which outputs them to pin 6. Next, the pulses are supplied to the gate of a powerful field effect transistor VT1 opening it. The drain circuit of the transistor supplies power to the primary winding of the pulse transformer T1. After which the transformer is switched on and the transmission of pulses to the secondary winding begins. The pulses of the secondary winding 7 - 11 after rectification by the VT6 diode are used to stabilize the operation of the A1 microcircuit, which in full generation mode consumes much more current than it receives through the circuit from resistor R1.

In the event of a malfunction of the D6 diodes, the source switches to pulsation mode, alternately starting the transformer and stopping it, while a characteristic pulsating “squeak” is heard; let’s see how the circuit works in this mode.

Power through R1 and capacitor C4 start the chip's oscillator. After launch, for normal operation higher current is required. If D6 malfunctions, no additional power is supplied to the microcircuit and generation stops, then the process is repeated. If diode D6 is working, it immediately turns on the pulse transformer under full load. During normal startup of the generator, a pulse current of 12 - 14V appears on winding 14-18 (at idling 15V). After rectification by diode V7 and smoothing of the pulses by capacitor C7, the pulse current is supplied to the battery terminals.

A current of 100 mA does not harm the active component, but increases the recovery time by 3-4 times, reducing its time from 30 minutes to 1 hour. ( source - magazine online edition Radioconstructor 03-2013)

Fast charger G4-1H RYOBI ONE+ BCL14181H

Pulse device for 18 volt lithium batteries produced by the German company Ryobi, manufactured in the People's Republic of China. The pulse device is suitable for lithium-ion, nickel-cadmium 18V. Designed for normal operation at temperatures from 0 to 50 C. The circuit design provides two power supply modes for voltage and current stabilization. Pulse current supply ensures optimal recharge of each individual battery.

The device is made in an original case made of impact-resistant plastic. Applied forced cooling from the built-in fan, with automatic switching on upon reaching 40° C.

Specifications:

• Minimum charge time 18V at 1.5 A/h - 60 minutes, weight 0.9 kg, dimensions: 210 x 86 x 174 mm. The charging process is indicated by a blue LED; when completed, the red LED lights up. There is a fault diagnosis, which lights up when the assembly is faulty with a separate light on the case.
• Power supply single phase 50Hz. 220V. The length of the network cable is 1.5 meters.

Charging station repair

If it happens that the product has ceased to perform its functions, it is best to contact specialized workshops, but basic faults can be eliminated with your own hands. What to do if the power indicator does not light up, let's look at some simple faults using the station as an example.

This product is designed to operate with 12V, 1.8A lithium-ion batteries. The product is made with a step-down transformer, transforming the reduced AC A four diode bridge circuit is performed. Installed to smooth out pulsation electrolytic capacitor. The indication includes LEDs for mains power, start and end of saturation.

So, if the network indicator does not light up. First of all, you need to check the integrity of the circuit through the power plug primary winding transformer. To do this, you need to test the integrity of the primary winding of the transformer through the pins of the mains power plug with an ohmmeter by touching the probes of the device to the pins of the mains plug; if the circuit shows an open circuit, then you need to inspect the parts inside the housing.

The fuse may break; usually it is a thin wire, stretched in a porcelain or glass case, which burns out when overloaded. But some companies, for example, Interskol, in order to protect the transformer windings from overheating, install a thermal fuse between the turns of the primary winding, the purpose of which, when the temperature reaches 120 - 130 ° C, is to break the power supply circuit of the network and, unfortunately, after the break does not restore.

Usually the fuse is located under the cover paper insulation of the primary winding, after opening which, this part can be easily found. To bring the circuit back into working condition, you can simply solder the ends of the winding into one whole, but you need to remember - the transformer remains without protection from short circuit and it is best to install a regular mains fuse instead of a thermal one.

If the primary winding circuit is intact, the secondary winding and bridge diodes ring. To check the continuity of the diodes, it is better to unsolder one end from the circuit and check the diode with an ohmmeter. When connecting the ends to the terminals of the probes alternately in one direction, the diode should show an open circuit, in the other, a short circuit.

Thus, it is necessary to check all four diodes. And, if, indeed, we got into the circuit, then it is best to immediately change the capacitor, because diodes are usually overloaded due to high electrolyte in the capacitor.

Buy power supplies for a screwdriver

Any hand tool and batteries can be purchased from our website. To do this, you need to go through a simple registration procedure and then follow the simple navigation. Simple site navigation will easily lead you to the tool you need. On the website you can see prices and compare them with competing stores. Any question that arises can be resolved with the help of the manager by calling the specified phone number or leaving the question to the specialist on duty. Come to us and you will not be left without choosing the tool you need.

Batteries play an important role in any mechanism that does not operate from the mains. Rechargeable batteries are quite expensive due to the fact that you need to purchase a charger along with them. IN batteries different combinations of conductor materials and electrolytes are used - lead-acid, nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), lithium-ion polymer (Li-Po).

I use lithium-ion batteries in my projects, so I decided to make my own charger for 18650 lithium batteries rather than buy an expensive one, so let's get started.

Step 1: Video

The video shows the assembly of the charger.
Link to youtube

Step 2: List of Electrical Components

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List of components required to assemble a charger for rechargeable batteries 18650:

• Charger module based on TP4056 chip with battery protection
• Voltage stabilizer 7805, you will need 1 piece
• Capacitor 100 nF, 4 pcs (not needed if there is a 5V power supply)

Step 3: List of Tools

To work you will need the following tools:

• hot knife
• Plastic box 8x7x3 cm (or similar in size)

Now that all the necessary tools and components are prepared for work, let's move on to the TP4056 module.

Step 4: Li-io battery charger module based on TP4056 chip

A little more about this module. There are two versions of these modules on the market: with and without battery protection.

The circuit board containing the protection circuit monitors the voltage using the power circuit filter DW01A (battery protection integrated circuit) and FS8205A (N-channel transistor module). Thus, the breakout board contains three integrated circuits (TP4056+DW01A+FS8205A), while the charger module without battery protection contains only one integrated circuit (TP4056).

TP4056 – charge module for single-cell Li-io batteries with linear charge DC and tension. An SOP housing and a small number of external components make this module a great option for use in homemade electrical appliances. It charges via USB just as well as a regular power bank. The pinout of the TP4056 module is attached (Fig. 2), as is the charging cycle graph (Fig. 3) with constant current and constant voltage curves. Two diodes on the switching board indicate the current charging status - charging, charging stopped, etc. (Fig. 4).

To avoid damaging the battery, 3.7V lithium-ion batteries should be charged at 0.2-0.7 DC current until the output voltage reaches 4.2V before charging. constant voltage and gradually decreasing (up to 10% of the initial value) current. We cannot interrupt the charge at 4.2 V, since the charge level will be 40-80% of the battery's full capacity. The TP4056 module is responsible for this process. Another important point is that the resistor connected to the PROG pin determines the charging current. In modules on the market, a 1.2 KΩ resistor is usually connected to this pin, which corresponds to a charging current of 1A (Fig. 5). To get other values charging current, you can try using other resistors.

DW01A – battery protection integrated circuit, shown in Fig. 6 usual scheme connections. MOSFETs M1 and M2 are connected externally by an FS8205A integrated circuit.

These components are installed on the breakout board of the TP4056 lithium-ion battery charger module, which is linked in Step 2. We only need to do two things: give a voltage in the range of 4-8 V to the input connector, and connect the battery poles with both the + and - pins. module TP4056.

After this, we will continue assembling the charger.

Step 5: Wiring Diagram

To complete the assembly of electrical components, we solder them in accordance with the diagram. I have attached a diagram in Fritzing software and a photo of the physical connection.

1. + connect the power connector contact to one of the switch contacts, and – connect the power connector contact to the GND pin of the 7805 stabilizer
2. We connect the second contact of the switch to the Vin pin of the stabilizer 7805
3. We install three 100 nF capacitors in parallel between the Vin and GND pins of the voltage regulator (use a breadboard for this)
4. Install a 100 nF capacitor between the Vout and GND pins of the voltage regulator (on the breadboard)
5. Connect the Vout pin of the voltage regulator to the IN+ pin of the TP4056 module
6. Connect the GND pin of the voltage regulator to the IN pin of the TP4056 module
7. Connect the + contact of the battery compartment to the B+ pin of the TP4056 module, and connect the – contact of the battery compartment to the B- pin of the TP4056 module

This completes the connections. If you are using a 5V power supply, skip all the points with connections to the 7805 voltage regulator, and connect the + and – of the unit directly to the IN+ and IN- pins of the TP4056 module, respectively.
If you use a 12V power supply, the 7805 stabilizer will heat up when a 1A current passes, this can be corrected with a heat sink.

Step 6: Assembly, part 1: cutting holes in the body

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In order to correctly fit all the electrical components in the housing, you need to cut holes in it:

1. Using a knife blade, mark the boundaries of the battery compartment on the case (Fig. 1).
2. Use a hot knife to cut a hole according to the marks made (Fig. 2 and 3).
3. After cutting the hole, the housing should look like in Fig. 4.
4. Mark the place where the USB connector of the TP4056 module will be located (Fig. 5 and 6).
5. Using a hot knife, cut a hole in the case for the USB connector (Fig. 7).
6. Mark the places on the case where the diodes of the TP4056 module will be located (Fig. 8 and 9).
7. Use a hot knife to cut holes for the diodes (Fig. 10).
8. In the same way, make holes for the power connector and switch (Fig. 11 and 12)

Step 7: Assembly, part 2: installing electrical components

Follow the instructions to install components in the chassis:

1. Install the battery compartment so that the mounting points are on the outside of the compartment/case. Glue the compartment with a glue gun (Fig. 1).
2. Replace the TP4056 module so that the USB connector and diodes fit into the corresponding holes, secure with hot glue (Fig. 2).
3. Replace the voltage stabilizer 7805 and secure it with hot glue (Fig. 3).
4. Reinstall the power connector and switch and secure them with hot glue (Fig. 4).
5. The location of the components should look the same as in Fig. 5.
6. Secure the bottom cover in place with screws (Fig. 6).
7. Later I covered the rough edges left by the hot knife with black electrical tape. They can also be smoothed with sandpaper.

The completed charger is shown in Figure 7. now it needs to be tested.

Step 8: Test

Place the discharged battery in the charger. Turn on the power to the 12V or USB connector. The red diode should blink, this means that the charging process is in progress.

When the charge is complete, the blue diode should light up.
I am attaching a photo of the charger during charging and a photo with a charged battery.
This completes the work.

I made myself a charger for four lithium-ion batteries. Someone will now think: well, he did it and did it, there are plenty of them on the Internet. And I want to say right away that my design is capable of charging either one battery or four at once. All batteries are charged independently of each other.
This makes it possible to simultaneously charge batteries from different devices and with different initial charges.
I made a charger for 18650 batteries, which I use in a flashlight, powerbanks, laptop, etc.
The circuit consists of ready-made modules and assembles very quickly and easily.

Will need

• - 4 pcs.
• - 4 pcs.
• Paper clips.

Manufacturing a charger for different numbers of batteries

Many may say that for little money you can order a special board from China, through which you can charge lithium batteries via USB. It will cost about 1 dollar.

But there is no point in buying something that can be easily assembled in a few minutes. Do not forget that you will have to wait about a month for the ordered board. And a purchased device does not bring as much pleasure as a home-made one.
Initially it was planned to assemble a charger based on the LM317 chip.

But then it will take more to power this charge high voltage than 5 V. The chip must have a difference of 2 V between the input and output voltages. A charged lithium battery has a voltage of 4.2 V. This does not meet the described requirements (5-4.2 = 0.8), so you need to look for another solution.

Almost everyone can repeat the exercise that will be discussed in this article. Its scheme is quite simple to repeat.

One of these programs can be downloaded at the end of the article.
To more accurately adjust the output voltage, you can change resistor R2 to a multi-turn one. Its resistance should be about 10 kOhm.

Attached files: :

How to make a simple Power Bank with your own hands: diagram of a homemade power bank Lithium battery ion batteries do it yourself: how to charge correctly