Hi all! I am posting my universal power supply with charging functions, which can be a universal solution for radio amateurs, car-moto owners, owners of electric vehicles, etc.

ATX conversion scheme

The principle of alteration is:

1. Fitting standard ATX computer blocks on TL494 to an adjustable power supply with voltage and current limitation.
2. Raising the output voltage to 90 volts by reworking the output part of the unit and replacing the transformer.
3. Integration of a charge circuit with pauses into the block (the simplest transistor multivibrator).

Initially, the unit was planned to charge and resuscitate electric bicycle batteries. Output characteristics of the unit are 0-90 volts DC and adjustable current up to 2.74 amperes. The ATX power supply is used as the basis. The transformer is taken from the power supply unit of the V770/570 monitor. Digital voltammeter - ready-made Chinese 100 V 10 A. Next, see a photo review of a homemade design:

The block contains a battery charging circuit with pauses (to charge the battery). There is also short circuit protection.

Video review during the setup process

If you have already practically converted your bike into an electric bicycle and the only thing left is the battery, then in principle there are few options - buy a ready-made one or make a battery for the bicycle with your own hands, assembling it from cells.

The battery is the most important irreplaceable part of an electric bike, the heart of the entire mechanism, with the help of which the bicycle engine is supplied with power. If the power supply runs out or fails, you will have to pedal the old fashioned way.
Types of batteries installed on a bicycle

Batteries differ in many ways, which determine the technical performance of the electric bike and, accordingly, the price of the issue. By type they can be:

· lithium ion battery;

· nickel-metal hydride;

· lead-acid.
Lithium

The most successful option for equipping an electric bicycle is lithium batteries with high capacity. They are the highest quality energy sources, have a longer service life than others, are low in weight, but due to their characteristics they are also distinguished by their high price.

There are several types of lithium energy storage devices for bicycles:

· lithium-manganese;

· lithium polymer;

· lithium iron phosphate.

All lithium batteries vary in their chemical composition, but are environmentally friendly because they are sealed and do not contain toxic substances.

The service life of such batteries is up to 5 years, the number of charging cycles is up to 1000, with the exception of iron phosphate, the most powerful and expensive of all, the service life of which, with proper care, can reach 10 years, up to 2000 cycles.

All elements in any battery must be balanced: this function is performed by a special BMS (Battery Management System) board - a management system. In addition to equalizing the charge of the cells, it completely controls the process of charging and discharging the battery. On factory drives, the board is installed by default, but on a homemade power supply you will have to install it in order to increase the life of your creation and not have to do the work for the BMS.

A nickel-containing battery contains a mixture of nickel and other metals. Such batteries are quite light and are in the middle price category. Their service life will be about 3 years, 850 charging cycles.

Most often, manufacturers put on a bicycle lead battery, characterized by high energy intensity, low self-discharge level, minimum price. But at the same time, such batteries are short-lived, weigh more, and are significantly inferior in their characteristics to lithium ones. Service life 2 years, approximately 700 charging cycles.

· Voltage, measured in volts. The battery can produce 12, 24, 36, 48 volts.

· Capacity is the entire stored energy of the battery before it is completely discharged, measured in ampere-hours. The larger the capacity, the longer the bike will travel without recharging.

· Power, measured in watts. In addition to the power of the cells themselves, this indicator is also affected by the BMS board, which monitors the safety of the battery, limiting the power if necessary.

There is a wide range of lithium batteries for sale for various types of personal electric vehicles. But sometimes you want to assemble a battery for an electric bicycle with your own hands in order to hone your skills, practice creating a useful device and be confident in the quality of the assembly. If you also set out to assemble your own battery With the necessary characteristics, you will need:

· sufficient number of Li-ion elements of standard size 18650;

· BMS control board – it is responsible for equalizing the charge of batteries, controls the process of charging and discharging the battery and extends its service life;

· connecting wires, connectors;

· a suitable sized box or case made of metal or plastic - you can buy it or make it yourself;

· 2 fire protection packages;

· ammeter;

· soldering iron;

· Charger.
Algorithm for assembling a Li-ion battery for an electric bicycle with your own hands

Prepared cells of standard size 18650 are placed in pairs in bags, taking into account polarity, providing a parallel connection. Power and balancing wires are connected to them. The packages are connected in series to each other to obtain the required voltage. The connectors are brought out using extension cords. The balance wires are connected in series.

All lithium-ion cells are carefully pulled together and placed in a prepared box or case, in which holes for the wires must be drilled in advance. The BMS board is soldered right there. The wires are brought out, after which a plug is connected to the top to further charge the battery. All openings of the case are carefully sealed. Finally, the assembled battery cable is connected to the electrical controller (load), and the power source is placed on the vehicle - on the frame, trunk or other suitable location.
Security measures

When planning to assemble a homemade bicycle battery with your own hands, remember that:

1. During operation and when testing batteries, it is important to be extremely careful and careful.

2. Batteries and the assembled battery must not be allowed to fall, heat up, be compressed, or foreign objects penetrate into them.

3. It is important to avoid short circuit, recharging batteries, using reverse polarity.

4. If excessive heat occurs, stop using the battery or charger.

5. Cells of questionable quality or with signs of damage should not be used.

If you doubt the sufficiency of your knowledge and experience, it is better to save time and effort - just buy a ready-made Li-ion battery with suitable parameters or order it to be professionally assembled to order, with a guarantee for the work performed. Manufacturing a battery to order allows you to independently select the cells for assembling the battery and strictly comply with the required characteristics. In particular, you can order a battery of the optimal shape, size, and capacity for you.
About soldering lithium cells

It is extremely undesirable to solder lithium cells - when heated with a soldering iron, they can easily be damaged. But for better balancing, soldering is needed, since excess resistance leads to distortion of the voltage information received by the charger. A compromise solution is to use elements with terminals and act on them with a soldering iron for a short time, a maximum of a couple of seconds.

An alternative to soldering could be:

1. Application of rare earth magnets as contacts. They are powerful, provide excellent cell contact, and are coated on the outside with non-oxidizing zinc or nickel. The wires must be soldered to them very carefully, without exceeding the Curie temperature of about 300 °C. It is important to use a soldering iron with thermal stabilization and low-melting solder.

2. A special holder, as for installing simple batteries. It will contain batteries without rigid fixation, which will allow you to change faulty “banks” if necessary.

3. Ready-made holder with provided protection for lithium-ion cells. Unprotected “cans” are simply inserted into it, without soldering or other difficulties.

A homemade battery for an electric bicycle is good decision subject to the use of high-quality batteries and the availability of knowledge and skills necessary for the professional assembly of such a device. If you need a good battery for specific requirements (non-standard shape, dimensions and other characteristics), you can assemble it yourself from a set of 18650 cells. But without experience in such matters, it is not always possible to create a reliable battery suitable for use on the first try.

Therefore, it is easier and safer to buy a ready-made battery for an electric bike. If there is no model on sale with the parameters you need, order its assembly at the VoltBikes workshop. Our specialists will manufacture the battery you need with a precise fit to the required characteristics and requirements, perform all work efficiently and provide a guarantee.

How to assemble an inexpensive lithium battery for an electric bicycle yourself?

Self-assembly of the battery has its own charm. Firstly, it’s interesting, you’ll practice your skills and create something useful with your rivers. Secondly, in most cases you will be able to operate it correctly, learn how to remove minor faults, and also be confident in the quality of the assembly. For ease of installation and maintenance, we recommend taking ready-made assembly kits that are used by cars, aircraft, and other amateur modelers.

Step-by-step instructions for assembling a lithium polymer battery:

1. Purchase of LiPo elements, a device for monitoring the voltage in the elements, a charger, fire protection bags (2 pcs.), wires, connectors;

2. The next step is purchasing or making a metal or plastic box.

4. In each package we place two elements with a parallel connection to increase the capacity. Then we connect the packages in series with each other to create the required voltage. We bring the connectors out using extension cords. We also connect the balancer wires in series, that is, we combine them into a block of 9 wires;

5. Then we put the entire structure in a box and attach it to it circuit breaker at 20 Ampere. The box and bags will be able to minimize the risks of fire;

From four elements you can quickly assemble a 33V 10Ah lithium-polymer battery with an 8S balance connector. The weight of our 4 cell battery with box was about 3 kg. A huge plus is that the assembly uses a minimum of materials and soldering. Such a battery is safely operated with a device for monitoring the voltage in battery cells, and is charged with a model (factory) charger. The battery capacity can be increased by adding more cells. Such an assembly will allow you to move at a speed of 30 km/h over a distance of at least 20 km.

So, the LiPo battery is ready for use. All that remains is to decide how to monitor the charge and discharge of the battery. It’s easier to charge; you can use a specialized charger, which, when connected, will evaluate the condition and correctness of the charge of each element individually. Discharge is a little more complicated. The easiest way is to use TM Volta bikes controllers, which, when the voltage on the battery drops to a certain level, automatically turns them off so as not to “kill” the battery, however, if one of the cells discharges much earlier than the others, the battery may still fail. The condition of the cells of a homemade battery can be assessed by regularly checking them using a special device that is designed to monitor and monitor the voltage in the battery cells.

Cell-Log – a device for monitoring voltage in battery cells

Such a device can also evaluate the correctness of the charge when connected from a direct current source, or another charge that does not monitor the state of the battery for each cell. This is not a particularly expensive method, but not very convenient, since the voltage will have to be measured quite often, and therefore you will need to develop a habit and understanding. Another way to monitor battery voltage is to install a battery management board (BMS). Such a board is capable of taking on all the functions and providing correct and high-quality charging, discharging, protection and monitoring of the battery. As long as the board is in good condition, the battery and its owner will be safe.
Assembling a lithium battery

In order to assemble a battery for a bicycle, we will need:

· several lithium cells;

· connecting wires, connectors;

· box or case, i.e. any suitable container, metal or plastic;

· ammeter;

· soldering iron;

· Charger.

We put the batteries in bags in pairs, taking into account the polarity (the elements must be in parallel connection). We sequentially connect the packages to each other, take out an armful of wires with the plus, already connected, and do the same with the minus.

It is good to pull together all the elements and place them in a prepared container. It is advisable to solder the BMS board immediately so that the effort will pay off in a long service life.

Lead the wires out of the box from pre-drilled holes, then attach a plug to the top through which charging will be carried out. All openings of the box must be sealed.

Now all that remains is to connect the finished battery cable to the electric motor and, of course, start placing the power source on the bicycle structure.

In order for the batteries installed on electric bicycles to last longer, they need to be properly charged, i.e. The service life of this important element depends on how efficient the charging method is chosen.

There are several methods: One is based on the use of a constant voltage of 13.8 W, the other, called two-stage, DC, and the third - constant current strength and charge, depending on the capacity of the nominal battery.

The first charging method is considered the most preferable. The battery in this case is connected to a source that maintains the charge throughout the entire charging process. constant pressure. As charging increases, the current decreases. Gradually it decreases to zero, becoming insignificant. In this way you can achieve 95% battery charge. It's useful to know that when developing lead acid batteries unattended ones, the low value of the recharging potential was taken into account, based on the need to minimize the volume of gases released during “bringing up” to full charging.

Electric bicycles have some nuances associated with charging batteries. For example, when the voltage during recharging increases to fifteen volts, sulfation noticeably decreases, and due to the design features of these batteries, corrosion of the positive electrodes increases, leading to rapid failure of the battery. Therefore, it is recommended to use an electric bike charger that supports higher charging requirements. Best choice for maintenance-free batteries there will be charging pulse type , capable of providing constant voltage.

It is even better if they are equipped with a temperature sensor, since its value slowly increases during the charging period, causing an increase in capacity, which leads to overcharging, i.e. the charge level is higher than the required value. This has a negative impact on battery parameters. If it is charged at a low temperature, the situation will be the opposite, i.e. the battery will be undercharged. Temperature sensors can correct these parameters, eliminating such effects and, therefore, extending the “life” of batteries.

In order to charge a lithium-ion battery used in electric bicycles, use a special charger connected to household power supply 220v. Two different cables are supplied with it, one of them is necessary for normal connection to an outlet and is about 1.4 meters, and the other to the battery socket (three-pin socket) and its length is 1.1 m. They are suitable for any bicycle that uses a battery with a capacity of ten to twenty amp/hours. These chargers automatically stop charging once the battery is fully charged.

To determine this, there is a special indicator on the charging case: it lights up red during the entire charging process, and, as soon as it is completed, changes it to green. Charging lasts approximately four to five hours. At the same time, you can charge the battery by removing it from the vehicle or directly on it. To extend its service life, it is not advisable to charge the battery in rooms with negative temperatures, or immediately after bringing it from the cold into a warm room. You can start the process as soon as the battery warms up to room temperature.

In online stores, of which there are many on the Internet, they offer the following types of chargers for lithium batteries installed on a vehicle called an electric bicycle:

• For lithium phosphate batteries with a capacity of 36V 12 A/h and 36V 12 A/h.
• For lithium manganese batteries with a capacity of 36V 16A/h.

You should not use a charger that is not designed for a specific battery type (specific voltage and capacity) to extend the life of the batteries.

For charging types of batteries: lithium magnesium, lithium ion, lithium polymer with values capacities 8-14 ampere hours and rated voltage 48 V V automatic mode, designed charger with voltage power supply 220 V, the maximum consumed current is 0.8 A. At the output it gives 0.8 A - the maximum consumed current and voltage - 1.8 – 0.05A, changing automatically. Its dimensions and weight are not at all large. They are equal to 166 x 84 x 60 mm and 0.650 kg, respectively.

A warranty card is issued for the charging device for a period of six months. In automatic TM devices “Volta bikes” the optimal current and voltage are ideally selected. The charging current should not be more than 10% exceed the rated battery capacity to extend the latter's service life. If you use devices with a higher current, the battery charging will speed up slightly, but the battery life will be shortened. TM “Volta bikes” with a nominal voltage of 24 V is capable of efficiently and quickly charging batteries whose capacity 10-14 A/h, producing an output current of 1.8A. It can also be used to charge batteries capacity 7-20 A/h. From negative consequences You can note a slightly increasing charging time, and that’s all.

For lead batteries, the following charger can be considered as an option.

Technical characteristics of NBC-01 (RV-24v)

• Maximum current consumption is 0.8A.
• Supply voltage and output voltage respectively: 50Hz, 220-240V and 28-28V.
• Automatically varying charge current – ​​0.05-1.8 A.
• Dimensions, mm - 160 x 89 x 54.
• Power cord, length for connecting the battery: 90 cm and 65 cm, respectively.
• Weight, g – 344.