Each of us faced a situation when the battery was discharged at the most inopportune moment, and the charger was not at hand. It seemed that it remains to patiently wait for the opportunity to charge the battery, but there is another way out.
There are several ways to build a charger from scrap materials and restore some of the charge to make an emergency call, start a car, or check the battery's performance.
To charge the phone battery without a charger or any other, it is enough to connect to it (according to polarity) a constant voltage source that meets the following conditions.
- Condition 1. The output voltage of the source exceeds the nominal voltage of the battery by 20-30%.
- Condition 2. The current strength is a constant value equal to from 1/10 to 1/20 of the battery capacity.
Eaton battery
In other words, if the battery is dead, you can build your own charger based on just two criteria. With sufficient knowledge of microelectronics, you can create a charger for a camera, car, phone or any other device.
Find out your battery charging time
We use UPS
There is nothing easier than using ready-made chargers, which is your UPS. An uninterruptible power supply for a computer is equipped with advanced charging with a lot of safety systems, so you can safely connect a car or screwdriver battery to it without a charger.
Charging batteries with a laptop power supply
Laptop power supply
If we are talking about how to charge a car battery without a charger, then the best way is to use a laptop power supply for this purpose.
The voltage output by the device (about 20V) is enough to fulfill the first condition, and the current (3.5-6A) is enough to charge the battery of a car.
Only one problem remains unresolved - the nominal voltage is above the upper limit for charging a 12V battery. For these purposes, ballast is introduced into the chain. Since we are talking about a car battery, we use a 12V incandescent bulb as a ballast, with a power of 80 to 100W.
Calculate the resistance of the light bulb:
- 80/12=6.7A (100/12=8.3A)
- 12/6.7=1.8 ohm (12/8.3=1.4 ohm)
From the calculations it can be seen that a standard 55 Ah battery will charge in almost 17 hours, using an 80-watt light bulb. When using a 100W ballast, the battery will take 13 hours to fully charge.
We strongly recommend not to use a more powerful ballast, and even better not to exceed the current indicated on the power supply. Otherwise, the device may go into emergency mode or suffer a short circuit.
By adapting the presented calculations, it is possible to calculate the full charge time, as well as the ballast power for any power supply. By reducing the power of the light bulb, you can lower the voltage to 12V, and charge the batteries from a 10V screwdriver. A 100W light bulb can charge a screwdriver with a 14V battery.
Important! Watch the charge time. After a full charge, the pulses supplied to the lead battery provoke boiling with the release of explosive substances.
How to charge from another battery?
The general scheme for replenishing the supply of electricity in this case is as follows:
- find an element that satisfies condition 1;
- according to the polarity, we connect both sources;
- wait until the charges are compensated (several hours).
The main differences of the method are the type of battery used. If you have a similar or similar battery in front of you, then copper wire and adhesive tape are enough to connect the corresponding terminals. It is better to take a wire of a large cross section, otherwise it may catch fire due to heating.
If we are talking about finger batteries (in the case of a phone charge), then it is enough to connect 3-4 cells in series to get 4.5-6V and enough current to charge.
A similar effect can be achieved with a couple of 18650 batteries, which are easy to charge the camera battery without charging. In some cases, if the battery capacity is much less than the battery capacity, charging may not start.
How to charge the battery from a 220V network
Important! This method is dangerous for your health, so we strongly recommend that you refrain from repeating it, without the appropriate skills in working with electrical equipment.
You can also charge a car or a screwdriver from the network. For this, a circuit is assembled, consisting of a 100 - 150 watt light bulb and a diode bridge, from which the battery is powered. The circuit looks like this (works with 12V or parallel connected 18650 batteries):
Therefore, if you have several suitable diodes lying around or a ready-made diode bridge, you can assemble a fairly efficient charger. The bridge can be found inside computer power supplies. Instead of a lamp, other loads can be used, up to 1kW. We also recommend that you get a voltmeter and an ammeter, with their help you can control the parameters and determine the duration of charging
- The easiest way to charge your battery without your own charger is to get help from neighbors, friends, or purchase a replacement.
- Instead of a choke that compensates for deviations in the voltage of the power supply, you can use a resistor or a ready-made rectifier.
- It is difficult to compensate for the lack of knowledge and skill in microelectronics "on the network", so if you are not sure, do not undertake to create even the simplest circuit.
Warning! The methods presented to charge the battery may cause short circuit, electrical shock, fire, and other adverse effects. If you are not confident in your abilities or knowledge, refer to the classic ways to charge the battery of a phone, camera, screwdriver, car, etc.
