How to charge a battery without a charger. Two schemes.

Anyone who has even a little driving experience has encountered the problem of charging a dead battery when there is no charger at hand.

The most common way to start a car in this case is to “light it up” from another car. We will not consider this method ... What is there to talk about? It's simple, many have tried ...

Let's talk about the case when you have access to a 220 V network nearby.

This method can be called as follows: charging the battery with a light bulb and a diode.

Let me tell you about SAFETY.

In the diagram below, there is no galvanic isolation from the 220V network. Therefore, any bare wire or connection carries the risk of electric shock!!! If you are not familiar with the basics of electrical engineering, it is better to give up the idea of ​​repeating this method!!!

All metal parts of the circuit must be securely insulated. Both power terminals of the vehicle electrical circuit must be removed!!! Do not allow touching of bare elements of the car body scheme!!! Do not touch anything metallic in this circuit with your hands.

The briefing has been completed and if you have not changed your mind, we will continue our conversation :)

So… how do you charge a battery without a charger? The scheme is as simple as frying scrambled eggs in a pan:

In addition to the battery itself, you will need the following items:

- insulated wires, with a cross section of at least 1.5 mm²

- a diode with a rated current of 10 A and rated for a voltage of at least 300V (I use the Soviet D 246A)

- an incandescent lamp for 220 V and a power of 100 W (we'll talk about power below)

- ammeter for measuring direct current with a measurement limit of up to 10-15 A.

The chain is assembled sequentially, so the order of the elements does not matter.

The main thing is not to confuse the “polarity” of the diode and the battery.

Diode

Where your diode has a “plus” - you can look at any site, for this, write a query in the search line, for example: “D246 pinout” or “D246 characteristics”.

The "positive" contact of the diode is connected to the "plus" of the battery - this is the main condition !!!

Ammeter

In principle, if you do not have an ammeter while charging, it's okay. It is desirable but not required. Now I will explain why. I would recommend at least once to “test” the circuit with an ammeter - so that you understand the whole dynamics of the process: what current is at the beginning of charging, what is at the end, and most importantly, how the light bulb shines! By the end of charging, it should noticeably fade.

Bulb

The light bulb has two functions in this circuit: as an indicator and as a ballast that reduces current. The lamp needs a "normal" one, with an incandescent filament. LED and housekeepers will not help here.

Charging current depends on what power bulb you have chosen.

Everything is simple here

Where:

I - current, A

P - light bulb power, W

U - mains voltage, V

All further calculations are very approximate, because. A light bulb has a non-linear filament resistance. The calculation error is about 10%, which is insignificant for us.

If we take a light bulb with a power of 100 W and turn it on without a battery, we will record a current of 0.45A. In a series circuit with a battery, the current will not exceed this value. The internal resistance of the battery is less than 1 ohm. Therefore, we can afford to neglect this value.

But! After all, we also have a diode in the circuit, which reliably “cuts off” the negative component of the sinusoid! Therefore, we divide the value of 0.45A in half - we get 0.27A.

Not enough for charging, agree! Especially when there is no time to wait. Therefore, a kilowatt lamp would be best suited for charging. Using it, the approximate estimated charging current will be 2.7A. This is already something!

By the way, I almost forgot about the second scheme. If you have 4 diodes and you can 'bridge' them together, then the current will be 2x the above circuit. That is, on a kilowatt lamp, you can achieve a charging current equal to 5-5.5A.

Experiment with using an ammeter so that if you don't have one, you can only charge the battery with a lamp and a diode.