How to make a car battery charger from a microwave oven

The microwave oven has a very powerful transformer, which can be used in a homemade charger for 12 V car batteries. Let's rewind the transformer to suit our needs and assemble the charger.

Will need

Diode bridge 50 A - http://alii.pub/5nfe4v
Tumbler - http://alii.pub/5nfe6f
Ammeter or multimeter - http://alii.pub/5nfe7e
Wire 2.5 sq. mm. - 5 meters.

Making a charger from a microwave oven

The first step is to disassemble the microwave oven and remove the transformer from it.

You also need to take a fan and a power cord from the microwave. At the transformer, use a hacksaw to cut off the high-voltage winding (2500 V) and the middle low-voltage winding (6 V). All these windings serve to start the magnetron. We leave the mains winding (220 V), usually the lowest one.

We clamp the transformer in a vice and use a chisel to knock out the remains of the sawn windings.

Now you need to wind a new, low-voltage winding on the transformer with a 2.5 kW wire. mm.

We wind 15 turns. We connect the transformer to the network and check.

Output is 13.3 VAC. This is not enough. We wind another 2-5 turns to a voltage of 15 V.

Now you can start making the charger. Charger diagram:

On a rectangular piece of chipboard we attach a transformer, a fan, a diode bridge with a fan, and a switch with a power supply box.

We connect everything with wires according to the diagram.

Instead of a fuse, for clarity, we’ll plug multimeter for current control.

The charger works, the battery is charged with a current of 4.5 A, which is quite normal. The transformer heats up, but much less than when working in a microwave. The fan does a good job of blowing. As a charger option, letting the battery charge for 1-2 hours to “revive” it will do just fine.