Tough battery charger for all conditions

The simple combination of a tractor’s alternator and an electric motor was the solution to persistent battery problems for a handy farmer from North West province in South Africa.

You get what you pay for, as the saying goes, and this is what prompted Rassie van Wyk, a crop and stock farmer from Leeufontein, near Wolmaransstad in South Africa’s North West province, to build his own sturdy charging system to counter the effect of the winter cold on his vehicles’ batteries.

Rassie van Wyk, crop and stock farmer from Leeufontein.

Rassie says that he and many of his fellow farmers agree that the winter cold is highly detrimental to their many farm vehicles which have to park out in the open. This is when problems arise with the batteries – when they are flat and need to be recharged.

For instance, in the last eight years or so, he has been let down by three reasonably good commercial chargers that eventually ended up on the junk heap. These chargers cost him roughly R3 500.

In desperation, Rassie assembled his own battery charger from a tractor alternator and an electric motor. “These parts cost me about R3 000. Although one could use a smaller motor, I decided to buy one for about R2 000. It has a performance of about 1.8kW at 2000 RPM.” The tractor alternator cost R772.

“Although these two components make the device a little expensive, the biggest benefit is that they make it easier and cheaper to repair,” says Rassie.

He mounted the two motors on a steel framework from a scrapyard, with two pieces of a plough blade for a base and two wheelbarrow wheels (about R200) on the other side to make it easy to move (PHOTO 1). The motor is attached to a channel iron with four bolts and the alternator has an adjustable connection that can set the tension for the fan belt drive.

The completed device fully charges a battery with a capacity of 70 amp-hours at 30A within 15 minutes.


The support arm attachment from the alternator is on the other side of the vertical channel iron beam, along with the connection of the green power cables that run to the battery (PHOTOS 2 AND 3).

The negative earth connection is on the right-hand side against the framework and the positive terminal is on the left – this is isolated with a rubber ring from an exhaust system.

Photo 2

The alternator’s positive terminal is connected with a blue wire to the positive terminal of the battery, via the light in the round instrument panel on the framework. The black wire is the earth connection. The motor is powered by an electrical socket.

At the top end of the framework there is a gauge with a red light attached, that lights up when the terminals are connected to the battery. The light is turned off as soon as the motor is turned on, similar to the way a tractor or vehicle works. Rassie first connects the battery cables before he turns on the charger to prevent a short circuit.

Photo 3

ENQUIRIES: Rassie van Wyk, email:; cell 082 484 1141.

share this