Hi Boat.Buoy Get yourself a 100w driving light globe and apply different voltages to it and measure the current at each voltage level.

The lower the voltage the lower the current.

The only time the current goes up in a motor as the voltage goes down, is when the voltage is so low that the motor stalls. At this point you can have a dead short. At all voltage level above the stall voltage, the voltage determines the current demand of a DC device, higher the VOLTAGE, the higher the current demand.

Again, the vehicle manufacturers are lowering the operating voltage, to LOWER the current draw being applied to the alternator, or have they all got it wrong? 2007 TDV8 Lux

I will most definitely try that when I have some time on my hands.

Ok lets just forget whats already been said for a second. If you were right, why would anyone with heavy duty applications look to use a 24volt electrical system if the current consumption was higher? Why would forklift trucks operate at 36v or 48v? They do this because the current is reduced, therefore the cable sizes are reduced, therefore the costs and installation complications are reduced. As voltage goes down, current goes up..its been that way since Carendish and Jars were electrocuting themselves with tubes of salt, about 50years before Georg Ohm get involved.

I'm also not too sure where you received the memo re-manufacturers reducing operating voltages - the VAG group are doing exactly the opposite! They now use ECU control alternators which can charge up to 14.90 VDC to shorten the time it takes to charge (because you can get more current in with higher voltages during charge cycles) the reduction in charge time means a reduction in engine load, which means great MPG!?

If you are really thinking of voltage in charging situations then that is something very different altogether. Yes, if you lower the voltage while charging, the battery can only accept less current. This has nothing to do with the discharge situation above. When you are charging a battery, the higher the voltage the higher the charge current a battery can accept. If you lower the voltage the battery can only accept less current. This is why advanced charging systems fluctuate their voltage during the various different stages of charge.

I’m sorry Boat.Buoy, but you are adding 2 and 2 together and getting 17.

Just get the light bulb and do your own tests.

You can do the same with a small motor, for example like a model train motor

The speed of the motor is controlled by the voltage being varied up and down.

The higher the voltage the faster the motor spins and the higher the current drawn by the motor.

Lower the voltage and the train slows down, and if you both to measure the current, it too has reduced.

The principle is identical for the way a starter motor operates. 2007 TDV8 Lux