I'm no Auto Electrician, so is there a very simple way of being able to check the Voltage draw on my Electric Fans, so I can see if the alternator will be able to keep up.

 

the voltage draw will be battery voltage what you need to be concerned with is amperage draw. The easiest way to test is an inductive amp meter. You can get an inexpensive one for what you are doing just make sure the battery is fully charged and engine running because as voltage goes down amperage goes up. https://www.amazon.com/Uni-T-UT210E-...n+dc+amp+meter

 

watts ÷ volts = amps . simple as that

 

Yes get a 0.1ohm 100Watt resistor and put it in series with the + power lead, measure the voltage drop across the resistor and current=voltage/resistance. You could use 10x 1ohm 10Watt in parallel.

so a 10volt measurement and 0.1ohms

10amps = 10Volts / 0.1ohms

 

Why make things easy when you can make them difficult.

Clip on ammeter from any auto motive store, clip it around one lead only and read the scale, simples.

 

As BC says the answer to your question is stamped on the fans.

The issue then is what to do with the information. You would need to know the amp rating of your alternator , and the existing current draw with AC on to know what headroom you have. That is where maybe the later suggestion for the ammeter might come in handy.

 

I think the ones on my X Type are around 30 amps.