Technical, Techniques, Hints, and Tips > Batteries & Chargers
Measuring Current draw?
aamcle:
This seems like a good place to ask.
What do I need to measure the current drawn by the motor, I fairly sure my multimeter although it measures Amps would be fried.
Thanks All. Aamcle
john44:
Hi, there is a product from hobbyking called a Watts-up meter, component shop also do
A similar unit, they measure watts amps, volts including peaks. They connect in between
Battery and load and scroll through the readings until the supply battery is disconnected
They will read 100 amps. If I am wrong I will be corrected by the experts.
The meters are small enough and light enough to be left on the craft on your voyage
So you get actual performance readings so you know what size fuses to fit.
Hope that helps, (most multi-meters only read upto 10 amps)
John
malcolmfrary:
Many digital meters have a 10A range. Being digital, they can display up to 19.99, but the test leads might not live through that.
Apart from meters that have external "range resistors", which are neither common nor cheap, an old world solution was to use an ammeter from a car scrapyard, which could be had in 30 and 60 amp versions. And things like the watts up meter. Some might record the figures for posterity.
Then there are clip-on or clamp meters that you clip over the wire without interrupting it and take a reading from the magnetic field generated by the current.
The down and dirty method is to get a bag of assorted fuses and experiment, noting the two values where failure happens regularly, and the higher value where it doesn't.
aamcle:
Thanks Gents.
Aamcle
Plastic - RIP:
When measuring current out of the water, you are just measuring the friction and inefficiency of the drive train.
You can do some interesting experiments seeing what is going on mechanically.
With no losses and no bearing/grease friction, the current should be almost nothing.
With multiple motors, any differences between them might mean you are looking at slight misalignment of propshafts and tight thrust washers.
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