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Re: (ET) Elec-trak Digest, Vol 19, Issue 88

OK. Let's say you are blowing snow. You have to have a certain amount of speed to do so properly without the chute clogging. When you start with a happy full battery the current is lower than when you're coming towards the end with an empty battery. Power is what moves the snow.
Yes, if you mow in say L with speed 4 locked in on a level ground the mower and the tractor will slow down together so amps will probably remain constant as power is reduced overall. But if you start flooring it to speed 5 you'll pull more amps.
I can hook up the E-meter and demonstrate this if anyone's bored. But this is one reason I run the NiCDs: They have a very flat voltage discharge curve right till they are empty then they fall like rocks. Until then I can blow snow at max power with minimal amps. 

C


On 10/18/2021 11:40 AM, Erv Troyer via Elec-trak wrote:

David,
  So many times I have heard someone say "Lower volts causes higher amps" which totally 
defies Ohms Law. UNLESS - your load is being controlled by something that tries to maintain speed 
(power) at any voltage.  Compressors in an air conditioner are speed controlled by the Hertz of the 
power supply - they have to maintain a constant speed to keep the flow of refrigerant going at the same 
volume. In this case when the voltage drops the compressor will still maintain the same speed, doing the 
same amount of work - so yes, the amperage will go up as the voltage goes down. Your explanation is 
a bit long, but it is completely correct. Your water analogies help explain things. Some of the 
statements given in previous posts are implying that a loose connection will cause higher amperage. Ohms 
Law says this is not possible - any restriction in a circuit will always cause a voltage drop, and amps 
must go down.
In a message dated 10/17/2021 12:00:08 PM US Eastern Standard Time, Dave 
Roden writes:

Aside from the action of back EMF, when a motor is running flat out from a
battery, Ohm's law reigns.  That is, P = E * I or P = E^2 / R.

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