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major major is offline
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Default voltage of dimmer output not reading same on two different DVM's

On 11/5/20 10:05 AM, major wrote:
On 11/5/20 6:48 AM, Phil Allison wrote:
major wrote:

===============


Sorry, the meters are a GE2524 Digital Multimeter that reads the 9V and
the other meter is a Etek 10709 that reads 4 V.

Not sure about dimmer frequency, but I can hear a faint whine as it
runs.


** What range are you using ???

Â* AC volts or DC volts?


DC on both meters on lowest range, 20 V.


PWM voltage waves can be read as an average value on any DC meter -
but true power will require something much fancier.

Why not just measure the DC battery current and multiply by the voltage?



If you mean input from the battery into the dimmer, yes, tried that.
Both meters show the same 12 VDC @ 7 A when the dimmer is set at
maximum.Â* Will have to check and see what happens as dimmer is adjusted.


Then subtract a watt or so for losses in the controller.


Would I only lose a watt or two through the dimmer?Â* If so, I guess I
could take all my readings from the input side and go with those.



....Â* Phil





Ok, just as a follow up, I did keep both meters on the input side of the
dimmer. Voltage remained constant and nearly the same on both meters,
11.97 and 12.01 VDC, respectively, with dimmer off. At dimmer maximum
setting, voltage remained nearly constant (drop of -0.3 V) but current
changed from nearly nothing to the 7 A maximum with dimmer at max
setting. I swapped out the meters to read current just to be sure and
each showed the 7 A maximum. Then, I just adjusted the dimmer to
different positions, made some tick marks with current values indicated.
I think I'll just go with this. As you mentioned, losses through the
dimmer are probably slight and not an issue, at least in this
application. Thanks for your suggestions.