CFL and modified versus pure sine wave

[Vern Faulkner]

So, yesterday, I was given (given) a major gift: a Prosine 2.0 inverter/charger. It spits out a pure sine wave. I tossed the thing into the system, fired it up, and it worked like a charm.

Now, as an aside, I fired up the three-stage CFL fixture - and it seemed brighter than when run off a modified sine wave. Further, the Kill-o-watt read less energy consumption.

Now, I can grasp how inductive motors would use less energy with a pure sine wave. But CFLs?

So, is the reduced power consumption data due to (a) reduced power consumption or (b) the Kill-o-watt struggling to read the accurate power due to a challenge reading RMS from the square-edged modified sine wave?

[inetdog]

Now, I can grasp how inductive motors would use less energy with a pure sine wave. But CFLs?

So, is the reduced power consumption data due to (a) reduced power consumption or (b) the Kill-o-watt struggling to read the accurate power due to a challenge reading RMS from the square-edged modified sine wave?

As some other observations have demonstrated pretty clearly, for most non-linear electronic loads (products that typically just draw current near the + and - peaks of the AC waveform) the Kill-a-Watt provides very inaccurate values. You can get a better idea of the real consumption of loads like this either by using a $1000+ laboratory or utility-grade wattmeter or by looking at the difference in battery current to your inverter as you switch the light or power supply brick on and off.
The latter is probably the best, since it gives you the measure you are really looking for when calculating loads for system sizing.

[Sunny Solar]

A suitably sized shunt placed between the battery/ies and inverter is the only way to accurately determine the inverters power consumption and the power use of any device connected to the inverter. This is a very cheap way to get the answers (a $10 multimeter reading millivolts is all that is needed)you are looking for and is even better than using a $1000 meter after the inverter to measure loads.

[Sunking]

A suitably sized shunt placed between the battery/ies and inverter is the only way to accurately determine the inverters power consumption and the power use of any device

True and a 100 amp @ 75 mV cost $10 to $20. However a accurate volt meter capable of reading 0 to 75 mV does not come real cheap, and you will have to make conversions from voltage to amps. Using a 100 amp 75 mV shunt 1 mV = 1.33 amps.

IMHO the best solution every Off-Grid Owner should have is to use a good quality AC/DC Clamp-On meter w DVM. There are a lot of good decent price meters out there if you shop around. Here is a short list to look around for:

Triplett 9310
Amprobe ACDC 100
Extech 380950
Extech 38389