Quality Question about Small Inverters
I'm shopping for a small, pure sine wave inverter. I'm interested in one that provides about 300 watts. Prices vary wildly, from around $40 to over $150 for a seemingly similar product. I'm not naive....
Forum Discussion
Lwiddis wrote:
nd, this is common:
“Efficiency: With 14 VDC input and a 100 Watt load the efficiency of the inverter measured 88.4%. That is very good for an inverter with true sine wave output. Efficiency at full load drops slightly and measured 86.4% with a 285 Watt load and 13.1 VDC input.”
Efficiency is watts out vs watts in.
The 100w load (out) and 88.4% means input was 113w. 14v in means amps were 113/14= 8 amps.
We usually use a divide by 10 for amps draw so that is 8 amps vs 10 using the 10 rule.
285w out at 86.4% is 330w. So amps were 330/13.1 = 25 amps vs 33 using the 10 rule.
I suspect those efficiency numbers do not take into account real world inverter to battery wiring and you should still use the divide by 10 rule for guesstimating
Idle draw is a different thing from running load efficiency. Eg the idle draw with an inverter/charger is high from all the fancy features that are always live.
