Maybe not, but as I said its hard to find one smaller that's well made. And, I would add, that the OP posted his setup with a 400 Watt inverter. And John shows (on his in depth battery backup thread) several inverters 150 Watts and up. And, ResMed recommends at least 150 Watts. And most importantly, I happen to have several 150 Watt inverters to test.billbolton wrote:You don't need a 150W inverter to do that!CapnLoki wrote:FIrst, you want an inverter capacity substantially higher capacity than the expected load to handle startups and unexpected events.
So you're discounting 20 years experience with inverters because they were on a boat??? Oh My!billbolton wrote:This discussion here is about powering xPAP kit from inverters, not your personal general use of DC power for a variety of maritime purposes.CapnLoki wrote:I frequently "pop" the breaker on the inverters using load that don't seem anywhere near the limit
I agree with you completely. Except that you're wrong. In the real world (and we are talking "real world" here, not some theoretical, book learned world?) its very hard to match the exact requirements. An xPAP will use well over 20 Watts at startup or when wide open. And pumps have a wide range of loads depending on settings, and, as noted, they turn on and off at every breath. The problem here is that inverter manufacturers play a numbers game of claiming 90% efficiency at a particular load, but they usually don't publish the efficiency over the full range. And we are limited to choices that the average consumer would have, at prices under the DC alternative ($90 for Resmed, $25 for PRS1).billbolton wrote:The bottom line is that inverters run most efficiently when the inverter capacity is reasonably well matched to the load. If you run an current technology inverter a with load which is very significantly under its capacity (for example a ~20W peak load on a 150W capacity inverter), the inverter will not be operating in it most efficent zone which is pretty much the only thing you demonstrated with your inverter measurements
Maybe, but I was making specific claims, based on reasonable testing and sound analysis and long experience.billbolton wrote:Making sweeping claims about the efficency of current inverter technology based on a flawed testing and analysis process is just plain silly
If you have some real alternative to suggest, I'd love to hear it? Please, if you actual have a 20 Watt (or smaller) high efficiency inverter I would buy it in a heartbeat, not for my pump, but for the rechargeable toothbrush and a host of other small devices.
