Cpap and camping

OldSmokey wrote:

MEXICOWANDERER wrote:
DW has a Phillips IP22 Cpap. 12v 6.6 a
Now, pray tell - why would a voltage converter be necessary to convert twelve volts to twelve volts?

shh.. don't tell him that....

There's a small chance that voltage accuracy matters. I don't know, and chose to make the "Home-Built Trailer Power Adapters" more capable, more stable than the corresponding 120V power supplies running at home. But it probably doesn't matter. Here's my background "trivia" about it:

Phillips didn't even have a DC Cord for my "then-brand-new" device when I bought it. I was worried about subjecting my machine to widely varying DC Battery Voltage in the Trailer (as low as 12.2V, when abusing the batteries, and as high as 14.4V, when bulk charging). When they did finally release an over-priced cord, it was purely a cord - with no VRM, just a couple of inductors at the ends. So THEY apparently don't see a strong reason to care about it.

For Resmed, a simple "doubler" is theoretically plausible - but Resmed machines already like to die young. Subjecting them to Voltage varying between ~ 23V (discharged batteries with "Voltage Drop" at high current) all the way up to about 28V (Trailer being charged at 14.4V, the Resmed first plugged in and not yet blowing)... feels a bit risky to me. YMMV of course.

Besides, for the Resmed case, the incremental cost of "Regulator" versus mere "Doubler" is virtually nothing.