View single post by GeoffR
 Posted: Mon Aug 6th, 2018 09:04
GeoffR

 

Joined: Wed Apr 11th, 2012
Location: Denham, United Kingdom
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novicius wrote: Inverters are a different matter, the output from a cheap inverter, such as might be used in a car, isn't a very accurate sine wave and may be far from "clean". Such a "dirty" output will cause the charger to get hot and may result in internal damage.

Actually, seldom as in Never, is the sine-wave from any wallsocket " clean".

Any charger could Not care two hoots about what that sine-wave looks like, as long as it is a Sine-wave...AUDIO Amplifiers would care, as the output will result in a " Gritty " sound.

I could see Two problems with a Not-well constructed DC -AC converter.

1) That it delivers a wave approaching a Square-wave , which is not very likely ,but possible.

2) That the DC-AC converter is " leaking" Direct Current ( Highly Likely !! ) which Will cause Problems for Any Alternating Current appliance.

To recap...AC are Pulses...DC is a steady flow , so DC into an AC appliance will Overheat said appliance , causing a Melt down, in Extreme circumstances even cause Fire...Hence Nikon`s Warning !!

A Well constructed DC-AC converter is Very Expensive,as in well over a Thousand Quid .
Norvicius, I am a qualified avionic engineer, I do know the difference between AC and DC as well as the means of converting one to the other. Converting DC to AC often starts with a square wave in low cost devices.

The mains in most Western countries may not be very clean but it is markedly better than that from a cheap inverter. Now, if I were Nikon I would be advising against the use of converters and the like because I don't want to accept responsibility for fixing my expensive charger when it is used with one.

Chargers do actually run hotter with a poor waveform, I have experienced it with a computer PSU run from an inverter. Run from a mains supply it was markedly cooler.

DC into an AC device where the first component is a transformer will result in a current flow, depending on the DC voltage  that may or may not result in the destruction of the primary winding. Actually delivering DC to an AC device takes some doing but a DC offset on an AC wave form isn't uncommon and may result in magnetic saturation of the core, with attendant problems. However, a Nikon MH22 or MH26 does not contain a transformer, I know I have opened one up to fix a damaged internal lug.

A switched mode power supply can be designed to run on a DC input. Now DC offset is not an uncommon occurrence so most appliances can happily accommodate a degree of offset without problems but too much is damaging. What level of DC is acceptable from a cheap inverter? I have no idea but if it is above the level Nikon designed their chargers to accept, it will be a problem.

So, both poor waveform and DC offset can damage chargers, given that cheap inverters are unregulated the extent of either, or both, could easily be outside the design parameters of a Nikon charger. If you were Nikon, would you risk it?