I'm in a country with an unreliable national electricity supply, where staff in the compound in which I live run a generator at certain hours if there's no national power.
Recently, the generator seems to have been outputting too much (light bulbs and fuses blowing, appliances breaking with burning smells) while the national power, when it's on, has seemed too low (light bulbs dimmer than usual, USB devices failing to charge if more than one is connected to one plug).
I wanted to check my more valuable DC appliances are safe, so, while national power is on, I checked the output of their adaptors using a multimeter:
- My laptop adapter seems fine: it's supposed to output 19V and is outputting something like 19.2V
- My adaptor for a lithium polymer battery pack is outputting too much: it's supposed to be an 18V adaptor but it's outputting 20.5V (and the battery itself says its maximum is 19V)
Why would this adaptor be outputting too high a voltage, and is there anything I can do about it? (Other than buying a voltage regulator for all my power outlets - they're hard to find and expensive out here, I intend to get one but would like something for the meantime, and also to understand under what circumstances what types of adaptors will output the wrong voltage like this)
To be clear - unlike most other power adaptor / voltage questions on this site, I'm using the manufacturer-provided adaptor, and I already know the impact of deviations in volts (dangerous if too high, likely to fail quietly if too low) and amps (simply goes unused if too high, might fail or struggle if too low).
