Jay Summet via EV wrote:
My vehicle has an old-fashioned dumb charger that contains a
(resonant) transformer, so the lower the input voltage, the lower
the current.
I have a 120 volt "QuickCharge" brand boat anchor (super big
transformer) charger and it has that same feature. It slows down when
you only get 108 volts at the end of a 200' run in a parking deck, but
it also works in reverse...
When connected to a 140 volt (poorly regulated AC generator) it kicks
up the current quite a bit!
If it's a big "dumb" transformer, a 10% drop in input voltage causes a
10% drop in output voltage. This causes a corresponding drop in charging
current, so less AC line current. Such a charger won't overheat your
cords or trip a breaker on undervoltage. But it *will* draw excessive
current and trip breakers with *high* line voltage.
If it's a "smart" constant-voltage transformer (as found in many Lester
chargers), its output voltage is regulated by the nature of the
transformer. The input current stays relatively constant when the AC
line voltage drops. This means the output voltage only drops slightly --
like a 2% drop for a 10% drop in AC line voltage. Similarly, *high* line
voltage barely changes the output voltage (and thus charging current).
Therefore, the AC line current is barely affected by AC line voltage.
A modern switchmode charger has a feedback loop that holds its output
voltage constant despite changes in AC line voltage. This type of
charger draws *more* current when the AC voltage drops, and *less*
current when it rises.
--
Don't worry about people stealing your ideas. If your ideas are any
good, you'll have to ram them down people's throats. -- Howard Aiken
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, [email protected]
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