iMiEV charger power vs voltage

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acmotor
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Real Name: Tuarn
Location: Perth,Australia

iMiEV charger power vs voltage

Post by acmotor » Sun, 18 Aug 2013, 05:57

Just another one of those tests that proves nothing but seemed interesting at the time....

I came across an old variac transformer (you know the round ones with 0-260V dial on top).
It was 10A unit really old probably made in the 1940's ? I mean bakelite, black wrinkle paint, 20kg or so.
It passed (amazingly) wiring continuity and insulation tests (1kV megga) so I tried a test that I've pondered for a while.

iMiEV charging off the panasonic brick EVSE (10A nominal) via the variac.
The following are the numbers...

V      W
130 1260
140 1398
150 1490
160 1595
170 1696
180 1775
190 1863
200 1948
210 2071
220 2187
230 2280
240 2410
250 2505
couldn't get to 260 as the current was causing the output to sag a bit on the old variac.
Voltage read with RMS multimeter. Power read with arlec powermeter.
Image

The EVSE itself would report a fault (even unplugged from the i) if the voltage was below 130V.
The i is meant to go down to ~90VAC so I guess ? the 230V EVSE was a limit.
Should try this test with other EVSEs...... maybe.

It is good that constant current EV chargers are just that. i.e. they don't try for constant power that would result in increasing current as voltage drops. This could have been a dangerous feature for EV charging i.e. current (thermal) runaway when cabling voltage drops or contact resistances occured. The current with a constant power charger would just keep increasing as voltage drops.
Image

iMiEV MY12     105,131km in pure Electric and loving it !

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offgridQLD
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Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

iMiEV charger power vs voltage

Post by offgridQLD » Sun, 18 Aug 2013, 19:48

Thanks for doing that it is interesting.

I was thinking when charging off grid having the ability to adjust the charge rate to match the weather conditions of the day could be handy feature.

I'm not sure if I should get the stock EVSE modified to give it this adjustable charge rate feature. Or take a different option - new aftermarket EVSE or home based fixed version with this feature.

Kurt



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