RE: Charger plug-in

["Eric Chang" <ericchang@my-deja.com>]

>From: "Chris Tromley" <chris_t@microtrac.com>
> Yeah, I guess point I was making (remember I'm electrically challenged) is
>that connecting/disconnecting under load, especially with a charger that
> pulls big amps, seems like a Bad Thing regardless of which goes first.  It
> came to mind because I have an Avcon receptacle and the contacts seem small.
>
>Is it really OK to just pull the plug when you're drawing 30-40 amps?  Maybe
> occasionally but not regularly??
>
>Chris

It is not a very good idea.  If you actually give it a try, you will see
a substantial arc when you break the flow of current.  The best thing to
do is to rely on soft shutoff, but most chargers will not do this
automatically.  If you can shut down the charger, its control circuitry
will throttle back the current flow smoothly without breaking any contacts.

Consider the Russco charger, for example.  Near the end of the charge, the
charger will throttle the current as it senses increasing voltage.  At
this time, it is relative arc-free to pull the plug.  But, if one is 
opportunity charging, or the charger is set incorrectly (too high a
voltage for old batteries), the arc problem will be back.  Pulling the
plug will erode it after several cycles.

Possible solutions are to pop the hood, and turn down the current control
on the charger before pulling the plug.  Another is to use a sacrificial
set of contacts.  For some odd reason, this seems to be more attractive
to the average EV owner.



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