RE: (ET) battery charger

["David Roden (Akron OH USA)" <roden ald net>]

> Speaking of the capacitor, naturally, it's an electrolytic.  I looked 
> long
> and hard at the old one on my charger, but couldn't determine which side
> was the + (there was a littel smudge of something red on the little 
> rubber
> cup around one of the connections, but who knows?) .  Looking at the
> schematic, it looks like it's on an AC portion of the circuit anyway, so
> does the polarity matter?  

Many large-value capacitors are electrolytics, so it would be reasonable 
to assume the charger capacitor is one.  In fact nonpolarized 
electrolytics are available (they're sometimes used for motor starting).

But it's almost certainly not an electrolytic.  I've never seen an 
electrolytic used with a ferroresonant transformer (the ET charger uses a 
ferro transformer to get voltage regulation).  Electrolytics have high 
internal resistance, so they are usually used only for DC filtering and 
motor starting (which is an intermittent use).

Most likely the ET charger capacitor is an AC rated oil filled capacitor.

In any case you cannot -- MUST NOT -- use a conventional polarized 
electrolytic on an AC circuit.  It will be ruined and may well explode.  
If you ever are in the same room with an electrolytic which blows up, I 
guarantee you'll never forget it!


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1974 Honda Civic EV 96vdc
1970 GE Elec-trak 36vdc