RE: (ET) charger voltage

["Bob Murcek" <rmurcek geisinger edu>]

Jeff,
The reason you're seeing an odd voltage across the diodes is that when 
operating as rectifiers there's AC on one side of the diode and DC 
(battery voltage) on the other.  So a DC meter sees the usual .6 volts for 
half the AC cycle while the diode is conducting, but then sees a 42-volt 
high half of a sine wave during the other half of the AC cycle when the 
diode isn't conducting.

To test the diodes DC drop you'd need to remove them from the charger and 
run a nice DC load thru them, like maybe a headlight fed from a 12V 
battery...Bob

>>> "Jeff Tickner" <JeffT softlanding com> 1/6/2003 11:31:18 AM >>>
So the voltage drop across the diodes is normal when not connected to the 
pack? I expected to see 42V and that it would drop when I connected the 
pack. The manual says 40V is OK but doesn't say where, before or after the 
diodes...

Jeff Tickner
Technical Support
800-545-9485, Ext 536
SoftLanding Systems




"Elie, Larry (L.D.)" <lelie ford com>
Sent by: owner-elec-trak cosmos phy tufts edu 
01/06/2003 10:47 AM

 
        To:     "'Jeff Tickner'" <JeffT softlanding com>, elec-trak cosmos 
phy tufts edu 
        cc: 
        Subject:        RE: (ET) charger voltage


That's not all that far off.  36V into a low pack is GOOD.  You can only 
source so much current (20 A for the standard charger) and you have to 
overcome the pack resistance.  Think about it; if you had a dead pack it 
would probably take 400A to bring it to 36 V instantly (and that would 
kill something...).  In time, you should reach 42-45V.
 
Larry Elie
 
 
 
-----Original Message-----
From: Jeff Tickner [mailto:JeffT softlanding com] 
Sent: Monday, January 06, 2003 9:37 AM
To: elec-trak cosmos phy tufts edu 
Subject: (ET) charger voltage


I was testing my charger to see if I had a problem with output voltage, I 
did it with the main disconnect out. I have recently replaced the 
capacitor and the diodes. I have a voltage drop across my diodes that 
seems unusual. I have 42V going into the diodes, but only 36V going out? 

But if I let the pack charge, the charging voltage will reach 42V once the 
pack is charged up... 

I have a diode bridge that I used instead of the stock diodes. I got it 
from a friend with a couple 36V EVs (Commutacar and Lectric Leopard) and 
he assured me it was well above specifications. 

Thanks 

Jeff Tickner
Technical Support
800-545-9485, Ext 536
SoftLanding Systems