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Old 09-17-2009, 06:43 PM   #162 (permalink)
jyanof
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Quote:
Originally Posted by vwdevotee View Post
I might also be wrong, but it's my understanding that after the bridge rectifier there is normally a filter capacitor which maintains the output voltage very near peak.
The peak voltage from 120AC is about 170V - I've noticed about 170VDC on the output side of the rectifier - my scope doesn't seem to be too accurate when 'zoomed out' that far, so it's probably a little less considering the diode voltage drop.

When a load is applied, the voltage on the DC side of the bridge looks like a saw tooth - it'll peak to 170VDC and drain as charge is drained from the filter caps.

So, true - if you had a large enough filter cap relative to your load, it should stay very near peak voltage. A smallish cap or a large load will make that saw tooth discharge slope very steep and your average voltage will be lower...

I've also heard that a 144V pack can be charged with a simple rectifier setup. However, that 170V peak is only for a short time every cycle, so I suspect the average current would be very low as the batteries charge. I suspect it'd take a long time to fully charge. Maybe the K&W limited battery voltage for this reason?
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