bearing wrote:If we neglect ESR of the cap, we have the RC constant of the output cap and internal resistance of the battery pack to smoothen the current. The cap will only make a noticeable difference if the RC time is as long as the distance between the pulses from the rectifier, or longer. Pulses come at 100-120 Hz, or about 0.01seconds apart. If battery IR is 0.01 ohm, then the cap needs to be about 1F. If battery IR is 0.1 ohm, then cap needs to be about 0.1F. Thats pretty big caps, especially if they need to be rated 400V.
I think I'll make mine without output caps.
Again, I highly recommend using a GFCI and fuses on both AC wires with this kind of charger.
fivari wrote:Aren't the electric circuits in your house protected by fuses and GFCI? You could count on those for protection,isn't it?
Skippic, in your schematic, I think the power resistors are not necessary. The current will be limited by the AC capacitor. It also seems the output caps are not necessary either.
You might want to power your 5v supply directly from the line too, as the output side voltage could vary over a wide range. A old cell phone charger works well for this.
bearing wrote:Are there any schottky diodes capable of mains voltage?
fechter wrote:bearing wrote:Are there any schottky diodes capable of mains voltage?
I've never found any, but didn't look too hard. Most of them are not rated high enough. Ones that are tend to be quite expensive. Making it out of individual diodes is probably cheaper, but more work. Even with Schottky diodes, you'll still need to dissipate some heat. It might be half. A 20W rated heat sink and a regular bridge will be much more economical.
Skippic wrote:Are these not good enough?
Are 250V diodes good for rectifying 220V mains?
Farfle wrote:V2 of this guy has been built. Goes in a a 240v outlet, outputs 55a @ 100v and weighs 4 pounds . 16 min charge on a 1330 wh/hr pack .
Alan B wrote:Bet he meant "old AMD processor heatsink".
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