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Fast Charge

A project log for Little Flash

Little Flash runs for twenty minutes, charges in ten seconds.

Mike RigsbyMike Rigsby 05/20/2019 at 19:522 Comments

Today is the big day--I prepared to (from a distance) connect 9000 charged farads (8.1 volts) to 1050 partially discharged farads (3.5 volts).

Nothing spectacular to report--probably got enough charge (in ten seconds) to run for 20 minutes.

Peak current during the transfer was around 45 amps and the hottest physical component (plug connector, #18 wire) reached 122 degrees F. The wiring and the connector represent about .1 ohm, so that resistance limits the transfer.

To charge Little Flash in one second, I would need to transfer about 400 amps. The connector and wire size to accomplish that (for a one pound robot) seem impractical--so I'll be happy with a ten second charge for now.

Discussions

Ken Yap wrote 05/20/2019 at 23:29 point

Probably the supercap has significant internal resistance too.

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Daren Schwenke wrote 05/21/2019 at 00:08 point

Resistance leads to heating, heating leads to the electrolyte boiling, and electrolyte boiling leads to explosions. This is the path to the dark side.  :)

More perfectly good capacitors than I care to admit have met their demise at my hands.  You think a gunshot is loud?  Trying overloading a supercap..

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