Ya think these could spin over a Wankel?

The energy density isn't quite up to NiCd or Lithium batteries but I bet
they are much more tolerant to being run down or left for dead over
winter than any battery technology.

http://www.youtube.com/watch?v=y33tDw6BZh4

-- Mark LaPierre

Capacitors leak :)

Paul Lamar


And batteries leak and explode too but that hasn't stopped anyone from
putting them in trains, planes, and cars.

Mark LaPierre


I don't think they leak down as fast as capacitors :)

There is a capacity/volume ratio question as well.

Paul Lamar


Oh, you were referring to electrical leakage, not liquid leakage, or
leakage of the magic smoke after which they don't work at all. ;-)

The newer capacitors, of the type referred to here, have a very low
leakage rate.  I bet that many people keep a trickle charger around for
overwintering their chemical batteries.  Hooking up such a device would
keep the charge up over time.  Also some experimentation to determine
the degree of charge loss over time would be appropriate.  Mouser has
some smaller sizes available for small money.  Maybe I'll order some up
and do some testing.

The major issue I see with them is the shape of the discharge curve.
Chemical batteries have a relatively flat discharge curve for the first
half of their capacity, varying to some degree by various chemistry,
where capacitors have much more of a straight discharge slope.

I think that combining them with a chemical battery would result in a
lighter weight storage system and more powerful starting impulse at the
same time.  The chemical battery would keep the charge voltage on the
capacitor up and the capacitor would provide the big batch of energy
required to crank the starter where the small battery would not be
sufficient for the task at hand.

Mark LaPierre