[jray3]

Caps won't prop up a failing battery because the battery will drain down the caps to a matching, low voltage, and a tired battery will only put extra load on the capacitors if the battery's voltage sags faster than the caps when under load (in parallel). Plus, capacitors won't recover any voltage when resting off of charge, unlike a battery. This means that you'll get one good crank out of a reasonably sized capacitor bank, maybe two, but if the engine fails to start you're out of luck. A solar trickle charger would be no help in that situation. Anybody carry a 12V hand crank generator?

For this reason, I think caps pair better with deep cycle batteries (which normally wouldn't have the cold cranking amps for reliable starting).

Ongoing balancing loads on the caps should be minimal between cycles.

One benefit of a bank of caps is fast boosting via jumper cables. Depleted caps will draw tremendous current, but not for long enough to damage the cables unless you've got a bad connection. Likewise, connecting your caps to a dead car means instant starting for them!