CO

Thanks for all the replies. Good information.

bpulv Loc: Buena Park, CA

Theoretically a capacitor in a DC circuit will hold a charge forever, however that is not true in the real world because there is always some leakage across the dielectric between the plates and or leakage through resistance in the circuit in which it is installed. Like all devices that use charged capacitors for electrical storage, capacitors do discharge slowly with time. Sometimes a fully discharged capacitor will become degraded as a result of a breakdown of the dielectric, the insulating material between the plates of the capacitor. If that happens, the capacitor can (not will) fail to charge properly or even short when a charging voltage is finally applied. Therefore, it is a good idea to make sure that there is some level of charge on the capacitors most of the time as a protective measure. Certain types of capacitors are more suitable to this than others. For example, electrolytic capacitors.

bobmcculloch Loc: NYC, NY

Slowly dissipates, depending on how 'conditioned' the capacitors are, should be used every month or so to keep the capacitors in good condition

abc1234 Loc: Elk Grove Village, Illinois

Look at Bill's advice to remove the batteries. That is more important than worrying about the capacitor. The advice is good because as long as you have them in the flash with the door closed, the flash will drain the batteries albeit very slowly. Do not be surprised if the next time you use it, the recharging time is longer. However, a more important reason for removing them or opening the door is to prevent the batteries from leaking. I do not know how true that is of current batteries but why worry.

To repeat another bit of advice, do not open the flash and play with the circuitry. The capacitor has enough juice in it to give you a shock you will remember. And if you have heart disease, you may not remember the shock and we may be remembering you. Anyway, you have no business opening the flash any more than you would fiddle with the brains of your camera.

bobmcculloch Loc: NYC, NY

Funny thing, kids are coming over today, need the flash for some shots of them indoors, don't remember when I last used it, got it out, found rechargeable batteries in it, no leakage, hit the switch instant on, instant ready, I am letting the capacitor charge a while but worked right out of the bag, that's the way I like it, got lucky this time.
Data, Sigma Flash, IKEA batteries.

SierraP Loc: Eastern Sierras

Good question, Since the insulation and nothing else in the capacitor is perfect, there is a very slow electrical leakage. In time the charge will be totally discharged. Don't worry about it. Almost everything electronic has capacitors in them and they are very reliable. In the "old days" capacitors were know to leak and even explode. Modern materials and techniques have about perfected them. There is even talk about using capacitors in automobiles instead of batteries.