In theory, yes. But in practice the drive would still see power applied and would not trigger the &#x27;dump the cache&#x27; firmware until it was too late. You need a little bit of extra circuitry to warn in time before the power gets too low.<p>Usually this works like this: an external voltage powers the drive, inside the drive this voltage is split into two circuit paths. One drives a voltage regulator with a large capacitor on the far side of it, the other drives, usually accompanied by a pull down resistor an input of the cpu in the drive. If that input goes below a specified value then the cpu knows the power is about to fail and will trigger the cache write to the persistent media.<p>Obviously that only holds for the data already present in the memory of the CPU on the drive, the rest of the computer will have to fend for itself.<p>So just adding a capacitor on the outside will keep the drive powered up for half a second longer but won&#x27;t initiate a cache dump (assuming that you&#x27;re not going to end up powering the rest of the circuitry as well, you need to add a diode or something to avoid backfeeding the circuit that charged the cap in the first place).