Audio capacitor to equalize glow plug drain?

[trbankii]

Was vegging out in front of the TV last night watching a couple car shows. In one they were installing an audio system and going over the components. When they were explaining the audio capacitors I lightbulb went on for me (electrical pun semi-intended...:)).

I typically sit there and watch the voltage gauge dip and rise as the glow plugs cycle and wait until they are finished to turn on headlights and start out. Would it be worth hooking one of those audio capacitors into the system to even out the current draw? Or is the glow plug draw more than those audio capacitors would expect to see?

Just brainstorming...

[DmaxMaverick]

A capacitor won't offer any advantage to the GP system. The capacitor in an audio system balances peaks, which can be quite sporadic, and occur rapidly at a high frequency over long periods. The GP's are on for a period of seconds, then off, at a very low frequency (relatively, several seconds, compared to several per second). There's nothing to balance over time, respective to the time involved. In the end, the current draw for the GP's will be the same (actually higher with a capacitor), over the same period of time.

That said, you could use a capacitor capable of charging to the capacity required for GP operation, and regulate the discharge, but the capacitor would have to be very large ($$$ + a place to put it). Essentially, an additional battery would be more effective than a "capacitor", but it's only terminology. A capacitor is a battery, but will only store a very small amount of energy, capable of storing and discharging rapidly, compared to batteries. But, it doesn't come free. The capacitor itself isn't 100% efficient (60-80%, IIRC), which would make the situation of your GP current draw worse.

The audio capacitors are rated at fractional milliamps/milliseconds, while your GP system will require several amps/seconds. The capacitors used to start high-load/high-output electric motors (50 HP+) could be adapted, but they are very costly, larger than 2 automotive batteries and weigh about the same.

[trbankii]

That's sort of what I figured.

Easier and less costly to just wait for the glow plugs to cycle. :)

[DmaxMaverick]

Pretty much. Patience is a virtue, as they say.