Just a question

Aug 20, 2006 5 Replies

When I was in the middle of the quagmire concerning my scooter batteries, someone mentioned that, in order to provide the best charge for his batteries, he installed a capacitor (I think that's what he said) on the positive side of the charging unit. Call me stupid; while I know about "Ohm's Law," as well as the basic elements with respect to how electricity works (i.e., electricity being nothing more than electrons traveling through a system that has some of the elements -- on the periodic table of elements -- that are able to 'transfer' electrons, as the outer shell has but one lone electron and therefore, electrons can travel through the process of transferring these electrons) -- I did take a few "double EE" courses while attending college -- but I never learned the "basics" of a circuit board, although I do realize that "electricity is, by nature, 'lazy,' as it will usually choose the easiest and shortest path -- I lack the knowledge of some of these other issues.



Therefore, my question, said in so many words, is: what does this device do? (capacitor) -- if that is what he used.



Thanks,



Mark



A capacitor smooths voltage.

I suppose it might do something if the charger uses pulsating voltage (most do), but then, the battery itself acts like a very large, rather slow capacitor itself, kind of swamping any possible advantage.

Tim

-- Deep Fryer: a very philosophical monk. Website:

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But yes - the battery is _very_ slow as a filter cap... ever tampered with a power supply with dried out electrolytic cap(s)? High ESR -->

slow --> high ripple and low effective voltage. So with pulsating voltage charger, the cap increases the effective voltage, by multiplier sqrt(2) (in case of sine wave).

Only if rectified, mind you.

Voltage doesn't matter if the output is in fact more like constant current (or current limited). In that case, voltage will rise to whatever it ultimately wants to.

Tim

Deep Fryer: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms

We used one of those thermocouple auto coolers as a small fridge. My friend was running it off a battery charger and it cooled poorly. I added a cap from an old printer and it started to freeze up - we had to drop it to 6 volts from 12.

Yes, if it's constan current or current limited, but if it's a constant voltage charging (like lead batteries usually), I was actually still wrong, as it's not the effective voltage even then that matters. But it's the effective time, which is increased by the cap (without filter cap the battery gets charged only at the peaks of the pulsating voltage, but with a filter cap added, it makes the voltage steady, charging the battery all the time).

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