removing surface charge

Can I remove surface charge on a maintenence-free or VRLA type battery the same way I remove surface charge on a typical non-sealed car battery? By turning on the high beams for five minutes, then waiting like 15 minutes after that.

AFAIK, that should be fine. Except for the dryness of VRLA/AGM batteries (hence no overcharging and don't leave them discharged), their behaviour should be similar. Question - does it take as much as 5 minutes on high beam (ie, 150W - 300W) to remove the surface charge? Is it a typical auto battery (300-600CCA; 40-120AH etc)? If it does, that will certainly blow audio "stiffening" capacitors to kingdom come (with the possible exception of one parameter...)!    Nice to hear someone else mention surface charge. I sometimes have difficulty explaining why people's batteries really are ~12.7V & not 13.7V etc....

thanks for the feedback oldspark......and dont worry.  I will disconnect the power cap when the high beams are on.  Even though it would be kinda cool to see one blow up (from a safe distance).

Excuse my ignorance Oldspark but is this related to disconnecting batteries for 20 minutes to remove static when playing around airbags, or removing both leads and touching them together?  Honest question, please remove my ignorance?

Calitech - forgive my bad! My "that will certainly blow audio 'stiffening' capacitors to kingdom come" was not intended as literally destroying them (though I do enjoy people destroying their multi-$hundred super-caps because they didn't pre-charge them as per instructions!). I was referring to those that insist on the electrical requirement for caps close to the sub/amp. I am one that suggests (or knows?) that a much cheaper small battery next to the sub/amp is as effective (if you call having 1,000 to 10,000 times the stored energy for 1/3rd to 1/10th the price as merely being "as effective"). I am not appealing to those that like their bling & show, merely those think they need a cap. Anyhow, I reckon that a battery's surface charge alone has more energy than a cap. The only other parameter of interest is their ESR (Equivalent Series Resistance) which even for a small $35 Yuasa NP7-12 AGM/VRLA battery is 25 milli-Ohms which is less than or similar to many cap ESRs. I'll leave that there - it gets real tech and complex, but I do have a good link somewhere.... And BTW - I wouldn't want to be around an exploding supercap. An old thumb-sized 12V electolytic was bad enough (pop, smoke, sticky gel and some schrapnel). Now for Howie's excellent question... (Ignorance? Nice try Howie - even though I interpret (continued) ignorance as NOT questioning something.) There is no harm asking a question - especially if it clarifies an ambiguity. (Not that I am ever ambiguous, except when "blowing" caps, or whenever I write or say anything.) And here we have a lovely ambiguity - "surface charge" as in static electricity or capacitor-plate stored charge, and battery-jargon's "surface charge". As to airbags? Sorry - my ol'Dear doesn't use batteries... Oh - airbags.... I get it --- they weren't even an option on my old T-model.... No - a battery's surface charge is not static or capacitive charge. A fully charged 12V battery is usually about 12.7V But charge a battery at (say) 14.4V and then remove the charger (or kill the ignition and engine etc). If you observe the battery voltage, it will quickly drop but be much higher than is "full" 12.7V; perhaps say 13.7V. This is due to the "surface charge" and it can stay for quite a while. (Hours, days - I'm not sure.) It takes a discharge to remove it. EG - a reasonable load should see its 13.xV surface charge voltage drop to its "full charge" voltage of about 12.7V (ignoring the battery's internal resistance voltage drop) where is should remain for quite a while (I guess for about 1/10th of its discharge rate before dropping to 12.6V etc). Otherwise a battery's self-discharge will eventually remove it. Geez - you got me dusting off various "old issues" there! And I haven't really defined surface charge - I've merely explained its behaviour. I/we could look that up on www, but I never trust anything I read out there! Alas like many things, I have forgotten the theory but recall its reality. (That's where there is little difference between the experienced "trained" person and the "uneducated" experienced person - noting that both are usually far better than an inexperienced but qualified "expert", IMO.)

Ta for the answers, I'm the second type in your last sentence, but even after 35+ years in the game, I still believe in gaining extra knowledge or asking advice. I still use a Snap-On test bulb for most of my work, when I'm unsure I'll use a DMM but then I've probably triggered 2 airbag lights in all that time, I do know when not to probe, though I still say you can't beat Mr. Snap-On for finding lock triggers or radio mutes. Hell I even use a Mac 120 tester with LEDs for finding tach, it's fast and it works.

Howie - yet again you impress me. And because I have always had a multimeter and know how to use it, I never use a test light. However, if not for my MM, I would surely have a test light. (As to modern mechanics that function without one...!!???) As to the number of times I think I'm being really stupid powering up a multimeter and reading some digits or dial when a test lamp would be so much easier.... No - maybe I'll paraphrase another forum - it's much better buying a $10 brake bleeder with a valve that seizes and rubber that perishes than using a bit of tubing (preferably clear plastic). I presume that is because it costs more and is more complex (and breaks down), and is therefore a superior tool. Else it is because professionals use it for their everyday work, therefore we need it twice a year, or bi-annually etc. (Is this an appropriate point for my new term "SLAM"? In this case I prefer my common term akin to fornicators with a sense of humour - aka F-wits - with F is as in PhD - Doctor of Filosphy - very clever wits.) Anyhow, no hijacking! I wanted to supply the "stiffening cap" link I was thinking of above... Although there are many like this site's (closed topic) " Capacitor Information", one I did like was at the MobileElectronics site as reproduced from an original article by Richard Clark (CarSound) - an apparent guru in the audio field. What is said in the MobileElectronics link below IMHO is good - both Richard Clark's writings, and others in support. I also like the "non-arguments" of the so called knockers (of Richard's cap debunking). I will usually recommend the much cheaper small AGM battery alternative (read: far superior solution!). And FYI - although that site's Pulse-R puts up some seemingly reasonable counter arguments.... No - I'll rephrase that - some seemingly valid debunks - he is way off track whether it be misinterpretation or confustigation. (This becomes apparent at the link he provides at the end of the link below.) If readers herein do not accept or understand that, I could explain what Richard means by half the charge being under 12V; provide the correct Nyquist Sampling Theorem; etc. Mind you, like Richard,, I'd want to keep it it basic - one step at a time - not introduce transient and Fourier analysis (frequency or time-domain) as Pulse-R does later on. Let's just deal with DC and low frequency (sub) stiffening capacitors behavior for now. If that isn't grasped, the high frequency & Laplace have no chance! To quote the Chinese: Enjoy! See " Capacitors, Taken From The Writings Of Richard Clark..".

Howie - "incandescent bulb" - you greenhouse gasser! Incandescents are banned here. Well, soon anyhow - we much prefer those high crestfactor low powerfactor CFLs (Compact Fluorescent Lamps) that take a bit more manufacturing energy than incandescents, and then emit the usual hazardous items (especially if broken) - all to reduce inefficiency by 1/20th from 95% to 90%. Luckily it only applies to our 230VAC domestic lighting - not automotive DC lamps. And thanks for clarifying the names. I'm a noob to them, but already I have been impressed! I intend to get Richard's original article(s) one day.... Amusing isn't it - the cap issue seems to have been solved long ago, yet it still survives. Money & bling? It reminds me of a recent response from a group that confuse a safety function with engine preservation, and still use an engine kill technique known to be damaging. Having rejecting a person's solution (despite underpinning his/her argument(s)), they then ask that person why people still use that old damaging method! (Please - ask Lemmings why they jump - not me!) Howie was worried about sidetracking. I have totally turned this into an Oldie & Howie conversation. For that I apologise. But I'm certain CaliT's original post/question has been answered. A related ambiguity was clarified (surface charge & static). Likewise the ambiguous "exploding cap (myth)" was clarified. And I think a few useful methods and techniques were covered. Now, if I would desist slipping in political comments.... (Whether as revenge or to provoke awareness....)

And the logic (that's my most obtuse pun this month) behind the incandescent bulb was that it "safely" tests things and draws enough current to trip things like lock triggers. Yes all my bulbs at home are low energy and yes unlike the US colonies we run 230AC, but do you know the reason why Europe went 230/240 as against 110?  I know house voltage is 220 in the US. But they split it and while HVAC runs at that, the actual wall outlets are at 110. Those low wattage bulbs remind me of the spurious reasoning behind the Prius. In fact build to scrappage you'd be better off in a BMW/VW/Focus diesel.