Battery charger shorts out?
in [Car Maintenance]
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From: Sylvain VAN DER WALDE on 3 Dec 2006 05:42 "redwood" <help(a)nooos.com> wrote in message news:4tdtkpF13l0acU1(a)mid.individual.net... > "Sylvain VAN DER WALDE" <sylvain.vanderwalde(a)which.net> wrote in message >>>> I've not yet tried it connected to a battery but it now powers on >>>> without clicking and connecting a DVM to the croc clips shows around >>>> 12.06v or 6.02 on the 6 volt setting. I shall give it a test on a >>>> battery tomorrow. >>> >> Is your meter reasonably accurate? >> These voltage readings seem rather low. > > I think the battery charger voltage increases when connected to a > battery, I will check it out tomorrow. cheers. I'm afraid not. With an unregulated supply, the voltage will drop when connected to a load. It would be interesting to know what the transformer voltage (AC) is with the rectifier disconnected. Those people more knowledgeable than myself should be able to work out the expected DC voltages (2 diodes in series dropping 1.5 VDC each ?). This would also check whether the rectifier is correctly connected. Sylvain. >
From: Dave Plowman (News) on 3 Dec 2006 06:03 In article <4tdtkpF13l0acU1(a)mid.individual.net>, redwood <help(a)nooos.com> wrote: > "Sylvain VAN DER WALDE" <sylvain.vanderwalde(a)which.net> wrote in message > >>> I've not yet tried it connected to a battery but it now powers on > >>> without clicking and connecting a DVM to the croc clips shows around > >>> 12.06v or 6.02 on the 6 volt setting. I shall give it a test on a > >>> battery tomorrow. > >> > > Is your meter reasonably accurate? > > These voltage readings seem rather low. > I think the battery charger voltage increases when connected to a > battery, That would be a clever trick. ;-) Unless there is some form of electronics regulating the output the open circuit voltage should be very much higher than that. Have you measured the AC voltage direct across the transformer - ie the input to the rectifier? > I will check it out tomorrow. cheers. -- *Laugh alone and the world thinks you're an idiot. Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: Stuffed on 3 Dec 2006 08:29 "Dave Plowman (News)" <dave(a)davenoise.co.uk> wrote in message news:4e8f65c60adave(a)davenoise.co.uk... > In article <4tdtkpF13l0acU1(a)mid.individual.net>, > redwood <help(a)nooos.com> wrote: > > "Sylvain VAN DER WALDE" <sylvain.vanderwalde(a)which.net> wrote in message > > >>> I've not yet tried it connected to a battery but it now powers on > > >>> without clicking and connecting a DVM to the croc clips shows around > > >>> 12.06v or 6.02 on the 6 volt setting. I shall give it a test on a > > >>> battery tomorrow. > > >> > > > Is your meter reasonably accurate? > > > These voltage readings seem rather low. > > > I think the battery charger voltage increases when connected to a > > battery, > > That would be a clever trick. ;-) Unless there is some form of electronics > regulating the output the open circuit voltage should be very much higher > than that. Have you measured the AC voltage direct across the transformer > - ie the input to the rectifier? I seem to recall my cheap n nasty charger puts out around 12v when not connected to a battery, but I've seen it reach 17v when charging a failing battery after 12 hours or so. Which I don't think was good for the battery but at least it was an old and tired one. I'm thinking about Heath Robinsoning something using an old 240v AC motor and spare alternator now...
From: Bill on 3 Dec 2006 09:14 In message <ekujcb$7vn$1(a)news.freedom2surf.net>, Stuffed <talking(a)rse.non> writes >> That would be a clever trick. ;-) Unless there is some form of electronics >> regulating the output the open circuit voltage should be very much higher >> than that. Have you measured the AC voltage direct across the transformer >> - ie the input to the rectifier? > >I seem to recall my cheap n nasty charger puts out around 12v when not >connected to a battery, but I've seen it reach 17v when charging a failing >battery after 12 hours or so. Which I don't think was good for the battery >but at least it was an old and tired one. What was the shape of the 12.06V though? The DVM was probably struggling to realise it was DC, try putting a large-ish electrolytic cap' across it to smooth it out and measure again. -- Bill
From: David Taylor on 3 Dec 2006 09:21
On 2006-12-03, Sylvain VAN DER WALDE <sylvain.vanderwalde(a)which.net> wrote: > > "redwood" <help(a)nooos.com> wrote in message > news:4tdtkpF13l0acU1(a)mid.individual.net... >> "Sylvain VAN DER WALDE" <sylvain.vanderwalde(a)which.net> wrote in message >>>>> I've not yet tried it connected to a battery but it now powers on >>>>> without clicking and connecting a DVM to the croc clips shows around >>>>> 12.06v or 6.02 on the 6 volt setting. I shall give it a test on a >>>>> battery tomorrow. >>>> >>> Is your meter reasonably accurate? >>> These voltage readings seem rather low. >> >> I think the battery charger voltage increases when connected to a >> battery, I will check it out tomorrow. cheers. > I'm afraid not. With an unregulated supply, the voltage will drop when > connected to a load. It would be interesting to know what the transformer > voltage (AC) is with the rectifier disconnected. Those people more > knowledgeable than myself should be able to work out the expected DC > voltages (2 diodes in series dropping 1.5 VDC each ?). This would also check > whether the rectifier is correctly connected. Without smoothing capacitors (or a battery) it's not DC, though, it's full-wave rectified AC... -- David Taylor |