Battery charger shorts out?
in [Car Maintenance]
|
From: Sylvain VAN DER WALDE on 3 Dec 2006 09:42 "David Taylor" <davidt-news(a)yadt.co.uk> wrote in message news:slrnen5nb6.msd.davidt-news(a)outcold.yadt.co.uk... > 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... > Hmm! I haven't seen a battery charger with a reservoir capacitor, a smoothing capacitor, a choke, or series resistor; yet such chargers are DC _in practice_, if not in theory. Thanks for reminding me about capacitors; in a conventional power supply they would raise the output voltage (not applicable in a basic battery charger). Sylvain. > -- > David Taylor
From: Duncan Wood on 3 Dec 2006 10:33 On Sun, 03 Dec 2006 11:03:32 -0000, Dave Plowman (News) <dave(a)davenoise.co.uk> wrote: > 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. > The DC voltage will rise when you attach a battery, as it will if you attached a cap, in the former to the battery terminal voltage, in the latter case to the peak voltage of the waveform.
From: Duncan Wood on 3 Dec 2006 10:35 On Sun, 03 Dec 2006 14:42:40 -0000, Sylvain VAN DER WALDE <sylvain.vanderwalde(a)which.net> wrote: > > "David Taylor" <davidt-news(a)yadt.co.uk> wrote in message > news:slrnen5nb6.msd.davidt-news(a)outcold.yadt.co.uk... >> 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... >> > Hmm! I haven't seen a battery charger with a reservoir capacitor, a > smoothing capacitor, a choke, or series resistor; yet such chargers are > DC > _in practice_, if not in theory. > Thanks for reminding me about capacitors; in a conventional power supply > they would raise the output voltage (not applicable in a basic battery > charger). > > Sylvain. > >> -- >> David Taylor > > They're not DC in practice, in pratice they supply a pulsed DC charge, hence why they're all rated at RMS. Wheras the rate of charge is the average current, which will be lower. Marketing :-)
From: Dave Plowman (News) on 3 Dec 2006 11:32 In article <AnBch.1723$_74.1486(a)newsfe1-win.ntli.net>, Sylvain VAN DER WALDE <sylvain.vanderwalde(a)which.net> wrote: > > Without smoothing capacitors (or a battery) it's not DC, though, it's > > full-wave rectified AC... > > > Hmm! I haven't seen a battery charger with a reservoir capacitor, a > smoothing capacitor, a choke, or series resistor; yet such chargers are > DC _in practice_, if not in theory. Thanks for reminding me about > capacitors; in a conventional power supply they would raise the output > voltage (not applicable in a basic battery charger). The battery acts as a vast capacitor, though. -- *If you ate pasta and anti-pasta, would you still be hungry? Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: Paul on 4 Dec 2006 11:07
redwood wrote: > "Andrew Gabriel" <andrew(a)cucumber.demon.co.uk> wrote in message > > S4VB is a 4A bridge rectifier, and the 10 means 100V working. > > > > A 10A or higher (50V or higher) bridge rectifier will be fine. > > (A 4A bridge rectifier was obviously inadiquate.) > > I would also get some heat sink compound to smear between the > > new rectifier and the heatsink. > > Got the rectifier from my local Maplins and is now fitted. It's twice > the size of the original with bigger spade connectors so had to replace > the ends of the 4 wires. It was a bit confusing knowing which way round > the - wires go as the only markings on the new rectifier only displayed > on one side showing the AC & +. Going round in a clockwise direction, > if the 1st terminal is AC+, the 2nd terminal is DC+, I connected the 3rd > terminal to AC-, and the 4th terminal to DC- > > 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. Don't buy anything from Maplins. My broadband started to go slow and my ISP said I needed a new filter. Maplins said I needed new cable. I bought new cable but the broadband speeded up again - must have been BT. So I took the cable back. But because it had been machine packed there is no way I would return it "in the same condition". The cable WAS "in the same condition". But the idiots said the packing had to be the same -- impossible! If they want to get things back "correctly" they should use packing it is possible to pack. Every other company I've taken anything back to, in living memory has accepted it back with full refund. Except Maplins. Don't even think of shopping with them. |