battery chargers, again
in [Design]
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From: Joerg on 29 Sep 2009 18:56 John Larkin wrote: > On Tue, 29 Sep 2009 13:29:09 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Mon, 28 Sep 2009 19:28:39 -0500, krw <krw(a)att.bizzzzzzzzzzz> wrote: >>> >>>> On Mon, 28 Sep 2009 09:06:34 -0700, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Mon, 28 Sep 2009 09:04:17 -0500, Tim Wescott <tim(a)seemywebsite.com> >>>>> wrote: >>>>> >>>>>> On Sun, 27 Sep 2009 21:16:46 -0700, John Larkin wrote: >>>>>> >>>>>>> Last time a car went dead in the garage, my wife's Fit, I hacked up a >>>>>>> charger from an old DSL wall-wart and a sabre saw as a series current >>>>>>> limiter. The garage geometry makes it essentially impossible for us to >>>>>>> push a car uphill to the street to jump it. Now The Brat left her Echo >>>>>>> in the garege for a month or so and it went dead, too. So I figure it's >>>>>>> time to buy a real charger. Went to Kragen Auto Parts and bought two >>>>>>> (one for here, one for Truckee) chargers. They are all "smart chargers", >>>>>>> namely switchers with electronics, these days. >>>>>>> >>>>>>> The battery is really dead, 1.8 volts. The first charger hums and >>>>>>> outputs nothing. Tried the next one: it hummed for maybe 3 seconds then >>>>>>> sparked and smoked inside. >>>>>>> >>>>>>> Went back to Kragen and traded up, two better chargers. Neither >>>>>>> charges... no current, battery steady at 1.8 volts. Both have their >>>>>>> "charging" LEDs off and "charge complete" LEDs lit. >>>>>>> >>>>>>> Back to Kragen, 3rd time, got all my money back. Passed by Bob Pease's >>>>>>> place all three trips, same collection of rusty VWs everywhere. >>>>>>> >>>>>>> A charger that puts zero amps into a dead battery does that by design, >>>>>>> and there's only one reason to do that: to convince people they need a >>>>>>> new battery. Kragen's sales pitch was exactly along those lines; "Tt >>>>>>> won't charge, so all the cells are shorted." >>>>>>> >>>>>>> So I went to work and nabbed a cute little Lascar bench power supply. It >>>>>>> current limits at 1.2 amps, so I just cranked it up. The battery went >>>>>>> instantly to 16.5 volts, then settled down to 12 or so in a few minutes, >>>>>>> and is creeping back up. >>>>>>> >>>>>>> Interesting. >>>>>>> >>>>>>> So I guess I'll buy a couple of 3 amp or so lab supplies, with nice volt >>>>>>> and amp meters, instead of battery chargers. They're handier to have >>>>>>> around anyhow, cost about the same as a "good" charger, and aren't booby >>>>>>> trapped. >>>>>>> >>>>>>> What Kragen is doing is fraud. >>>>>>> >>>>>>> John >>>>>> I've never had a battery come back from being that dead, and I've had >>>>>> numerous chances to try it (I'm stubborn that way). You'll be lucky to >>>>>> see 12V out of it with the charger disconnected, and I doubt that you'll >>>>>> see that after the first time you touch the key. If you _do_ get the car >>>>>> started it'll just be an opportunity for you daughter to get stranded >>>>>> some place. >>>>> It started OK after about 6 hours at 1.2 amps, started vigorously >>>>> after charging all night. My wife's car was zero-volts dead a couple >>>>> months ago, got rebooted from the DSL wall-wart, and it's fine. >>>>> Lead-acids will sulphate and lose capacity if they sit dead for a long >>>>> time. >>>>> >>>>>> One new battery is cheaper than one tow truck ride. Do the math. >>>>> Our insurance covers the truck ride. >>>> It's the brat's vehicle, IIRC. I wouldn't beg *any* trouble for a >>>> woman's vehicle. ...for more reasons that I can count. The brat's, >>>> never. >>> She left the Echo - her high school car - in our garage because all >>> she wants to drive now is her Jeep Rubicon. Gotta get her to sell the >>> Echo so we can have our garage back. >>> >> Why is everyone spoiling their kids so much? Same with the daughters of >> a business friend, they got cars courtesy of daddy. Plus tuition, room >> and board at rather ritzy colleges. I had to work for my first car. Dad >> wanted to chip in to get me a somewhat decent looking used car upon >> nailing my masters but I said I should really try to pay my own way. And >> did. Couldn't possibly show up for interviews in my old Citroen but the >> TUEV had just blown it out of the water anyhow, declared it >> unroadworthy. You could see the road surface fly by when looking down. >> >> >>> http://www.rubicon-trail.com/ >>> >>> But if her car battery did go dead, she wouldn't have any trouble >>> getting a jump start. >>> >> Like Keith, I'd be concerned about what happens afterwards ... > > > Please select one of the following options: > > _ > / / Drive kid to/from school, to/from softball practice, to/from > friends houses, to/from weekend activities, to/from mall > > or > > _ > / / Buy kid a cheap Toyota. > Option three, in Europe in the 70's: Tell kid to work and use proceeds to buy a bicycle, which can then almost indefinitely fulfill all the tasks from option one :-) Why didn't she just keep the Echo? It's a nice car for college and university, very economical. Probably sips half the fuel of a Wrangler. Of course the coolness factor is only 10% or so. BTW, my first car _after_ receiving my masters degree was a used Chrysler Horizon. Before that the predominant mode of transportation was a 10-speed. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 29 Sep 2009 19:09 Jan Panteltje wrote: > On a sunny day (Tue, 29 Sep 2009 14:58:38 -0700) it happened Joerg > <invalid(a)invalid.invalid> wrote in <7ife8iF31g9tmU1(a)mid.individual.net>: > > >>> Drive a LCD display. >>> Have 4 or more 10 bit analog inputs. >>> Processor core inside. >>> FLASH memory inside. >>> EEPROM inside. >> >> Doesn't need any of that. Just like my car doesn't have too much in >> electronics, on purpose :-) > > Yea, but for some application this is really nice. > http://panteltje.com/panteltje/pic/pwr_pic/ > That link makes a nice bench power supply actually, > digital readout, adjustable current limit and voltage, > just the thing to charge a car battery :-) > And you can program charge curves with timing for any battery. > I've always hoped uC would get some basic necessities to make a real PWM supply. Such as a programmable fixed width blanker in front of one comparator and, ideally, a HV section that can drive one or more port pins to at least 10V (supplied externally). >>> Available in DIL so humans can see it. >> >> No, MSOP10. But I've got a microscope ... > > Oh, but I have got a microscope too:-) up to 1200x with zoom. > But useless for electronics. > I use the Veho "toy scope". Very useful, decent working distance, 20x, just about right for tiny SMT stuff. > >>> Directly drive a logic level MOSFET. >> >> It drives a standard level FET to 10V, which is a requirement in most of >> my apps. Try to get a logic level FET at 200V+. >> >> Ahm, can your PIC swing 2500pF in around 10nsec? If it can't go from >> zero to at least 7V in less than 30nsec you'd hear a loud pop and a >> smell would waft through the air. > > Maybe in your application, but no pops here. > I have shown you the math for the PIC solution some time ago, check memory. > Yeah, but math doesn't miraculously pull a logic level FET out of a hat for my apps. Not even if a black cat crosses the road. > >>> For the price of a PIC. >>> Available from every electronics shop in the universe. >>> >> From regular distributors. > > If I need to order from the US here, it is already too expensive. > Just the posting, and then the VAT import duty. > Yes, I painfully remember that, have lived in Europe myself. But my career started with a US company so we had a nice regular shipping channel. > >> Oh, minor detail, and does you PIC come in rad hard? > > Why? I have no space shuttle ;-) > And I would not dish out a million to fly on the ISS, and > not a 100,000 to fly with Virgin to the 'edge of space'. > And Borsele (nuclear plant) is far enough away from here. > And the remaining Tjernobyl radiation is too weak to make a difference. > And, to use your own arguments against you, is it not nice to have that remote > control option if the thing has to work in a dangerous environment? > Intercase for data logging is very very very nice to have. > Well, my stuff sometimes has to perform at higher altitudes. Remote control isn't useful, if it fails then not so nice things will already have happened. It's like spilled milk. > >> Anyhow, without >> precise current mode control most of my switcher designs wouldn't work >> at all or result in a loud bang. > > Well, I very rarely experience bangs, if so it is because of new years fireworks. > That's because your switchers are probably fairly small or you can afford to oversize your inductors. If your SMPS is >100W, the inductor must be small and the whole thing has to be very fault tolerant you either have current mode control or you cannot do it, usually. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Spehro Pefhany on 29 Sep 2009 20:27 On Tue, 29 Sep 2009 21:45:57 GMT, the renowned Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Tue, 29 Sep 2009 12:50:58 -0700) it happened Joerg ><invalid(a)invalid.invalid> wrote in <7if6p4F31e03vU1(a)mid.individual.net>: > >>> Ah, but, my PIC 16F690 has 2 *hardware* comparators, >>> and does current limit just fine: >>> http://panteltje.com/panteltje/pic/pwr_pic/ >> >> >>Yeah, but: Can your PIC do 500kHz, provide clean current mode control of >>the inductor and blank out the first 200nsec of the MOSFET gate drive >>spike at the current sense node? That's kind of the state of the art >>these days :-) > >OK, but can your 'state of the art' chip do: >Programmable frequency of 19.6, 39.6, 76.9, and 153 kHz AND >Drive a LCD display. >Have 4 or more 10 bit analog inputs. >Processor core inside. >FLASH memory inside. >EEPROM inside. >Reference dividers inside. >Available in DIL so humans can see it. >Directly drive a logic level MOSFET. >Internal oscillator. >Able to replace plenty of other stuff in your circuit because of programmability. >Work on 2.5 to 5 V. >Have serial communication. >Remotely adjustable current and voltage via RS232. >For the price of a PIC. >Available from every electronics shop in the universe. > >Just to mention a few points. For a few cents more you can upgrade to a pin-compatible 64MHz chip! Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Rich the Cynic on 29 Sep 2009 20:12 On Tue, 29 Sep 2009 15:10:06 -0700, John Larkin wrote: > On Tue, 29 Sep 2009 13:29:09 -0700, Joerg <invalid(a)invalid.invalid> >>John Larkin wrote: >>> But if her car battery did go dead, she wouldn't have any trouble >>> getting a jump start. >>> >> >>Like Keith, I'd be concerned about what happens afterwards ... > > Please select one of the following options: > _ > / / Drive kid to/from school, to/from softball practice, to/from > friends houses, to/from weekend activities, to/from mall > or > / / Buy kid a cheap Toyota. or: / / Give kid a bicycle for Xmas. / / Teach kid to walk. Cheers! Rich
From: krw on 29 Sep 2009 20:34
On Tue, 29 Sep 2009 15:56:14 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Tue, 29 Sep 2009 13:29:09 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Mon, 28 Sep 2009 19:28:39 -0500, krw <krw(a)att.bizzzzzzzzzzz> wrote: >>>> >>>>> On Mon, 28 Sep 2009 09:06:34 -0700, John Larkin >>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>> >>>>>> On Mon, 28 Sep 2009 09:04:17 -0500, Tim Wescott <tim(a)seemywebsite.com> >>>>>> wrote: >>>>>> >>>>>>> On Sun, 27 Sep 2009 21:16:46 -0700, John Larkin wrote: >>>>>>> >>>>>>>> Last time a car went dead in the garage, my wife's Fit, I hacked up a >>>>>>>> charger from an old DSL wall-wart and a sabre saw as a series current >>>>>>>> limiter. The garage geometry makes it essentially impossible for us to >>>>>>>> push a car uphill to the street to jump it. Now The Brat left her Echo >>>>>>>> in the garege for a month or so and it went dead, too. So I figure it's >>>>>>>> time to buy a real charger. Went to Kragen Auto Parts and bought two >>>>>>>> (one for here, one for Truckee) chargers. They are all "smart chargers", >>>>>>>> namely switchers with electronics, these days. >>>>>>>> >>>>>>>> The battery is really dead, 1.8 volts. The first charger hums and >>>>>>>> outputs nothing. Tried the next one: it hummed for maybe 3 seconds then >>>>>>>> sparked and smoked inside. >>>>>>>> >>>>>>>> Went back to Kragen and traded up, two better chargers. Neither >>>>>>>> charges... no current, battery steady at 1.8 volts. Both have their >>>>>>>> "charging" LEDs off and "charge complete" LEDs lit. >>>>>>>> >>>>>>>> Back to Kragen, 3rd time, got all my money back. Passed by Bob Pease's >>>>>>>> place all three trips, same collection of rusty VWs everywhere. >>>>>>>> >>>>>>>> A charger that puts zero amps into a dead battery does that by design, >>>>>>>> and there's only one reason to do that: to convince people they need a >>>>>>>> new battery. Kragen's sales pitch was exactly along those lines; "Tt >>>>>>>> won't charge, so all the cells are shorted." >>>>>>>> >>>>>>>> So I went to work and nabbed a cute little Lascar bench power supply. It >>>>>>>> current limits at 1.2 amps, so I just cranked it up. The battery went >>>>>>>> instantly to 16.5 volts, then settled down to 12 or so in a few minutes, >>>>>>>> and is creeping back up. >>>>>>>> >>>>>>>> Interesting. >>>>>>>> >>>>>>>> So I guess I'll buy a couple of 3 amp or so lab supplies, with nice volt >>>>>>>> and amp meters, instead of battery chargers. They're handier to have >>>>>>>> around anyhow, cost about the same as a "good" charger, and aren't booby >>>>>>>> trapped. >>>>>>>> >>>>>>>> What Kragen is doing is fraud. >>>>>>>> >>>>>>>> John >>>>>>> I've never had a battery come back from being that dead, and I've had >>>>>>> numerous chances to try it (I'm stubborn that way). You'll be lucky to >>>>>>> see 12V out of it with the charger disconnected, and I doubt that you'll >>>>>>> see that after the first time you touch the key. If you _do_ get the car >>>>>>> started it'll just be an opportunity for you daughter to get stranded >>>>>>> some place. >>>>>> It started OK after about 6 hours at 1.2 amps, started vigorously >>>>>> after charging all night. My wife's car was zero-volts dead a couple >>>>>> months ago, got rebooted from the DSL wall-wart, and it's fine. >>>>>> Lead-acids will sulphate and lose capacity if they sit dead for a long >>>>>> time. >>>>>> >>>>>>> One new battery is cheaper than one tow truck ride. Do the math. >>>>>> Our insurance covers the truck ride. >>>>> It's the brat's vehicle, IIRC. I wouldn't beg *any* trouble for a >>>>> woman's vehicle. ...for more reasons that I can count. The brat's, >>>>> never. >>>> She left the Echo - her high school car - in our garage because all >>>> she wants to drive now is her Jeep Rubicon. Gotta get her to sell the >>>> Echo so we can have our garage back. >>>> >>> Why is everyone spoiling their kids so much? Same with the daughters of >>> a business friend, they got cars courtesy of daddy. Plus tuition, room >>> and board at rather ritzy colleges. I had to work for my first car. Dad >>> wanted to chip in to get me a somewhat decent looking used car upon >>> nailing my masters but I said I should really try to pay my own way. And >>> did. Couldn't possibly show up for interviews in my old Citroen but the >>> TUEV had just blown it out of the water anyhow, declared it >>> unroadworthy. You could see the road surface fly by when looking down. >>> >>> >>>> http://www.rubicon-trail.com/ >>>> >>>> But if her car battery did go dead, she wouldn't have any trouble >>>> getting a jump start. >>>> >>> Like Keith, I'd be concerned about what happens afterwards ... >> >> >> Please select one of the following options: >> >> _ >> / / Drive kid to/from school, to/from softball practice, to/from >> friends houses, to/from weekend activities, to/from mall >> >> or >> >> _ >> / / Buy kid a cheap Toyota. Kid takes bus, bicycle, or feet. After high school, I did give ours the minivan to go to work and college (until he dropped out). >Option three, in Europe in the 70's: > >Tell kid to work and use proceeds to buy a bicycle, which can then >almost indefinitely fulfill all the tasks from option one :-) > >Why didn't she just keep the Echo? It's a nice car for college and >university, very economical. Probably sips half the fuel of a Wrangler. >Of course the coolness factor is only 10% or so. > >BTW, my first car _after_ receiving my masters degree was a used >Chrysler Horizon. Before that the predominant mode of transportation was >a 10-speed. Our first car was a '70 AMC Gremlin. The in-laws bought it for us as more or less of a wedding present. |