battery chargers, again
in [Design]
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From: Jan Panteltje on 29 Sep 2009 17:45 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.
From: Joerg on 29 Sep 2009 17:58 Jan Panteltje 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 It can do a lot more, and higher. > 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 :-) > Reference dividers inside. Yes. > Available in DIL so humans can see it. No, MSOP10. But I've got a microscope ... > 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. > Internal oscillator. Yep. > Able to replace plenty of other stuff in your circuit because of programmability. Not needed. > Work on 2.5 to 5 V. Yes. But can yours work at 40V? > Have serial communication. > Remotely adjustable current and voltage via RS232. No need. It's set and forget. > For the price of a PIC. > Available from every electronics shop in the universe. > From regular distributors. > Just to mention a few points. > Oh, minor detail, and does you PIC come in rad hard? Anyhow, without precise current mode control most of my switcher designs wouldn't work at all or result in a loud bang. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 29 Sep 2009 18:10 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. John
From: Rich Grise on 29 Sep 2009 18:18 On Tue, 29 Sep 2009 10:24:57 -0700, John Larkin wrote: > > 1.2 amps from a Lascar bench supply, overnight, is hardly > overcharging. Contrary to stated theory, the car works fine now. > > I guess several of the posters here, if they left their lights on and > killed their battery, will always have their car towed and the battery > replaced. They have no need for jumper cables, and are happy buying > chargers that only charge batteries that don't need to be charged. > Ouch! John, I've never heard you scathe before, but geez! This post singed my eyebrows! Keep it up. >:-> It helps dispel that "leprechaun" image. ;-D Cheers! Rich
From: Jan Panteltje on 29 Sep 2009 18:42
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. >> 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. >> 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. >> 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. >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. >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. |