Forums

car usb charger not durable

Started by bob March 28, 2014
bloggs.fredbloggs.fred@gmail.com wrote:
> On Saturday, March 29, 2014 2:22:50 PM UTC-4, mrob...@att.net wrote: > >> What I have done in the past, if I had a car battery that only wanted >> to sip a few mA from the 6 A or 10 A charger, was to stick the dumb >> 1 A charger on it and let it cook for a few hours. After that, I >> could put the "big" charger on it and it would actually charge at a >> decent rate (5 A to 10 A) and then taper off as normal. > > Did you have a meter on that 1A charger?
It didn't have a built-in one, but sometimes I used my DMM (20 A range) inline.
> Was it delivering 1A or just a few hundred miliamperes too?
The 1 A nominal charger would deliver less than 1 A, but more than the 6 A or 10 A charger would. It was 15+ years ago, but I vaguely remember that the battery would initially draw something like 0.2 - 0.3 A from the "1 A" charger, but 0.0 - 0.1 A from the "6 A" or "10 A" charger.
> I suspect the big charger was using a 3-stage algorithm and was > knocked right into stage 3 float charge by the high terminal voltage, > whereas the 1A charger was some simple 1-stage taper charge.
The 1 A charger was indeed a taper charger, but so were both big chargers. Each one had exactly four pieces of silicon in it, no "smarts". I have seen the effect you are talking about with smarter chargers and batteries that have a high terminal voltage for some reason. Sometimes you have to load the battery for a minute or two to drop its terminal voltage and get the charger to switch back to "bulk charge" mode. Matt Roberds
In article <lh89kq$gsf$1@dont-email.me>, mroberds@att.net says...
> > I suspect the big charger was using a 3-stage algorithm and was > > knocked right into stage 3 float charge by the high terminal voltage, > > whereas the 1A charger was some simple 1-stage taper charge. > > The 1 A charger was indeed a taper charger, but so were both big > chargers. Each one had exactly four pieces of silicon in it, no > "smarts". > > I have seen the effect you are talking about with smarter chargers and > batteries that have a high terminal voltage for some reason. Sometimes > you have to load the battery for a minute or two to drop its terminal > voltage and get the charger to switch back to "bulk charge" mode. > > Matt Roberds >
The biggest problem is poor power management in the start up circuit, which for many have none. One of the biggest problems of cheap unmanaged power for starting up these things is the fact that outlet power in the vehicle at times gets turned off/on abruptly, mostly during the starting cycle of the vehicle. These cheap charging units do not provide an instant reset for a proper restart on the controlling chip and thus, could hang the MOSFET into full on, with no switching. So if one has a vehicle that drops the voltage out or dips a lot at the accessory socket during start cycling, it's very conceivable for this to happen. I've had several pass my bench just for an inspection of contents and found the fusible link or component to be opened but no shorted components, a couple did exhibit signs of escaping smoke. Most of them work fine after the fusible component was rectified. Just some thoughts.. Jamie
On Sunday, March 30, 2014 1:21:32 AM UTC-4, mrob...@att.net wrote:
> bloggs.fredbloggs.fred@gmail.com wrote: >=20 > > On Saturday, March 29, 2014 2:22:50 PM UTC-4, mrob...@att.net wrote: >=20 > > >=20 > >> What I have done in the past, if I had a car battery that only wanted >=20 > >> to sip a few mA from the 6 A or 10 A charger, was to stick the dumb >=20 > >> 1 A charger on it and let it cook for a few hours. After that, I >=20 > >> could put the "big" charger on it and it would actually charge at a >=20 > >> decent rate (5 A to 10 A) and then taper off as normal. >=20 > > >=20 > > Did you have a meter on that 1A charger? >=20 >=20 >=20 > It didn't have a built-in one, but sometimes I used my DMM (20 A range) >=20 > inline. >=20 >=20 >=20 > > Was it delivering 1A or just a few hundred miliamperes too? >=20 >=20 >=20 > The 1 A nominal charger would deliver less than 1 A, but more than the >=20 > 6 A or 10 A charger would. It was 15+ years ago, but I vaguely remember >=20 > that the battery would initially draw something like 0.2 - 0.3 A from >=20 > the "1 A" charger, but 0.0 - 0.1 A from the "6 A" or "10 A" charger. >=20 >=20 >=20 > > I suspect the big charger was using a 3-stage algorithm and was >=20 > > knocked right into stage 3 float charge by the high terminal voltage, >=20 > > whereas the 1A charger was some simple 1-stage taper charge. >=20 >=20 >=20 > The 1 A charger was indeed a taper charger, but so were both big >=20 > chargers. Each one had exactly four pieces of silicon in it, no >=20 > "smarts".
Okay, the simplest "old time" bulk chargers, like those manufactured by Mot= orola e.g., were pretty bare with a heavy 60Hz step-down transformer drivin= g some SCRs with a zener in the gate circuit. They were very reliable and l= asted forever, no electrolytics used, the zener would taper the firing angl= e to zero as the battery approached 2.4V/ cell. That type of charger has a = very non-linear operating characteristic as a function of battery terminal = voltage so a few hundred mA here or there, not too mention the difficulty o= f measuring a true average DC charging current, is no big deal.=20
>=20 >=20 >=20 > I have seen the effect you are talking about with smarter chargers and >=20 > batteries that have a high terminal voltage for some reason. Sometimes >=20 > you have to load the battery for a minute or two to drop its terminal >=20 > voltage and get the charger to switch back to "bulk charge" mode.
Your batteries were sulfated, not worth salvaging or risking a breakdown in= the middle of nowhere. Replace them when they lose cranking power, you're = not going buy yourself much time using a charger. The battery charger indus= try is as much a ripoff as the exotic audio garbage.
>=20 >=20 >=20 > Matt Roberds
On Saturday, March 29, 2014 12:05:46 PM UTC-4, Jeff Liebermann wrote:
> On Fri, 28 Mar 2014 15:56:41 -0700, bob <nospam@hotmail.com> wrote: > > > > >I have gone through several car usb chargers that plugs into cigarette lighter plug. > > >They usually die in a few months. > > > > I passed out about 15 of those to various friends and customers last > > Christmas as "stocking stuffers". None have failed so far. Most are > > being used to charge phones. Unlike yours, these have two USB > > sockets. One wired for Apple, and one for the rest of the planet. > > Something like this one: > > <http://www.ebay.com/itm/111192401361>
Ooooh, $2.99- weren't you the big spender!
On Sun, 30 Mar 2014 11:31:50 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

>On Saturday, March 29, 2014 12:05:46 PM UTC-4, Jeff Liebermann wrote: >> <http://www.ebay.com/itm/111192401361>
>Ooooh, $2.99- weren't you the big spender!
I overpaid. Here's a similar 5V 2A device for $1.74 including shipping from China: <http://www.ebay.com/itm/221391009053> They were for my friends as Christmas/Hanukkah gifts and are what we call "reefers", which are free or bargain marijuana cigarettes passed out by drug dealers to entice users into buying the more expensive hard drugs. In this case, my logic was to give away devices that are both addictive and of dubious quality, which would then inspire them to purchase a better device from me: <http://www.ebay.com/itm/390759035788> Unfortunately, none have failed so far, making my holiday sales promotion a rather unprofitable affair. Incidentally, the really good friends also got USB charge/sync cables with their adapters, most of which were either lost, loaned, or in some way destroyed. The geeks got one of these cables instead, which have so far proven to be nearly useless: <http://www.ebay.com/itm/271276827920> $4 including tax and shipping. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Sat, 29 Mar 2014 10:17:55 -0700 (PDT), haiticare2011@gmail.com
wrote:

>snip!
Ouch.
>> Jeff Liebermann >> 150 Felker St #D http://www.LearnByDestroying.com >> Santa Cruz CA 95060 http://802.11junk.com
>OT: Say Jeff, do they still have that big nude hot tub place in Santa Cruz? >I thought that was rather unique, when I was there... >jb
There are two in Santa Cruz that I know of: <http://teahousespa.com> <http://wellwithinspa.com> They're both about 50 meters from each other, so you can easily walk over and try both if you're so inclined. There are also the usual assortment of massage parlors, spas, and medical marijuana dealers. If you can survive in cold water and morning fog, try the nude beaches: <http://www.santacruz.com/guides/santa-cruz-nude-beaches/> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Sat, 29 Mar 2014 10:12:24 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

>On Friday, March 28, 2014 6:56:41 PM UTC-4, bob wrote: >> http://www.ifixit.com/Teardown/Generic+1A+USB+Car+Charger+Teardown/10108
>That website is the usual internet electronics site: junk. The schematics >are both obviously wrong in that the feedback to IN(-) requires a DC >input and therefore should be connected to the output node and not the >diode node. Other comments there are similarly smug and probably wrong.
With all due respect for your instant judgement, I think you'll find that iFixit is one of few sites on the internet that offer help to the shrinking minority of people that have a genuine interest in fixing things. This is largely a self-defense effort against manufacturers (and possibly designers) who favor throw-away electronics and unrepairable devices. The web page above is a user contributed page, which lacks the benefits of a proper editorial review. I would not judge the entire web site on the basis of one web page. <http://www.ifixit.com/Manifesto> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Sunday, March 30, 2014 3:58:30 PM UTC-4, Jeff Liebermann wrote:
> On Sun, 30 Mar 2014 11:31:50 -0700 (PDT), >=20 > bloggs.fredbloggs.fred@gmail.com wrote: >=20 >=20 >=20 > >On Saturday, March 29, 2014 12:05:46 PM UTC-4, Jeff Liebermann wrote: >=20 > >> <http://www.ebay.com/itm/111192401361> >=20 >=20 >=20 > >Ooooh, $2.99- weren't you the big spender! >=20 >=20 >=20 > I overpaid. Here's a similar 5V 2A device for $1.74 including >=20 > shipping from China: >=20 > <http://www.ebay.com/itm/221391009053> >=20 >=20 >=20 > They were for my friends as Christmas/Hanukkah gifts and are what we >=20 > call "reefers", which are free or bargain marijuana cigarettes passed >=20 > out by drug dealers to entice users into buying the more expensive >=20 > hard drugs. In this case, my logic was to give away devices that are >=20 > both addictive and of dubious quality, which would then inspire them >=20 > to purchase a better device from me: >=20 > <http://www.ebay.com/itm/390759035788>
Is that your ad?
>=20 > Unfortunately, none have failed so far, making my holiday sales >=20 > promotion a rather unprofitable affair. >=20 >=20 >=20 > Incidentally, the really good friends also got USB charge/sync cables >=20 > with their adapters, most of which were either lost, loaned, or in >=20 > some way destroyed. The geeks got one of these cables instead, which >=20 > have so far proven to be nearly useless: >=20 > <http://www.ebay.com/itm/271276827920> $4 including tax and shipping.
That thing is ridiulous, dunno who would make use of it unless they think c= lutter is beautiful. The OP's charger could be made to last forever if he tacks a P-FET in there= to deliver the bulk of the current. If you look at some of the Chinese des= ign notes, they're more obsessed with the package, and the electronics is m= erely an afterthought, they refer to the regulator as the 12-to-5V conversi= on circuit and represent it as a very small block of negligible importance-= probably a bunch of "industrial" engineer/designer types. Let's hope and p= ray they stay out of the coffeemaker business.
>=20 >=20 >=20 >=20 >=20 >=20 >=20 >=20 >=20 >=20 >=20 > --=20 >=20 > Jeff Liebermann jeffl@cruzio.com >=20 > 150 Felker St #D http://www.LearnByDestroying.com >=20 > Santa Cruz CA 95060 http://802.11junk.com >=20 > Skype: JeffLiebermann AE6KS 831-336-2558
On Sun, 30 Mar 2014 13:29:39 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

>On Sunday, March 30, 2014 3:58:30 PM UTC-4, Jeff Liebermann wrote: >> <http://www.ebay.com/itm/390759035788>
>Is that your ad?
No. I sometimes resell stuff I buy on eBay for those who do not like to buy things online. There's an amazingly large number of people who live in morbid fear of hackers, cyber criminals, crooks, Chinese vendors, and resellers like me.
>> <http://www.ebay.com/itm/271276827920> $4 including tax and shipping.
>That thing is ridiulous, dunno who would make use of it unless >they think clutter is beautiful.
It's an improvement over carrying a tangle of cables or seperate chargers for each device.
>The OP's charger could be made to last forever if he tacks a P-FET >in there to deliver the bulk of the current. If you look at some of >the Chinese design notes, they're more obsessed with the package, >and the electronics is merely an afterthought,
That's correct. It's the package that sells, not the electronics. A few cents spent on attractive package will yield far more sales than the same amount spent on overvoltage and spike protection. When you're building something to sell for $1.74, there's no room in the budget for frills like protection circuity. Adding a P-FET might cost $0.30 more, which would price the device out of the market.
>they refer to the >regulator as the 12-to-5V conversion circuit and represent it as >a very small block of negligible importance-
Next time I draw a schematic, I'll try to remember to draw blocks of importance somewhat larger.
>probably a bunch >of "industrial" engineer/designer types.
What do you have against industrial engineers and designers? Or do you prefer products that have a miserable user interface, are clumsy o use, that don't fit together, are a pain in the posterior to manufacture, and look awful? Without industrial engineers and designers, everything you own and use would be drab, ugly, clumsy, ugly, dangerous, ugly, boxy, ugly, non-ergonomic, ugly, overly utilitarian, ugly, ugly, ugly, etc, and probably more expensive.
>Let's hope and pray they >stay out of the coffeemaker business.
I switched to tea, but I see your point. For examples of your future coffee hell, see: <http://www.yankodesign.com/?s=coffee+maker> Some are design concepts, but many are available for purchase today. Some may even produce drinkable coffee. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Like a complete idiot, I decided take apart one of my cheapo USB car
chargers and see what makes it work.  I know they are junk, but I
never expected them to be this bad.  Start here:
<http://802.11junk.com/jeffl/LTspice/Cig%20Lighter%20USB%20charger/>

What's inside:
<http://802.11junk.com/jeffl/LTspice/Cig%20Lighter%20USB%20charger/Circuit%20view.jpg>
<http://802.11junk.com/jeffl/LTspice/Cig%20Lighter%20USB%20charger/Top%20view.jpg>

They ground off the numbers from the switcher chip so I couldn't
identify it.  I *ASSUME* that it is a common MC34063A, but that's
apparently not the case because there's a heat sink on the bottom of
the chip that is suppose to be sweat soldered to the PCB.  I therefore
have the wrong chip number.  (Sorry about the focus problem but you
can see the metal bottom on the chip).
<http://802.11junk.com/jeffl/LTspice/Cig%20Lighter%20USB%20charger/SOIC-8%20with%20heat%20sink.jpg>
Of course, it's not soldered, so heat dissipation will suffer.

I'm still not sure it's an MC34063A, but if that's the chip, it's only
rated to 1.5A, not 2.1A.  Argh.  Duz anyone have a clue as what other
chip it might be?

So, I then traced out the schematic. 
<http://802.11junk.com/jeffl/LTspice/Cig%20Lighter%20USB%20charger/Cig%20Lighter%20USB%20schematic.jpg>
It's not an MC34063A because it doesn't oscillate and the schematic is
somewhat different from the test circuits in the app notes and data
sheet.  The LTspice simulation results in zero output.  I'm also not
certain of some of the part values.  The resistors are probably
correct, but the small cap and inductor are bad guesses since my LRC
meter is not available.

I then noticed something odd in the resistor network around the USB
connector.  If you look at R3, R4, R5, and R6, on the schematic, it
makes no sense.  The traces between the data pins on the two
connectors should have been seperated (or cut).  The way it shows on
the PCB and schematic, the pins are shorted together.  No way is that
going to work for both Apple and Non-Apple products.

To be continued, possibly with some measurements, as time permits.


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558