- LiIon charger ct - 4 Updates
- It's that time again. - 5 Updates
| Mike S <mscir@yahoo.com>: Apr 05 12:58AM -0700 I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. I hack sawed the transformer case open and found that the primary winding was open somewhere that I couldn't see, so I didn't try to repair it. Also the charge adapter that the battery slides into has a burnt out resistor on the circuit board. It's a very simple circuit board, there are 4 diodes on the input side which I assume is a full wave bridge rectifier. After the rectifier there is a small series resistor (R1) powering an LED across the dc power lines coming out of the rectifier, and a larger resistor (R2) which got hot enough to char the circuit board near it as it was blowing up. I'm guessing it was over-voltaged, or maybe more likely the outputs were shorted together. The V+ output voltage passes through R2. I don't have a schematic, and would like to repair the ct. board if I can choose a replacement resistor that doesn't unsafely charge the batteries. If I get a transformer with the same V and I ratings (14.5V 200mA) I'm wondering what value Resistor to replace R2 with. I am including a picture. http://tinypic.com/m/k2ck8j/3 I read this, "Most consumer orientated lithium ion batteries charge to a voltage of 4.2 volts per cell and this has a tolerance of around ± 50 mV per cell. Charging beyond this causes stress to the cell and results in oxidation that reduces service life and capacity. It can also cause safety issues as well." https://www.electronics-notes.com/articles/electronic_components/battery-technology/li-ion-lithium-ion-charging.php Since the batteries are labeled "12V", if it uses the same LiIon technology the article is referring to, I assume it has 3 cells totaling 12.6V. The transformer was clearly labeled 14.5V 200mA. Also from the web page, "Charging lithium ion batteries can be split into two main stages: Constant current charge: In the first stage of charging a li-ion battery or cell, the charge current is controlled..." It seems like it might be a simple matter of trial and error, power the charge adapter attached to the battery, and find a value of R2 that leaves 12.6V on the output side, when the battery is fully charged. The adapter has no current regulation, other than the series R2. Is that a safe approach? Would a 12V car trickle charger work safely, with a maximum charging current of 2A (based on the web page)? The transformer had a much lower current rating. I'm surprised the charge circuit is so simple after reading this web page! TIA, Mike |
| Mike <ham789@netscape.net>: Apr 05 01:59AM -0700 On 4/5/2019 12:58 AM, Mike S wrote: > current rating. > I'm surprised the charge circuit is so simple after reading this web page! > TIA, Mike Short answer...don't do anything until you figger out what you're doing. Are you sure that they're lithium? Is the picture showing EVERYTHING that is in the charger path? That ain't nearly enough stuff to charge a lithium battery. The picture suggests that you have the typical symptom of what happens when a NiCd battery shorts and the crap unregulated charger melts trying to charge it. |
| tabbypurr@gmail.com: Apr 05 04:49AM -0700 On Friday, 5 April 2019 08:58:51 UTC+1, Mike S wrote: > current rating. > I'm surprised the charge circuit is so simple after reading this web page! > TIA, Mike A 14.5v transformer when rectified would give over 20v output. A resistor that will let the cells charge then drop the V_out to 12.6 when current falls does not exist. I suspect Mike may be correct that the battery is NiCd or NiMH. If you can verify that it is, they usually use 1.3Ah sub-C cells with a card case. Those typically have a 5hr charge time in power tools. The burnt resistor & oc transformer both indicate a significant overload. One plus with 12v & 14v tools is that if all else fails you can run them off a car. Thick wire is necessary. NT |
| Jeff Liebermann <jeffl@cruzio.com>: Apr 05 09:16AM -0700 >I was given an electric drill that uses 12V lithium ion batteries >because the charger didn't work and the batteries died and the owner >lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. -- 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 |
| "Ron D." <ron.dozier@gmail.com>: Apr 04 02:10PM -0700 .PDF is named for Portable Document Format, but it needs a free reader from www.adobe.com. Think of it as a non-editable (not necessarily true) file containing text & graphics that is readable on almost any device. It may contain an index and it may be searchable. It can also be password protected. It can contain forms where you can fill in information. It can also act on those fields like add them and create an answer. PDF's are inherently safer to open. I routinely print to PDF format and rarely print a hardcopy. e.g. An Invoice for an online order. e.g. Print this page for your records. == I bought laces from the auction site. Just bought boot laces. They like to become untied. Good ends and strength. Can be purchased by the inch. |
| Martin Gregorie <martin@mydomain.invalid>: Apr 05 01:08AM On Thu, 04 Apr 2019 14:10:41 -0700, Ron D. wrote: > .PDF is named for Portable Document Format, but it needs a free reader > from www.adobe.com. Or you can try XPDF, free from https://www.xpdfreader.com/ I use the 64 bit Linux version, but it has versions for 32 bit and 64 bit Windows. Its a free open source program. -- Martin | martin at Gregorie | gregorie dot org |
| Jeff Liebermann <jeffl@cruzio.com>: Apr 04 07:35PM -0700 On Fri, 5 Apr 2019 01:08:48 +0000 (UTC), Martin Gregorie >Or you can try XPDF, free from https://www.xpdfreader.com/ >I use the 64 bit Linux version, but it has versions for 32 bit and 64 bit >Windows. Its a free open source program. Many years ago, I got tired of dealing with Adobe Acrobat bugs, hangs and crashes. So, I switched to PDF-Xchange (free version): <https://www.tracker-software.com/product/pdf-xchange-viewer> which works nicely and does most of what I need. One very useful feature is the built in OCR reader, which will convert a non-searchable PDF into one that can be searched. -- 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 |
| bruce2bowser@gmail.com: Apr 05 04:47AM -0700 On Friday, March 29, 2019 at 10:07:28 AM UTC-4, Fox's Mercantile wrote: > it's really slow. I thought you guys might be able to tell me where to > find NOS catgut laces. > I don't want the cheap Chinese catgut. I want good old 'Merican catgut. How should you spell American, anyway? 'Murican? 'Murkin? 'Markin? |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Apr 05 06:03AM -0700 > How should you spell American, anyway? 'Murican? 'Murkin? 'Markin? Keep in mind that the Average American: Does not have a college education, including an Associate Degree (60%). Does not have a passport (64%). Speaks one language – badly (74%). Has never traveled voluntarily more than 200 miles from his/her birthplace (57%). Has never visited a foreign country, not even Mexico or Canada (71%). Cannot name the Speaker of the House, even today (82%) Cannot name the three branches of government (64%) Cannot read at a college level (83%) Cannot read for content (54%). This person cannot follow written-only directions. 60% of American Households do not buy any book in a year. Does not believe in Evolution (42% creationism, 32% evolution, 26% no opinion). Making your question either over the head, or beneath the dignity of the Average American. Peter Wieck Melrose Park, PA |
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