Battery Charger

Against what? What sort of an environment are you going to put this into that it needs more isolation than provided by that wall-wart?

Or do you not trust that wall-wart? (I would be surprised if CUI knowingly shipped out defective parts -- they're not just an eBay seller, they've got an office door in the US for process servers to pound on if they electrocute someone).

Or are you planning on using some other wall-wart that you trust less?

If you want direction, here it is: stop borrowing trouble, or explain your real situation. That wall-wart has sufficient isolation in and of itself to make any regulatory agency happy for ordinary usage. You haven't come forth with any planned extraordinary usage, and the best rationale you can come up with is that you want to provide the user "more protection".

I think you're done. Really.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

If the Chinese really put their minds to it I'm sure that they can figure out how to build a profoundly cheap iron transformer adapter that ignores all safety standards, then put it into a case that has a claim of Class 2 or Double Insulation protection stamped on it.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

Well, figuring out what you think you need and why you think you need it is certainly challenging.

You need a means of transmitting power across a gap that is big enough to provide total protection against a totally unspecified electrical phenomenon. Since you just want "more" isolation, and you already have perfectly reasonable isolation, that means that no matter how much isolation you have it won't be enough.

So -- it just can't be done.

There. Problem dispensed with. Unless you choose to communicate your real needs.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

I'm sure they could. The Japanese made a replacement power transformer for cable converters in the early '80s. They left out the thermal fuse, and left off the end bells. We had two catch fire in customer's homes. One burnt away most of the converter's plastic case before the customer pulled the AC plug. We had to track down 300 units out of 10,000 that had been repaired by a New England based converter service company.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

"Tim Wescott"

** Irrelevant, crazy bullshit.

YOU are not SURE of any such thing.

Fuck off - wanker.

Hi Guys,

I found the following link

See Page 36. What do you think? I have no idea how does his circuit work.

melissa

Hi!

This group need some information about what your purpose with the isolation/charger is e.g.:

• fun

• learn

• save money

• design a professional charger

• safer charging

Please note that standard li-ion cells are potentially very unstable if you do not follow some security rules. They can explode and catch fire instantly - or sometimes long after they have been mishandled.

So do not start with standard li-ion chemistry cells.

-

Instead start with LiFePO4 li-ion - or LSD-NiMH.

LiFePO4 - please note the pdf-papers. This accumulator very robust, but still needs care when used. Can under optimally circumstances be fully cycled more than 7000 times. Will not catch fire even if shot with a nail:

-

LSD-NiMH:

These might work 5 years and/or up to 1800 cycles under optimally circumstances. An unloaded LSD-NiMH can keep the charge for more than a year:

Generally:

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Test of another LiFePO4 (LFP) accumulator:

SANDIA REPORT SAND2008-5583 Unlimited Release Printed September 2008 Selected Test Results from the LiFeBatt Iron Phosphate Li-ion Battery Thomas D. Hund and David Ingersoll Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California

Citat: "... Test results have indicated that the LiFeBatt battery technology can function up to a 10C discharge rate with minimal energy loss compared to the 1 h discharged rate (1C). .... The majority of the capacity loss occurred during the initial [!] 2,000 cycles, so it is projected that the LiFeBatt should PSOC cycle well beyond 8,394 cycles with less than 20% capacity loss. .... [See graph pdf-page 23] [ Read: 48% capacity available at -30°C. ] [ very useable! ] [ Read: 65% capacity available at -20°C. ] [ Read: 74% capacity available at 0°C. ] ....

3.8 Over Voltage/Charge Abuse Test In Figure 16 the events in an over charge/voltage abuse test are documented. Initially, as expected, the cell voltage increases quickly while being charged at 10 A, but then slowly increases after 4.7 V. The cell voltage slowly increases for about 30 minutes while the cell temperature continues to slowly rise to about 100 °C at which time cell voltage spikes to the maximum value of 12 V. At about 110 °C the cell vents liquid electrolyte without any fire or sparks and then open-circuits at 116 °C. After open-circuiting and a loss of electrolyte, the cell looses all voltage at 120 °C. The data acquisition shuts down due to a no voltage condition, but temperature is manually monitored until the cell reaches its maximum value at 160 °C about 20 minutes after the cell open-circuited. ..."

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Test of LiFePO4-accumulator:

Nail penetration testing A123 Li-ion [ one of the best LiFePO4-accumulators ]:

-*-

Comparison with other Li-ion chemistries (non-LiFePO4):

Exploding Laptops on Good Morning America:

Nail penetration testing Standard Li-ion:

World's Most Dangerous Battery!:

Modify Li-Po Battery Nail Penetration Test:

Glenn

Even Boing have problems with li-ion:

Quote: "... It is reported that the plane has had two major battery thermal runaway events in 52,000 flight hours, which was substantially below the 10 million flight hours predicted by Boeing, and had done so in a dangerous manner.[2] ..."

Glenn

Yes I am sure. I've seen enough crap from China to be quite convinced that they'll sell anything for a buck (or renminbi).

And it's neither irrelevant, nor crazy, nor, given my experience with Chinese goods, bullshit. You claimed that an iron-transformer wall-wart is automatically safe. I say no, not if some unscrupulous businessman starts shaving pennies by shaving safety.

It's kind of ironic to see an "that's absolutely safe" statement coming from someone who is so prone to telling people that they'll shock themselves to death by not following your arbitrary pronouncements.

I guess the World According to Phil is just a simpler one than the real world. (And somehow always flattering to Phil, oddly enough.)

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

I already have the following battery available

I am trying to learn and this seems like a good problem to solve.

melissa

Hi Melissa

A Li-ion accumulator is not the best place to get started and learn about chargers of reason I wrote earlier.

You need a dedicated fire proof laboratory to learn about standard li-ion charger. I strongly advice against you do this at home, where other sleeps. You also need personel safety equipment, because you can not expect to make an error-free charger the first time. I suspect you do not have access to a dedicated fire proof laboratory?

A li-ion fire can not be stopped with water. Lithium is a very reactive metal like sodium. This is not like blowing some transistors - you are literally "playing" with fire - and disorienting smoke.

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2012-04-11, GM Lithium-Battery Explosion Sparks Fire at Company Test Lab:

January 23, 2013, 787 battery blew up in ?06 lab test, burned down building. The Arizona lab fire showed the challenges facing Boeing?s strategy to safely manage that energy, prevent such a blowout and contain any less serious battery problems.

Quote: "... A single battery connected to prototype equipment exploded, and despite a massive fire-department response the whole building burned down. ... ALPA quoted a 2006 FAA report on transporting lithium-ion batteries as cargo, which concluded that a relatively small amount of heat is sufficient to cause the flammable chemical inside a lithium-ion cell ? called an electrolyte ? ?to forcefully vent ... through the relief ports near the positive terminal.? ... People familiar with the investigation so far confirm that electrolytes sprayed out of the battery in the ANA jet, leaving a dark sooty residue across the electronics bay. Photos show the insides of the battery burned out and blackened. ... To completely rule out any catastrophic high-energy fire or explosion that could result from overcharging a battery, Sinnett said, Boeing designed four independent systems to monitor and control the battery charge.

However, he conceded that if an internal cell shorts and overheats, ?the electrolyte can catch on fire and that can self-sustain.?

?Something like that is very difficult to put out,? Sinnett said. ?Because the electrolyte contains an oxidizer, fire suppressants just won?t work.? ... During testing of a prototype charging-system design in the 2006 incident, ?the battery caught fire, exploded, and Securaplane?s entire administrative building burned to the ground,? according to a summary by the administrative law judge in a related employment lawsuit. ... The cause of the battery explosion was not firmly established. The battery may have been overcharged, and human error in the testing was not ruled out. Indeed, Boeing insists it was an improper test setup. ..."

Glenn

More:

Oct 30, 2012, More Than A Dozen Fisker Karma Hybrids Caught Fire And Exploded In New Jersey Port After Sandy:

Quote: "... water from Hurricane Sandy?s storm surge apparently breached the port and submerged the vehicles. As Jalopnik has exclusively learned, the cars then caught fire and burned to the ground. ... The vehicle, despite only being in limited production, has already experienced numerous fires due to equipment failures and electrical shorts. How, exactly, they caught fire after being submerged in sea water is unclear. It?s possible the salt water caused a short that led to a fire. ..."

Safety Issues for Lithium-Ion Batteries:

Quote: "... As such, failure (in either performance or safety) can be caused by poor execution of a design, or an unanticipated use or abuse of a product.

Passive safeguards for single-cell batteries and active safeguards for multi-cell batteries (such as those used in electric vehicles) have been designed to mitigate or prevent some failures. However, major challenges in performance and safety still exist, including the thermal stability of active materials within the battery at high temperatures and the occurrence of internal short circuits that may lead to thermal runaway [read: Fire]. ... The most common product safety tests for lithium-ion batteries are typically intended to assess specific risk from electrical, mechanical and environmental conditions. ..."

Glenn