Charging your battery with 5V from the USB port is a very bad idea and might cause the battery to explode and set your house on fire.
I must say I find the above comment quite insulting, for three reasons:
1. The output voltage for most cell phone chargers is 5v, as I confirmed it is with the charger from my old phone (which is where the battery I used came from).
2. I am not foolish enough to leave the battery charging unattended or for prolonged periods of time.
3. The above YouTube clip was of somebody that was INTENTIONALLY blowing up Li-ion batteries, and for all we know he could have been charging them with 10x the designated operating voltage.
If I should stop posting within a few weeks I have probably died of Li-ion toxicity or burnt my house down. If that happens I will be sure to modify my USB remote accordingly. Thank you for your concerns.
P.S. Despite feeling slightly insulted by your comment, I do appreciate the constructive criticism.
I have no idea why you find my warning insulting as I am only warning you about a very serious safety issue.
The cell phone charger you mention, is just a 5V power supply, the actual charging of the battery is done inside the phone which contains a charger circuit, most likely something like this:
As you can see, this is a very small and very simple circuit but it is necessary and you simply can not safely charge a li-ion battery without such a circuit. Li-ion chargers follow a CC/CV (constant current/constant voltage) algorithm. In the CC stage, a constant current is applied until the battery voltage reaches 4.2V at which time it than changes to the CV stage where the voltage is held at 4.2V and the current slowly drops and than terminates when the current is < 3% of the battery capacity.
Manufacturers of Li‑ion cells are very strict on the correct setting because Li-ion cannot accept overcharge and the charging voltage should never exceed 4.2V (+/- 0.05%)
When li-ion cells are used inside consumer electronics, unprotected cells will be used and the device will have a circuit that protects them from over charging or discharging. If they are used in flashlights (like 18650 cells), the cells will have an added protection circuit.
http://www.lygte-info.dk/info/battery%20protection%20UK.htmlYou might think that it is trivial but In March 2007, Lenovo recalled approximately 205,000 batteries at risk of explosion. In August 2007, Nokia recalled over 46 million batteries at risk of overheating and exploding. One such incident occurred in the Philippines involving a Nokia N91, which uses the BL-5C battery.
In December 2006, Dell recalled approximately 22,000 laptop batteries from the US market. Approximately 10 million Sony batteries used in Dell, Sony, Apple, Lenovo/IBM, Panasonic, Toshiba, Hitachi, Fujitsu and Sharp laptops were recalled in 2006. The batteries were found to be susceptible to internal contamination by metal particles. Under some circumstances, these particles could pierce the separator, causing a short-circuit.
In October 2004, Kyocera Wireless recalled approximately 1 million mobile phone batteries to identify counterfeits.
Frans
