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Old Aug 11, 2011, 12:35 PM
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Quote:
Originally Posted by utx View Post
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Yes, it looks so. Can you measure your car charger voltage? My dedicated "charger" provides 4.20v on pin 4, and my camera has a schottky diode on pin 4 as the only part. By principle, the voltage on battery module can not raise above 4.02v. I measured there about 3.95v - i. E. Far from fully charge.
My first test sequence that yielded the 35 min. battery-only recording after the car charger power test was done with the car charger that came with the #2 camera. It has the mini-USB cable integrated into the car charger plug. I could not safely measure the voltage on pin #4 with this one due to the size of my voltmeter probes and no separate mating mini-USB connector available to access the pins. But others have tested the similar car chargers and reported elsewhere in this thread voltage on pin #4 similar to your measurement.

On my second test sequence I used the car charger that came with my Jumbo #11 to power the same small #11 used in the prior test. That car charger has a plug with no integrated cable. Instead it plugs into the car charge socket and has a standard 4 pin female USB plug, with two supplied cables... one being a two wire cable terminated with the special mini-USB plug for powering the camera while recording, and the other a standard 4 wire mini-USB cable for just charging the camera, I guess, via the normal voltage on Pin #1 through the camera's dedicated CC-CV charging IC. I was able to measure the voltage on JUST the charger plug (with no attached cable), and that outputs an even 5.0V between the two outer contacts, consistent with a standard USB plug. And I was able to check continuity on the two-wire special mini-USB plug, confirming that the +5V from the car charge plug normal USB pin#1 does, indeed, cross over to pin#4 on the mini-USB end. So this car charger supplies a full 5V to the camera! I don't know if the Jumbo circuit board has any other components to drop the voltage down futher, or just relies on the battery protection circuit board to clamp the excess voltage from reaching the battery terminals (but I will contact the developer to find out. I have used my 4 AAA cell NiMH external battery pack to power my #2 with no adverse results (yet!), and it delivers close to 5V to the camera when freshly charged.

I guess this newer charger cable could be used to power the camera from a computer while recording.

Quote:
Originally Posted by utx View Post
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There are two circuits in my camera - cc/cv charger ic that limits voltage to 4.2v and limits current. But it is used only if i power the camera from pin 1.

If i power the camera from pin 4, the only protection represents the breaker inside the battery. I can measure exact voltage when it breaks, but is is probably a bit more than 4.2v (4.3v?). Keep in mind, that the circuit inside the battery module is not intended as charging controller. It is a last resort damage protection.
Yes, I fully understand this! The protection circuit on a battery has been tested on a battery from the old 808 camera (results in chucklohr.com). Not the same battery, but I believe the protection circuit boards all function similarly. It brackets the voltage, chopping off excess voltage at slightly above 4.2V and chops off power for low voltage cutoff battery protection. down around 3.0V. But the LVC is never reached WHILE RECORDING, because the camera cannot operate at a voltage below approximately 3.6V. It will stop recording, save the file, then shut down. The LVC 3.0V trip would only be reached if the camera is left idle for a very long period, because the internal clock is kept powered while the camera is shut off. At any rate, if the camera stops recording at 3.6V, there is a slight voltage recovery in the lipo cell when the load is reduced. This has been measured on the old 808 battery test to be about 3.7V.

Quote:
Originally Posted by utx View Post
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no, connecting any power supply in parallel with lipol battery is always a bad design. Even with only 4.2v power supply, there is a risk of over-current when the battery is depleted.
Yes, I understand this, too. I did not mean to imply otherwise. When I connect my lipo flight packs in parallel prior to charging, I make sure they are within .1V of each other using a cell balancer, and they are charged and balanced with a dedicated lipo charger. The voltage surge when connecting lipos in this manner is well controlled and safe. If the resting voltage of the camera cell is about 3.7V after the battery gets low as mentioned above, this represents about 15% of the battery capacity still remaining in the cell. Not fully depleted, but low never the less. Connecting an external battery pack is best done with the internal cell fully charged, though I have done it with the camera having just shut down from a low battery voltage with no obvious problems.
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Last edited by Tom Frank; Aug 11, 2011 at 02:20 PM.