OT: Looking for an odd battery for a camcorder

[Barrington]

One last thought. The standard 7.4V FV50 is so ubiquitous that one would inevitably get fitted to one of these cameras by accident by someone, somewhere, sometime. Assuming that would be catastrophic if the design voltage is indeed 3.7V then it might hoped that there would be a warning sticker near the battery compartment to that effect.

Powering up and shutting down after a second or two when battery voltage is very low is not uncommon. Sometimes it's because an additional load has to be applied for a short time before measuring the voltage to test internal resistance. Usually some graphic would be displayed rather than just the backlight powering up. (A backlight might possibly work o.k. on half the supply volts.)

So, if out of other options, rather than dump it straight away I'd just try it at 7.4V. Worst case it'll destroy a 'found' camera valued at less than $20 which uses a non-standard, now apparently unobtainable battery... Not much to lose.

Cheers

[J Tiers]

Doubt it. The charger for it is 5V, in fact it can charge from the supplied charger or a USB port (charger has USB connection). The battery is charged from the USB when in the camera.

While it is possible that the camera includes a boost charger, it seems like the long way around. There is, of course, no voltage information on anything but the battery that it came with, and the known voltage of USB.

Whatever importer slapped "OMNI2" on this very standard looking camera was not interested in having anyone able to buy batteries from others.

I do understand your point. But, the probability is that the apparently unused camera actually came with this battery. The only further thing I can do, and may, is to check the battery terminals of the camera when it is in charge mode. Somehow I did not check that, despite intending to, last time I was in the lab.

One interesting thing is that the battery checks "open", but when voltage is applied to it, there is no draw of current until about 3.4V. At that point, current draw would rapidly increase if allowed to. However, it does not appear to charge the battery even when current is limited. (nobody have a cow, here, I don't charge Li batteries that way)

That may indicate that the battery is below the 3.7V which is possibly the minimum for the cell.

[J Tiers]

Well, it seems to be charging off an HP supply, using a VLCC protocol, limited at 4.15V, and 95 mA. The voltage limit is just under the marked limit, and the 95 mA is C/10 for the battery. SHould be about right. So far the volts under charge are up to 3.6 (about 3.55 when resting).

The charging circuit in the camera is questionable, although it may not operate unless it finds a battery both present, and within the voltage specs. I do not find anything but a low voltage present. But the charger seems to be trying to find a battery, as it kicks up voltage every so often.

Yeah, no machining content, but ther may be some video content if I can get this up and running. (You should have known that an EE could not leave something like this alone without trying stuff)

[J Tiers]

Got it up to 3.8V, and put it in the camera to finish charging, if it will.

[psomero]

The quiescent current on a protection circuit should be in the microamp range and internal self discharge will be a couple percent per year, so it could be salvageable.

You will need to open up the pack and poke cells directly. The PCM will likely have a protection FET that opens on LVC/OVC and effectively unplugs the cells from the world.

If cell(s) are severely depleted (say 0.5V/cell), it's donezo and your best bet is to find a comparable size and form factor cell and do a swap. To charge them back to life would be a legitimate fire risk and I highly advise against that. You can form lithium metal dendrites at low SoC and those spikes will actually get big enough to poke through your separator and make dead shorts in the cell, which is very bad.

Find a cell that has an equal or higher charge current rating so that you can use the existing charger without pushing too much current and harming the new cells.

If they're like 2.5V/cell you might be able to bypass the PCM circuit and directly punch them back to a level above the low voltage cutoff value of the PCM circuit, then it will work like normal.

[J Tiers]

One last thought. The standard 7.4V FV50 is so ubiquitous that one would inevitably get fitted to one of these cameras by accident by someone, somewhere, sometime. Assuming that would be catastrophic if the design voltage is indeed 3.7V then it might hoped that there would be a warning sticker near the battery compartment to that effect.

Powering up and shutting down after a second or two when battery voltage is very low is not uncommon. Sometimes it's because an additional load has to be applied for a short time before measuring the voltage to test internal resistance. Usually some graphic would be displayed rather than just the backlight powering up. (A backlight might possibly work o.k. on half the supply volts.)

So, if out of other options, rather than dump it straight away I'd just try it at 7.4V. Worst case it'll destroy a 'found' camera valued at less than $20 which uses a non-standard, now apparently unobtainable battery... Not much to lose.

Cheers

Well, I am pretty confident it does NOT run on 7.4V. I got the battery (that came with it) charged up far enough with a bench supply that the camera would charge it. It charged to 4.15V, nearly exactly what I set the bench supply for based on the battery label, and then shut off. That tells me the camera has no boost supply, and runs indeed on the single cell lithium battery, as it seems, based on the 5V charging supply.

However, the camera has started up only three or 4 times. Twice with the display showing a splash screen, but then stopping (both times during charging). Another time, possibly 2, where I shut it off, and it gave me a "goodbye" message. Once when it did start up, with no display, and then would not shut off.

The battery charged, but it did not take long enough, so the battery is likely severely damaged from being "down" so long. It looks like the battery, despite charging, is actually not working, and probably has too high an internal resistance, so that it cannot power the camera.

Messing about with it to replace the battery innards is possible, but not attractive.

Essentially, I cannot tell if the camera works without getting a better battery (it will not run on voltage supplied to the +and - terminals, it wants that 3rd terminal), and the battery is not worth replacing if the camera does not work.

[J Tiers]

So, I try it this morning. This time, it lights up, and I can take video, so I do. About 20 seconds in, the display just fades out over 5 or 10 seconds, and then the power button will not turn the device off. Had to take out the battery to shut it down, which naturally lost the video.

According to the manual, the display will show a low battery indication, and then the camera will shut off, if you do not do it first yourself. That did not happen. And, the battery appears fully charged, the charger does not charge it, nothing seems wrong.

Cheapo chines knock-off product? Chinese completely counterfeit product?

It's chinese all right, and the suggestion earlier by someone that it is a panasonic product seems to be not correct. The manual is complete shiz, it at one point shows the battery as "lithium, 1.5V", which is total nonsense.

Yeah, it does not matter much, but it's one of those things that just are so odd you want to know why. And, it could be useful if the problem is just something silly like not understanding how it is supposed to work.

[genea]

. . . . And, the battery appears fully charged, the charger does not charge it, nothing seems wrong.

Test it with a 1C or 2C load to see how long the voltage stands up.

[J Tiers]

Did that already, and it seems to hold up. Did not use 1C, I used a load that should give the rated work time of the device, which is more realistic long term. Of course, there may be spike loads, so a 1C may be better.

The load I used did not drop the voltage anywhere near the cutoff voltage.

In any case, it recorded for at least 30 seconds, which should be a constant load, and then did NOT do what the manual says. If voltage was dropping, (which it was not, since the battery still shows almost full voltage-wise), then it was supposed to indicate battery low.

Instead, the display just faded out.

In fact, I have yet to find the manual correct in anything but the main points, and even there, it is not 100%. Looks like a bogus cheap chinese counterfeit type product. Probably best in the estate sale pile for the spring sale at the MN house.

I may look at it some more when I am not doing anything else.

[J Tiers]

Checking with a 1C load indicated under 100 mv change in voltage. Should not be an issue, I'd think.

[wmgeorge]

My guess is even when it was New it was a POS, there is zero online about them. Save yourself some time now and toss it into recycling.

[J Tiers]

Oh yes, that is the destination.

I'm just amazed that it really IS such a complete POS.... Such "perfection" can be explained by either my failure to comprehend (although the "on" button surely should be simple enough even for me to understand), or, alternately, by bad firmware, or perhaps by the total failure of the operator manual to consistently provide good information. The few things I know for sure about the thing are described wrongly in the manual.....

The chance that I just do not understand it in a way that prevents me from using the perfectly good camera, seems low now..... I am liking those explanations that say it is a POS...

I could not find anything about it either, although there are a bunch of cameras that "look" identical to it. I am guessing bad chinese copy.