Voltage/current on charged & discharged CRV3 batteries

[Alan T]

I've done some current & voltage measurements on charged & discharged rechargeable CRV3 batteries, used in my Kodak Z712is superzoom.

The battery just after the camera has shut itself down due to 'low battery' has a open-circuit terminal voltage of 3.11-3.13V, having started at 3.8-3.9V. This explains why AAs are a poor substitute in a camera designed for Li-ion. 2xNi-MH gives about 2.8V after a bit of use, and only about 3.2V immediately after charging. Mn-alkaline aren't much better, and won't deliver much current anyway.

My Vigital Dolt Meter has a useful 'battery test' facility with two ranges. It measures the current through a 37 ohm resistor for testing AA cells, and a 360 ohm meant for 9V cells.

A charged AA Ni-MH cell gives about 36-38mA on the AA range.

Charged rechargeable CRV3s have terminal voltage of around 3.88V, falling to 3.84V after a day, and 3.76V after a week or so.

A freshly charged CRV3 gave 93mA through 37 ohms, and 9.8mA thorugh 360 ohms.

A charged cell after a week, unused,delivered 91mA through 37 ohms, and 9.5mA through 360 ohms.

After having the camera shut down due to low battery, a CRV3 showed 3.11V, 72.3mA, 7.7mA.

I haven't yet measured when I first see the 'low battery' indicator. I'm hoping to get myself a least a very rough indication of battery condition before the 'low' indicator appears. I'll report if I find anything useful. It's possible the nice flat discharge curve will defeat me.

Have fun, Alan T

[Alan T]

Since I wrote the above, I have realised through a little more research that rechargeable CR-V3 batteries are not, as I had assumed, a direct substitute for Kodak KLIC-8000 batteries. Other users of Kodak Z712is cameras, most of whom will never have handled, or even seen a close-up picture of a KLIC-8000, will make the same assumption as I did, as the camera comes with a throwaway CR-V3 disposable.

It is a natural assumption, if batteries labelled "Rechargeable CR-V3" are on nearby shelves to the supplies battery, that theyhave similar case design & contactsto Kodak's own brand proprietary battery that fits in the same hole in the same camera.

The 'Rechargeable CR-V3' work just fine in the Z712, and presumably in other CR-V3 powered cameras. However, I find little (& very variable) time from first appearance of the 'battery low' signal to final shutdown. Others report plenty of time, and I think it may be because they were using the proper KLIC-8000 battery.

As I've said before, a KLIC-8000 and a charger were included in the earlier Z612 package. As I've also said, often, it's a wonderful camera.

[domang]

Alan T wrote

My Vigital Dolt Meter...

No Vestigial Dolt D'Arsonval to try?

[Alan T]

domang wrote:

Alan T wrote

No Vestigial Dolt D'Arsonval to try?

Very apposite & erudite! I had to do my homework to identify the allusion at...

http://www.history.com/encyclopedia....fw..el025300.a

and http://en.wikipedia.org/wiki/Mirror_galvanometer

I do remember using moving-spot galvanometers, in big, heavy, rounded triangular grey cases, with a projected circular spot and crosshair moving along a horizontal curved scale on the front.

I suppose any surviving examples went into museums with the onset of the digital, LED & LCD revolutions. Since then I wasted much time trying to persuade folk not to quote currents & voltages to 4 or 5 significant figures, when we were interested in whether there were none, 1, 2, or 3 volts or amps, or kAmps, present.

[domang]

Very apposite & erudite!

Yes, I am old. :-)

One advantage of a 'what you said' meter is that it gives an RMS (DC equivalent) reading of AC voltages of differing waveshapes. Vigital Dolt Meters do not unless they are specifically RMS meters.

[ac.smith]

Alan T wrote:

As I've said before, a KLIC-8000 and a charger were included in the earlier Z612 package. As I've also said, often, it's a wonderful camera.

No, the KLIC8000 and charger weren't in the package, I just ordered them at the same time.

[Alan T]

ac.smith wrote:

No, the KLIC8000 and charger weren't in the package,

Ah, thenthis must have happened only in the UK then, or in different packagesfrom your purchase in the US.

It was a surprise to my camera shop when the Z712 arrived without the battery & charger, but with a disposable, because the Z612 had included them.

Comparison of the user guides for the two cameras on the Kodak uk website at http://wwwuk.kodak.com/ makes this apparent.

So UK Z612 users won't have needed to buy a rechargeable because it was supplied as part of the package, and Z712 purchasers like me and Crazy4Stang's wife will have looked around for the cheapest rechargeable that would fit. We'd have soon used up the supplied disposable while learning the new camera (there's a lot to learn).

I put a charger on order immediately I bought the camera, but it was a long time appearing, so I found one in a nearby 'Maplin', & cancelled the first.Both were for a 'rechargeable CR-V3' and not a KLIC-8000, because I didn't know the difference. I might well have bought an after-market 'KLIC-8000 replacement battery' and charger if I'd known they existed, distinct from 'rechargeable CR-V3'.

You need to have the two batteriesside by side, or read the specs in detail & see pictures to realise that they're quite different.They fit the same hole but with different contacts.

Regards, Alan T