Strange battery issue with Canonet G-III QL/17

[Tony-S]

For some reason, my CRIS MR-9 battery adapter does not work in my QL/17. It works perfectly in my Canon F-1n and a 1.5V alkaline battery works in my QL/17 (but of course gives an improper exposure reading and is not regluated). Any ideas what might cause this? The camera's terminals have been cleaned.

 

[BrianShaw]

No idea why it wouldn't work. A Gossen adapter worked in mine. The battery check lite won't work, but the shutter functionality worked accurately.

 

[Ian C]

The first thing I’d do is a test to verify that the converter + 1.5v alkaline cell is actually making contact in the Canonette. I’d inspect the camera’s terminals carefully to verify that they properly contact the body of the converter and the end of the 1.5v cell installed in the converter.

It might be possible for the combination to fail to make contact. You can measure the stack height of the combination with a micrometer or dial caliper by placing small pieces of paper over the ends of the stack (converter + 1.5v) to insulate the terminals. Then do the same with the 1.5v 625A replacement cell. They should have the same height. If the converter + 1.5v cell is shorter, then the stack might not complete the circuit.

Place a cell in the converter and measure the output at the converter terminals. Test both the voltage and amperage. It’s possible that the voltage-reducing circuit of the converter drops the amperage too much for the Canonette to operate properly.

There is some useful information here that might help.

http://www.butkus.org/chinon/batt-adapt-us.pdf

The instructions that came with my CIRS MR-9 converters recommend the 1.55V silver oxide cells rather than the 1.5v alkaline cells. I don’t know if matters, but I’ve used the silver oxide cells as recommended and had good results with a Nikon FTN finder. With the converters it gives similar readings to other meters of know accuracy.

 

[Thomas.Goehler]

I'm just wondering why you use an MR-9 device in your F-1N. This camera does not need mercury cells.

 

[Tony-S]

No idea why it wouldn't work. A Gossen adapter worked in mine. The battery check lite won't work, but the shutter functionality worked accurately.

OK, so why won't the battery check light work? I just stuck the MR-9 in the QL/17 and it seems to meter just fine, but the check light does not illuminate. What is the cause of that?

The instructions that came with my CIRS MR-9 converters recommend the 1.55V silver oxide cells rather than the 1.5v alkaline cells.

Ian, I'm using the silver oxide. It seems my problem was that I was fooled by the test light not working with the MR-9/silver oxide, but it works fine with the 1.5V alkaline. Any idea what might cause that?

 

[Tony-S]

I'm just wondering why you use an MR-9 device in your F-1N. This camera does not need mercury cells.

It's an F-1n, not an F-1N.

 

[Ian C]

Re: Post #5

See page 3 of the article (link given in post #3). “Attention…”

It cautions that the MR-9 might fail to give the normal battery check because that momentarily imposes an unusually high load to test the cell. But the original 625 mercury cell is larger and its chemistry produces a relatively high size/current ratio that is considerably greater (I think) than the much smaller 1.55V button cell installed in the converter.

For this reason, it might fail to produce sufficient current to operate the “battery check”, but still produce sufficient current to operate the camera.

 

[Tony-S]

Got it. Thanks for that link. Makes perfect sense.

 

[BrianShaw]

OK, so why won't the battery check light work? I just stuck the MR-9 in the QL/17 and it seems to meter just fine, but the check light does not illuminate. What is the cause of that?

I don't know for sure, Tony, but have read that it NEVER works with voltage adapters or voltage-dropping diodes. In my situation the meter worked fine but there was no way to determine when the battery was failing until the metering stoped being accurate.

 

[BrianShaw]

ooops... I just saw that Ian knows why bettery check doesn't work. I need to read his posting, and should have done so before posting my own ignorance.