Wondering if I keep using PX625A(alkaline battery) on my MR4 meter, what will happen? will it ruin the meter eventually? I found the reading is about half stop diff to mercury 625, but I can't fully zero the needle by adjusting the screw like I did with the mercury one. What's your experience about the diff? I know there're places selling mercury cells, but I guess it's worth by sacrificing half stop to save the environment...

Thanks.

-- Fred Ouyang (yo54@columbia.edu), March 30, 2002

Answers

It won't ruin the meter but you'll have to compensate like you already found out. You can also get an adapter to use the common S76/SR44 silver oxide cell:

http://www.criscam.com/mr9.htm

It steps the voltage down from 1.55V to 1.35V and is shaped just like the PX625, the S76 fits neatly into it.

-- Anon Terry (anonht@yahoo.com), March 30, 2002.

The other thing you'll find is that the amount of compensation will vary as the battery gets used up...alkalines lose voltage throghout their useful lives. I recommend the Cris adaptor but be wary: it is just a hair thicker than the PX625...not a problem with devices that use threaded battery compartment covers with sufficient thread depth, but as I recall (I never actually owned one)the MR-4 has a different type of battery door. Check with Criscam.com or perhaps someone here or on the LUG may have actual experience with it.

-- Jay (infinitydt@aol.com), March 30, 2002.

Don't attempt to use an alkaline battery because you will never get acceptable results. Go here for solutions to your problem...

http://www.nemeng.com/leica/012e.shtml

BTW, the best solution is still a 1.35V mercury battery if you can find one.

-- Bud (budcook@attglobal.net), March 30, 2002.

Fred,

I use an HD625/1.35V battery in my MR-4 with no adapter and have had no problems with it. I simply used a screwdriver on the screw on the underside of the meter to adjust the needle and make sure that it hits the center of the silver circle when the battery test button is pressed. The lower voltage should not damage the circuitry.

Peter

-- Peter B. Goldstein (peter.goldstein@us.cgeyc.com), March 30, 2002.

Hi Peter, How long does your Wein cell battery last? I saw people reported a month lifetime only after you open it. Thanks.

-- Fred Ouyang (yo54@columbia.edu), March 30, 2002.

Fred,

I understand the Wein's have a short life, but mine's a Duracell. The one in the meter has been there for at least four months. I keep a spare in the freezer.

Peter

-- Peter B. Goldstein (peter.goldstein@us.cgeyc.com), March 30, 2002.

Fred. I don't know if an alkaline battery 1.5 V will damage the MR4 but for sure it will give you inaccurate readings. This can't be corrected by 0 adjust because it is not a simple offset. And as mentioned above, the alkaline battery loses power steadily. Unfortunately, Metrawatt did not build a voltage regulator into their MR meter because the mercury battery chemistry is so reliable. You need to use one of the other solutions suggested above such as the Wein cell.

-- Eliot (erosen@lij.edu), March 30, 2002.

In addition to using an adapter, you can also have the MR4 meter recalibrated for modern silver oxide 1.5V batteries, which discharge more like the old mercuries. I can heartily recommend George Milton of Quality Light-Metric in Hollywood, CA (323-467-2265), who specializes in the repair & restoration of light meters.

-- Chris Chen (Wash., DC) (furcafe@NOSPAMcris.com), March 30, 2002.