OM 1 battery conversion

[jgoody]

Thanks for all the responses! Basically I am torn between keeping the camera "original" and using the MR9 I have - or having the same battery for my OM 1 as OM 2, which would be handy.

 

[thuggins]

I had a diode added to my OM1 MD when a CLA was done earlier in the year so I could use it with 1.5 volt battery. I have a brass adapter that I got off ebay a few years ago that bulks an LR44 sized cell up to PX13 size.

The LR44 is an alkaline cell and can never be used in a camera that was designed for a mercury cell, whether it has been modified or not. The advantage of mercury cells was that they had a constant voltage over their useful life, so the cameras did not need a bridge circuit. The voltage of an alkaline cell drops as it discharges so the meter reading will not be accurate. Whether using a MR9 or modifying the circuit, you must use a silver oxide cell.

 

[AgX]

Well, he said LR44 sized cell.

 

[CMoore]

I thought (when the work was done IN camera) that the correct battery to use was a 625.?

 

[MattKing]

I thought (when the work was done IN camera) that the correct battery to use was a 625.?

If the camera modification is simply an electronic one, you still need to deal with the fact that the battery compartment is sized to fit a 625 battery. I've not encountered a silver oxide cell that is sized that way. No electronic modification (other than adding a bridge circuit) is going to give satisfactory results with a 625 alkaline battery.

 

[CMoore]

Are you saying that the "typical" fix of adding a diode to drop a small amount of voltage does not work well with a 625 Alkaline Battery.?
Thank You

 

[MattKing]

Are you saying that the "typical" fix of adding a diode to drop a small amount of voltage does not work well with a 625 Alkaline Battery.?
Thank You

Nothing you do in an OM 1 will work well with an alkaline battery. Alkaline batteries do not supply anything close to the constant voltage that one requires.
You need a power source with consistent voltage. Zinc air cells work, as do silver oxide cells. The silver oxide cells are the ones that require the diode, because their voltage, while consistent, is too high for the circuits that expect the 625 mercury cells that are banned.
There are cameras that work with alkaline cells because they are designed to be relatively voltage independent. The OM 1 (and many others) are not among those.

 

[CMoore]

OK...I see.
Regards the Alkaline.....is their voltage inconsistent throughout its entire life-span, Or is it just a problem as the Alkaline Battery ages.?

I read back through this tread, and the PDF, but sorry, i am still confused about the right battery. There are a lot of numbers being discussed.
Assuming the camera has had the proper diode added to drop some voltage:
1. Does the 357 work with an O-Ring.?
2. Exell makes the 625PX. That is silver oxide. Is that the correct size for the Olympus.?
Thank You

 

[MattKing]

OK...I see.
Regards the Alkaline.....is their voltage inconsistent throughout its entire life-span, Or is it just a problem as the Alkaline Battery ages.?

I read back through this tread, and the PDF, but sorry, i am still confused about the right battery. There are a lot of numbers being discussed.
Assuming the camera has had the proper diode added to drop some voltage:
1. Does the 357 work with an O-Ring.?
2. Exell makes the 625PX. That is silver oxide. Is that the correct size for the Olympus.?
Thank You

The Alkaline cells voltage changes throughout their lives, with the change accelerating toward the end.

I've used a 357 with one of Jon Goodman's metal adapters. They permit operation with cameras that rely on contact with either the edge of the battery, or the face of the battery. I don't know that applies to an OM-1 (in fact I don't think it does). O rings work with cameras that rely on contact with both faces of the batteries, and not the edge of the battery (which is most cameras, I believe).

If the 625PX is the same size as the 625 mercury cells, it will be the correct size for an OM 1 that has had no physical modifications.

 

[CMoore]

Matt...Once Again.....Thank You, and APUG.

 

[mr rusty]

Your OM1 is (hopefully) not original anyway, unless you still have the foam over the prism which is slowly turning into mirror-silver dissolving gunk.

Get the diode fitted. Get a little packing in the battery compartment, and use SR44 cells. Job done. The very small discrepancy that might still be there is so small (and I certainly cant measure it) that it is lost in other variabilities and scope of most films to be under/over exposed by a stop without any real issues.

 

[CMoore]

Yes, my OM-1n has been cleaned out.
I do have a couple of the 357 silver oxide.
When you say "packing", are you talking about some small O-Rings.?
Thanks

 

[AgX]

Regards the Alkaline.....is their voltage inconsistent throughout its entire life-span, Or is it just a problem as the Alkaline Battery ages.?

There is that article "The Mercury Cell Problem" that hints at all aspects.
(It is on several servers, look for the latest edition.)

 

[mklw1954]

I have one OM-1 that I use with a 675 battery in this holder/adapter:
http://www.paulbg.com/Nikon_F_meter_batteries.htm

and an OM-1n that I bought from John Titterington that he CLAd and did a battery conversion on (I'm still using the PX625 alkaline battery he supplied).

Both provide excellent metering. Based on the discussion here, I will try a silver oxide 625 battery next (S625PX) instead of an alkaline.

I had a battery conversion done to a Konica Autoreflex T2 by Greg Weber and he applies a sticker on the bottom of the camera indicating that a battery conversion has been done and which batteries to use - a good idea.

 

[CMoore]

I have one OM-1 that I use with a 675 battery in this holder/adapter:
http://www.paulbg.com/Nikon_F_meter_batteries.htm

and an OM-1n that I bought from John Titterington that he CLAd and did a battery conversion on (I'm still using the PX625 alkaline battery he supplied).

Did you ever compare that camera (with an Alkaline) to another, and see if the meters were close to agreement.?

 

[Bobkins]

guys,
I use on OM1 SR44 battery,
if film ISO is 100 I set camera ISO 25 - light meter works good
which ISO need to set on camera if use
film ISO 200 and 400?

thanks!

 

[Steve Roberts]

My question is whether there is any downside to having John make the internal conversion vs keeping the adapter. Thoughts?

Personally, I'd have it converted (or do it myself) and just get on with using and enjoying the camera. Parallels with originality of classic cars can be drawn, but even in that area there is scope to, for instance, upgrade the ignition system by using a small piece of electronics that sits inside the distributor cap increasing the performance and reliability whilst not affecting the appearance.
Best wishes,
Steve