Adapter for Spotmatic Battery

**stemked** · 04-15-2023, 12:30 PM

Hi All.

I know this exists. The recommended batteries for Spotmatics of the correct voltage are too small for the body and I recall hearing there is an adapter of sorts that you can use with the smaller battery. Does anyone know where I can pick one up?

Thanks!

Doug

**JoelA** · 04-15-2023, 02:16 PM

For what it is worth, it's really easy to get the correct battery and not have to do a work around.

I just recently got a Spotmatic SP and purchased a wein cell 1.35 replacement battery. It's their code MRB 400.

Replaces RM 400R & V400PX: For use with Spotmatic, Spotmatic II, Spotmatic IIA, SP 500 and SP 1000.

Works perfectly.

Just please remember to turn your light meter off after you take the reading or you'll drain it quickly.

I ordered two - just in case. Finished one roll of film and a lot of playing around and the first battery is still just fine.

Hope this helps!

titrisol · 04-16-2023, 06:25 AM

Adapter? Just use a 392/AG13 battery (you might need a small plastic o-ring)

womble · 05-11-2023, 03:12 PM

Wein cells work perfectly but have a fixed life once you let the air in due to the way they work. Various work arounds with O-rings etc work.

The Rolls-Royce solution (which is admittedly expensive but the replacement batteries are then cheap) is: H-B Adapter. Replacement for PX400, EPX400 or RM400 discontinued Mercury cells.

Which you choose is really up to you. All three solutions work with varying degrees of fiddlyness. I'm happy with the H-B adaptor.

lotech · 05-31-2023, 10:45 PM

I've no such camera on hand to test, but as far as I know there is adapter to use with modern LR44 batteries. As far as I can see on vintage camera review, the battery adapter has a tiny back dot thing on it, I believe it's a Germanium diode that has a voltage drop of 0.2V, so that to make the 1.5V of LR44 to drop close to 1.35V the camera designed for. You can not simply put a resistor to adjust the voltage, unless you know the current drawn by the camera and it is constant, so that a semi conductor diode must be used, but I could be wrong.

04-15-2023, 12:30 PM	#1
stemked Site Supporter Join Date: Feb 2009 Location: Indianapolis Photos: Gallery \| Albums Posts: 527	Adapter for Spotmatic Battery Hi All. I know this exists. The recommended batteries for Spotmatics of the correct voltage are too small for the body and I recall hearing there is an adapter of sorts that you can use with the smaller battery. Does anyone know where I can pick one up? Thanks! Doug

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04-15-2023, 02:16 PM	#2
JoelA Loyal Site Supporter Join Date: Feb 2019 Location: Florida Photos: Gallery Posts: 187	For what it is worth, it's really easy to get the correct battery and not have to do a work around. I just recently got a Spotmatic SP and purchased a wein cell 1.35 replacement battery. It's their code MRB 400. Replaces RM 400R & V400PX: For use with Spotmatic, Spotmatic II, Spotmatic IIA, SP 500 and SP 1000. Works perfectly. Just please remember to turn your light meter off after you take the reading or you'll drain it quickly. I ordered two - just in case. Finished one roll of film and a lot of playing around and the first battery is still just fine. Hope this helps!

04-16-2023, 06:25 AM	#3
titrisol Pentaxian Join Date: Dec 2007 Location: In the most populated state... state of denial Photos: Gallery \| Albums Posts: 1,852	Adapter? Just use a 392/AG13 battery (you might need a small plastic o-ring)

05-11-2023, 03:12 PM	#4
womble Pentaxian Join Date: Apr 2010 Location: Hertfordshire Photos: Gallery Posts: 4,324	Wein cells work perfectly but have a fixed life once you let the air in due to the way they work. Various work arounds with O-rings etc work. The Rolls-Royce solution (which is admittedly expensive but the replacement batteries are then cheap) is: H-B Adapter. Replacement for PX400, EPX400 or RM400 discontinued Mercury cells. Which you choose is really up to you. All three solutions work with varying degrees of fiddlyness. I'm happy with the H-B adaptor.

05-31-2023, 10:45 PM	#5
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312	I've no such camera on hand to test, but as far as I know there is adapter to use with modern LR44 batteries. As far as I can see on vintage camera review, the battery adapter has a tiny back dot thing on it, I believe it's a Germanium diode that has a voltage drop of 0.2V, so that to make the 1.5V of LR44 to drop close to 1.35V the camera designed for. You can not simply put a resistor to adjust the voltage, unless you know the current drawn by the camera and it is constant, so that a semi conductor diode must be used, but I could be wrong.