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03-01-2011, 10:04 AM   #1
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Asahi spotmatic sp battery recommendation

Does anyone recommend a battery type for the asahi spotmatic sp.
The mercury 1.35v b+ is no longer around.


Last edited by CACTUS24; 03-02-2011 at 08:09 AM.
03-01-2011, 11:43 AM - 1 Like   #2

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Google is your friend (Search term: 1.35v mercury battery).

Find your battery on the left and the replacement is within the text on the right of the table.

Camera Batteries - a complete chart -'s Classic Camera DB

aka Energizer E400N, ANSI 1116M, IBC MR42

Mercuric Oxide

1.40g 11.6Dx3.60H mm.


Asahi Pentax Spotmatic SP, SPII, SPIIa, etc.

1) The 1.55v silver oxide Energizer E387S is an exact fit. This is also sold as the Radio Shack 387S (RSU #11608452), but is a special RSU order. has the S400PX as a replacement.

2) Both of the above are 1.55v silver oxide. They work with the Spotmatic which has voltage regulating bridge circuitry, but other older cameras may be more problematic.

3) CRIS H-B Adaptor and silver 377 batteries. The CRIS adaptor has a diode to take it down to the proper voltage, although the Spotmatic doesn't need the lower voltage.

4) Wein zinc-air cell have a stable voltage over their life and are thus suited to many older cameras. The disadvantage is that these only last a few months. Sources for Wein cells noted below.

03-02-2011, 11:05 AM - 1 Like   #3

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your best bet, honestly and I endorse it fully as I use it myself, is to get a CRIS adapter. its more expensive up front, but the only batteries with the correct voltage, that I know of are zinc air batteries, but they are expensive and don't last long. you get a CRIS adapter and you can use a 1.5v silver oxide button cell and reap the benefits of cheap, plentiful availability and long constant life of the battery. its a really simple adapter and is designed specifically for the spotmatic (among others).

CRIS Camera Repair and Services - Mercury Battery Adapters

but as I understand it both the SPII and the earlier SP have 'bridge circuits' that allow the voltage to be regulated so a 1.55v battery should work fine. I however still use the adapters.
03-02-2011, 06:53 PM - 1 Like   #4
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Silver Oxide cells type SR44, EPX76, V76PX, B-SR444, will all work.

At least one of these should be available at your local "Battery Bar" or "Battery World" (or equivalent), and be an exact fit.

03-03-2011, 08:07 PM - 1 Like   #5
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As I understand any 1.5V battery that fits will work, all the Spotties are SUPPOSED to have bridge circuits to regulate the voltage. Also, if you're having a CLA or repairs done, most places can adjust the circuitry.
03-14-2011, 07:35 PM   #6
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I use Energizer 392s in my SP1000 and SP II, and they work fine, you'll want to find a rubber o-ring to put in the battery compartment to keep it somewhat centered. They're readily available at Walgreens. ( the batteries that is, not the o-ring )
03-14-2011, 11:11 PM   #7
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SR44s are not the right size (ok for ES11), & 387s are very hard to obtain....don't even know if they're still made.
The perfect replacement (size etc same as original) is the 1.5v EXELL S400PX.
The Spotmatic meter will work perfectly.
Cheers, Pickles.

10-20-2012, 09:36 AM   #8
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I also need a new battery for my old Spotmatic. Not a SPotmatic F, just plainspotmatic. I tried a Duracell D357H/ms76, but it doesn't fit. Which battery do I need?

10-20-2012, 10:11 AM - 1 Like   #9
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Try the Energizer 392, it works fine for me
10-20-2012, 02:23 PM   #10
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Energizer 387S available on Amazon, maybe at a local battery store if you have one in your area. I use them all the time in my Spotties and they work just fine. There's no need to modify anything.
10-20-2012, 02:43 PM - 1 Like   #11
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QuoteOriginally posted by magkelly Quote
Energizer 387S available on Amazon, maybe at a local battery store if you have one in your area. I use them all the time in my Spotties and they work just fine. There's no need to modify anything.
+1 for the Energizer 387S. Just got one for my SP today at a local battery store for $6.00.

10-20-2012, 04:47 PM - 7 Likes   #12
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Spotmatic Battery Information.
Here is the information about batteries that is sent to each new member of the Yahoo! Spotmatic Group (of which I am the owner):

Spotmatic Battery Information

The most experienced members of the Spotmatic group have compiled the information below and many of them have been using Spotmatics since they purchased them brand new in the sixties and seventies. This information is being provided so that you do not have to ask about it as a discussion topic on the forum. It has already been discussed and answered many times and there is nothing more to add so please do not ask again. All you need to know is contained in this document.

For battery cap information go to the bottom of this document.

In relation to batteries, there are 5 groups of Spotmatic cameras:
1. SP Series. This includes SP, SP500, SP1000, SPII and SPIIA.
2. SP F
3. Electro Spotmatic and ES
4. ESII.
5. SL. This camera has no meter and, thus, no battery.

SP Series
The 1.35-volt mercury (mercuric oxide) battery originally used in the Spotmatic SP is no longer available due to environmental protection laws.
Replacement batteries available today are 1.55-volt but the Spotmatic uses a "bridge" circuit in its meter, making it insensitive to battery voltage variations. So, despite what you may have read - No meter recalibration is necessary as all Spotmatic SP series cameras can handle the increased voltage.

The alternatives are:
• Spend about $30 for an adapter from CRIS Camera Services (Camera Repair by CRIS Camera Services: Digital Camera Repair: Canon, Fuji, Nikon, Pentax, Ricoh, Sigma) and a battery to insert into it. But this would be a waste of money as it is definitely not required.
• Spend about $10 for a Wein Products MRB400 cell (modified Zinc-Air cell). They are quite expensive and have a limited life (about 6 to 12 months) unless you remove the battery after each use and seal up its air hole (it needs air to work). This is not a recommended solution.
• Spend about $3.00 for one of the many 1.55-volt silver oxide batteries available over the Internet, at Radio Shack, most drugstores, camera stores and even some supermarkets. They will last you for about three years if our experience is typical. Make sure you insert it the right way for proper polarity, and take up the excess space in the battery box with a rubber O-ring from the hardware store, that will cost you about 49 cents. You might have to bend up the battery contact in the battery box to make good contact.
• Silver oxide batteries that work are: Mallory PX-400 or RM-400-R, Varta V394, Maxell SR936W or SR936SW, Renata 394, or any type 392 equivalent.
• Do not be tempted to use alkaline battery equivalents as they have a much steeper discharge curve. The silver oxide batteries have a flat discharge curve similar to the old mercury batteries.

• Mallory PX625, Duracell PX625A, Excel Z625PX, Eveready E-625N.
• The Spotmatic F uses a dual coil meter movement that, like the bridge circuit, cancels out battery voltage variations on the level we are dealing with here. So it is immune to the difference between 1.35v and 1.5v, too. The original battery for the Spot F was a mercury type. In this case, Pentax used the identical circuit in the KM and K1000, without any electronic changes. They substituted the silver types with NO ALTERATION at all.

Electro Spotmatic and ES.
6-volt Eveready #544, Duracell 28L Lithium.

Eveready S76E, Mallory MS-76H, in fact any 76-type battery works -A76, S76, MS76.

Places on the Internet to purchase from: - photo battery Resources and Information. This website is for sale!
Batteries Plus battery store - All your battery needs for Laptop, camera, cell phone, camcorder, SLA, batteries recycling and much more (good model search facility)
Swatch Swatch batteries, watch batteries Watch Battery Renata Energizer (very cheap, good quality)
Welcome to - Right Battery | Right Price | Right Now ? (you need to know the battery number you want)
Welcome to - Right Battery | Right Price | Right Now ? Look for the S400PX (for SP series) or the S625PX (for SPF) on this page.

Battery Caps.
The following are two known sources for Spotmatic SP series and SPF battery caps:

Pentax Camera Service (Eric Hendrickson)
“I still have new caps for the Spotmatic.
If you would like one just send 15.00 plus 2.00 postage.
Email me at
12-21-2017, 05:40 PM   #13
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No, the voltage does matter. The bridge is loaded by the asa resistance when balanced against the output of the cd cell at 1.35 volts. I did a side by side comparison and the results for 1.55 and 1.35 volts were hugely different. Also using a 1.55 volt battery and an external light meter also gave huge diifferences
12-22-2017, 01:42 AM   #14
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Light meter final word

According the info from Pentax, the meter (the circled M uppercase on the schematic) has an internal resistance of 3 Kohm. They also say that the needle is centered when a current of 3uA (microAmp?re) traverses the meter. Hence a higher voltage battery will give a higher current at centre, so the needle will be off!
01-02-2018, 02:32 AM   #15
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A normal hearing battery works ok for about 4 months in my climate.
But they can leak. They should last longer if you remove them and replace the sealing tape.
They are available from most pharmacies many open on Sundays and a pack is cheap.

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