PX625 battery replacement in Canon EF

<p>This is another mercury battery replacement thread but with a slightly different question than I've seen asked or answered previously. Yes, I used the search function.<br>

<br />First of all, a while back I posted a question as I was looking for an FD Canon. Thanks to some of your help, I went with a Canon EF camera. Part of the reason I chose this is because the camera actually shows you the light meter kind of like what I'm used to with DSRL's. I didn't want a dumbed down viewfinder screen like in my AE-1 Program. <br>

<br />So I got the EF on ebay and the guy tells me the light meter works, even showed a pic of the viewfinder with it working, but didn't send the batteries with it because he needed them. So I did some research and picked up some 675 cell batteries. The light meter is pegged in the upper red box the whole time with these. If I bring the aperture down all the way, the light meter will dip into the range of numbers slightly but not actually be responsive. A multimeter shows these batteries have charge (although my multimeter's battery is almost dead itself but it read that these batteries are pushing 1.8 and 1.9V). <br>

<br />I see the replacement PX625 batteries and the adapters brag about having the collar. This obviously helps it fit better but I want to know if that collar serves an electrical purpose. I put a foam ring in the battery compartment to help it stay center and it doesn't behave any differently. I've tried everything short of buying different batteries to test this camera and the results are always the same. Could a battery at 1.8-1.9v be causing the pegging meter? These batteries are not supposed to be that high so I'm not sure if I got bad batteries or my multimeter is reading wrong because its own battery is dying. More work to do in that regard. UGH. <br>

Two questions:<br>

1. Does the collar help make a better electrical contact for the battery in some way or in the case of replacements is that collar purely for fitment?<br>

2. What battery are you using in your EF?</p>

<p>Greetings.<br /> I have been through the battery issues questions before with the wonderful EF, one of Canon's finest 35mm's of all time.<br /> First of all, you need to make sure you have an accurate voltmeter. You COULD have gotten some sort of bizarre aftermarket or mislabeled or cheap battery that is indeed no good. 1.8 to 1.9V is extremely high for a 675 (1.5V nominal) cell. So make sure up front that you have a good meter (borrow another one?) and can verify whether the camera batteries are good or bad. Second of all there is an "MR-9 voltage adapter" available via eBay that converts the 1.5V cells down to 1.3V. The bad news is you would have to buy two of these. (They are a gold cup-shaped device containing a Schottky diode that drops the 1.5V to 1.3V)<br /> But . . . I have even BETTER news for you. The EF does NOT need to run from the 1.3V batteries as it has a built in voltage regulator that reduces 1.5V batteries to 1.3V. Many folks, even some long-time EF users, are not aware of this.<br /> Get some known good 1.5V cells and then recheck your camera. If you have a continuing issue, then your camera needs service. I do know that the EF had some issues with meter failures but I believe these got corrected as the model years progressed.<br /> Also I recommend you buy from ADORAMA Camera in NYC a ZTS MBT-1 Battery Tester. This tester, unlike a voltmeter, actually "pulse loads" a battery and gives you a percentage reading of the battery life. It tests many types (most types) of camera batteries, including AA, AAA, etc. (And no, I do not sell nor represent this tester or its manufacturer nor ADORAMA.)<br /> Please continue to keep us posted as to your problem or solution. We are always here to assist you.</p>

<p>Yes, with the EF get some 1.5v silver oxides and it will drop the voltage down to 1.3v. Only a few cameras of this era had regulators and this was the only Canon that I'm aware of that did. I have the MR9 with my F-1n.</p>

<p>Because the meter in the EF uses two batterys and the shutter control only uses one the camera has internal voltage regulators. You can go down and buy cheap drug store 625 alkalines and the meter will work properly. Granted they will have a weird discharge curve and should be replaced often but they will show you if your meter works. While you wait for the Silver Oxides you order show up.</p>

<p>Yes, the EF is the only Canon model that I am aware of too. I no longer use the MR-9 with my F-1n. During a recent CLA, the service tech offered to re-calibrate the F-1n's meter for 1.5V cell use, so I accepted. That is always another option that you F-1n owners out there can have done. If you do go that route, remember to place a label on the bottom plate to the effect: "METER CAL'D FOR 1.5 V" so you or a future owner are reminded. The voltage difference in an F-1n with an incorrect power supply (meter voltage therefore not correct) can cause about a 1/2 to 3/4 stop metering error. I tabulated this from running my own tests using both 1.3V and 1.5V to power my F-1n camera. Not a huge deal breaker, but it could be a noticeable issue, especially with transparency {"slide"} film and its typically narrow exposure range. Thank you for reminding me about my F-1n's modification, Tony -- I need to attach a meter voltage calibration note label to it.</p>

<p>I had an EF and used alkaline cells in it because the camera's circuitry is designed to bring 1.5 volts down to what is needed. I think it is called a "bridge circuit". You might look at http://www.photo.net/canon-fd-camera-forum/00Xtny</p>

<p>My serviceman fitted a coiled spring into each battery chamber and used size 357 batteries. I don't know if they are alkaline or silver oxide but they are definitely 1.5 volts.</p>

<p><img src="/canon-fd-camera-forum/h;\canonef.jpg" alt="" /></p><div></div>

<p>what's the point of the spacers? I've tried the 675 and 357 batteries and they fit well enough I think. They're sorta loose until you put the caps on but I don't really see that being an issue.</p>

<p>You've got a point there. When I bought the camera I sent it straight off for a check over / CLA. I didn't know what batteries were installed. I guess my service guy is just a bit fussy. The 357 batteries are held perfectly central in the chamber so I'm happy.</p>

<p>The camera got a clean bill of health. The main part of the work needed was to apply an anti corrosive to all electrical contacts to ensure future reliability. Exposure and shutter speeds were spot on except for 1/1000 which was a bit inconsistent but within tolerances. (Not worth the cost of a major tear down to rectify this). Not bad for a 40 year old unit. It's now one of my favourite shooters along with an F1-N. Gotta love the old iron.</p>

<p>Some more old stuff: http://www.photo.net/canon-fd-camera-forum/00RAfa</p>

<p>I've been using the 675 hearing aid batteries in my EF ever since I bought it a few years ago. Even though they aren' t the same diameter, this doesn't matter, since the spring clips hold them in place.</p>

<p>Good to know about the voltage regulation circuit. I'd just as soon put a set of 1.5v silver oxides in the camera and forget about having to replace the batteries for the next couple of years or so. The 675s, being zinc-air, only last about 10 months or so. But then, I buy them at Costco -- 40 of 'em for $10, so I don't mind it if I go through them frequently. I just have to remember to pack spares.</p>

<p>Ordinary PX625 A Alkaline batteries work fine in an EF because the camera has a built in voltage regulator circuit that reduces the voltage to the correct 1.35V and gives correct exposures.</p>

<p>Yeah, but Alkaline has a really lousy discharge curve, which is why it isn't recommended. Coincidentally, the zinc-air battery's discharge curve is almost identical to that of the original PX625 mercury battery --- long and flat. Other materials, such as silver oxide and lithium also have good discharge curves, which makes them suitable for replacements, if they can be found in a size that has close to the correct voltage and is about the same size.</p>

 

<p>I am a long time user of Canon FD and my camera of choice is the EF. I also have a good background in electronics. I have been using an EF for 5 years or so for general photography. The 625A 1.5V Alkaline cell is ideal, the discharge characteristic is unimportant because of the built-in voltage regulator. However some of the low-cost unbranded cells are not suitable as they are not quite the right shape and do not make contact correctly. I recommend Duracell 625A. With new cells the battery test LED will flash quite quickly. When it flashes slowly the 1.5V cells will be well discharged and should be replaced.<br>

I have had few problems with my EF's but I do tend to use the old style breech-lock lenses as I ran into a problem where one of my New FD lenses did not always couple correctly with the camera body. A pin on the lens signals to the camera if the lens is in auto or manual mode and sometimes the camera thought the lens was in manual when it was in auto. This results in gross underexposure as it stops the lens right down. I have tried this lens on about 10 other Canon FD cameras and it works fine so I conclude that it is a tolerances problem. My trusted repair shop could find no fault.<br>

For flash I use a 277T and in poor light use it in the normal F Number Set mode. For fill-in flash set the shutter speed to 1/125 and the lens for auto exposure. Set the aperture on the flash unit to 1 stop wider than the camera's auto exposure reading. You will find it works a treat.</p>

<p>I've only had my EF for a couple of months, and all I could get hold of easily in the UK were the 1.5v 625 alkaline cells - They work fine. It really is a great camera to use and the meter is spot on. At least when it runs flat I can still use the faster speeds and sunny-16 my photos.<br>

I will get a voltage dropping adapter at some point as I have other cameras that don't have a built in regulator. As I'm a hobby photographer, and only use my cameras a few days a month, I can't justify the £10 a cell in the UK for Zinc-air buttons.</p>

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<p>As I'm a hobby photographer, and only use my cameras a few days a month, I can't justify the £10 a cell in the UK for Zinc-air buttons.</p>

</blockquote>

<p>Are you referring to the Wein zinc-air batteries? Geez, they're only about $7 here in the States. Still, though, even at $7, they're an outrageous rip-off. The only difference between a Wein and a 675 hearing aid battery, which costs 40 cents at Costco ($10 for a card of 40), is the Wein has that collar and the 675 doesn't. But on Canons, that collar isn't necessary since spring tension keeps the battery in place. And if it bugs you, you can always add an or-ring or a small ring of wire to the bottom perimeter of the battery compartment.</p>

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<p>Are you referring to the Wein zinc-air batteries?</p>

</blockquote>

<p>Hi Michael, yes I am. The cheapest I've seen a Weincell over here is £8, which probably works out at around $12-13 in the US. I've not seen any other brands available here.<br /><br />I can get the correct shape alkalines for a couple of quid each, hence why I use them!</p>