Secrets of Digital Photography

Socket To Me!     Updated 12 18 02



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This entire subject is for your entertainment and/or enlightenment.

The fact that it works well on my cameras, a 775, a 995, a 4500, a 5000 and a 5700 may be some grand coincidence.

I have been using this quite a bit during the last month, and so far, no problems at all.

If you try this idea and break your camera somehow while using this setup, remember: I take no responsibility. But let's put that into perspective:

I cannot guarantee how well this will work with your camera and batteries.

I can't guarantee that a given CF card will work in your camera, either...

Dang! (Tales from Doodle* Land)

The battery is dead.

ALL the batteries are dead.

It's 10:59 PM on a Sunday Night in Valdosta and there are no EN-EL1s to be had -- let alone a 2CR5 -- within a hundred miles. But the 7-11 is still open...

And YOU have to shoot the picture of your life. Big Foot is about to step out of a UFO with David Duchovny in his arms, but without power you are as dead as your camera -- at least in a paparazzi sense.

Then you remembered that you came prepared.

A while back you read an article that told you how to supply your 775, 885, 995, 5000, 4500 or 5700 with emergency power from an easy-to-find 9V battery.

In fact, this is that very article.

Several thoughts cross your mind at once:

  • Where can you get a 9V battery?
  • Where did you put that little 9V+Doodle with the 5mm power plug?
  • Did you wire the 9V battery clip so the positive lead was soldered to the center sleeve of the power plug?
  • And how did the guy who wrote that article know that you would be in Valdosta with Big Foot and Duchovny so late at night?

Never mind that now, clip the 9V battery into the doodle, plug the doodle into your dead camera ( you must leave the dead battery in--it will perform a supporting role in this drama) and...

...hey! The thing's powering up.

Yeah, and depending on the degree of exhausted your EN-EL1 or 2CR5 battery currently experiences (is that a pun?), you will get a number of added shots before the combined power supply drops down too far to take pictures. I've gotten well over 50 shots in a combined test with monitor on, a mix of flash pictures and a normal amount of reviewing/deleting.

It's not much, but it's something.

Mostly, it was cheap.

  • 9V clip with wires: $2 for 5.
  • 5mm x 1.2mm DC power plug: $1 or less.
  • Solder: Priceless. At least it didn't cost any price I could track.

Operational Notes:

The 9V battery is not made for this sort of use.

Find the strongest ones you can obtain.

Keep the exhausted camera battery in the camera. There is still a healthy amount of power there. The external 9V battery will bring the total power up.

They won't last long. Turn the monitor OFF and use the optical viewfinder. You can easily get 25+ shots, but don't use the flash unless there is no other option.

Swap the 9Vs out, but don't throw the used ones away. They lose voltage quickly but recover pretty quick, too, as the chemistry inside the battery evens out over time. That might get you a few additional shots later.

The short pigtail wires that came with the snap-on clip allow you to hold the battery with your right hand as you grip the camera. No tangles.

Theory of operation:

  • 9V batteries put out about 9.5 Volts when fresh. The drain of the exhausted camera battery in concert with the 9V cell will bring the external battery down way under 9 Volts instantly. By measurement, into the 6 to 7 Volt range!
  • These 9V cells are really made for circuits that sip power slowly, like a smoke alarm. Digital cameras use up power more rapidly than the 9V cell is ready to deliver.

On the other hand, 9V batteries can be found almost anywhere. Even a 7-11 in Valdosta at 10:59PM.

  • The two batteries work in parallel, so the voltage threshold is being raised by the 9V battery while the steady, strong amperage of the battery inside the camera is assisting.
  • An exhausted camera battery isn't fully dead. But its Voltage has dropped below useful so the camera has decided it is too low to be used. The 9V battery brings enough Voltage into the equation to raise the total power available. But only for a limited time.
  • The power input socket on 775, 885, 995 and 5000 are labeled "8.4V." Pretty close to that 9V battery. But that marking is for an external AC power supply that is not necessarily limited in its available Amperage, the way a 9V battery is. Even when powering the camera, the Voltage here will NOT drop as dramatically as the Voltage from a 9V cell running in concert with the exhausted internal battery.
  • Think of it this way: The 9V battery is relatively high in Volts but puny in Amps. The exhausted camera battery is too low in Volts to continue pushing power through the camera, but the addition of a 9V/low Amp battery in PARALLEL with the camera battery tends to average the qualities of the two batteries together. The external 9V battery drops its Voltage quite a bit. The combined Amperage of the two is now available with just enough push to keep the camera running for a while.

Just a refresher in Volts and Amps:

Volts are electrical pressure (How pushy are these electrons?). Amps are electrical reserve (How many total electrons are there in the tank?).

Volts can blow circuits up. Static electricity, for example, has lots of Volts and almost no Amps, yet static electricity can destroy tiny circuits. Too pushy.

Very low Volts backed up by very large Amps doesn't have enough push to kill circuits (I've got lots of electrons available to me, but I'm paddling them into the wire with a feather!). That's why sockets for external power supplies are always referencing the Volts the device is looking for.

If you have a boom box, computer or cell phone that can run off a car power plug, it might seem logical to you that the huge car battery might be too much for your small electronic gadget. As if the bigger battery would blow up your device because the battery had so much more size.

Not so!

As long as the voltages are compatible, the big car battery can't push more electrons through your device than the device's normal battery. Of course, it can run your device many, many hours longer...

Making a Doodle.

The 9V battery clips and 5mm x 1.2mm DC power plug are easy to find at a Radio Shack or other electronics supply stores. The center pin (sleeve actually) of the plug is the red -- or positive -- lead. The black lead from the battery clip is negative and attaches to the outer sleeve of the power plug.

Do NOT use the 5mm x 2.5mm DC Power Plugs. Their inner sleeve won't make contact with the narrow pin inside the Nikon camera socket. You want the 5mm DC Power Plug with the small, 1.2mm inner hole.

Solder them. Yank on them to make sure the connections are really rugged. They may have to endure a life at the bottom of your camera bag for months or years before being brought out in an emergency, so anything you can do to make them rugged and durable will only be rewarded later.

Operational notes from real life experiences:

I've tried this with a number of EN-EL1 batteries that have discharged down to the level of uselessness in the camera. They were so drained that the camera couldn't wake up at all.

When the total power available to the camera drops below its own internal threshold, the camera emits a fast double beep to warn you that no images are possible, while the battery indicator on the monitor and LCD panel will flash rapidly and the monitor will go off (995, 5000) or show a "Warning! Battery Exhausted" message on the monitor (775).

Switch the camera off. Then plug in the 9V+Doodle. Inside the camera, the Operating System stops having an opinion about the battery power and will draw a new conclusion when you switch the power back on.

By plugging in the 9V+Doodle, before turning the power back on, the camera (775, 995, 5000) will power up AND SHOW NO "DRAINED BATTERY" ICON AT ALL !!

Wow! That was encouraging. Suddenly the available Voltage and Amperage from the 9V battery, working in concert with the remaining Voltage and Amperage of the exhausted camera battery, have raised the available power to a point at which the camera appears perfectly comfortable.

After shooting for several shots, the "half full" indicator showed again and the 9V battery (the one shown in the image above) felt warm. Not hot, but warmer than my fingers were making it. The half-full indicator seems to be a pretty good indicator as to the point at which you have just somewhat less than half of your power left. Perhaps a third of the power remains.

Since both the internal and external batteries are working in concert, once the external 9V no longer helps, trying a new 9V without inserting a "freshly exhausted" EN-EL1 doesn't help much at all. In other words, swap BOTH internal EN-EL1 and external 9V batteries at once. The internal here being one you cycled out of the camera before inserting your last fully powered EN-EL1.

Without the camera battery still assisting the external 9V power supply, the results suck. You might get a shot or two, or your camera may just sit there blinking and complaining that it simply cannot proceed. I've experienced both. The 9V battery on its own is a truly lousy power supply alternate.

Power Strategy:

The intimate working of the camera with its available power causes several phenomena. As a fresh EN-EL1 loses power, it loses Voltage as well. At a certain threshold, the camera detects the power drop and signals its Operating System to display the "half-exhausted" battery symbol.

Let's call this the point at which the "Primary Charge" of the battery is used up. Only the "Reserve Charge" remains at this point. Once the Reserve Charge is used up, let's call the battery "Freshly Exhausted." If any more power is pulled out of the battery, let's call that draining process heading towards "Fully Exhausted."

Nikon recommends that you swap out the battery when the Primary Charge is used up. But what if you didn't? (And, let's face it: Most people don't.) The interesting thing I've discovered by ignoring this symbol, is that the camera will continue to work with its Reserve Charge perfectly fine for a very long time before the battery is completely exhausted.

Nonscientifically, it feels like the "half-exhausted" icon shows up about 2/3 of the way through the power curve of the EN-EL1.

When the Primary Charge is used up, you could swap batteries without question. But the battery you were putting back into your camera bag or pocket would be still quite useful. It's Reserve Charge would still be intact. No need for the 9V+Doodle yet!

If you used up the Primary Charge on your last remaining EN-EL1 and had no 2CR5 cells as an emergency supply, the earlier EN-EL1(s) would be your next best power supply. They would deliver many shots with their Reserve Charge before giving up.

After the very LAST EN-EL1 in your possession used up its Reserve Charge, and no longer was capable of making pictures, the 9V+Doodle would now become useful.

You probably won't find usable 2CR5 batteries at the souvenir counter of a Museum, Zoo, Theme Park, Visitor Complex, Smithsonian, Hollywood Tour Destination, Eiffel Tower Shop, Dracula Castle or Strip Mall, but you might find a source of snap-top 9V cells. When you think you might need that emergency Doodle solution, keep your eyes peeled. Buy a 9V cell or two before all camera power is completely lost.

Now you are in emergency mode.

Remember to pair a Freshly Exhausted EN-EL1 with a fresh 9V battery for best results, and turn off your monitor as much as possible. Try not to use flash. BSS uses less power per shot than one flash! Make every shot count.

Don't use a Fully Exhausted EN-EL1 with a fresh 9V battery. It probably won't do you any good. But you might try using a seemingly exhausted 9V battery with a Freshly Exhausted EN-EL1 if there is no other 9V battery available. That might get you a few extra shots.

How many shots:

Here are some unfair tests.

I shot a not-so-Freshly Exhausted EN-EL1 in concert with a used (!) 9V battery (that tested at 8.94 V when under no drain) for a long stream of VGA Sequence images in my 995. How many shots did this less-than-optimum emergency pair produce before giving up the ghost?


What makes this unfair is two-fold. The batteries were not at their Fresh + Freshly Exhausted states, and the VGA Sequence is a fast-exposure mode that is particularly kind to the power supply.

On a more positive note, another test with a Freshly Exhausted EN-EL1 in concert with a fresh 9V battery in a CP775 produced --get this:

Over 360 VGA Continuous images.

I know from other types of test that the EN-EL1 can shoot over 1500 exposures this way without showing exhaustion, so don't think you can do this many shots in more normal shooting conditions. This kind of shooting isn't a balanced test, just a test of how many times the camera will make exposures shooting as fast as possible. Your mileage will vary.

Good luck, and have fun.


Keep in mind that if Nikon ever found out that you used this technique, they might have a conniption fit. We wouldn't want Nikon to experience a hissy! And we certainly wouldn't want your camera to become damaged or declared "Out Of Warrantee."

It works with my cameras, but what if that were just a coincidence or a fluke?

The instant voltage drop reduces the external battery voltage so far below the socket's marked "DC IN 8.4V" that this option should be safe for you to use, as long as the instructions above are followed.

I use it and I take full responsibility for using it with my cameras only. I do not take responsibility for your use and experiences.

Since the EN-EL1 is being drained farther than the camera normally drains it, this is an area of concern. Does this harm the battery? I don't know. These EN-EL1s seem quite stable and hold their charge so well that they may be unfazed by this sort of occasional deep discharge. Most other types of battery, including the NiMH AA cells so often used in the CP990, seem to actually profit by the occasional deep discharge. As if the deep discharge somehow exercised nooks and crannies inside the battery that had grown chemically complacent.

If you know how this deeper discharging of the EN-EL1s might actually harm (or not) them, please drop me a note and bring the evidence to my attention. That said, my own experiences indicate that the EN-EL1s I've used to test this idea show no problems in recharging that I can observe. My guess is that the level of discharge is not a problem for them. But I would caution you to use this technique for emergencies only, if at all.

December 27, 2001. I've had these caveats published here since November 4, 2001. So far nobody from Nikon or from the electronics community of power supply engineers --or anybody else, for that matter-- has disputed the principles of operation or relative safety of this technique. Not proof of anything, but it suggests that one's fear of using an odd power supply like this would be unfounded.


* Doodle (doo-dull) Noun. Thingie. Thingamabob. A Whachamacallit. See Gizmo.

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