Or, How to Beat Canon’s Money Grab
Canon 7D with main battery removed.
I purchased a factory refurbished Canon EOS 7D digital SLR camera several years ago. It’s worked great and I’ve been pleased with it—and I’m still using the original proprietary battery pack. Several weeks ago I’d picked it up after several months of disuse and tried to turn it on. The camera was dead. I wasn’t too surprised, so I pulled the battery and put it into the charger. After a charge I put it back into the camera. Still wouldn’t turn on. Pulled the battery again and placed it back into the charger, which thought it was fully charged. Hmm.
After reinstalling the battery and futzing around a bit I finally got the 7D to turn on, but with an error message on the display: “Cannot communicate with battery. Use this battery?” I selected ‘Yes’ and was able to use the camera, but there was no feedback as to the battery’s charge level on the status display. It turns out this is a common problem with the camera, and the most common solution is to return the unit to Canon with a $250 payment for repair. Although the problem seems widespread Canon has not enacted a recall. This is an unsatisfactory situation and seems to me like a money grab by Canon.
I wondered whether or not the battery contacts (on the battery itself or the contacts within the camera) had become fouled. I removed the main battery from the camera as well as the memory backup coin cell (a CR1616) from the battery compartment. Next I dug out my trusty can of Caig Laboratories Deoxit D5 (available at most fine electronic parts retailers, or at Parts Express and MCM Electronics) and some cotton swabs.
Here’s what I did to restore the camera’s normal operation:
1) Remove the main battery from the camera and look at the flat side. You’ll see two silver rectangular contacts side-by side. There are also two side-by-side slots halfway between the left and right sides on the same end of the battery. There are contacts within these slots as well.
2) Wet one of a cotton swab with Deoxit. It should be damp when you’re finished, but not dripping wet. DO NOT SPRAY DEOXIT DIRECTLY INTO THE CAMERA OR ONTO THE BATTERY.
3) Look into the camera’s battery compartment, using the location of the contacts on the battery itself to guide you as to where to apply the Deoxit. NOTE: when looking into the camera you’ll see a lot of copper-colored circles at the bottom of the battery compartment, as shown in the photo above. THESE ARE NOT BATTERY CONTACTS. The contacts will be on the wider, flat side of the compartment down close to the spring. Wipe the four contacts with Deoxit.
4) Now wipe the battery contacts with Deoxit. For the contacts in the slots, you may have to pull and shape the cotton on the swab to make it thinner and flatter. Alternatively, you can take a corner of a paper towel and fold it several times, spray it with a little Deoxit and work the towel into the slots.
5) Re-insert the battery into the camera, but pull the white latch to the side with one finger and hold it while you repeatedly push the battery in and allow the spring to pop it back out again. Do this fifteen or twenty times to help polish the contacts and ensure they’re coated with Deoxit. When finished remove the battery and set it aside for ten minutes or so.
6) Take the opportunity to remove the CR1616 coin cell from the battery compartment and change it if you’ve never done so. With the carrier that holds the coin cell out of the camera you can see two sets of silver contacts in the slot. Wipe those with Deoxit, then carefully insert and remove the battery/carrier a few times. (This battery’s contacts aren’t as robust as the other set so be careful.) When finished, insert and leave the coin cell in the camera.
7) The last step is to insert the main battery and try turning the camera on. You may still have to futz around with the controls a bit for the first turn-on cycle; I didn’t. You should be greeted by a prompt to change the time and date.
Fortunately this routine allowed me to resuscitate my camera and one week out it’s still working. Now what could possibly have caused the issue? My theory is that some small amount of gasses produced by the battery’s internal chemicals may have escaped and fouled the contacts as the battery slowly discharged inside the camera. Perhaps this is why it’s recommended to remove the batteries from your electronics when they’re not being used for a period of time. In the future I intend on following that advice. If this helped you please pass it on. Why should anyone spend $250 that they don’t have to?
UPDATE: November 2, 2014
This blog post has gotten a lot of interest since it was published! I have a few updates for you.
First, you’ll notice a very well-documented comment post by James Holtzman, which reflects something that many Canon 7D owners have discovered–the cause of the issue may be a loose screw inside the camera. Thank you James! James sent along a picture but was unable to post it (and I could not put it inside his comment) so I’m placing it here:
Please read his post below for more information. So for some of you this may be the fix. I’d add that there are two additional screws you should remove that are not mentioned in the disassembly video James linked to. These make it a little easier to remove and re-attach the bottom plate. Since my only camera is the 7D I’m unable to make the pics of the screw locations, I’ll describe them:
1) The first additional screw is black, and is directly below the lens mount on the bottom of the camera. You can’t miss it.
2) The second screw is below the rubber grip, near the lens and closest to the bottom of the camera. It’s a silver screw.
Now for my own experience…I purchased my camera several years back as a Canon factory refurb. When I opened the camera the screw was firmly in place. Gentle tapping on the table did not produce any other loose screws from the camera’s guts. Despite this it developed the battery communication issue as I had described. There may still be some validity to my theory of battery outgassing, but the loose screw issue may be the primary cause of the 7D’s problem.
I wonder if the new 7D Mark II will have this same problem?
The Virtual Venesect 
Just found this page, my 7D popped up with the same exact problem/error about a week after you posted this. Using Canon batteries and the grip. Any errors since? I’ll try this, I’m still using the camera and it’s guesswork on how much battery life I have left – it seems like it’s using much more battery life then normal though. (I’ve read about the $250 fix also on other forums, many times the user doesn’t even know what is replaced/fixed!). It is amazing this error is a widespread issue on this model, Canon should recall this problem, if it’s from the firmware updates or some odd flaw, they need to address it.
Mostly it is the battery that´s been oxidized. One of the pins on my battery were green and i cleaned it with deoxit spray and a toothbrush. Problem solved!
KanyesSkirt, I just checked the camera and it’s still okay. I’ve read that the camera will work if you can get it to start without battery communication, but it will drain the battery at a higher rate. I agree; Canon should own up to the problem. It’s getting them a lot of bad publicity.
I have just run into this problem. unfortunately the cleaning contacts solution did not fix it.
I was reading elsewhere that there is a problem with the battery. I have 4 genuine Canon batteries of various ages. They all have the same problem in my canon 7d.
They all work perfectly well in my canon 5d III. Why is it so?
This problem only occured after I let a battery discharge to exhaustion in the canon 7d. I have a feeling that this is the problem.
Either it fries some internal connection with corrosion, or the software has a melt-down because of the discharged battery.
It has been suggested that taking out the cr1616 and letting the camera “lose” its memory may fix this problem
Raj,
You can certainly try removing the memory battery. I did that in the course of my troubleshooting and, in fact, replaced it with a new one. As of today the camera is still working well with my fix. Perhaps I lucked out.
I’ve tried that and the freezer trick – no joy. I guess the Camera is 4 years old. and I expect to be hit with a $250+ bill. Almost not worth it when I can buy an EOS M with EF adapter for $390
Hi. I have to say that you saved my money. It really works. I had to do it twice, but it worked. for the second time I put a kitchen’s paper between the battery and the contact cleaner, and I spayed directly, for the camera compartment I did what you say. thanks a lot for your help. I have had this problem almost one year
It works!!! Thank you very much!!!
Short circuit by screw!!! SOLVED: Canon 7D “will not communicate with battery”
http://www.dpreview.com/forums/post/54348668
I’m not sure if this completely solves the problem, or whether there are a number of things contributing to the issue–but there seems to be mounting evidence that Canon needs to do two things. First, admit there’s an issue and be upfront with their loyal customers. Second, fix the problem(s) at no charge to their customers. It looks as though Canon is trying to take a page from Apple’s playbook: Deny until you cannot deny any longer. The question is how many customers will still be loyal and continue using their products?
Customers do not know what the problem is and get paid for the repairs. If you will be to identify more cases of problems with just a screw tightened enough, the chance to make free repairs after the warranty service will be higher.
Until yesterday, I found only one message that bolts are gone and the author has put newer, but not searched, which could disappear old. Hopefully after my posts will begin to change the situation.
7D owners, I hope this fixes your problem, don’t waste your time resetting the camera, putting it in the freezer, etc.
I didn’t mention in posts on other forums, I’ve been an instrument technician for more than 40 years and don’t have a problem going into the camera and making the repairs, I’ve done so on other Canon cameras and Canon lenses. Service manuals don’t always give the order of which screws need to be removed. I wouldn’t know in the case of the 7D because I’ve never seen a service manual.
We have been led to believe that the cause of the problem was due to a screw making the ground connection on one of the circuit boards had come loose and was floating around inside the camera. The first symptom is that we get the famous error as described on the subject of this thread. If the problem goes long enough unfixed, not only can we not read the battery level, I’ve heard that even if the camera is turned off, the battery will discharge over a very short period of time. Worse than that, if the loose screw shorts between some traces on any of the boards, catastrophic results will occur, then circuit boards actually will have to be replaced.
I held off repairing my camera, simply because I didn’t have the time. I put out the request on multiple forums asking which screws need to be removed. As it turns out, a total of eight screws need to be removed to remove the bottom panel of the camers. Six screws on the bottom and one screw on each side of the camera. I took my camera apart, found the loose screw, applied a tiny drop of #242 blue loctite and put the screw back where it belonged. It should have been loctited in the first place, never was, I have heard that Canon is charging people as much as $300 for a repair that never should have been necessary, because of a factory defect. I took a photo showing the bottom removed, it is obvious as to where the screw is missing from. The screw was jammed up into the camera, a couple taps on a table top loosened the screw. There are three types of screws, three of the screws on the bottom have a blue thread lock, probably loctite. Three of the screws on the bottom do not, they are the same size. The two screws on the left and right side near the bottom of the camera are a little longer than the bottom screws, don’t get them mixed up.
I would attach my photo showing where the screw is missing from but don’t know how to attach a photo to this post. (Image added above in body of blog post. –PC) I’ve seen similar photos elsewhere on the web.
We owe the help to John Clark–
Pelagic Visions Marine Imaging
Blue H2O Cozumel Watersports
http://www.padiowsi.wix.com/blueh2ocozumel
USA Direct 813 398 0791
Mexico Cell 987 111 2170
Facebook Pelagic Visions
John made a 15 minute video, it is on youtube showing exactly what he had to do to perform the repair.
This video is being shared with John’s permission:
As I mentioned, if you let this problem go too long, it may only get worse, damaging more boards and costing you more money.
And, yes, I did ask others which screws were to be removed, I didn’t have the time to experiment, I had other priorities.
Jim, owner of many Canon products
Empirical Technology
Jim, if you send the photos to (redacted) I’ll edit the blog post and put them in the body. And thanks for the great information!
Thank you so much for this video. I just followed the directions and this 58 year old woman fixed her Canon7d. Hopefully it will stay fixed 🙂
Hi Jim,
I had the same issue and first went to the store where I bought the 7D years ago. They had no idea. Found your video though. I am usually not the type to open up a camera. But followed your instructions and it worked. Amazing!
Thanks a lot,
Bart
So that Canon might take this problem seriously I thought that it would be a good idea to gather some information/data to show them.
So I wrote a form where one can enter information about ones “loose screw” problem.
If enough people fill out the form, then I hope that Canon will make this a “official screw-up” which they will fix free of charge.
https://www.allanach.dk/canon-error.php
That loose screw fell out of my 7D nearly a year ago but luckily I’d held onto it — it didn’t affect the electronics until now. Thank you so much for posting this! Worked like a charm.
i came across this blog and hope the link is still viable. i have a 7D, i saved forever for and little money for repairs…so 1 month after the waraanty expired the camera shut down..screen went blank with a flashing battery icon…i have changed several fully charged batteries to test..no change..also oddly..the icon flashes whether the camera is on..or off..any suggestions before i start saving for repairs. i appreciate any and all time answering my question
Turn off printer. Wait until the cartridge carrier returns on the side. If the carriage gets stuck, open the lid and move the carriage to the side.
Turn on printer.
For More: https://www.canonprintersupport247.com/blog/fix-canon-printer-error-code-u043/
I’m not sure what you were replying to, but my post was about fixing a digital SLR, not a printer.
Excellent information.I like the way of writing and presenting.