Photo Gear,  Photography

Canon 7d – Cannot Communicate to Battery Error Fix

Two days prior to a photography trip to Yellowstone while charging and checking my batteries, I received the error “Cannot Communicate to Battery” while inserted a freshly charged battery in my Canon 7d. The camera still appeared to have power. However, the battery indicator showed that the battery was empty and I received the error each and every time I turned the camera on.

After scouring the Internet and finding limited information, I thought I’d pass along how I fixed the problem.

The fix was simple. Remove both the LP-E6 battery and the clock battery for around 20 minutes. The clock battery is located inside the main battery compartment right next to the hinge for the compartment door. When you reinstall both batteries, the problem should go away. I received the error one additional time after reinserting the batteries. But, once I set the date and time, and turned the camera on and off the problem went away.

If this doesn't work, you may have to send the camera off to be repaired.  The functioned correctly to take photographs.  It only lost the date and time and got an error each time a new battery was inserted.

But before you send your camera off for repair, try this quick and easy fix first.
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  • Penjo

    Hi Martin,
    Sounds good, I have just the same problem, have done all you've said but it's not working yet. Any other idea please. Whenever I put my battery, it only shows the signal of an empty battery, so I don't know what to do. It has taken more than two days now that it started. Please let me know if you have any other solution to this. Pete

  • James Holtzman

    7D owners, I hope this fixes your problem, don't waste your time resetting the camera, putting it in the freezer, polishing battery contacts, but if that fixes your camera good, otherwise, it's probably caused by a loose fastener (screw) inside.  Read on:

    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.  I've seen similiar photos elsewhere on the web.

    We owe the help to John Clark
    Pelagic Visions Marine Imaging
    Blue H2O Cozumel Watersports

    USA Direct   813 398 0791
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    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 expirment, I had other priorities.

    Jim, owner of many Canon products

    Empirical Technology

  • Paul Hendricks

    Removing the button battery inside of the battery case did the job immediately! How simple a fix that was! Thanks for sharing that great tip!!!

  • Paul Hendricks

    Removing and replacing the button battery inside of the battery housing, solved the problem immediately! Thanks for sharing that great tip!!

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