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Cannot communicate with battery - 7D


Dear Friends,

I am a proud owner of 7D for the past 2.5 yrs and have done many trips and shooting with that.

I am not using any battery grip. Have 2 Canon original battery with me.


Fromyesterday night I am getting an error  "Cannot communicate with battery". It is same described in the below link also :-


I am using Original Canon battery and I have tried with both of them but no result.

As per User Guide ,


If the message "Cannot communicate with battery" is displayed when checking the battery status, select [OK] and continue shooting. Please note that the battery level indicator will appear blank.


My concern is :-

1. If I ignore that and continue shooting , will it create any problem to the Camera functionality ?

2. Wil the battery drain fast due to that ?


I am Ok with not displaying the battery infor as of now ( which I will repair by Canon) but need to confirm that the battery functionality will remain as usual. I will be travelling for a birding trip soon and I due to short time I dont want to send it to repair...


Please guide.


Warm Regards,



I'm in the same boat you are in and am willing to repair my own camera, was a tech for most of my life and willing to do anything.  I've been collecting photos.  You realize that more than one camera have this problem and seem to be built on the same frame.  I have about 15 photos so far but not a step by step.  I know some of the "rubber" needs to be pealed back to get access to the screws.  What's the best way for me to share these photos I've gathered from various forums?  I just zipped them, shrinks down to about 17 MB, but could be larger.  I'd put them on my own server but it's down yet.


I found a Canon parts list for the camera but have not been able to find a service manual.  Canon won't sell them to you unless you are an authorized repair center.  I found a manual for my GL-2 but it took a lot of work.  If you can find a 7D service manual, that would help.


I've found sources on ebay that sell Canon parts, but Canon is very friendly when it comes to purchasing parts, and often the prices on the net are actually higher than Canon.


The photos from the previous post (a Hungarian forum) were not too clear, I contacted a friend who speaks many languages but Hungarian is not one of them, and if it matters, that's not the name of the actual language.


Let's share what we find here, $300.00 labor to do the work by Canon for a problem they created isn't right.


I'm going to take a chance and post my personal email here, sort of:    emptech@surewest.xxxxxxx where the last part is net



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 my previous post, 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 


Moderator Note:  Edited personal information out of post per forum guidelines.



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 expermiment, I had other priorities.


Jim, owner of many Canon products


Empirical Technology



I just had this problem start about a week ago. Now fixed, thanks to Jim, owner of many Canon products, and John, who made the video.

My screw was way up in the top cover, so i had to do a lot more disassembly. Thankfully, the camera is very easy to take apart.

While disassembling, I recommend using pieces of masking tape, sticky side up, to keep track of the screws. I like to lay them out in the same relative positions as they go in the camera. I learned that lesson while working on a computer. When I was done, I discovered it was over engineered with 3 extra screws... not so with the 7D.

"Anyone have any idea how to remove the bottom panel to allow access?"


The fact you need to ask this question is a very good reason to stay out of your 7D.  Not knowing what to touch and not and what to do and not is a prescription for disaster.


Fair warning to all of you.  Now go on and tear into your expensive cameras.  I kmow you will.

EOS 1DX and 1D Mk IV and less lenses then before!

Please check my post where I gave a link to a youtube video on making the repair:


BTW, I must appologize for also asking for information on how to take the camera apart, I had no business doing such, cheating Canon out of a repair job, and not being a camera technician (I was an instrument technician), I had no business asking for help on this subject either, if you read some of my previous posts, you might learn a little about some of the circuits.



Thanks John & Jim!

I fixed mine this morning after watching the YouTube video, it now works perfectly 🙂
Hopefully it won't flatten the batteries even when 'off', as it was when using it with the 'can't communicate' fault.

Shocking behaviour from Canon in not recalling the 7d to be fixed by them.
It's nothing a local repair centre can't do for you in about 15 mins with Canons permission, you'd just about have time to finish a complimentary coffee!

I'm very happy to have fixed it myself with John & Jims help.

Thanks again Guys 🙂

Glad to hear you fixed it, where did you find the screw?


Please spread the word on this, there are so many rumors out there about how to fix the camera and 99% of the solutions are wrong.  I've been hitting as many forums as I could find.  I think that you will find that your camera after resetting all the settings has been returned to normal.



I will spread the word. Saw the video and can't thank John, Jimi enough. I'm very confident if this does happen again, I have no problems doing the DIY. The video is well explained

I did comment stating this started exactly one year ago today - thinking back. No that is when the last time the camera worked ok. The NEXT time I turned the camera on was when I first received the error.

I'll say it again for the final time. It's sad being a long time Canon user dropping thousands of dollars on the camera, lenses, speedlight, batteries, the grip..etc - and this is being ignored. Add a $300+ fix for a screw..labor of 10 minutes max? It's insulting.

@emptech wrote:

Please check my post where I gave a link to a youtube video on making the repair:


BTW, I must appologize for also asking for information on how to take the camera apart, I had no business doing such, cheating Canon out of a repair job, and not being a camera technician (I was an instrument technician), I had no business asking for help on this subject either, if you read some of my previous posts, you might learn a little about some of the circuits.



Yes, Canon's reluctance to publish DIY instructions is self-interested, but not necessarily in the way you seem to think. They're probably just following their lawyers' advice. If they post instructions on how to fix the problem, someone who screws it up and damages something will blame them for the poor instructions and try to get the damage fixed for free. (Whether Canon should fix the original problem for free anyway is a separate, barely related issue.) If someone follows your advice but botches it, Canon's not on the hook.


I have two 7D's, but have not seen the problem. (I'm a CPS member, so my cameras get cleaned and inspected with some regularity.) If I do, I'll watch your video. Maybe it will convince me that I'm qualified to do the fix.  Smiley Wink

Philadelphia, Pennsylvania USA

I'm not suggesting that people do their own repairs, I do, but I worked on instruments for a living.  I'm sure that if a local camera shop was reluctent to repair the camera, they might change their minds after seeing the video that John created.  The most difficult part believe it or not was snapping the bottom panel loose and snapping it back in, if you are all thumbs you could snap it, but one good thing about Canon, they are real good at identifying the parts you need and selling them to you.  I don't think they stab you either, their prices are reasonable.


I have a couple GL2 pro-sumer video cameras.  The cameras had a known tape deck problem, Canon was getting almost $500 to repair the deck. Finally after getting many of these cameras back with the same problem, they admitted it was a design problem and started doing the replacements for only the cost of labor, but it took a long time for them to admit they had a problem. 


In this case, it's interesting how the same screw on the 7D cams and some other cams in the same family comes loose.  I added a tiny drop of blue loctite.  But, I'd say, the screw was never torqued correctly.  Other screws seem to be OK.


I wish Canon would give an official response on this, one possibility is that if the cam is sent back in and they find the same problem, they might do the repair at no charge, but if you wait too long, the loose screw can blow some boards and that will cost you money.  So, this isn't the first time this has happened with Canon, but it doesn't give me enough reason to go to another brand, almost all of my equipment is Canon.


One last possibility, they "might" be repairing these cameras at no charge but nobody on the forums has admitted it.



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