T7i Battery Grip.

[fewcrank]

I, for the life of me, can't find any battery grips for the t7i. Are they any at all that fit it?

[John_]

Yeah, go figure that one out! I guess it is a wait and see deal. Will be interesting to see if that UK site removes it from the list of battery grips. 

[Waddizzle]

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@John_ wrote:

Yeah, go figure that one out! I guess it is a wait and see deal. Will be interesting to see if that UK site removes it from the list of battery grips. 

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In addition to the lack of control contacts, I would also be worried about the actual operation of a third party grip.  

Consider how a grip works.  First and foremost, some cameras are not designed for use with a battery grip.  A battery grip does not connect two batteries in parallel, which could cause the batteries to short out one another.  

Cameras that use battery grips seem to only use one battery at a time, and alternate between the two batteries as their charge gets used up.  I am not so sure that a camera not designed for a battery grip has the smarts to do that.  

Maybe I am wrong about how a grip works, or how a camera interacts with the batteries.  One thing is certain, though.  The batteries are not connected in parallel, as that would smoke the batteries.  

I can look in my menu at the battery status, and I can see the percentage charge remaining on each battery.  Immediately after a recharge, the will both read 100%.  After a little bit of use, one may read 98%, while the other may still read 100%.  

If I take some more shots, then the second battery will start showing signs of discharge.  It might drop to 96%, while the first will stay at 98%.  At this point it might switch back to the first battery discharging.

To me, it strongly suggests that the camera body can read the remaining charge on the batteries, and switches between using one or the other.  What does that tell you about how a battery grip might work?  

[RobertTheFat]

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@Waddizzle wrote:

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@John_ wrote:

Yeah, go figure that one out! I guess it is a wait and see deal. Will be interesting to see if that UK site removes it from the list of battery grips. 

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In addition to the lack of control contacts, I would also be worried about the actual operation of a third party grip.  

Consider how a grip works.  First and foremost, some cameras are not designed for use with a battery grip.  A battery grip does not connect two batteries in parallel, which could cause the batteries to short out one another.  

Cameras that use battery grips seem to only use one battery at a time, and alternate between the two batteries as their charge gets used up.  I am not so sure that a camera not designed for a battery grip has the smarts to do that.  

Maybe I am wrong about how a grip works, or how a camera interacts with the batteries.  One thing is certain, though.  The batteries are not connected in parallel, as that would smoke the batteries.  

I can look in my menu at the battery status, and I can see the percentage charge remaining on each battery.  Immediately after a recharge, the will both read 100%.  After a little bit of use, one may read 98%, while the other may still read 100%.  

If I take some more shots, then the second battery will start showing signs of discharge.  It might drop to 96%, while the first will stay at 98%.  At this point it might switch back to the first battery discharging.

To me, it strongly suggests that the camera body can read the remaining charge on the batteries, and switches between using one or the other.  What does that tell you about how a battery grip might work?  

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Isn't it far more likely that the battery switching is done within the circuitry of the grip itself?

Does the camera actually differentiate between the two batteries, as you seem to imply? If so, even that surprises me. I wouldn't have expected the camera to know that a second battery is present.

Full disclosure: My first-hand knowledge of grips is zero. They gave me one free when I bought my 5D4 last spring, but I've never used it. I guess I could live with the additional weight, but the extra size is a show stopper.

[Waddizzle]

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@RobertTheFat wrote:

Isn't it far more likely that the battery switching is done within the circuitry of the grip itself?

Does the camera actually differentiate between the two batteries, as you seem to imply? If so, even that surprises me. I wouldn't have expected the camera to know that a second battery is present.

Full disclosure: My first-hand knowledge of grips is zero. They gave me one free when I bought my 5D4 last spring, but I've never used it. I guess I could live with the additional weight, but the extra size is a show stopper.

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I am almost certain that the batteries take turns being the lead or lag battery.  Ohm’s law says that you cannot connect the batteries in parallel.  You could if you connect them with additional diodes and load resistors, but doing so would only detract from battery life.

When you use a battery grip, the camera can see both batteries separately.  It can display the serial number and remaining charge of each battery.  I wish I knew how to take a screen shot of the rear display, short of taking an actual photo.  It can even display which battery is in which position inside of the grip.

I do not see evidence of any electronics in a the battery tray or the grip.  There might be something inside of the vertical piece that sticks up into the camera body.  The camera can read the real time status of both batteries at the same time, which strongly suggests that both batteries are connected to the camera.  

With all of the extra contacts in the battery compartment, it makes more sense to put any smarts in the camera.  You can implement any battery switching in the firmware.  This is a much better arrangement, and a far less costly arrangement, than putting any electronic components in the grip.

[John_]

Batteries can and are often connected in parallel to increase the MAH while the total voltage remains the same. In series the voltage of the batteries adds together while the MAH remains the same., of this I am sure. One basic example is jump-starting a car, the batteries are connected in parallel. The only damage you can cause leaving 2 car batteries connected in parallel together is if the alternator tries to charge them both it could be damaged but not the batteries. In my Logitech mouse, the 2 AA batteries are connected in parallel which makes it last longer, more MAH and I can remove one battery and the mouse still works. 

As far as the internal circuitry, anything is possible.

[ebiggs1]

"The batteries are not connected in parallel, as that would smoke the batteries."

If you don't know, make it up? 

"As far as the internal circuitry, anything is possible."

Absolutely.

[Waddizzle]

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@ebiggs1 wrote:

"The batteries are not connected in parallel, as that would smoke the batteries."

If you don't know, make it up? 

"As far as the internal circuitry, anything is possible."

Absolutely.

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 Warning,  You are crossing the line, once again.  

[Waddizzle]

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@John_ wrote:

Batteries can and are often connected in parallel to increase the MAH while the total voltage remains the same. In series the voltage of the batteries adds together while the MAH remains the same., of this I am sure. One basic example is jump-starting a car, the batteries are connected in parallel. The only damage you can cause leaving 2 car batteries connected in parallel together is if the alternator tries to charge them both it could be damaged but not the batteries. In my Logitech mouse, the 2 AA batteries are connected in parallel which makes it last longer, more MAH and I can remove one battery and the mouse still works. 

As far as the internal circuitry, anything is possible.

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Sorry, you cannot connect any type of battery in parallel, as they would short together.  True, they can reach a equilibrium point, but the batteries need to be closely matched electrically.  I would not mix batteries from different manufacturers.

When it comes to cars, you are talking about a lead-acid batteries, and you are talking about a brief connection.  I have also seen a dead battery in one car, kill the batttery in a ssecond car used to jump start it.

As far as the circuitry goes, anything is possible, but some things are improbable, while other things make no sense.  You have your opinions, while I have my facts.  The batteries in a grip discharge separately, and alternate as they do.  To me, tha tis proof positive that they are not connected in parallel.

[RobertTheFat]

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@John_ wrote:

Batteries can and are often connected in parallel to increase the MAH while the total voltage remains the same. In series the voltage of the batteries adds together while the MAH remains the same., of this I am sure. One basic example is jump-starting a car, the batteries are connected in parallel. The only damage you can cause leaving 2 car batteries connected in parallel together is if the alternator tries to charge them both it could be damaged but not the batteries. In my Logitech mouse, the 2 AA batteries are connected in parallel which makes it last longer, more MAH and I can remove one battery and the mouse still works. 

As far as the internal circuitry, anything is possible.

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You shouldn't have a problem connecting two identical batteries in parallel, as long as they start out at about the same level of charge. But if one is fully charged and the other is nearly drained, the weaker battery may try to draw down the stronger one, causing either or both to overheat. Battery chargers are designed to avoid that phenomenon; but if you let a second battery get tricked into trying to function as an ad hoc charger, bad things may happen.

[Waddizzle]

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@RobertTheFat wrote:

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@John_ wrote:

Batteries can and are often connected in parallel to increase the MAH while the total voltage remains the same. In series the voltage of the batteries adds together while the MAH remains the same., of this I am sure. One basic example is jump-starting a car, the batteries are connected in parallel. The only damage you can cause leaving 2 car batteries connected in parallel together is if the alternator tries to charge them both it could be damaged but not the batteries. In my Logitech mouse, the 2 AA batteries are connected in parallel which makes it last longer, more MAH and I can remove one battery and the mouse still works. 

As far as the internal circuitry, anything is possible.

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You shouldn't have a problem connecting two identical batteries in parallel, as long as they start out at about the same level of charge. But if one is fully charged and the other is nearly drained, the weaker battery may try to draw down the stronger one, causing either or both to overheat. Battery chargers are designed to avoid that phenomenon; but if you let a second battery get tricked into trying to function as an ad hoc charger, bad things may happen.

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Great observation and comment, Bob.  

That has been exactly my point.  You cannot just simply connect two batteries in parallel, because it creates an electrical hazard.  Some types of batteries can tolerate it, but that assumes that they are manufactured in a similar fashion.  Not all lithium batteries are created equal.  Canon batteries seem to hold their charge longer.

Designers of the battery grips cannot assume that both batteries are similar, even though the instruction manual tells you that they should be.  Designers cannot assume that both batteries will be similarly charged, either, even though the instruction manual tells you that they should be.