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Canon DC Coupler DR-400 Pinout

Battery packs have a trigger button on them so you can them to take a shot. I think this third contact is used exactly for that reason.

Gary Haran
Mon Jun 21 13:41:49 PDT 2004

On viewing your website I have come across an article relating to the Canon dummy battery and power cord. I suspect the extra, seemingly redundant, ground connection on the dummy battery is used to allow the camera to determine that a battery/dummy battery is connected. The camera registers a voltage between the + power terminal and the dummy terminal - this allows the camera to determine if the power source is a dummy battery or a real battery (the dummy having one less connector than the real battery).

This is only a theory, but I hope it sheds some light on the matter?

Ben James
Mon, 04 Oct 2004 20:17:57 +0000

Dear Sir,

You have a very good article on Canon adaptor and battery "DR-400 pinout". In that article, you asked about the B and D pins on the battery. The missing information can be found from a generic battery supplier such as GP Battery: GP Rechargeable Speciality Batteries

Keep up the good work.

Mr. LIN Yih . . . Singapore
Mon, 29 Nov 2004 00:19:37 +0800

That was a very good web-site, Mr. LIN Yih. They even have technical handbooks on Lithium Ion, Nickel Metal Hydride, and Nickel Cadmium.

I managed to find the B and D connector schemetic and specification (attached below) from the GP VCL002 Data Sheet.

I am not sure what it means exactly.

Attached Image:

BP-511 Connector Specification.gif

Chieh Cheng
Sun Nov 28 13:05:04 PST 2004

Usually one of them is connected to a thermistor - a temperature sensing variable resistor to sense the battery temperature during charging. For example, see

Overcharge, Overdischarge, Overcurrent Safety Circuit

Since Canon has two pins D and B, I suspect the D pin is the thermistor, and the B pin is either obsolete or for Identification (tell the charger that "I am connected"). See

Rechargeable Battery Pack Protection

Of course, I have not confirmed the above. If I have more information, I will let you know.

My quest started because I was looking for a compact size charger for my Kodak battery pack (for SLR/c). The Kodak charger is large - AC/DC adaptor plus charger combo. Since I also have a Canon compact charger (for BP511) and both batteries are 7.4V lithium-ion, I wondered if I could use the Canon charger for the Kodak. But so far, I have found that the thermistor values are different - Kodak about 8.2K ohm and Canon about 74.5K ohm (D pin). Furthermore I cannot use the Canon charger by tapping the + and - pins only. Something needs to be connected to D (or B). Details to be confirmed.

LIN Yih
Mon, 29 Nov 2004 08:58:28 +0800

That's quite interesting. Which Canon charger do you have?

My Canon CS-PS400 charger does not have an interface to B or D . . . It charges the BP-511 battery pack by interfacing to + and - only. My Lenmar Mach 1 charger is also the same way. Yet, both are able to detect that the BP-511 is fully charged.

I am quite surprised to hear that your charger interfaces to the B or D pin.

Chieh Cheng
Mon Nov 29 20:29:03 PST 2004

Thanks for the tips. My Canon CB5L charger definitely senses D but B has no effect. I tested by tape masking away D and B pins in different combinations. Yes, I have a X-brand charger too, and works with only + and -. However, that charger is not compact (compared with CB5L). I have not tested X-brand with Kodak. Canon CB5L came with the 300D.

Thanks for the tips. I will be out of Singapore for the rest of week (work). Will revert back to the Kodak when I am back.

LIN Yih
Tue, 30 Nov 2004 19:34:55 +0800

Ahhh . . . Yes . . . I can see the B and D pins on the following picture of the CB-5L charger:

How interesting . . . What kind of effect did you see when you mask away the D pin?

Attached Image:

Canon CB-5L Battery Charger.gif

Chieh Cheng
Tue Nov 30 11:47:10 PST 2004

If you take a look into camera's (20D)battery compartment you'll find that neither B nor D pins are connected :)
So they don't play any role in feeding up the camera.

Konstantin
Sat Feb 5 11:30:01 PST 2005

You guys rock! Sharing your knowledge with people who care enough to learn is awesome. Our throw it away society has a lot to learn about the value of things. Knowing how to do something well and teaching it to others is one of the most valuable resources we have. Rock on.

Tina
Mon, 19 Feb 2007 21:54:17 -0800

The 2 extra contacts are used when charging. 1 is the thermistor, its a variable resistor that changes with temp, it lets the charger know the battery temp, if the temp is outside a certain range, it will not charge the battery (to hot or cold). The other is serial data communication. This allows the charger to talk to the battery and vise versa.

Li-Ion batteries can be dangerous is not cared for during charge and discharge. The pack has a saftey chip. Each of the 2 cells is monitored for correct voltage range (4.20v is max and the min is around 2.5 to 3.0). If either cell is out of the range, the saftey chip will shut the output of the battery pack off, like wize to hot or cold. There are other parameters this saftey chip preforms, like max charge and discharge current, if to hi, it shuts down, max charge time, ect.

Oz
Mon, 08 Oct 2007 04:45:43 +0000

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