Maker Pro
Maker Pro

Noob question about an external battery pack for my T2i DSLR

azzbla

Jan 24, 2014
3
Joined
Jan 24, 2014
Messages
3
Greetings!

I was wondering if you guys could point out if this idea of mine has a chance of working.

I'm going out hiking and I wanted to shoot a time lapse so I'd need a big battery. Just so happens I have a spare 12v battery lying around. I want to attach this 12v to 7.5v transformer to the battery, then attach the 7.5v to this external battery rig.

My main concern is this - will the 12v car battery have too much amperage capacity to fry it? The transformer has a capacity of 3 amps. Also, the AC power adapter that comes with the DSLR dc kit is only 2 amps. Will the DSLR fry due to too many amps hitting it? Or will the transformer/DSLR only pull what it needs and nothing bad should happen.

Should I include diodes or some other basic circuit parts?

I'm really new to these things so try to explain it like I'm 5 or something, thanks!
 
Last edited by a moderator:

GreenGiant

Feb 9, 2012
842
Joined
Feb 9, 2012
Messages
842
Your concern is legitimate, and most people just wouldnt care to even consider it.

But you are in luck, as long as the voltage is correct and you have safeties to ensure that the voltage reaching the camera is only going to be the 7.5 that it requires, it will only draw the current it needs.

Now you may want to add some safeties to the battery so that it doesnt get potentially completely drained which can possibly cause problems, but depending how long you are looking to run it you may not need to.
 

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
Hi azzbla
welcome to the forums

I'm going out hiking and I wanted to shoot a time lapse so I'd need a big battery. Just so happens I have a spare 12v battery lying around. I want to attach this 12v to 7.5v transformer to the battery, then attach the 7.5v to this external battery rig.


you have a few misunderstandings .... dont call it a transformer
a transformer has a very specific meaning in electronics, they are components with coils of wire that one of the common uses is for converting AC voltage from one level to another Transformers DONT work on DC
it is called a DC to DC voltage converter.
The one you linked to is called a BUCK converter as it drops the DC voltage
the other type is called a BOOST converter as it increases the voltage

so your linked buck converter takes the battery 12V down to 7.5V DC. No problems there :)

the next item you linked to, the external battery rig, isnt going to work with your buck converter, as it requires mains AC voltage input 120/240VAC whatever in your country
so forget about that item

The 7.5V DC from the buck converter can go straight to the camera.
The camera will only draw the current it needs, regardless of the current capability of the 12V battery

Do you know the current drawn (consumption) of the camera?
hopefully should be in your camera manual

lets say its 400mA (0.4A), then it would be wise to put a ~ 800mA to 1A fuse in the
7.5V line between the buck converter and the camera

hope you understand that
any questions, ask :)

cheers
Dave
 
Last edited:

azzbla

Jan 24, 2014
3
Joined
Jan 24, 2014
Messages
3
Do you know the current drawn (consumption) of the camera?

Yep, it should be 200mA max according to battery specs anyhow.

Thank you guys so much, you really eased my mind about taking this on and not destroying my camera in the process.

Cheers!
 

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
OK I would then use a ~ 500mA (0.5A) to 800mA (0.8A) fuse

you understood what I said about the second device you linked to ?
that its Not Needed / Wont Work ?
you didnt comment

Dave
 

azzbla

Jan 24, 2014
3
Joined
Jan 24, 2014
Messages
3
Thanks for the tips on the fuse.

Also, the plan was to cut the AC to DC output barrel plug and tie that into the external battery pack 7.5v output. I was just going to store the AC adapter.

On a side note do you guys know of any easy/sure ways of finding the dimensions a barrel plug short of plugging it into a known port? If I could just find the barrel plug size for the DSLR kit I wouldn't have to cut the AC adapter, I could just order a wire and tie it in to the external battery directly.

Thanks again!
 
Top