It is currently Sun May 16, 2021 3:37 am

Post new topic Reply to topic  [ 2 posts ] 
 Newbie construction TL battery maths help required 
Author Message

Joined: Wed Sep 03, 2014 12:34 pm
Posts: 1
Post Newbie construction TL battery maths help required

I have a calculation I’m having difficulty comprehending. I need to establish what 12v deep cycle battery I need to last 5 days.

I want to make a time-lapse for 14 hours per day Monday to Friday. My camera (canon 30d) says it uses 7.4v but actual reads 8.1v.

The camera uses 1w in standby and 4w’s when taking a photo and to write to card (5 seconds max). I will ask it to take a photo every 6 mins for 14 hours per day.

To go from 12v to 8.1v I will use a step-down board (LM2596S, I don’t know how much this uses?).

How many 12v Ah will this consume over 5 days…and if you have time can you explain it like I’m a 5 years old so I can work out how to do it myself in future?

Thank you in advance


Wed Sep 03, 2014 12:41 pm
User avatar

Joined: Sun Oct 09, 2011 7:34 pm
Posts: 116
Location: Melbourne, Australia
Post Re: Newbie construction TL battery maths help required
Hi Reuben,

This from our electronics engineer:

This link should explain it in detail. Start from step one. ... ations.htm

Quiescent Current of the LM2596 is 10ma (worse case). So you need to add 10ma as a constant duration.

Also the LM2569 only switches at 73% efficiency (worse case, although from 12V to 8 it’s probably not that bad). But to be safe, once you’ve done all the maths you should take the 73% efficiency into the consideration as well. (just multiply the final Ah x 1.27)

Sorry the calculation isn’t actually that simple, I don’t have time to explain it in much more detail bit you should have enough to get started.


_________________ | Long term time-lapse for the pro! | 3G enabled | Use your own DSLR | Web config | Download images direct to FTP/Dropbox | Solar-powered | IP65 weatherproof |

Also Aussie distributors of eMotimo TB3 motion control head: eMotimo in Australia

Sun Sep 07, 2014 8:31 pm
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

Who is online

Users browsing this forum: No registered users and 2 guests

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © phpBB Group.
Designed by Vjacheslav Trushkin for Free Forums/DivisionCore. pozycjonowanie