Best battery choices for low energy bluetooth?

Discussion in 'Wireless & RF Design' started by FHUGO, May 17, 2016.

  1. FHUGO

    Thread Starter New Member

    Nov 2, 2014
    2
    0
    Hi, I am looking for some help finding an appropriate battery for a project. The device is a small remote essentially and spends most of its time on standby only powering up to send one command via LE bluetooth from one button press. It also runs very dim LEDs for a short duration of around 2 minutes. What I am looking for is potentially the longest duration between recharging or replacing with the smallest size.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Lithium battery cells are smaller for capacity, like 18650 cells, best thing is to measure the current it takes and what voltage, then look at batteries in that range, that will give you an idea for sizing.
     
  3. hp1729

    Well-Known Member

    Nov 23, 2015
    1,957
    219
    Replacing or recharging how often? Is size profoundly important, like a hearing aid, and changed daily?
    It is difficult to make a suggestion without knowing how much current, for how many hours and how much space is available. Most lithium or alkaline coin cells are rated by diameter and thickness. CR2032 is 20 mm in diameter and 3.2 mm thick.
    If you can work at 1.5 Volts Alkaline AG13 (LR44, A76) cells are real popular and cheap.
    Consult battery manufacturer web sites.
     
  4. FHUGO

    Thread Starter New Member

    Nov 2, 2014
    2
    0
    Thanks for the replies. Size is quite important so the size of about two 12-16mm button batteries or one A23. The component with the highest drain would be the LED and that is dependent on what the lowest energy LED I can find is. What I am looking at is around 10-15 min of run time per day every day of the year. Much like a garage remote or door bell where you replace the battery very infrequently I would like to aim for once a year at most. If it was a toss up between Alkaline and Lithium besides price which would win out?
     
  5. hp1729

    Well-Known Member

    Nov 23, 2015
    1,957
    219
    I would opt for lithium. Output voltage stays fairly steady up to the very end. So, say 1 mA, 15 minutes a day, for365 days is about a 100 mAH battery. Sounds easy. Shopping.
    (edited to add ...)
    Closest I can find is a CR1632. Most I could find that were > 100 mAH were 20 mm in diameter.
    Shop around and see if you can find something better.
     
    Last edited: May 18, 2016
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