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Battery Pack for Arduino + Chip + LEDs

Discussion in 'Power Electronics' started by Ferrock, Apr 20, 2016.

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  1. Ferrock


    Dec 9, 2014
    Hey guys

    I have a circuit that consists of a adafruit TLC5497 chip (, an Arduino and a small SD card module. I need to be able to power this for 12 hours.

    I have to assume all 24 LEDs will be running at maximum brightness for this since it is a possibility. Most likely won't happen - but since I am designing this for somebody else I have to assume it may happen.

    So am I correct in thinking that, 24 LEDs with a maximum current of 30ma = 720mA. + the arduino at ~25mA. Not sure how much the SD card module uses ( ... UTF8&psc=1) and I'm not entirely sure how to measure it! But I can probably assume that is negligible as far as battery sizing goes since the SD card is only checked once at the beginning to load settings.

    So then take that 745mA, multiply it by 12 and get 8,940mAh?

    I have been looking into this and it seems that due to the way batteries behave as they discharge, it is good practice to aim for a battery that is 3x the size of what you require. So something around 27Ah - this is to prolong the life of the battery as you won't be completely discharging it each time and is also to make sure it maintains a steady output (something like 5V (arduino voltage) and 750mA in this case).

    These are a few I am looking at: (They don't all hit the 27Ah requirement but I just want to know that I am looking in the right place! Also if 2x the requirement is fine rather than 3x then these would be (hopefully) be suitable!) ... B00MWJKXZO ... _qh_dp_hza

    Thanks in advance!

    - The chip is current sink, so does that mean I don't need to supply anywhere near the amount I am calculating? I'm not sure entirely how this works, I'm a newbie!
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