Just a helpful note for the blinky lovers out there… all my projects previously have been power supply, so as long as the supply was beefy enough and rated correctly… thats as much thought as i put into it.
but now im in the process of a battery powered blinky, and whilst i was sure of my maths, i guess theres nothing more annoying that designing a project, only to realise of an issue that can only by solved by adding a different battery and substantially ruining your product.
i bought myself one of these little voltmeter / ammeter, and its got a cute timer, with mAh linked to it…
i cant comment on its reliability, and it was cheeep! but it seems to be working fine, and i would heartily recommend!
http://www.ebay.co.uk/itm/301836634879?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I have the exact same one, its useful to an extent! it uses power itself, so your readings may be off, don’t trust what it says for voltage its lying! However its amazingly usefull for working out how long your led project will last on X amount of batteries!
I have two of those and they helped quantify the good from the bad. I also ended up buying an Opus BT-C3100 charger/tester. It can charge/test 4 18650’s at one time. Awesome!
Those things are junk!
Some things don’t work while connected.
It drains power away from the device!
Don’t believe the hype!
It’s £3 so I’m not developing military grade hardware… But if it says that I’ve used 24mAh in just over an hour, can I reasonably assume that a 240mAh battery will last around 10 hours?
@Kelvin_Mead nope, depends on the type of battery - I assume LiPo or LiIo. You cannot discharge those fully, nor shouldn’t you charge then to the max. (serious fire hazard). Best case you get 80%
i hoping that i can slyly ignore those issues in my project… i have a purchased lipo charger…
may need to spend more time on it in the future though.
It’s all approximate, and you’ll get losses in wiring etc (which can depend on the quality of your solder joints, thickness of the wires you use). You’ll have to sit there with a stopwatch and your actual project to know for sure.
But for some reasonable approximations without going to the trouble of even prototyping, if you’re on iOS give my app LEDstimator a go: https://itunes.apple.com/us/app/ledstimator/id945794010?mt=8