voltage/current regulator from 3.7V 18650 battery 2400mAh to omnia i900 1440mAh

Discussion in 'General Electronics Chat' started by ultracrix, Oct 25, 2010.

  1. ultracrix

    Thread Starter New Member

    Oct 25, 2010
    hello, Im Cristian, new here :)
    I have normal knowledge of electronics, I can build a circuit, but I can figure out how to use a 18650 battery on my omnia i900
    it's an Ultrafire 18650 3.7V 2400mAh, the omnia i900 battery is 3.7V 1440mAh

    I tryed to connect directly to the battery connectors (I take out the batt from the phone), (+) on (+), (-) on (-) with wires but the phone doesn't turn on, the wires get a litte hot near the connectors and make a spark when I touch it, I don't understad why, it's same energy, buts more current?
    when I test with a multimeter the voltage of both batteries at full charge are the same 4.16V, both are li-ion batteries
    plus I use 3 AA rechargeable and alkaline batteries to supply my sony ericsson K310@W200, it has a 3.6V 750mAh battery, the rechargeable batteries I use are original sony's 2000mAh, both test on success, but the phone shows 0% at battery metter and acts weird, its turn off at times, others nope, with the 18650 it doens't turn on

    so, what I need to do here, a current regulator? and a circuit to give to the phone whatever it needs on the middle contact?
    I think that should be plausible to use this battery (never mind about the wires, its for emergency)

    in the other hand, a converter to 5V usb-like charger using a 18650 battery will be ok, perhaps this battery can make 1.5 or 2 full charges
    but I really want to directly supply the omnia, I mean directly on the connectors, taking advantage from 2400mAh, probably it last much more
    ideal for long trips

    can someone help me on this, to build a regulator
  2. tom66

    Senior Member

    May 9, 2009
    You shouldn't need a regulator.

    A load (the phone) only draws as much current as is necessary for it to run. Besides, mAh is a measure of battery capacity, not current.

    Your phone is probably not switching on because it does not like the third wire being disconnected. The third wire probably provides some piece of information like internal battery temperature, or maybe even battery voltage or current.

    Some phones will just show the battery as empty, some as a safety mechanism will shut off.
  3. ultracrix

    Thread Starter New Member

    Oct 25, 2010
    ok, so, how can I cheat the phone with the middle connector? there must be a way, think, 18650 batteries are cheap than original ones and you can use a 18650 like a keyholder, maybe you can make it look fancy, and get a batt that last longer, but how?
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    U can cheat, but to do tht we'll need to see the original battery specs
  5. ultracrix

    Thread Starter New Member

    Oct 25, 2010
    sorry for mistaken, I think maybe a problem with the omnia giving to it so many energy from the 18650, but...

    the original omnia i900 battery specs are 3.7V 1440mAh, 1440 / 1000 x 3.7 = 5,328 Wh (is labeled 5.33)
    the 18650 I had are 2400mAh 3.7V
    both at full charge show 4.16V with a multimeter

    I find an extended battery for omnia i900, is 2400mAh 3.7V
    comes with a extra back cover, there is not this battery where Im lives, buying it on ebay is expensive and complex to me, Im from argentina, well not expensive but isn't what Im trying to do, that extended battery is about 32 U$S wherever its sales from, Im get this 18650 Ultrafires here at 15 U$S

    I cover the middle connector with electrical tape using the omnia i900 battery and it's turn on! so isn't an issue with this connector, so what it is?
    idem with my sony ericsson k310 and both works perfectly!

    they shows the battery metter at well

    energy is energy right? maybe 2400mAh is "too capacity"(?) for the phones and need some kind of regulator
    I think is like if you want to fill a bottle with water, if it from the faucet nothing happen but is if from a giant tank of water it can explode, so the phone prevent it and if you want to pass this prevention circuit need to regulate the amount of energy you give to it, right?, but how???