Mobile charger as Ni-MH charger

Thread Starter

Arup

Joined Apr 13, 2006
3
Hi,
I've a LG mobile phone fast desktop charger lying around with the following ratings
input 12V, 0.3A
output 4.2 V 0.5
it has 3 pins at the output, the battery fits into a slot over it and has a bicolour LED for charge indication (red - charging, green - done)
the circuit consists of 3 ICs
K1A494AP - PWM controller
LM358N - OP AMP
GMS81C1102 - 8 bit CMOS microcontroller.

My question is can this charger be used as a Ni-MH charger after modding the output voltage to 1.8/2.0 V.
also what is the function of the third pin on the charger and the battery?

Thanks and regards
Arup
 

kubeek

Joined Sep 20, 2005
5,719
Originally posted by Arup@Apr 13 2006, 06:53 AM
My question is can this charger be used as a Ni-MH charger after modding the output voltage to 1.8/2.0 V.
best answer is: maybe
it depdends on the circuit.

also what is the function of the third pin on the charger and the battery?
the third pin is usually connected to temperature sensor.
 

paultwang

Joined Mar 8, 2006
80
Originally posted by Arup@Apr 12 2006, 11:53 PM
Hi,
I've a LG mobile phone fast desktop charger lying around ...


My question is can this charger be used as a Ni-MH charger after modding the output voltage to 1.8/2.0 V.
also what is the function of the third pin on the charger and the battery?

[post=16138]Quoted post[/post]​

A quick note: Your phone charger probably recharges a lithium ion battery. I am not sure if you can apply the Li-ion recharge pattern to NiMH batteries.
 

Gadget

Joined Jan 10, 2006
614
Originally posted by paultwang@Apr 13 2006, 07:47 AM
A quick note: Your phone charger probably recharges a lithium ion battery. I am not sure if you can apply the Li-ion recharge pattern to NiMH batteries.
[post=16144]Quoted post[/post]​
Thats pretty much the way I understand it as well. Not 100% on LIon charging, but I think is a constant voltage charge (4.2v per cell which would tie in with your figures) and Charge detection based on a drop off in current.
NiMH however (like NiCads) use a constant CURRENT charge with detection using either a slight drop in cell voltage at full charge, or the rise in cell temperature. I believe NiMH also like a fast charge.
 
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