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4 pins with unknown polarity, i want to charge a battery with it? Answered

So I have 4 pins with unknown polarity, and a rechargeable battery with 2 pin with known polarity, and i got a multimeter.

How am i going to solve this?

I randomly did something and it worked, but it did not charge, but it could use the battery, but now its empty it cant anymore.
layout used is --++

please help :)

17 Replies

user
lhu (author)2012-04-20

No,

everything what i have:
1 calculator
1 battery
1 usb cable


usb cable > calc > battery
is what i want,

the calc can transform the usb voltage to normal level and current.

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user
iceng (author)lhu2012-04-21

You know to charge a battery, the charger voltage must be greater 
than the battery voltage in order to make current to flow through the
battery in reverse.  The amount of current is a function of the voltage
difference. 
Too much current and the battery can get hot enough to make it
vent steam and damage its chemical balance.
Some batteries have a thermistor imbedded between the walls of the
separate cells to provide a warning if the temperature is to hot and that requires an additional set of pins to monitor.

A

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user
lhu (author)2012-04-19

there is only 1 battery and that is the one on the picture

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user
lhu (author)2012-04-19

ok here is the pciture which will clear up any misunderstnadings

red = 1st cable
black = 2nd cable
yellow = 3rd cable
green = 4th cable,


connected order is
--++

this order lets me to use the battery but does not let me recharge the battery with the power from the calc that comes from the USB

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user
lhu (author)lhu2012-04-19

higherquality : http://img41.imageshack.us/img41/1633/imag0331t.jpg

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user
lhu (author)2012-04-19

no the calculator can turn the usb power into recharging power,

we have a calculator and a battery while THE calculator, not a source battery should be able to use the USB power to charge the battery it doesnt.

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user
lhu (author)2012-04-19

we have a calculator that works on batteries, there is no battery because i couldnt buy it in my country, so i found a replacement.

but the replacement has only 2 terminals instead of 4 of them.

the colors of the cable has no connection to what it really is, as red (multi) on red(calc) and black(multi) on black(calc) gives me a negative reading.

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user
lhu (author)2012-04-18

its 3.7V 2000 mAh?
how did you come up with 6VDC?

im sure i didnt make any typos,right?


also i said it almost has the same specifications as the battery that SHOULD be in there, i dont have exactly the same the capactity of this one is a lil bigger, 2000mAh in stead of 1730mAh. but that shouldnt matter.

the voltage is coming from the mainboard not directly from the usb, so it doesnt need to be 5V it might be even lower.

thanks for trying to make a hypothesis, but my issue still remains lol

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user
lhu (author)2012-04-18

yes,

well better said: those 4 wires normally connects to a rechargeable battery of theirs, with 4 conn points. which is ofc able to charge and be used.

but my battery only has 2 connection points.

if i use it in this order --++ the battery will be used, and if i put in my usb and try to charge it will be not charged, when it should be charging.

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user
lhu (author)2012-04-18

the cables are soldered on by me on random order ! as i did not know the polarity and still not know for sure.

with yellow black on postive
and green red on negative i get a reading that changes from 100mv to 2v?

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user
lhu (author)iceng2012-04-18
user
iceng (author)lhu2012-04-18
user
lhu (author)iceng2012-04-18

that doesnt matter does it?
its a calculator

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user
lhu (author)2012-04-18


okay let me rephrase it:
it is a electronic that can use rechargeable batteries, which has a connector with 4 pins( 4 cables you see came from there).
The battery wasnt for sale in my country to I found a battery with same Voltage 3.7 but higher mAh, the battery got 2 connections, a + and -

order:
red = 1st cable
black = 2nd cable
yellow = 3rd cable
green = 4th cable,

If you connect on
to the minus red and black, and on the positive side of the battery yellow and green, it works can use the battery but the recharging function doesnt work. the battery i found was a DS lite battery, and those should be able to charged right?
so I wondered if it might be the order of the connections which why it doesnt charge?

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user
rickharris (author)2012-04-18

To charge your battery safely you need a voltage above the battery voltage AND some way to control the current flow.

Connecting things haphazardly isn't a really good idea.

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user
Re-design (author)2012-04-17

Looks like phone wires to me. Don't try to use these for other than the intended purpose. When it rings you get +- 90 volts.

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