Cell Phone Battery Terminal Details Required

its probably to connect a thermistor for temperature measurement during charging.

probe out the terminals on the battery or pull the thing apart and have a squiz at its internals.

might help for information if you mention the brand and model of the phone.

Hello specrafi

All good rechargeable battery packs have the third terminal.

Dependent on Maker and type of rechargeable battery, this is connected to either:

1. Thermistor to monitor battery temperature/control charging current as suggested by stoney above.
2. Voltage sensor which also controls the charging current.

There have been a number of cases of exploding rechargeable battery packs, and in certain situations that has included the recall of many millions of faulty batteries, and/or chargers, by single manufacturers.

Be careful, therefore, about your cellphone use, as sometimes the thermistor type of sensor requires very close coupling to the charger to work correctly.

Thus ion that type, a short cable between the cellphone and the charger would be unsuitable and unsafe, because risk of explosion/fire and injury.

Kind Regards....

What system your cellphone is? If it is a CDMA, than the main reason for which your power supply failed is the current capability.

In transmitting mode, a CDMA cellphone works in bursts and the battery has to deliver spikes of current.

The best way to understand what you need in terms of power supply, use a shunt and measure with a digital oscilloscope the jumping current.

As a quick fix to your problem, put a supercapacitor in parallel with your regulated power supply.

Or extend/keep the battery connection and add a charger to it. You get backup power when utility fail.

FYI, the Nokia N810 tablet battery has 3 terminals, and one of their engineers posts that in "R&D" mode, the tablet disables some battery checks to enable use of a power supply such as you have.

This suggests that it is indeed a sensor of some sort. I suspect you could fake up a "sensor" with a couple of resistors to produce the "right" voltage - unless there are active components inside the battery, which I doubt. Disassembly would tell you.

Maybe there are active components ... but not digital ones. It may still be possible to fake the thermistor voltage.

http://www.electronics-lab.com/articles/Li_Ion_reconstruct/