BU-912: How to Test Mobile Phone Batteries

Build a business giving mobile phone batteries a second life

Smartphones draw more power than a cell phone and the runtime can be shorter even with a larger battery because transmitting data uses roughly twice the energy to talking. The battery in many handsets is the only replaceable part and it gets the most blame when the expected runtime cannot be met. In the absence of point-of-sale battery testing, the packs are often replaced, only to have the problem recur.

Storefront battery testers check the battery in about 5 minutes with rapid-test methods. Most are compact single-bay units that are simple to operate (Figure 9-32). With PC, advanced analyzers print service reports, store customer information and connect to the Internet.

Cadex C5100 analyzer to estimate the state-of-health of lithium-ion batteries

Figure 1: Cadex C5100 evaluates state-of-health of lithium-ion batteries. The analyzer rapid-tests, charges and cycles batteries. A universal battery adapter (RigidArm™) allows easy interface to cellular batteries. QuickSort™ tests batteries in 5 minutes. (See BU-907: Testing Lithium-based Batteries.)

Courtesy of Cadex

Storefront testing gives a customer a clear assessment of the battery performance. Short runtimes could be caused by the device drawing excess current due to location or an intrinsic fault. Knowing the limitation satisfies the user and ends the suspicion that the battery might be at fault. Testing also saves money as only faded packs are replaced.

Figure 2 illustrates a storefront service model that tests a battery while the customer waits. If the battery is low on charge, a store clerk may ask the customer to browse in the store while giving the battery a quick charge, but if the pack has a genuine fault, an alternate pack can be given from a pool of previously tested batteries. These pre-tested packs have proven to be as reliable as new ones.

Storefront Testing
Figure 2: Storefront service. Batteries are serviced while the customer waits. A faulty pack is replaced from the pool of previously serviced batteries. Storefront testing reduces handling, lessens disposal and improves customer satisfaction.
Courtesy of Cadex

Hooking up the battery needs some skill as mobile phone batteries have typically three or four contacts. The battery’s positive [+] terminal is normally at the outer edge and the negative [–] is towards the inside. The third contact is the thermistor, which monitors battery temperature. For a quick test, the thermistor does not need to be hooked up. The fourth contact, if available, provides a code for battery identification. Figure 3 illustrates typical contact positioning.

Typical contacts on a cellular battery

Figure 3: Typical contacts on a cellular battery.

The positive [+] is normally at the outer right and the negative [–] is on the inside. Most batteries have a thermistor; some also offer a code.

To allow quick and easy testing of batteries, Cadex developed the RigidArm™ (Figure 4) that is compatible with most Cadex battery analyzers. This universal adapter features spring-loaded arms that meet the battery contacts from the top down and apply the correct pressure to the electrical contacts. Lockable mechanisms allow quick and repetitive testing of the same type of batteries. The retractable floor holds the battery in a vertical position, and magnetic guides keep the battery in place if laid horizontally. A temperature sensor monitors the battery during the test for added safety.

RigidArmTM for cellular batteries

Figure 4: RigidArm™ for cellular batteries. The universal adapter simplifies the interface with small batteries. The adapter holds 10 of the most commonly used mAh ratings and is compatible with Cadex battery analyzers.

Courtesy of Cadex


Some smartphones no longer provide access to the battery. In the fast evolving consumer market, device manufacturers reckon that a battery lasts as long as the device and glass breakage is likely the most common failure of a smartphone. However, service centers still need to check the batteries and adapters are available to test mobile phone batteries for Apple, Samsung and other similar products at the service level.

QuickSort™ vs. app

Apps are available that provide SoC and SoH estimations in mobile phones. These software solutions appear to work at first but inaccuracies develop once the device is broken in. This is also the time when battery problems begin.

QuickSort™ takes a "snapshot" of the chemical battery to give a true picture of battery SoH, unencumbered of peripheral readings that lose the ability to track the battery over time.

Last updated 2018-02-14

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Comments (16)

On June 6, 2012 at 6:50pm
LDV wrote:

Can anyone please tell me the recycling process for mobile phone batteries - it’s for a school project.

On July 28, 2012 at 12:59pm
Steve wrote:

typo maybe:

“this analyzers print service reports, “

On July 30, 2012 at 10:25am
Cadex Electronics Inc. wrote:

Thanks Steve, the typo has been corrected.

On February 13, 2014 at 11:57am
ranny wrote:

how much this cost

On February 28, 2014 at 3:11am
Jeugene wrote:

how much Cadex C5100

On May 30, 2014 at 10:57pm
fine raja wrote:

the information of service really excellent to service man.

On August 27, 2014 at 3:57am
venkatesh wrote:

good invention ...

On June 16, 2015 at 8:06pm
Allan Weeks wrote:

There doesn’t seem to be much information on Primary Lithium batteries.
I can think of at least 5 different types of Lithium primary (that’s non chargeable) types and they all have different applications and characteristics.
Comments would be appreciated as this is new ground in battery technology.
Regards -  Al Weeks

On October 5, 2015 at 11:27pm
Zeal Angelo wrote:

my phone is kata i4 and i am having trouble charging my phone now, It is a built in battery. when i am charging it, at first it is like grounded that my phones notification says that charging then not charging then charging, it happens every second. It takes 2 to 3 mins. for the charging to be stable. Sometimes instead of charging the battery is draining. I don’t know whats the problem, please help me fix this if there something preventive maintenance i need to do. Thank you and Godbless

On February 8, 2016 at 4:25am
Asanga wrote:

I need to purchase one unit of Cadex C5100 . please let me know from where I Can purchase it. I’m located in Seychelles

On April 30, 2016 at 3:01pm
Ronald A Arjune wrote:

I have a Kyocera Rise phone and my battery is a scp-49lbps 3.7v 5.6 wh 1500mAh. The resistance from negative to center of the three terminals is 79K ohm. With the battery installed in the phone the voltage from center to negative is .9 V and 2.64 from center to positive. The battery was not fully charged and the charging cable was not plugged in. With the charging cable plugged in the charging voltage from positive to negative was 3.77 read from the battery. I used a thin wire to get the measurement from my Micronta meter. I am a schizophrenic and with my paranoia, I think the center terminal of the battery is for a current regulator in the battery and a thermistor is not fully correct. Most of the time when I use the phone while not charging, the battery would overheat and die quickly and I have to charge it again. I think that if there is a current regulator in the battery, it must be getting shorted inside the battery because I don’t think the phone is shorted. With my paranoia again if I may, I think the overheating condition indicates that there is an identity or person somewhere in need of help that is being kept captive. Please note that my paranoia may represent a viable explanation and does not warrant deleting my post as inappropriate.

On September 18, 2016 at 1:59am
seif wrote:

how to repair a battery contacts?

On February 1, 2018 at 6:14pm
donald kidrowski wrote:

i have been wondering if i could use cellphone batteries for drones and i mean a s*** ton of them, my objective is to get past the only 15 minutes of fly time with the drone, which i find rather lacking, as i believe with all the technology today, i don’t understand why there couldn’t be a fly time of an hour, and eventually i will be building my own drone, but lately i have been wondering about cellphone batteries for them, and if it will be effective to switch a drone over to cellphone batteries or is it a waste of my time?????????

On February 7, 2018 at 10:00pm
Research wrote:

This article has the wrong title “BU-912: How to Repair Mobile Phone Batteries”. Nothing here mentions the repairing.  This article just advertises the device for testing the battery.

On June 17, 2018 at 7:44am
latedev wrote:

Title is BU-912: “How to Test Mobile Phone Batteries” although the google search says “How to Service Mobile Phone Batteries - Battery University” probably changed after your comment.
No matter an interesting article and reading between the lines, the other pin/pins are not required for testing.

On March 3, 2019 at 2:12am
md.nurul alam wrote:

mobile battery lode mAh need