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Így kell tisztességesen megoldani egy másra nem használt okostelefon folyamatos töltőről működését; ki kell szedni...

Így kell tisztességesen megoldani egy másra nem használt okostelefon folyamatos töltőről működését; ki kell szedni az akkut. Kezdők ne álljanak neki!

Originally shared by Zsolt Pinter

Project: Resurrecting the Nexus 4 part 2

I am a qualified professional. Do not try this at home if you don't know exactly what you are doing. You have been warned.
I still use the broken display Nexus 4 as a smart TV, and love it, I still can do much more things as a TV (details in the end of this post).
But the battery died twice a year due to constant charging and hot temperature. (I still believe that it outputs 1080p 60FPS through HDMI, even it has 720p display which generates lot more heat than a normal usage).
I decided I won't buy batteries anymore, so I show you how to run your phone without a battery:

1) Just remove the battery:
The phone did not start with USB charger without the battery. The RGB notification LED was showing red light while the charger was connected.

2) Hardware needed:
I bought a 12V 5A power supply from the local store (this overkill was the cheapest) and I bought this cheap DC-DC converter from Ebay:

3) Get the electronics out from the battery:
The battery has a protection circuit inside, I needed to take it out. This is a dangerous operation, you easily can short the battery which can cause fire and serious damage (check Note 7), take care like a surgeon.
First, I checked the voltage on the cell terminals, and I used a DC electronic load to drain it. Keep it mind, 0% not equals with 0V. When the phone shows 0%, the battery still has a huge amount of energy for over-discharge protection. For safety reasons, the battery needs to be over-discharged. In this condition, the battery can be opened from the top with removing the insulation tape first. The electronic module can be safely cut off with an insulated tool. Be very careful not to short anything.

4) Cell simulation:
I connected the power supply output to the input of the DC-DC converter and I set the output voltage to 4.25V CV mode, in this way the phone won't try to charge the electronics (the microUSB to HDMI Slimport adapter will try to charge!). Try to use short wires to avoid voltage drops.
This value is for my device only, and may differ from other models.
I measured around 0.7A while using the phone, but it changed often. The current limit is currently set to 1A, but if I will notice signal drops, or random power off, I will increase it to a higher value.
I connected the DC-DC converter output to the battery electronics main terminals. Again, the polarity is extremely important!

5) Cleaning up:
After I checked that the phone can boot successfully, and the battery is shown as 100% fully charged (which never will drain), I drilled 2 small holes for the wires. Next time I will make a nice little box to hide the PCBA.
For improvement, maybe I will attach a small heatshink in the future because the device quickly gets rather hot.

I think I am the only person who runs a broken display Nexus 4 without battery for the best smart TV experience :D

Part one is accessible here: