Hey everyone! I'm curious if there's a way to use an iPhone 8 without its battery in place. I've got a logic board from a battery I salvaged from an old device, and I was wondering if I could use a resistor or capacitor to make the phone think there's a battery installed. I plan to replace it with a real battery later on, so any tips on how to accomplish this would be appreciated! Also, I've found that I can boot the phone using a special USB setup with two ports—one for the lightning connector and another for the positive battery terminal. Is there any way to tap into a 3.7-5V source inside the iPhone 8?
3 Answers
You might want to try looking into "Battery Boot Cables." They’re designed specifically for scenarios like this and can basically trick your device into thinking it has a battery installed.
I've managed to start an old iPhone by connecting it directly to a power supply set at 4.2V on the battery connections. Just link it to the positive and negative terminals. Some folks recommend using a large capacitor to smooth out the current spikes. The voltage settings depend on the battery chemistry; for instance, mine was around 3.7V nominal, which is about 4.2V when fully charged.
Absolutely, you can power it up without a battery! However, a Battery Boot Cable is usually necessary because it communicates with the device to confirm it’s connected to a workbench. Apple has a 'Fuel Gauge' system that tracks battery health and can shut down the phone after reporting a 'flat battery' even if you’re supplying voltage directly to the terminals.

I’d prefer to use components from my Arduino kit, like capacitors and resistors, instead.