Droid X Battery Hard wire to car.

[xpbr2000]

Hello,

this is a bit of a custom job. I want to take my Droidx and make it a dedicated display in my car. My issues are the battery is shot and buying another is more investment than I prefer. also the battery is not going to work for what i'm doing because it will not be on charge as frequently as it need to get a full charge.
so here is what i want to do. I want to hard wire the battery terminals to a 3.7 vdc source and use that as the primary power to the phone. and use the usb power to wake it on entry and while the ignition is on. right now i've got the usb cord without the battery and it works fine. but I wanted to maybe use the battery/usb to wake it. Anyone able to power the phone on the terminals for the battery?

Thanks
-xpbr2000

 

[AECRADIO]

The phone's power control circuits will not allow this, as they have a soft power feature, meaning the on/off cycle is handled by ASICs, and not simply via battery voltage or current.
You can use a toggle switch in place of the top mounted lock/power button, but that would defeat the screen lock, and may cause the phone other issues as you are causing a constant 'on' command that was designed to be momentary.
Powering the phone via the battery contacts should be fine, as long as you are using well filtered D.C, with almost no ripple. The supply should be robust enough to provide at least 4 Amps of current continuously, as you need to remember that the supply to the phone also uses current to power the phone.
There is no free lunch in power supplies!
Filtered D.C, with almost no ripple from switching supplies, input D.C also filtered from the effects of the vehicle's charging system, instantaneous spikes in current draw from fans, stereos, amps and A/C compressor clutches. Anything that uses D.C, and draws current can become a potential spike that can damage a phone's regulation/charging supply.

You do not need to get elaborate, but if designed well, you should not incur any troubles if you decide to make this a permanent mount.

Always follow the K.I.S.S methodology: Keep It Simple, Stupid!

Inductive kickback from coil fields collapsing has ruined many a phone, as well as other equipment running of a vehicle's power system.