Battery Eliminator??

[bluplanet]

The Rezound can use lots of power with everything running. In fact, it will use power faster than a connected charger is capable of keeping the battery charged. The problem isn't with the amperage of the charger--its that the phone's internal charging manager isn't capable of utilizing power from ANY charger to charge the battery as fast as the 1080p screen, 4G, GPS etc. is capable of using it up.

I've got an extra phone back. I'm thinking I'd like to mod it into a battery eliminator. I'd like to have an external power supply that the phone uses INSTEAD of the battery when the moded phone back is in place.

Does anyone know what problems I might run into? I'm sure putting the battery charging process in-between the charging cable and the phone buffers the power and smooths it out but there should be a work around.

There are 5 little unused spring-loaded contacts next to the internal Micro SD card. I wonder if a couple of those might already set up for the purpose.

Does anyone have some ideas?

 

[techguru]

The 5 contacts you identified are used by the wireless charging back, so there is a possibility of a hack there, but I have no idea which pin does what. However, I am assuming you are talking about in vehicle use since you mentioned GPS, and there is a much easier solution.

The problem with every in-car charger I have tried, regardless of whether they are .5 amp, 1 amp, or 2.1 amp is that they are all wired wrong. The Rezound (and any properly configured USB device) determines if it is connected to power or a USB port based on the condition of the data lines in the USB connection. Every home charger, even the cheapest ones, short the data lines so the phone knows it is connected to power and draws the maximum amps it is designed for (in the case of the Rezound, that would be 1 amp). Every car charger looks like a USB port, so the Rezound will only draw .5 amps, which you are correct, is not enough to charge the battery while using GPS, streaming music, and using the camera.

Easy fix is to take a micro USB cable, and strip a bit of the insulation. Pull back the metal shielding (doesn't matter if you cut it, only matters on a data connection anyway). In the center will be 4 wires. Black, Red, Green, and White. Cut the Green and White wires, and on the ends that connect back to the phone, strip some insulation and twist the wires together to create a short towards the phone. Best to solder the connection and then wrap with electrical tape. Cut the other ends short.

The Rezound will now draw 1 amp which will charge and operate most functions.

I also noticed when testing with a multi-meter that all of my home chargers actually put out between 5.1 and 5.5 volts instead of 5.0 volts, but every car charger put out 5.0 exactly. So I took this a step further and got an adjustable output adapter from Radio Shack, and did the same cable mod. I set it to 6 volts and my Rezound charges faster and I can use virtually every function at once, but it does sometimes over-heat. I am thinking of replacing it with a more adjustable transformer so I can set it to 5.5 or 5.1 volts instead.

Alan

 

[Snoking]

Under settings, power, battery status. You can see if it is charging (AC) HIGH or USB (LOW). CHRIS

 

[bluplanet]

Two Replies:

Snoking...

Thanks. I will certainly check the status when the phone is charging in the car.

Techguru Alan...

Your reply is interesting. The phone actually has 18 contacts inside the back of the phone. The 5 ones I said were "unused", really are just that. There are no mating contacts inside the phone back that touch them.
View attachment 61217View attachment 61218
(I assume this photo won't really help. I'm just practicing posting it.)
I just noticed three extra contacts just before posting this reply. They're also not used by the phone back and you would have to stick wire probes into holes to make contact with them.
I don't want to cut into my cable. I'd rather break the car charger apart and solder a jumper inside. Its a bitty thing--it just fills the power socket on the dashboard up to flush with the face of the hole. It has two USB slots which are rated at 1 amp and 1.2 amps (no indication which is which). Getting it apart properly might be a trick. It's hard plastic and ultrasonically welded together. Guess I'll try a Dremel and a thin cut-off wheel.

 

[flamewalker]

It may be the usb cable... I bought a super cheap one a while back and it couldn't charge very fast on any charger, car or otherwise... Bought a replacement and that one charges just fine in the car and home. I'd try a more expensive cable before breaking or cutting anything... If still no then it might be the adaptor..

 

[techguru]

Those 5 contacts are used by the wireless charging back, so at least two of them do provide power, and I assume the other three them are related to signaling to the qi charger.

I had plenty of spare cables, so cutting one wasn't an issue for me. In fact, I have a couple of 3 inch usb pigtails so I modified one of them so I only need to travel with one full length cable and can use it for data without the pigtail and power with it.

Alan

Sent from my ADR6425LVW using Tapatalk 2

 

[bluplanet]

Ah, a charging back!

I'm guessing that those actually charge slower than a wired hookup.

I should recount the experience that prompted this thread.

I was driving from Ohio to Florida back when I had the Gingerbread OS. The phone was new and I'd had it about 2 weeks. Gingerbread would notify you if the battery was getting low and needed recharging, but the phone checked if recharging was taking place before displaying that notice. If it was hooked up to power, it didn't display the warning message even though power was getting dangerously low.

I was using the phone for a GPS and had the screen brightly lit the whole time. I have a suction-cup window mount that holds the phone just like it was a Garmin or a Magellan. I made it as far as South Carolina and the phone went dead--and it was HOT. It was so dead that after recharging for two days, it wouldn't boot. I took it to a Verizon factory store and they looked at it for a half hour or so and told me it was bricked. I didn't buy insurance on it and was pretty bummed. But then, a couple days after that, I was able to re-boot it after playing with it for a while. Not sure what I did right. A couple months later I bought an extended battery and HTC extended battery back.

I upgraded to ICS about a year ago. ICS is a bit smarter. It knows the phone is capable of using power faster than the battery can be charged and displays a message that says so if the battery is being drained faster than the phone is charging it. (Now, if I'm using it for a GPS, I turn the screen off and just listen to the lectric lady talk unless I'm really close to my destination.) I don't know, but I suspect that HTC uses battery charging as a power smoother and doesn't allow the phone to run directly from the charger. And I know the battery is only capable of being charged at a certain rate and charging it too fast damages the battery. I think that's the issue in a nut shell.

My phone isn't rooted. I would have rooted it long ago if my computer had a Windows OS. But I'm using Ubuntu Linux and wouldn't return to Windows for anything. I know there are ways to still root with Linux, but they' were just a bit more complicated than I was willing to tackle the last time I looked at what methods were available.

 

[techguru]

Yes, the charging back is significantly slower than a direct connect, and it loses a lot of energy to heat too. My rezound regularly overheats on the wireless charger. I put a little fan next to the one on my desk to keep it cool.

I use Battery Monitor Widget Pro to see how many mili-amps the phone is drawing or using, as well as keep track of the temperature, which is how I first discovered why I had the same problem as you when trying to charge and use the phone in the car. A little research and I found the cable trick to tell it to draw one amp instead of 1/2 amp and then some testing with voltage and I got it working even better, but just the cable trick will allow GPS and screen at the same time. With my slightly overvolting, I can also stream music over bluetooth and run "Daily Road Voyager" which is a dash-cam/blackbox application. With all running, I still slowly charge now.

Other phones I have owned were better at this. The Rezound will draw a maximum of one amp and if you are using more than one amp, it won't charge. I had the Motorola OG Droid and the Droid X and both of them would draw an amp in addition to whatever the power use was if the power source would provide it (like a 2.1 amp iPad charger), but I like my Rezound better for other reasons.

Alan


Alan

 

[bluplanet]

That settles it. I'm getting another car charger and modding it.

I'll put the short inside the car outlet charger instead of in the wire.

By the way, using bluetooth doesn't use extra power if it's replacing the phone's amplifier. It uses significantly less than a headset or the phone's speaker.