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Battery Replacement


Android Expert
Feb 1, 2019
- by puppykicker

TLDR- I replaced the 'unreplaceable' battery in a ZTE Maven 812, and it works!

Yeah, I know.
This is a weak, old, outdated phone.

But it was my first 'smartphone'.

I learned a lot with it, and because it was so limited in so many ways it was a great training device.

This thing has 8GB of total internal memory, and a SD card slot with a capability of 32GB.

The OS takes up about 4¼GB by itself, leaving little for the user.

The OS is 5.1.1 and as far as I know was the last system that allows some user app info to be stored on the SD card as an inbuilt option.

Although only about half of most any user app can be moved to the SD card, this can actually prove to be helpful on a device with such small memory.
Unfortunately, not all apps are moveable, and you can lose some functionality (especially with widgets or icons) of the ones that you do get to move.

Most, if not all, of the stock media apps have unnecessary permissions and should be replaced with small, efficient, third party apps. Things like the launcher, gallery, file manager, video player, music player, etc.
Allow me to thank God for KISS and Simple Mobile Tools.

Anyway, more than two years ago, the battery began to bulge, and I nursed it along until it just would not work anymore- even when plugged in.

So, at least it got me through long enough so that I could skip the entire Marshmallow OS. That alone would have made what I am about to describe worth every minute.

The phone has sat out in the garage, with the back off, on concrete since then because the battery had actually popped a bit and released toxic fumes, then got very, very hot.

This is a phone with an 'unreplaceable' battery, so until I could mess with it the garage was where it would stay.

Last month I saw the poor little thing once again. Occasionally it had caught my eye, but I had only made sure to keep it away from any flammables.
I had put a screen cover on it so that it wouldn't get scratched from laying face down on concrete.
I used my air compressor to thoroughly blow it out.

Then I began my hunt online for the battery, as no store around me has such a thing.

I actually had done this online search before, with lousey results.
It turns out that this phone was limited not only in performance, but also in production and distribution.
For a brief time, it was everywhere, and then suddenly it was nowhere- replaced quickly by the Maven 2 and then that by the Maven 3.

This time I had an idea.
Instead of looking for the battery by what phone it was installed in, I used a magnifying glass (along with my reading glasses) to read and enter the model number of the battery.

In fact, I just entered that number into the search bar in my browser.

I got loads of results.
Not many even mentioned my device at all, some even listed different devices.

I took the chance.
For $10 USD + shipping it was going to be some entertainment during this ****** (not a swear word) lockdown.

While I waited, I decided to remove that fire hazzard of a battery.
Care to guess what the manufacturer of that battery was?
(comment to see if you guess right!)

First, there is a very durable, secure, metal (steel) cover over the battery- with various 'end of times' warnings about what could/would happen if it were to be removed.

It was quite the effort to get it off, as I could not see exactly where or how it was fastened.

Notice that I said 'was'. I really thought that I was going to destroy the phone. Prying on this metal cover is how I had 'popped' the bulging battery years ago.
When it came off, I was relieved.

For about 20 seconds.

The battery was glued in, and also has a flat ribbon cord with a plug on the end that goes to a miniature jack on the circuit board.
Not only was I going to have to pry this battery out, I had to be careful with this dainty little cord so that I didn't damage it or what it plugged into.
(I didn't know if I was going to need to reuse this cord in some way, perhaps to retrofit a different battery into this thing.)

I literally just took a little jeweler's screwdriver and 'gently' pryed the battery out.
Then I unscrewed the multiple micro phillips screws on the back of the phone.

This turned out to be a lost cause, as even though the screws were removed I still could not get the cover to come off.
So I resorted to just prying the cover as much as I could to get the ribbon cable unplugged from the circuit board.

So, after finding the exact battery by matching the model number of the battery itself, I placed my order and waited about a week.

When it came, I immediately got to work on it.

Upon opening the battery packaging, I was elated to see that the battery actually has ZTE markings on it, so this is a genuine ZTE battery.
Not only that, the markings of the company that made the original battery are nowhere to be seen! (Yay!)

I then realize two things:
I am not going to glue the new battery in, and I am not going to try to straighten and then reattach the protective metal cover.

That way, the battery would then be less opt to get hot, and if it ever needs to come out, it will without a fight.

Getting it plugged in turned out to be a bit of a challenge.
I tried multiple times, but not having the cover off was the stopper.
After some debate as to how, and some more prying, I finally decided that for sanity and simplicity it would be better to just tear the plastic cover directly over where the ribbon cord plugs into the circuit board.

I should have used a knife tip on a soldering iron, but I only know where the iron is- and not that particular tip.

After some more prying, I actually got a small tear to begin just by using my thumbs.

Sure enough, when I checked again, I was able to get the plug into the jack and firmly plug it in.

I pushed the tear back together, held the battery in place, and put the back piece onto the phone. This thankfully completely covers the hack job I did to the inside of this thing.

Then the moment of truth- I plug the phone into a charger, and then the charger into the wall.

The phone lights up, and begins to do its thing.
This is it, I think.
The phone would do this even without a battery, and after a few seconds it would go into endless bootloops.

This time was different.
The little LED was red, then turned orange.

Then the screen lit up, and the AT&T logo of the spinning planet appeared!

After about one minute, my old friend was booted up, and looking good as ever.

I spent the next couple of days implementing what I have learned since its past demise.

This device will not be on any cellular network, only on Wi-Fi.

One thing I really missed about it was its loud speaker and excellent Dolby Surround Sound.

A gift from a local liquor store is a cool wooden box for a smartphone. It holds the phone while concentrating and projecting the sound forward.

I have been using this box in the restroom.

Now I have a dedicated 'bathroom' phone.
(Yes, I know this sounds terrible. And yes, that makes me laugh even more when I call it that.)

I have copied all my music onto it, as well as added my preferred streaming app (RadioDroid) onto it.
As the charging jack comes out of the side of the device, this is ideal for the phone sitting in its box.

I am so glad that I kept this little project for as long as I did- there were many, many times where I just about trashed the thing, thinking that I would never get to it or that I would fail in any attempted repair.

I am going to be home later on, and will attatch a photo of my new 'toilet' phone.

Is that better than calling it a 'bathroom' phone?
I guess not. Most likely worse.
But that doesn't matter, so long as I am not texting with my wiping hand ;}
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