PCE GT Lithium Battery Mod Guide

[MasterofBiscuits]

**See below for updated versions of this mod**

I recently added a lithum battery to my GT and there doesn't seem to be much detailed info around for this mod, so I thought I would share what I did in case anyone else wants to try it. This was based on some posts by Superkon/ Turbokon, but there wasn't much detail given on those threads.

I used the Adafruit Powerboost 1000C board which is a combined balance charger and 5.2v boost converter. Superkon mentioned in one of his posts that he used a voltage divider to adjust the voltage to 5v, but there is no need to do this as the board has a voltage divider which you can modify. The datasheet for the TPS61090 )https://cdn-shop.adafruit.com/datasheets/tps61090.pdf ) even gives you the correct value to use - 1.8Mohm (instead of the original 1.9Mohm). So switch out resistor R3 for a 1.8Mohm 0805 SMD package:

Then wire the board like this:


There may be more efficient wiring possibilities, but this method definitely works.

I also broke out the LEDs from the board to indicate battery status. For this I used an SMD RGB LED (ROHM MSL0104RGBU1https://uk.farnell.com/rohm/msl0104rgbu1/led-red-grn-blu-700-1200-400-mcd/dp/2688619) connected with magnet wire. I put this in the TV Tuner latch hole behind some smoked perspex, and glued in the micro usb on top of it. Blue = charging, green = charged, red= = low battery. I didn't bother with the 'power on' led as it's a bit unnecessary.

The battery is a single cell Lipo (this board is only compatible with single cell Lipo/Li-on batteries) 3.7V 5000mAh size: 105080. When you remove the battery contacts in the compartment it fits very nicely without any cutting required and with space either side to remove the case screws when needed.

This GT has the 3.5" screen mod and I get around 8 hours of battery life and it takes about that or slightly less to fully charge. It can also charge while playing. I imagine with the original screen it will be an hour or two less than that. With the GT running an Everdrive and charging the battery it draws around 1.4A, so any decent USB 2A charger that can power a modern phone/ tablet will work fine, or it could even run off a power bank.

That's pretty much all there is to it, hopefully this is useful to someone.

[Necromancer]

Heh, pretty sweet mod.  Thanks for sharing.   

[Keith Courage]

Excellent write up. Thanks for the info.

[MasterofBiscuits]

I reworked this mod for one of my own consoles where I didn't want to mod the case. It re-uses the dc port for charging and is really easy to do. Note that this works only on LCD modded consoles, although you can still add a lithium battery with a stock screen, it just requires an addtional step which I will detail in another post.



Just need to remove Q502 and wire the 5v to the large pad, hook up the USB charge input to the rear pin of the dc adapter (I wired it around the board, but you can just remove the grey silicone and connect to the pin) and the ground goes on TP510.



For charging I'm using a USB cable that has changeable barrel ports: https://www.amazon.co.uk/gp/product/B07GTKBVKN/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I've only wired one LED inside the power switch to light it up when charging is finished. A 3mm LED will just push fit which is pretty cool.



A second red/ orange LED is wired for low battery/ charging:

[MasterofBiscuits]

Someone messaged me asking if this works with the stock screen - it will but needs an additional adjustable boost converter for the backlight circuit. The circuit should look like this:



Remove the solder jumper BLH to isolate the backlight circuit from the input, then wire your 7v boost output to the test point just below it (or the bottom pad of the jumper). I found 6.9v works well for this voltage (make sure you set the voltage before wiring it up!)



Note: do not mount your boost converter and charging board here when using the stock screen, or you won't be able to close the case 

Battery life in this configuration is around 7 hours.

[xelement5x]

Awww snap this is nice.  Just got an express myself and might want to add this to my mods list.

[C4KE]

Followed this thread and decided to do it myself and I did a small edit to do Type-C instead of Micro-USB

Battery :



Type-C Breakout board from adafruit with charging/done indicator



Completed mod with charging led showing "Done"



Type-C close-up



I am waiting for double-sided tape and lcd mod to come-in to finish and close this up.

[2huwman]

Thanks @MasterofBiscuits, this looks great. Thanks for the really clear instructions - I've ordered the parts to do this myself. Couple of quick questions:

-is changing the resistor on the Adafruit Powerboost 1000C strictly necessary? Is it done just for efficiency, or would it damage the GT if I didn't do it?
-what is the function of the Q502 that needs removing?

Thanks again!

[MasterofBiscuits]

-is changing the resistor on the Adafruit Powerboost 1000C strictly necessary? Is it done just for efficiency, or would it damage the GT if I didn't do it?

Maybe not - 5.2v is probably not going to damage anything, but it would be more than it was designed to take. I've never tested it with 5.2v so it would be up to you.

-what is the function of the Q502 that needs removing?

It's the voltage regulator, we remove it to create a break between the charging input (repurposed DC jack) and the output (where we connect the output of the Powerboost board).

[2huwman]

Great, thanks very much for your help.

[userofapples]

does anyone know what type of potentiometer that people are using (a link to digikey or the like) to connect up to the lcddrv boards so that one can then have the opportunity to be able to adjust the brightness and the like by removing the old brightness dial on the turboexpress? i see them all over the web but no where is it detailed which is being used.

[Keith Courage]

does anyone know what type of potentiometer that people are using (a link to digikey or the like) to connect up to the lcddrv boards so that one can then have the opportunity to be able to adjust the brightness and the like by removing the old brightness dial on the turboexpress? i see them all over the web but no where is it detailed which is being used.

You can just wire the stock brightness wheel up to adjust the brightness. Also, turn the brightness pot on the LCDDRV board down to 25%. So 1/4 of the way up from the lowest setting.

[userofapples]

didnt know that! thank you! now it is complete with the lithium mod and the screen! thank you!

[userofapples]

hi, this does not seem too complicated but when i follow your direction and turn the brightness to the 25% as per without the brightness hooked up and then solder in the wires i get no display at all on my pc engine.  do you see what i have done wrong from these photos?
https://ibb.co/7VQfGRQ
https://ibb.co/hYtcsts
https://ibb.co/x7fgwXx

[Keith Courage]

Swap the green and red wire on the screen. Meaning if the green wire is soldered to the upper point on the dial, it should go the the lower point on the screen.