Beepy charge mods for infinite battery life - M0YNG.uk

Created 2023-09-03

Tagged

Hacking

Beepy

Well, effectively infinite anyway.

I <3 my Beepy and use it a lot, something which is hindered by the fact that the stock charging current is limited to 100mA due to a 10k resistor on the TP4054 charging IC.

So, I ordered a bunch of tiny resistors and got the soldering iron out.

Increasing charge current

The charge IC is limited to 500mA so although the 2000mAh cell could in theory take a full 2A of charge current, we're going to stick with around 500mA for now.

You will need:

A working Beepy

A 2k 0603 surface mount resistor

Soldering iron

Flux, solder, etc.

The resistor to change is R4 just by the charge controller.

A tiny resistor highlighted with a pink ring, it's on the positive side of the battery connector above a 5 pin component and is marked 103 [IMG]

Simply (ha!) add some flux, heat the pads, and slide the component off with a little force - not too much, we don't want to damage the pads.

Clean it up however you want, if you want, and maybe add some fresh solder and flux ready for the new resistor.

Use tweezers to position the new resistor and melt the solder on one end, then the other, hopefully it lines itself up with the pad and you're done. Just clean up the flux with some IPA.

A tiny resistor marked 308 [IMG]

It was at this point I took a photo and noticed the resistor I'd got from a multipack wasn't actually the right value and I didn't have a 2k resistor in the set! I fudged it with the closest value I had to hand and repeated the process. No photos, it wasn't as pretty the second time!

EDIT: I've been told that it is actually a `30B` resistor which IS 2k at 1%, but I've never worked with components like this before and that's my excuse. Now you hopefully won't make the same mistake. (p.s. this edit made on the beepy!)

Beepy in a bright pink case connected via USB to a power monitor reading 0.5A [IMG]

It works!

"Infinite" battery life

Ok, great, now we can charge it faster than it discharges itself at idle, pretty good.

But, what if, Qi?

Qi is the name of the standard most of us know as "wireless charging" and you can buy bare bones receiving coils and circuits quite cheaply, and small enough to hide in the Beepy.

I ordered a 1cm by 1.5cm circuit and coil for £6.65[1] - it can deliver 0.6A and charge the Beepy fine when it's turned off, but struggled and stops working after a few minutes when the Beepy is running so you may want one that can do around 1A. If they exist.

1: https://www.ebay.co.uk/itm/195734513610?var=495595119135

Back of the Beepy PCB facing towards the USB C connector. Arrows point to small wires soldered to the far right pin of the USB C port which is ground and the bottom of a resistor which is 5v [IMG]

Solder the ground wire to any ground pin, I used the end pin of the USB C Port.

Solder the 5v wire to the top of Diode 1 (D1) this has a direct connection to the USB C port's 5v line so DO NOT CONNECT Qi AND USB AT THE SAME TIME.

That's basically it, I wrapped the Qi PCB in heat shrink (yes, I had to unsolder it because I forgot!) and tucked it all into the case.

The coil is placed on the battery, which probably isn't ideal due to heat, but there isn't much space and you need the coil in the middle so when you naturally place the Beepy down on the charger it is in the right place. You WILL need the little black pad behind the coil for it to work (in my experiments.) Maybe a suitable case could place the battery lower down and have a slot of the coil in the middle?

Now you have basically infinite battery life! Just pop the Beepy down on the charger when not using it and it will charge, the pick it up to use without having to faff with wires.

Beepy in a bright pink case on a Qi charging thing with a power monitor reading 0.78A [IMG]

(This reads more than over USB due to the inherent inefficiencies of Qi charging.)

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