7
votes
Upgrading power bank with modifications?
Hello ~tech,
I have a Mi Power Bank 2C (PLM06ZM) and wish to upgrade it to able to charge or be charged with a 65W USB C port, with minimal damage, harm and according to USB C PD standards.
My chargers use 9V, 12V, 15V and 20V, the last one which my ThinkPad X280 uses.
Online searches for a 65W power bank enclosure without the batteries yield no suitable results, so I might need to use a PD Decoy board.
Are there any advice, links to guides and resources I could use to accomplish my objective?
Thank you.
Speaking as an amateur, messing with Li-ion charging is not an amateur's game. I know enough electrical engineers to know that these devices are carefully designed, and that messing with any of their assumptions wrt battery design and charging can and will cause problems that often involve fire departments.
I love the idiom I learned here on Tildes "Anybody can build a bridge that will last 100 years. It takes an engineer to build a bridge that will just barely last 100 years."
I was hoping for this to be a fun side quest, but you make more sense.
Don't get me wrong, I love repurposing old stuff...I've got some old solar LED decorative lights I was gonna start tearing apart and wiring in to a custom battery solution. But the bits that go between wire and battery and back out to load are 100% being treated as a black box.
As long as you're aware of what risks there are, it's more just an issue of jamming everything back into the case. I built my own lithium iron phosphate batter bank, just know your voltage, amperage, fuses, etc., and insulate everything. You would just wire it up to the 12 volt trunk, and add any necessary in-line fuses.
I agree with vord. Reading this post gave me anxiety. It is not safe or wise to do amateur work with lithium battery charging. It's the stored potential energy you need to think of, and what damage would occur when it's released all at once.
Besides what everybody else (they're right) already said concerning lithium fires, consider that 20 Ah worth of cells are pretty cheap on their own.
The thing that makes a 65W power bank expensive is all the electronics, the charge controller for the cells and the USB power delivery board.
So not only would you probably end up setting the cells form your old power bank on fire, you would also not save any money because you'd have to buy/design and assemble 100% of the electronics in your power bank.
As someone who has worked for a battery supply company, I want to springboard off this.
Lithium batteries are a lot more complex than the car batteries you use to start your car. They have electronics in them (often called BMS) to manage their output and charge. The charge and output rate is managed this BMS, not the cells.
If you want to increase the wattage your charge can output you would need to replace the BMS circuit board with one that can support it. At that point you're looking at building one from scratch rather than a simple upgrade. The reason you can't really find battery packs without batteries in them is because all the batteries in a pack need to the same, or super close to each other in voltage and capacity. Manufactures cannot guarantee that average user would respectful of this so they seal the entire thing off to discourage tampering. (mismatching batteries like this causes huge amounts of heat if the batteries cannot charge/discharge together at the same rate, which can lead to fires, so sealing them off is for the better)
If you still want to explore building your own, DIY Perks has a great video of him building one. He really has a way with making this approachable to newcomers. However If you want drive right in with more detailed information I recommend this book here
Batteries are really cool technology, that you can have a lot of fun with, but you just need to know what you're getting yourself into because its really easy to burn your house down.
Cheers, and I hope we didn't scare you away :)
Before going any further, I would advise looking up the cells in the power bank for their spec sheet. That will give you max charging specs, which you want to look at first before introducing a higher charge rate.