I probably shouldn’t; I’ve been procrastinating all week (don’t tell my employer).
It’s really tight inside but here’s how the wiring goes (during initial testing):
Not shown is the GX12; never mind the brown wire–it’s what I had at the time. I eventually replaced it with the proper color.
I got rid of that massive piece of black plastic as it’s only job was to hold the shunt anyway. I also got rid of the fuse cover (holder’s still intact) because space.
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I forgot to mention I also have a 90 WH powerbank that can push 60W.
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Almost. At the end he reckons 80% efficiency for boosting 20V PD to 42V
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Can’t wait to do mine… It’s still on the list just got deprioritized
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I’ve got a buttload of space in the enclosure of my hub board, this is something I should do. I’ve been carrying my charger around in my car and backpack for two years. Being able to just stick it on the front seat and charge from the car’s usb (time to charge doesn’t really matter) or use my laptop cable when I’m working in a cafe or something would be ideal.
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I wanted to make an 8S PD charger adapter and found this DC booster that fit the bill. That very cheap 8S balancer thing has a display which is sweet and works for Li-ion and Lifepo4.
I was thinking I could combine them to quite the small unit. The DCDC booster is a bit of and odd shape but still should fit in your hand.
I did not include the 100W wall charger in the price because I will use the ~$15 XY-PDS100 and a free power supply/battery bank.
With a balancer/BMS in the charger you could use BMS-less modules for ultra compact or high impact use cases.
I forgot to add, the attempt to make this unit compact seems silly when you might also carry a 6ft USB cable that takes up more room than the charger. I guess that charger cable is multipurpose at least.
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Thinking back on what @Battery_Mooch said about using PD supply bucks then boosted 20V being silly.
I guess just having power banks with DC output and possibly the DC DC booster built in could give you the wanted function of charging in a pinch and also you can still technically pass ~100W into the power bank while discharging it into board at the same time.
I guess the tradeoff is you have to carry a heavy power bank instead of just a PD booster and phone charger. So a power bank for charging and the board having integrated USB C port for charging I think has all the bases covered.
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Size/weight for travel minimalistic options
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Efficiency when not charging from AC
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Power bank with built in booster presents best plug and play option. Basically no cables if designed to mount to the board.
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I’ve more or less got the same setup as you: got a variable voltage decoy as that was available, and the 250W boost. Decoy board works outputting 20V… until it’s connected to the boost, at which point it just shuts down and outputs nothing.
If I trigger a 5V input from the decoy, it DOES work, but the boost isn’t designed for 5V inputs nor is that helpful for charging a board anyway…
Anyway, hoping you might expand on the fault you said the 250W model had? Did you experience the same issue?
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The defect was some pins on capacitors were literally broken off. I just got a 400W thinking over spec’cing would be fine but in retrospect, I didn’t need to.
Check your boost pots; they may be currently set to output too much so the decoy just shuts down to protect itself from too much draw. Get your tiny screwdriver out of the toolbox.
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Right, good tip though - I’ve bought a replacement 250W since you don’t think the 400W is necessary
I came to the same conclusion and brought the current right down to the min, and the decoy was back to functioning! But that just introduced a new issue… at the lowest current, the voltage output does not change (same as input). If I bump up the current, the voltage does finally boost up, but I could only get it to max out at about 30V and even that is a bit iffy as it kind of ramps up over various seconds and it doesn’t seem to really stabilise.
Not sure if accidentally running it at 5V might have busted something? Doesn’t seem like expected behaviour at all from the videos I’ve found on YT of the module… (hence buying a replacement to test).
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Those pots are really just fiddly but they can be adjusted quite precisely. Just use smaller twists of your screwdriver.
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would you not want to do this test setup step with a Bench DC power supply?
Ok, so I’m gradually isolating the problem… had to buy a new booster cos I broke the first lol, but connected to a car battery it outputs 42V, yay. The current potentiometer has to be set at some higher-than-minimum value though, and here’s the issue:
As soon as I go back to the PD input, it seems to me that the power supply cuts out. I can adjust the current down enough that it doesn’t cut out, but then the current isn’t high enough to sustain the voltage and boom we’re back to square one with 20V in and 20V out, fuck.
The power supply is 100W capable, there’s obviously no freakin chance that 5A, or even 4 or 3, aren’t enough run the booster so what the hell is going on!? I’m waiting on a USB C cable with the wattage being used displayed on a little LCD (are they even accurate?) so that miiight help diagnose, but I get the feeling that it can’t be an overcurrent protection issue, cos the current required can’t possibly be high enough to trigger that. I’ve also got a bunch of the decoys coming in the mail so might see if that piece is faulty, but signs don’t seem to point to that either…
Any ideas? I presume that you got your setup working right? Did you need a load on the boost output to get the voltage etc. working? Spec sheets suggest no, but fuck me I’m just tryna throw shit at a wall and hope something sticks at this point lol
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I’ve been using mine when I’m out and about.
Voltage is pushed so it doesn’t need a load, unlike current which is drawn.
Are you adjusting the converter under a load, or open circuit?
But without voltage there can be no current flow. Many would argue (me included) that this means current is pushed. 
Makes no practical difference either way though.
The converter’s topology will determine whether it is stable or not (or even able to start) with no load. Some are, some aren’t. Whether current is pushed or pulled won’t affect this.
True; I don’t have enough equipment though and lazy at times. So I just adjust voltage first, hope to God I won’t overload something when I put a load and then adjust current (and voltage again).
Also, I should probably invest in proper equipment if I’m to continue down this path.
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Love this thread haha. Just mentioning for no reason.
I will likely make two threads close to this topic soon.
“DC DC general info BUCK”
“DC DC general info BOOST”
if its a buck-boost module, then use whatever thread you like.
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Yeah, every time I come back, it’s always gone on a different direction.
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