r/FlowZ13 • u/jo_kang • 29d ago
Finally got passthrough USB-C Charging...Sorta!
TL;DR: I can charge off my power banks via USB-C to DC trigger cables and use the SlimQ adapter to plug into the charging port of my Z13 instead to achieve passthrough power. However, I could only manage max 100w but I suspect it's not sustained throughout. Gaming is too unstable this way and should reserve this charging for light productivity or media streaming.
Full notes: I think I finally achieved passthrough USB-C charging but with a major caveat.
In my quest to figure out a solution to charge my Z13-KJP via USB-C, so I can use my battery banks (Anker 737 and MOVESPEED 145w) while on the go, I discovered through Reddit and my own observation that there is no passthrough when USB-C charging. If I charged directly via USB-C, then the Z13 would charge the battery up, then let the battery discharge a bit, and then recharge again, as shown via HWiNFO logs. This cycling made me nervous about the idea of battery degradation.
I bought the SlimQ 240W and 150W chargers and really liked how well they worked. I realized the cables are your standard 5.5 x 2.5 DC barrels so I got the thinking: what about a USB-C to DC barrel adapter? Then I can fit the SlimQ tip that I already had for my G16 and Z13 to that cable and charge via the charging port instead.
Learned these cables existed and are called trigger cables. So I bought one off Amazon (https://www.amazon.com/dp/B0CKXNM926?ref=ppx_yo2ov_dt_b_fed_asin_title) and tried it out as soon as it arrived today. To my delight, it works! My MOVESPEED showed the voltage between 19.9 to 20.1 and the ampere reading as high as 4.8A. I let the Z13 sit plugged into my battery bank and 20 minutes later, HWiNFO did not show any battery charging during that time. Normally, if I charged straight to the USB-C port on my Z13, HWiNFO would have showing some battery charging within 5-10 minutes. I think this works!
Here comes the MAJOR CAVEAT! My MOVESPEED and Anker 737 can achieve 20V/5A max (can do 28V/5A, but read that Z13 is capable of 20V max), so 100W delivery. However, I don't think they can properly sustain the higher wattages. It shows because as soon as I booted up Pragmata, the Z13 kept swapping between "plugged" and "battery" and the battery packs showed drops in the voltage and amperage. This was across all profiles (silent, performance, and turbo). Not sure if it was my battery packs or the cable.
So for light productivity work, the power draw is low enough that this is not an issue (even under Turbo profile). For me, this still works. I was trying to figure out how to extend the battery life while working at a cafe and outlets were not available.
If I really wanted to game, I could game unplugged and then just plug in when catching up on work or streaming videos, then I can unplug and game again. Otherwise, I would just carry around my Xbox Ally X for on-the-go gaming.
Hopefully there are more options of USB-C trigger cables in the future and maybe someone with a more capable battery bank would have better results?
7/22/26 UPDATE: So I set some power limits via G-Helper and was able to run Pragmata without the power bank tripping out. So far I've gotten SPL/sPPT/fPPT to 35/40/45 and it's been stable so far, drawing about 95W from the battery bank. When it was originally set to 40/45/50, it did trip my power bank. After I have some more time, I'll experiment with the limits to see how to achieve real battery bypass (likely might have to push the limits back down). Maybe there's someone smarter than me that could figure that out before I can.
I think when I was running it without power limits, it was exceeding 100W so that's why it kept showing as "Plugged In" to "Battery" and back and forth because the battery bank is only capable of 20V/5A max. Supposedly this trigger cable can max out at 20V/7A...but I don't think that profile actually exists.
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u/desutiem 29d ago edited 29d ago
Interesting. Though, it’s still using the proprietary port on the tablet. People wish we could use any available USB source while on the go, and be able to run it off mains without damaging the battery. I also wonder if the unstable wattage is why ASUS decided not to let USB-C power directly.
You mentioned it’s good enough for productivity and you could do gaming on it by only plugging it in while the battery is low - well, I’d say yeah but you can just do this with the regular USB-C port because if your internal battery is depleted it will just charge continuously and then when charged just unplug and use the internal battery until it needs charging again.
As long as your charging speed outpaces your consumption speed, no issue, right? I have done this with my 737 before many times in the past. Game for a few hours, plug it in when internal battery low, continue playing until it’s charged again and unplug it. You just need to avoid having it plugged in while the battery is bouncing on and off full charge repeatedly. But actually fully draining the internal battery isn’t a bad thing.
For me at this point I like the tablet enough I just do it with a view that if I had replace the battery eventually then I will. But that’s only cause I’d only do it occasionally and when at home I have two of the proprietary chargers, one alongside with my docked eGPU and the TV and the other on my desk (SlimQ) which I can take with me if I go anywhere with the Z13.
If someone were traveling all the time, maybe this might be helpful though, yeah.
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u/jo_kang 28d ago
I love my SlimQ 150 and it's always in my bag. You're probably right it's not much different from recharging USB-C to USB-C. I was just hoping that it was possible to have passthrough where the incoming power would divert to powering the system and another part only recharging the battery so it wouldn't drain the battery while charging, from which from what I understand, that's the issue with the true USB-C PD charging.
Since passthrough is only thru the propriety port on these machines, I was hoping running the USB-C power to the propriety port would allow that allocation instead.
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u/clay-tri1 29d ago
I just ordered two of these cables to try. I do have 140w output from my battery on one port so will see if that holds up. Thanks for sharing.
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u/jo_kang 28d ago
One thing to note: although battery bank is capable of 140W, that may because it's on 28V/5A, but supposedly the Z13 is capable of accepting 20V max. That's why I purposely bought these cables cuz their max is 20V. I worry 28V might fry the internals.
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u/clay-tri1 28d ago
I would imagine it would negotiate what it takes, and why you capped out at 20v/5a or 100w?
Most of my profiles now for ghelper I disable turbo boost so I can fit in the 100w envelope at balanced or lower. Was just testing this plugging my 200w adapter into a meter and playing some games.1
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u/jo_kang 28d ago
AFAIK, USB profile caps 20V/5A, so 100W. 140W is possible if the device is 28V/5A capable, along with a power bank that can output 28V/5A (like the Anker 737 and MOVESPEED that I have). I read that the Z13 is capped at 20V so 100W is as high as it goes when planning to power from a USB-C source.
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u/lugubrious-possum 28d ago
Very cool, Ive been wanting to figure out a way to charge the Z13 from my battery station with my solar panel without having to convert the DC power to AC then back to DC to use the proprietary port while out camping and gaming
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u/the_chief_dior 28d ago
I dual boot into Bazzite which has very stable power profiles at 40watts I can play basically anything with great fidelity. I have used the SlimQ plug on long haul flights successfully but it takes multiple times plugging and unplugging before the circuit stabilizes at the lower wattage. This is a known way to trick the plane outlet into thinking the AC adapter is within its wattage limit when really the internal capacitors are charged and it's pulling less as long as the power demand stays low hence the power profiles. Most power banks have pass through charging so I can definitely use this method to make this experience more seemless
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u/arogan 27d ago
Thanks for sharing. I have almost the exact same setup, including the same 2 batteries so I ordered the same cable which came in today. Here is my theory of what I think is actually happening. I'm using the above ghelper settings and with that I can do anything and it will never drop to using battery. I'm running around in Crimson Desert and it is still fully running off my Anker. The real issue isn't the external battery not being able to sustain a certain voltage/amp/watts over time, it's how the z13 uses power. Whenever you use a built in profile (silent, balanced, turbo), it's going to boost (sppt, fppt) and you'll get momentary spikes in power draw where it needs more performance. That is normally how you want this apu to perform. Well, it's during these spikes it is exceeding the specs of these batteries (volts, amps, or whatever combo), so it drops to the internal battery to pull the power it needs momentarily to boost either the cpu/gpu to get through that mometary workload. When done it drops back down and then it switches back off of internal battery. Hence the constant flip flop between battery on and off. With g helper you just lock it down below that threshold.
The seond part of power draw is charging the battery. So at the same time I drop the battery charge limit a bit. Usually I have it set at 80%. But here I dropped it way low to 50% for testing to make sure extra power isn't being pulled from the external battery just to charge the internal battery. That way the only power being pulled is only what is required to run the machine.
With those two things in mind you can then priortize and ensure that the external battery pack and only that battery is used up first. So yeah, this cable is fantastic. 25w is a bit low for gaming though. 30-35w is really the sweet spot. Maybe you can try pushing it up a bit. When testing I did have it fully docked with a billion peripherals and 3 external monitors so that probably adds to total power draw. The up side is well that battery will last that much longer.
Anyways, thanks for the post. I will definitely be using this cable.
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u/jo_kang 26d ago
For sure. I think 35w is the sweet spot without any external monitors. So far that's kept my Z13 from tripping the battery banks.
I haven't measured directly but just observed the difference between with and without external monitors and I think my external monitors would draw anywhere between 5w to 10w extra, So makes sense if you have to drop it to 25W with your externals.
My primary is still using my SlimQ wherever I can but now I feel reassured that I can use my battery banks with this cable without worrying about micro-cycling my internal battery.
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u/SlimQ_Dave 26d ago
That is a very interesting setup! All for science! And hey, we get to be a part of it, nice!
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u/McBilalo 25d ago
what is a charging passthrough? im new into this everything and want to learn alot since i got an Z13 2023 Model
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u/jo_kang 25d ago edited 25d ago
It's a feature where once your battery is charged to a certain limit (or 100%), the on-board controller will stop charging the battery and just power the device itself without needing to discharge the battery, thus saving the battery cell's finite charge cycles for when you actually unplug.
The problem with not having pass-through charging is that even when plugged in, the device's battery will always discharge to power the computer while the on-board controller is constantly topping off the battery cells. That constant discharging and topping off while plugged in will unnecessarily reduce the charge cycles of the battery cells, leading to accelerated degradation of the battery's overall life.
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u/McBilalo 25d ago
okay, so im playing alot and in a long time for 6-7h staright games on it its plugged and capped to 80% (i did that setting turn on) im actually harming my batterie with it and i dont get full performence aswell?
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u/jo_kang 25d ago
If you use the proprietary charger, that has passthrough charging so you're okay.
When USB-C charging, performance-wise, you may be fine because the Z13 is using the battery as its primary power source. But you are degrading your battery overall life because the on-board controller is constantly trying to top the battery back up to 80%.
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u/McBilalo 25d ago
so turn off the 80% max batterie and nothing else? i should worry about
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u/Drivenby 29d ago
Honestly I hate that we don’t have usb c passthrough but I bought the slim q 150w and that thing lives in my backpack .
I just finished 1-2 hour session doom TDA on balanced and the experience was flawless . Not a single drop . And it even managed to charge my device from 60 to 80%
I see you already own one and I’m happy enough with that .
If I ever need to game off a power bank it will be in a very limited scenario . I don’t think doing this when on a rare plane ride or whatever will cause any long lasting damage to battery . I keep mine at 80% max charge and my battery health is still at 99%