Xtar PB2S 18w vs 20w usb c charger question

24 posts / 0 new
Last post
supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136
Xtar PB2S 18w vs 20w usb c charger question

With a 18w usb c charger I can only get one slot to charge at 2A sort of, the second slot doesn’t seem to charge. The first slot is iffy with the 18w, voltage seems to fluctuate and doesn’t hold steady.

With a 20w usb c charger it works great charging both slots at 2A.

Anyone else experience this?

ChrisGarrett
ChrisGarrett's picture
Offline
Last seen: 13 hours 26 min ago
Joined: 02/12/2014 - 22:03
Posts: 875
Location: Miami, Florida

I recently got a PBS2, but only have an Apple 12w wall wart, so I can’t help you there.

Not all wall warts are created equally and a lot are outright dangerous!

Chris

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

What amp can the 12w charge at? My 18w is usb certified, I don’t remember the exact terminology but I was able to verify and view the certification

I don’t want to purchase another 20w charger if I don’t have to

ChrisGarrett
ChrisGarrett's picture
Offline
Last seen: 13 hours 26 min ago
Joined: 02/12/2014 - 22:03
Posts: 875
Location: Miami, Florida

supreme wrote:
What amp can the 12w charge at? My 18w is usb certified, I don’t remember the exact terminology but I was able to verify and view the certification

I don’t want to purchase another 20w charger if I don’t have to

The Apple 12w WW is 2.4A I believe.

Chris

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

Does it charge both slots of the xtar at 2A?

ChrisGarrett
ChrisGarrett's picture
Offline
Last seen: 13 hours 26 min ago
Joined: 02/12/2014 - 22:03
Posts: 875
Location: Miami, Florida
supreme wrote:
Does it charge both slots of the xtar at 2A?

No , probably not at 2.1-2.4A total.

Chris

Perception
Online
Last seen: 4 min 10 sec ago
Joined: 10/01/2019 - 20:11
Posts: 76

2 slots x 5V x 2A= 20 watts. Anything less than a 20 watt charger is not going to get you to 2A charging on both slots, and you probably need a little more than that to be reliable and cover whatever conversion losses the charger has.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136
Perception wrote:
2 slots x 5V x 2A= 20 watts. Anything less than a 20 watt charger is not going to get you to 2A charging on both slots, and you probably need a little more than that to be reliable and cover whatever conversion losses the charger has.

Thank you! I need to start learning about amps, watts, now that I’m delving a little more into flashlights.

I’ll end up sticking with the 20W charger since I don’t really want to hit 2A max all the time when charging 21700 batteries

TheIntruder
Offline
Last seen: 2 weeks 4 days ago
Joined: 03/09/2018 - 02:11
Posts: 257

According to the specs, it shouldn’t require more than 18W input.

(I’d like to know which chargers are putting 5V into the typical Li-ion cells we use, so I can avoid those chargers)

If the Xtar acting flaky, I’m willing to be it’s more of a handshaking, or implementation issue, causing insufficient power input. What adapters are in use haven’t been specified. There’s also the possibility that the PB2S might be quirky even if provided sufficient power, which can’t be discounted.

PD and QC are more capable, but more complex, and implementations may be incomplete, if not faulty. The adapter needs to properly inform the charger what it can supply, and the charger needs to correctly ask for the level it wants, and then put it to proper use.

The Apple 12W adapter isn’t going to be sufficient to allow full current on both slots, based just on power capacity alone. Plus, there’s also the question of whether the Xtar is set up to accept the Apple 2.4 standard for full power. The specs only indicate it can handle 10W input, so it would only use Apple 2.1. IIRC, those are the only two standards it supports, so a non-Apple device might not necessarily be the best pairing for that adapter.

Even Apple’s own devices that were designed as PD first, such as the iPads Pro, don’t support Apple 2.4, and will drop down to BC 1.2 when connected to a non-PD source.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

The device itself states 9V input 2A and 12V input 1.5A. QC 3.0 & PD 3.0. So 18W may or may not give you 2A depending on if it is inputing via QC or PD?

TheIntruder
Offline
Last seen: 2 weeks 4 days ago
Joined: 03/09/2018 - 02:11
Posts: 257

Should make no difference whether it gets the 18W it needs from a PD adapter or a QC adapter. Both support it.

Do you have a USB meter to see what’s really going on? Without one, it’s only guesswork.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

I do not. Apparently there’s different USB C protocols. Maybe the 18w charger I had wasn’t using the latest protocol or xtar is using a different protocol and both can’t communicate with each other properly.

USB C protocols

I have very limited experience with USB C PD and it looks like it’s messy/difficult to fully understand.

ChrisGarrett
ChrisGarrett's picture
Offline
Last seen: 13 hours 26 min ago
Joined: 02/12/2014 - 22:03
Posts: 875
Location: Miami, Florida

supreme wrote:
I do not. Apparently there’s different USB C protocols. Maybe the 18w charger I had wasn’t using the latest protocol or xtar is using a different protocol and both can’t communicate with each other properly.

USB C protocols

I have very limited experience with USB C PD and it looks like it’s messy/difficult to fully understand.

Don’t fret too much and just buy the best wall wart you can find/afford and go from there. You’re probably talking minutes from one to the other.

They’ll be charged when they’re charged!

Chris

nick779
nick779's picture
Offline
Last seen: 5 hours 55 min ago
Joined: 03/09/2018 - 15:46
Posts: 453
Location: Pittsburgh, PA

Usually it has more to do with the brick not being able to support the outputs at full power or not supporting QC/PD at specific voltages.

The PB2S seems to be flexible with 9v or 12v so most QC/PD bricks should work just fine. All of my 18w bricks will easily put out 20-22W without overheating using a PD trigger and electronic load so I would think there is some wiggle room.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

I’ll use the Apple 20w usb c charger with the PB2S and purchase another 20w charger down the line. I just found it weird how the 18w charger wouldn’t work but works fine with the phone I’ve been using for 1-2 years. The article explains why it might not work with the PB2S.

Hopefully USB C gets sorted out when I do need another 20W charger.

TheIntruder
Offline
Last seen: 2 weeks 4 days ago
Joined: 03/09/2018 - 02:11
Posts: 257

Yes, in its zeal to implement a single, unified connector, the USB IF failed to recognize that having one doesn’t make everything else go away, or any simpler, just harder to discern, because there are no longer different connector types to accommodate all the various functions USB now covers.

The standards are also in flux, with new versions issued faster than the market can catch up. Those standards can also defy logic, as evidenced by the multitudes of cable types, and allowance for a state-of-the-art cable to not have to conform to the most current data standard. Why don’t all C2C cables support USB 3.0 speeds at a minimum? And then there’s the implementation by the manufacturers, which can be less than perfect.

It’s a classic “by committee” outcome that tries to please everyone, but results in a cluster**** that can hinder more than help. The practical results are predictable.

The Apple 18W adapter is a well designed unit, as their power adapters are in general, but even they can lack full support, which isn’t evident until newer versions are issued, as with the 20W model, which is required to support their latest accessories. They’ve also updated their 29W to 30W, and another higher capacity model to fill in some functional blanks as well.

However, that’s only half of equation, and as noted above, the device in question also has to play its part, and the possibility that the Xtar may be at fault can’t be discounted.

My experience with one of their chargers has been frustrating, in its refusal to 30Qs at anything higher than 1A, despite verified combinations of various adapters and cables, just via a simple, relatively dumb Micro USB connection that isn’t subject to the issues surrounding PD. Whatever their logic is in automatic current selection is, and the inability to override it, has me wary of considering another.

If you’ve found a solution that works, that’s what matters, but sadly, unexpected issues can occur.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136
TheIntruder wrote:
The Apple 18W adapter is a well designed unit, as their power adapters are in general, but even they can lack full support, which isn’t evident until newer versions are issued, as with the 20W model, which is required to support their latest accessories.

So the 20W has full support now? It’s too bad I don’t have the 18W and I don’t think it’s available to purchase. I don’t really want to spend time looking for a reputable 18W charger just to test the xtar and satisfy my curiosity

Is gtrusted a good source for usb c hardware reviews? Looks similar to what Benson used to do.

This confusion kind of makes me miss micro usb. Simpler times.

nick779
nick779's picture
Offline
Last seen: 5 hours 55 min ago
Joined: 03/09/2018 - 15:46
Posts: 453
Location: Pittsburgh, PA

I’ve bought the two pack of INIU 18w bricks for $13 and have been pretty satisfied with them. I wish they were just a smidge smaller to only take up one slot on a power strip.

Ravpower’s 31w GaN charger is $15.99 and they have a 61w for $20 that both support all PD voltages (5v, 9v, 12v, 15v, 20v). Great for the Nintendo switch too.

TheIntruder
Offline
Last seen: 2 weeks 4 days ago
Joined: 03/09/2018 - 02:11
Posts: 257

supreme wrote:

So the 20W has full support now? It’s too bad I don’t have the 18W and I don’t think it’s available to purchase. I don’t really want to spend time looking for a reputable 18W charger just to test the xtar and satisfy my curiosity

Is gtrusted a good source for usb c hardware reviews? Looks similar to what Benson used to do.

This confusion kind of makes me miss micro usb. Simpler times.

The 20W model is an updated version of the 18W, enhanced to support a 2.22A output level, which is what new accessories like the MagSafe wireless chargers require to operate at full speed. No need to seek the older model.

Benson hangs out in the USB-C hardware Reddit group.

Despite the complexity, and potential issues, these new standards do bring benefits, and work well when done properly.

But, it’s no surprise if the relatively inexpensive chargers used here, and more so, a budget flashlight with a cheap driver, aren’t exemplars of the standards, even if they may have USB-C ports.

Recall that the first lights with C ports would not charge with a C2C cable, only an A2C cable, for lack of a simple resistor.

QC and PD can supply all the power that chargers need, yet many of them still employ a wall wart with a barrel plug, because it’s cheap and simple.

Probably better that way, since it would take cost and effort to implement the new standards, and the balance between the benefits vs the risks of mucking it up is debatable.

The PB2S primarily targets a different use case, as a powerbank for mobile devices, so there are clear benefits, if not a need, to employ such standards.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136
TheIntruder wrote:
Benson hangs out in the USB-C hardware Reddit group.

Yes, what I meant is gtrusted a trustworthy source for reviews? Benson doesn’t do much testing or reviews anymore if I recall correctly

TheIntruder
Offline
Last seen: 2 weeks 4 days ago
Joined: 03/09/2018 - 02:11
Posts: 257

The site is owned by the company that makes the testing equipment cited in the tests, and also provides testing services.

If they can’t be considered trustworthy, then I don’t know who can.

supreme
Offline
Last seen: 12 hours 57 min ago
Joined: 11/20/2020 - 12:18
Posts: 136

Thank you. I have another source for information now when researching usb c hardware.

d_t_a
Offline
Last seen: 1 hour 49 min ago
Joined: 08/04/2017 - 23:58
Posts: 2352
Location: Manila, Philippines

My guess is that different QC3 chargers behave a bit differently. The Xtar PB2S seems to request 9v/2Amp from QC2 when I plug to a QC3 power adapter.

I’ve got a few different QC3 chargers (a few are cheaper ones which I don’t try to use at max power) — I have a USB meter to check the USB voltage, and notice that not all QC3 chargers give the same voltage at different power consumption. If the USB power adapter drops more in voltage (ie. not 9.0v, eg. 8.8v may still be ok, but 8.4v or lower might be a bit low already — then the PB2S will negotiate a lower charge current, than if the USB voltage is at a higher 8.8v or 9.x v).

It could be that the voltage + current combination is not high enough, so it’s charging only 1 slot at 2A while the other slot is not (due to not sufficient power)..

NiOOH
Offline
Last seen: 1 day 7 hours ago
Joined: 05/02/2021 - 05:28
Posts: 19
Location: EU

When talking power delivery over USB, don’t forget the cables. I’ve seen cables with quite high resistance that induce a significant voltage drop at high power. In any case, it is worth trying with another cable, preferably no longer than 0.5 m.