ChuWi Forum»Forum Chuwi Tablet Discussion Chuwi Hi13 ChuwiHI13 and the Keyu battery charger

Follow Us

ChuwiHI13 and the Keyu battery charger

[Copy link]

szucsi|Post time:10-13-2017 11:19:38 View:3786|Reply:79

FaTmAt| Post time 10-12-2017 07:17:31 | Show all posts

Hello, I'm too looking for a replacement charger juste to avoid using the original Keyu charger.

The charger PA-Y7 suggested in different subjects around here is not available anymore nor on or (I'm in France). So I'm looking for an alternative but I'm having a hard time finding one that suit the 24W (12V 2A) for the Chuwi Hi13.

I, too, have found the Aukey PA-Y8 27W, which is Power Delivery 3.0, but in the modes listed, all I see is:

Output USB-C : (PDO) 5 V 3 A, 9 V 3 A, 12 V 2,25 A, 15 V 1,8 A, 20 V 1,35 A ; (PPS) 3-11 V 3 A

So 12V 2.25A seems to be the closest match, but I'm wondering how PD 3.0 will work, will it send 12V 2.25A and fry the USB-C port of the Hi13, or will it detect it is too much and fall back on 9V 3A, which is 1A above the original Keyu charger... I almost ordered this Aukey PA-Y8 but I don't think it will go with the Chuwi Hi13.

Unfortunately, everytime I find a new charger that looks like it could deliver more that 24W, in the modes listed, I never see 12V 2A :-(

So, will you be kind enough to give a feedback about the Aukey PA-Y8 when you will test it please?

Did anybody else found an alternative? Searching for "USB C 24W 12V 2A" (or variations of this) on Amazon doesn't give much results unfortunately.

Also, I find the silence of Chuwi about this essential problem, really annoying and when I see people having problems, writing to Chuwi and waiting for weeks for an answer from Chuwi, that doesn't make me feel confident at all about their customer service.

I'm very happy with this Chuwi Hi13 for now, but I can't recommend it to other people because of the Keyu charger issues, the big lack of reactivity from Chuwi, the lack of clear official drivers etc... There should be a topic which explains clearly where to get the proper drivers, updated every time a new version comes out, with the proper BIOS for each version, clear instructions on how to reset Windows and have a clean install with working drivers etc... I have a OnePlus phone and on their forums, everything is clear, well explained, with as much as possible, fall back solutions etc... Here, it gives the feeling that Chuwi sell us a product and then we are on our own for any problem we can have. That's scary and I cross my fingers for not having any problem... :-/
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-12-2017 23:05:08 | Show all posts
I understand your confusion. I like the tablet a lot too.

I am not sure if it's a must to replace the original charger...  but there is a latent risk when the plug fails that crossing contacts may damage the port or more. Unfortunately there is no guarantee that all 3rd party cables have better plugs... so my personal conclusion is treat any USB-C plug and connector with care.

If I assume the delivered charger does not fully comply PD spccs (or the plug/connectors) why should I believe the tablet's usb c port does...? This is why I think without official confirmation we can only guess here...

I'm trying to learn more about USB-C, but it's not easy because there are so many options... and makers can support them or not.

As others said, the only basic thing with PD that had to work is 5V/3A. Or to answer you question in advance, 'up to 3A'

To explain the technical basics we talk about is the formula. 'U * I = P'

U is the voltage in the unit 'V' volt (practically this determns the needed insulatin jn a cable)
I is the current in the unit 'A' ampere (practically this determines the diameter of copper/metal and related warming of a cable)
P is the product of these values, the 'power' in the unit 'W' watts.

There is a related thing called energy. This is what you pay with  your bill... it's summing up how long you used a certain amount of power.

Puhhh. But it's necessary you understand this first.

The point with PD is that it depends what the consumer (the tablet) requests. This is what noone has been experimentally examinating and given any evidence when we talk protocol so far (ok, would be complicated to do) but the assumption is constant voltage of 12V up to 2A, referring to the original charger's specs. We are also talking DC ere btw.

The usual thing is that a power supply provides a constant voltage and the current varies according to the power needs of the device. In this context the specified current is a maximum spec. only. It just tells current may not exceed this point. If it does modern supplies have protection against overload (the most simple one is a fuse, the most comfortable is active limiting)

The confusing point is that PD allows certain coarse voltage steps between 5V up to 20V and a mode with fine steps. On top there are constant current an constant power modes as well... It's unikely that Hi13 uses or needs this too but it's specified by PD too... If you got it all so far you see for yourself what may varying in the formula when other values than voltage are set constant.

So far tbe theory.

In constant voltage mode cureent/power specs are maximum limits only. You can use a 45W or 100W supply as well. If anything is in ordef thie shall work too.

The practical problem choosing a PD charger is also wether it supports the needed voltage level or not. Some charger's (targeting smartphones?) Seem to end at 12V an can not charge notebooks demanding 15V or 20V... others lack 12V in the step inbetween and onny support 5,9,15,20V mayve other steps. In theory the consumer could use fine voltage step mode, making 12V available thar way... but who knows what's really implemented?

To make the long story short, I expect this Aukey charger to be working. There is a stronger model I'd expect to work too. However I do not finally now either.
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-12-2017 23:29:24 | Show all posts
Maybe the situation with the original charger isn't as bad as some dramatic reports may indicate, probably it's really a limited issue with a certain batch.

But people including my self get nervous... Chuwi needs to comment on this clearly, otherwise the suspicion of latent issues will persist.

I'm not happy spending money on probably unnecessary replacement items either.
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-13-2017 02:12:38 | Show all posts
Interesting video here:

Not easy to digest... but there are some of my personal conclusions. I doubt Chuwi has implemented some dirty tricks with USB-C PD. The specs are too complex to implement PD compatibility and something else at the same time. The only reasonable conclusion is there must be something in the plug or charger that negotiate the configuration. Configuration is independent from power and data lines, so assuming plain 12V without any configuration does not make much sense to me. In addition power lanes are completely separate from data and configuration lines. I doubt charging logic is so stupid not being protected against harmful voltages exceeding 12V and always expecting 5V (which seems not to charge anyways) just for the purpose to damage circuitry...

The only thread that makes sense to me beiing a hazard is the plug's build quality itself and bent contacts crossing.

I don't believe in anything else unless there is a clear evidence.

In other words my opinion is the original charger is fine as long as the plug is fine.

The point is now, how serious is the plug issue and which units are affected at all?

I've exclusively used the original charger for many times already. I didn't notice any heat issues. I've checked USB 2 and USB 3 devices via USB-C otg. All works fine.

What remains is speculative.
Reply Support Not support

Use magic Report

artowi| Post time 10-13-2017 07:28:27 | Show all posts
I think I now have a quite full understanding of the problem.  

Fact is:

The KEYU charger has the 12V hard wired to VBUS.   This is not ok according to the PD standard because nobody must put a voltage greater 5V on the VBUS lines unless a successful communication was established via CC1 (or CC2) signal lines which exist just for the purpose of power negotiation and are not the data lines for USB or other communication.

The KEYU charger plugged to a Smartphone with USB may cause the phone to burn because it may not be ready to accept 12V.

There is a very simple method for a device to tell if it needs power or if it supplies power by just pulling the CC1 line low (towards GND) or up (towards +5V)

Pulling CC1 low indicates there is a request for getting out power.   If you plug an USB-C connector to the Hi13 with a small DC motor on GND/VBUS it will not run unless you pull CC1 low.   This works very well and is a rather safe experiment for anybody who wants to try.

pulling the CC1 to +5V with resistor signals that power is provided.   

The KEYU could not pull to +5V because there is no  +5V voltage so they just decided to pull to +12V which is clear violation of the PD standard.

The datasheet of the PD controller chip states that the maximum allowed voltage on CC1/CC1 is  6V.   

The resistor will limit the current so that the internal protection diodes probably will limit the voltage on CC1 so usually no damage will occur.

Thanks to member scuszi we know that the connectors are bad and if the plug gets slight pressure from the side the VBUS may touch the CC1/CC2 pin and I guess this is the exact moment when the PD controller chip will burn to death.  The pullup resistor will limit the current to mA range but the 12V power supply capeable of delivering 3A connected to the CC1 specified 6V absolute maximum will kill the PD chip immediately.

Assuming you have a true PD charger but bad cable with cheap plug and VBUS accidentally hits CC1 there will be no damage.   The PD chip will just see the 5V which is not harmful.  There will be no successful communication to negotiate the voltage to be risen to 12V so the Hi13 will not charge but also will not get damaged.

Some theory which has not been confirmed is that maybe the PD controller could attempt to put +5V on the VBUS not being aware that the VBUS is forced to +12V by the charger.

In order for the PD chip to burn some severe current flow is necessary.  It is either +12V high current flowing into CC1/CC2 because of misaligned plug or +12V colliding with +5V on the VBUS pins when the PD chip thought it would be safe to switch VBUS to +5V output.

Whatever, it is never fault of the customer but a faulty product.

My burnt pcbs are in the hungarian repair shop now.  Unfortunately the repair shop gets no support, parts or payment from CHUWI so they are waving the white flag and give up.  I can send money to hungary for postage to get my burned Hi13 sent back to Germany to keep as a reminder never ever to buy from CHUWI again.

Reply Support Not support

Use magic Report

artowi| Post time 10-13-2017 07:34:43 | Show all posts

My fireworks started when turning the Hi13 on while charging.  I did not notice the connector to be loose but maybe it was misalined.  Maybe in rare occsion on power up the BIOS boot sequence will send instruction to PD controller to provide power (for checking for boot deivce?)  I can neither prove nor disprove.

Make sure NEVER EVER to connect any other device to the KEYU charger.  No other family member should accidentaly plug a nice phone!

Just keep using the KEYU charger and when you smell the sweet scent of burned IC check if the plug was loose or not.
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-13-2017 09:48:03 | Show all posts
Have you any evidence that 12V is hardwired?

As far as I understand the configurarion lines have their own supply line which is 5V of course. To create 5V from 12V can be done cheap. I doubt the full 12V are connected without any resistors, this would kill configurarion asap imho.

Isn't Vbus (4 individual pins) for supply only? It isn't directly connected to anything but the charging logic, isn't it? I could imagine that firework if Hi13 would Power Vbus while the charger does the same... probably by a firmware bug. But before any port configurarion I would assume the Hi13 to accept nothing from Vbus. Configurarion works independent. If not it would kill itself asap when accepting higher voltage and Vbus would b used directly... that does not sound very convincing.

Whats more convincing to me is that Vbus pins ares direct neighbour pins to cc1, cc2 and tbe rest of configurarion lines... crossing here instantly feeds Vbus voltage 2ithout any limiting resistors to any of the configurarion pins... an that exceeds the spec you refer to when crossed.

I'm still guessing - Chuwi is the one who's in charge to officially comment.

The only probability I can imagine is maybe a boot issue providing power which shorts with the charging power. But even with a 'proper' 5V charger this can lead to uncontrolled current. Voltages are newer exactly the same so there will be a balancing procsss... which is probably an explanation why one case of a defective port is reported while having used an alternative charger...

I really think we can discuss forever without concluson. We would need a lab and reference hardware with analysis devices to make sure.

Which bios did your unirs run?

Maybe there is something strange going on. My units bios clock seemed not to work when I got mine. After a windows update I noticed a driver update and the tbe clock worked... I have no clue what this is abouf either. After this update my cameras stopped working.

Finally, how many cases of burnt port chips are known and how many units have been sold? I understand that you are angry, I'm alarmed too. Just I am not convinced that an alternative charger will resolve any issues - if there is any beyond the cheap plug.

To be honest, I've the Aukey charger laying around and hesitate to connect that either because I'm in doubt wether this won't do any harm either.
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-13-2017 10:32:26 | Show all posts

When I read over again your arguments I think we basically agree about most options of damage.

I understand your argument that constant 12V without being negotiated is dangerous when the contacts cross while it isn't with initial 5V. But what if crossing contacts happens after successful negotiation? Then the situation isn't different to the original charger and the problems remains even with an alternative charger.

If specs don't allow initial constant 12V and the original does so that's not ok. But does Chuwi specify the charger to be PD compliant with other devices?  If other devices (most phones?) can't use 12V at all it's obvious that they migh blow instantly.

If I take your statements for granted I agree that the original charger is potentially dangerous to Hi13 and definitely to other devices.

On the other hand an alternative charger does not ensure full protection against bad plugs when crossing happens after proper negotiations...

If there is a bug in vbus powering from Hi13 then we face a general issue with any charger. Again initial 5V may be less dangerous but there is still a risk remaining while the original charger will for sure create damage, a 7V difference between sources (with low inner resistance) results in a massive current peak.

I believe this last idea is somewhat theory as I believe I have booted my device several times with the charger plugged in - so the bad case should have already happened to me - but it didn't. Luck maybe? Who knows for sure?

Anyways, you convinced me to try the Aukey charger, it can't do worse, can it?
Reply Support Not support

Use magic Report

artowi| Post time 10-13-2017 10:45:57 | Show all posts

Its a fact that the 12V is hardwired and there is just a pullup for pulling  CC1 to +12V  

I am electronics engineer and of course you could use a Zenerdiode or cheapest 5V regullator to do it properly.   The supplied charger is a fixed 12V hardwired to VBUS and GND and a 47 k resistor from 12V to CC1.   This is definitely nothing you could call PD compliant charger.

The AC Adapter is 'dumb' and I don't know at what current the current limiter will kick in.   

VBUS runs 2 directions on the mainboard.  VBUS connects to the EJ898A PD controller chip because the  EJ898A needs to provide 5V to the USB-C in case you connect an external device requiring power.  As long as the EJ898A is ok pulling down CC1 will switch on power output.

VBUS also runs hardwired to a stepdown regulator for charging the main battery.  This charging circuit is independent from the PD controller EJ898A and will still work even if the EJ898A got toasted.   Whenever VBUS is 12V and the battery voltage below certain voltage the step down will charge the battery.

Another stepdown from VBatt will provide the voltages for the system (+5 +3.3 and probably lower voltages for the CPU)

With a proper PD charger the risk is little.  Even if there are a few mV difference the current in either direction is little.  

With roasted EJ898A a proper PD charger will remain at 5V because no negotiation.   5V cannot charge the main battery because it is step down converter only - not a step up.

I think the Aukey charger is perfectly safe and 5V will not harm a 5V system.  I don't have any bad feeling to connect two true PD compliant devices.  

I could not find a full datasheet for the PD898A to check the SPI command set to see if it would be possible to force the VBUS output to +5V even if 12V are applied.  

I believe there is a big number of Hi13 with burned PD chip out there with customers not knowing they have a problem.   The original KEYU charger will continue to work.  The USB-C will no longer provide power to any connected device.  The killed EJ898A will have a high power dissipation so the Hi13 will have some extra heating but battery life will be significantly short.

Both of my Hi13 got cooked.  For the first one I ordered a new mainboard (fully paid myself) from CHUWI so I fixed myself and now only use with Aukey charger.  #2 and the fried mainboard from #1 now are at the hungary repair center but apparently ingored from CHUWI.  They had promised to send replacement weeks ago but nothing happens.  

Enjoy your Hi13 while it works and forget it when it gets broken.  Don't waste time and nevers hoping to get it fixed.
Reply Support Not support

Use magic Report

MemberChuwi| Post time 10-13-2017 11:19:38 | Show all posts
Ok, I trust your findings.

I'm just checking the Aukey 27W charger. The estimated charging time sounds plausible.

However, the RawPower charging cable does not fit snug. The metal part seems to be too short. Think I have to return this an get something else.

I still think the cable is important and this obe seems to wiggle quite easy...
Reply Support Not support

Use magic Report

You have to log in before you can reply Login | Register

Points Rules

Quick Reply To Top Return to the list