ddHifi TC28Cpro - continuously overcharge the phone or tablet... warning

[giuca70]

I point out something that I discovered using the new ddHifi TC28CPro -usbc to usb-c OTG and power adapter.
With a usbc tester I verified that if the mobile phone or tablet signal charging completed, the power supply continues to supply 5 Volt 1.9 Ampere to the host.
This thing is very dangerous, the battery should never be overcharged.From the diagram on the box there is no room for doubt.
It is very dangerous to use it.I advise whoever bought it to be very careful, the risk is serious. The battery could explode.

There is no usb data exchange between the host and the charger, as the usb data is diverted to the usbc OTG port

 

[inscythe]

I think that's normal.

When the battery is fully charged, the battery will indeed stop charging, which is ensured by the internal battery management system (BMS), so it doesn't need to directly communicate with the charger. Usually, BMS will monitor the temperature and overall health of the cells, then control the charging flow and report back to the phone's OS, but it also can operate independently (e.g. while the phone is off). However, when the battery is full, the phone still consumes electricity when it is on, so the charger will take over powering the phone instead of the battery, that's why charger will still output power to upkeep the phone. That 5V 1.9A is likely to maintain the operation of the phone and the dongle.

This passthrough charging mechanism is not new, it will just serve as a middleman between the charger and the phone to negotiate charging speed, in this case in a PD or normal fast-charging protocol. So, if your phone has non-standard fast charging, it will default to whatever the passthrough supports. For example, when I connect my Warp Charger 65W to my Oneplus 9 Pro directly, it will trigger the super-fast Warp charger. But when I use the TC28Pro, it will default back to just normal PD 18W since that's the protocol that the TC28Pro and the Warp charger brick support. I can confirm that the phone has stopped charging at 100% using Ampere app.

Was your phone turned on and running when you take the measurement? Was a dongle connected?

 

[giuca70]

This is with direct charge from PD3.0 at full battery 100%

and this is charge with ddHifi from PD3.0 at full battery 100%

phone turned on, and only the charger connected.
with and without ddhihi.

Is normal ?

 

[inscythe]

This is with direct charge from PD3.0 at full battery 100%



and this is charge with ddHifi from PD3.0 at full battery 100%



phone turned on, and only the charger connected.
with and without ddhihi.

Is normal ?

Try downloading the Ampere app and check whether the battery is still charging or not. The increased current can also be explained by the ddHifi adapter itself needing power to operate. The battery has the ability to stop charging on its own.

 

[inscythe]

This is the screenshot of my Ampere app showing 100% and the battery stopped charging.

Also note the top right hand sign of the battery no longer shows charging.

I have it attached to my phone without any dongle.

It's a 45W standard PD charger. I charged from 99% to 100%, previously it shows charging.

The battery should be the one deciding whether the charging is running or not. I think you can ask ddHifi what's the additional current is caused by, but definitely not the battery charging.

 

[giuca70]

Ok good idea
pernaps my DC28Cpro is defective, I'm happier that way.

here is the photo with direct PD and end of charge

and here is the photo with ddHifi and continuous charge, also after 5 minutes....

 

[inscythe]

Ok good idea
pernaps my DC28Cpro is defective, I'm happier that way.

here is the photo with direct PD and end of charge




and here is the photo with ddHifi and continuous charge, also after 5 minutes....

Not sure about your phone, but it took a while for my phone after hitting 100% until it actually stopped charging. Sometimes 100% is due to rounding up of the value. But since you waited 5 minutes, I'm not entirely sure where the problem lies.

Anyway, in your first screenshot, where the cable is connected directly, seems like your phone still shows charging at 100% too, so it may have something to do with your phone charging behaviour (trickle charge as it gets closer to full)

 

[giuca70]

In teh first photo in italian "carica" = Full
In the second photo in italian "in carica" = charging
Also not a problem, my item is defective.

 

[inscythe]

In teh first photo in italian "carica" = Full
In the second photo in italian "in carica" = charging
Also not a problem, my item is defective.

You misunderstood my point. What I was trying to say is that the "charging" might still happen for a few minutes after the OS indicates 100%, due to rounding up of the battery percentage.

These are the screenshots of my phone of Ampere app about 3 mins apart (you can see from the clock).




This was taken when I'm on my Warp Charger, and the same behavior can be observed when I'm using my TC28C Pro too, like when I took the screenshot my previous post (although I didn't really remember how long between hitting 100% and actually charging stopped at that time). It is really phone and charger dependent, so YMMV.

In short, I think the behavior is still normal, although I don't know how to explain the reading from the charging cable with display of yours.

 

[brjoon1021]

What is the final verdict ?
Does this overcharge or not ?

 

[inscythe]

What is the final verdict ?
Does this overcharge or not ?

It does not.

 

[brjoon1021]

That is good !

If you plug this device into your phone then plug a dongle (non-battery) into it can you play music ?
Or do you have to bring a 5 volt power source into the other side of this ddhifi device?

What I'm trying to figure out is does the ddhifi cut the power from the phone?
That's exactly what I'm looking for... something that will filter out the power and will only send the music from my phone to the dongle.

 

[brjoon1021]

Please someone who has this unit, let me know, please...

The question is:

If you attach this to your phone and attach a battery pack or power supply to one USB input and a dongle that is NOT SELF POWERED, to the other port ...
can you listen to music? That's all I'm trying to figure out ?

 

[inscythe]

Please someone who has this unit, let me know, please...

The question is:

If you attach this to your phone and attach a battery pack or power supply to one USB input and a dongle that is NOT SELF POWERED, to the other port ...
can you listen to music? That's all I'm trying to figure out ?

Yes, you will be able to, it's literally the entire purpose of this device.

The powerbank will also charge your phone too by the way. This is unlike the power split cable (like the one that iBasso recently released) where they just redirect the power from the USB port to an external power source. TC28C Pro will power both your phone and the dongle simultaneously. You can also use it with the power input port empty.

This is me running RU7 with a powerbank.

 

[Singaravelan]

Yes, you will be able to, it's literally the entire purpose of this device.

The powerbank will also charge your phone too by the way. This is unlike the power split cable (like the one that iBasso recently released) where they just redirect the power from the USB port to an external power source. TC28C Pro will power both your phone and the dongle simultaneously. You can also use it with the power input port empty.

This is me running RU7 with a powerbank.

Great to know. And it's dependable, not fickle with connection? (into the phone slot as some usb c devices can be) and charging issues etc... Will be using a Android phone in my use case.

And love that usb c to usb c cable! unfortunately (10 cm short one) not available in my country shop