usb fast charger question...

T

T

Guest
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?

https://www.amazon.com/dp/B08786SHXV

Many thanks,
-T
 
On Friday, November 19, 2021 at 3:43:36 PM UTC-8, gnuarm.del...@gmail.com wrote:
On Friday, November 19, 2021 at 11:28:37 AM UTC-4, Ed Lee wrote:
On Friday, November 19, 2021 at 3:41:11 AM UTC-8, gnuarm.del...@gmail.com wrote:
On Friday, November 19, 2021 at 4:48:47 AM UTC-4, Ed Lee wrote:
On Thursday, November 18, 2021 at 11:48:09 PM UTC-8, Jan Panteltje wrote:
On a sunny day (Thu, 18 Nov 2021 12:07:38 -0800 (PST)) it happened Ed Lee
edward....@gmail.com> wrote in
2900a7d8-299d-4688...@googlegroups.com>:
On Thursday, November 18, 2021 at 11:53:24 AM UTC-8, Jan Panteltje wrote:
On a sunny day (Thu, 18 Nov 2021 11:16:46 -0800 (PST)) it happened
\"ke...@kjwdesigns.com\" <ke...@kjwdesigns.com> wrote in
0a51460d-1038-47c7...@googlegroups.com>:
On Thursday, 18 November 2021 at 11:06:35 UTC-8, Ed Lee wrote:
...
Fine. Nobody needs to follow what i do. All i am saying it that beyond
60%
SOC, internal resistance is the thing limiting charging rate. It doesn\'t
matter
what voltage you are setting. The charging rate is limited by IR. You
are saying charger is the limiting factor, but in fact it is trying to avoid

the real limiting factor: internal resistance.

Yes, beyond about 50-60% SOC the charger would typically use constant voltage

charging where the internal resistance does control the charging current.

However, the current is still being measured by the charging circuit and
if
it attempted to go above the limit set by the battery or the source the charger

it would go back into constant-current mode.

The ultimate limit is not the current determined by the internal resistance

but that determined by the battery characteristics, temperature, and power

source etc. For example, at low temperatures, the charger would dictate a
lower
charging current and reduce the terminal voltage to meet that current
limit.

kw
I usually charge batteries on my lab supply (set voltage and curent limit),

for example with eneloop 1.5V AAA charging at 1.6V 1C you will see a clear
temperature rise when the cell is full.
Normally one should measure that and switch the charger off.

There are charging ASIC that will fully charge cells to 100% with auto shut-off,
but problem is that it only charge at maximum of 300mA and it would take
hours to charge.

My current device must be charged in 15 minutes or less; so, just a fixed voltage
source using 40% capacity of the cell. Beyond that, the \"Internal Chemical
Resistance to Charging\" limits the charging rate. Don\'t call it Internal
Resistance, as per Internet Police.
OK, what I forgot to mention is the volatge drop (when charging current limited)
that happens when the cell is full (there is a name for that, delta V or something?)
and normally used by chargers to detect \'battery full\'.
Get your battery cherging curves from the internet (google).
I have made charge curve pictures for all my battery types.
nimh_charge_curve.png
eneloop_800mAh_AAA_charge_discharge_curve.gif
lifepo4_charge_curve.jpg
etc
I routinely charge at 2.5C (20% SOC) and 1C (60% SOC) for most 2Ahr cells. They hardly get warm at all, as long as the total charge time is short (15 minutes). With USB (5V) supply, you can hardly drive it over 1.5C (3A for 2Ahr cell). If the cell does not get warm, then most of the energy is stored instead of heating up due to \"Internal Chemical Resistance to Charging\". Heat is the biggest problem.
Here you are showing you don\'t understand the difference between power and energy. Damage to the cells happen from the overcurrent regardless of the temperature. By your reasoning you should be able to pump the cell with 100C if you do it for a short enough time.

One wear mechanism is plating of lithium on the graphite anode instead of lithium being intercalated. Intercalation is a reversible reaction while plating is not. Lithium is preferentially plated at higher currents. It doesn\'t matter that the current is short enough the battery temperature doesn\'t rise a lot.
But we are not talking about 100C, just 2C.

Highlights
Harvested electrodes are tested at high discharge and charge rates.
Several limiting processes were observed within a single 10 s pulse.
In 10s pulses, the cathodes could be charged at 10C and stay below the 4.2 V limit.
The anodes voltages went negative at 5C, but the limiting process was diffusion.
Repeated pulsing with 20C, 10s pulses lead to lithium plating on the anodes.

https://www.sciencedirect.com/science/article/pii/S0378775321002330
Ok, I give up. No point in talking when no one is listening.
Click to expand...

I listen to facts. They tested 5000 cycles of 20C for 10s and find lithium plating on the anode. I don\'t know how much it would degrade, but sound like it would take a while to cause problem. Anyway, i am not even getting close to 20C and even if i cycle it everyday, it would last 10 years.
 
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.
Click to expand...

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.
 
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.
Click to expand...

I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
 
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.
Click to expand...

I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
 
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.
Click to expand...

I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
 
torsdag den 18. november 2021 kl. 02.18.47 UTC+1 skrev T:
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
Click to expand...

if it is regular USB it is just 5V an the device will draw as much current as it needs up to the 2A USB charging limit

if it is USB-C the device can ask for higher voltages and will be told how much current it is allowed to draw
 
On Wednesday, November 17, 2021 at 5:18:47 PM UTC-8, T wrote:
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
Click to expand...

The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.
 
On Wednesday, November 17, 2021 at 5:18:47 PM UTC-8, T wrote:
On 11/17/21 07:30, Ed Lee wrote:
On Wednesday, November 17, 2021 at 2:15:43 AM UTC-8, Carlos E. R. wrote:
On 17/11/2021 08.58, T wrote:
Hi All,

I asked about the voltage of a USB fast charger. I got back:

5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3A

My Android tablet wants 5.2V, 2.0 A


Uhhhh. Is there something about the USB cable that
tell the charger not to fry what I plug it into?
Not the cable. The voltage is negotiated between the device and the
charger. Before that, you only have \"1 Load unit\" available.

There is very limited voltage range to negotiate anyway.

The 3A rating is mainly to protect the cable and connector, so that you don\'t drive 3A through a 2A device.

As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
Click to expand...

The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.
 
On Wednesday, 17 November 2021 at 17:18:47 UTC-8, T wrote:
....
As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
Click to expand...

With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.

kw
 
On Wednesday, 17 November 2021 at 17:18:47 UTC-8, T wrote:
....
As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?
Click to expand...

With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.

kw
 
On Wednesday, 17 November 2021 at 18:11:48 UTC-8, Ed Lee wrote:
....
> The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.

That is wrong.

the charger within the device will manage the charging current to not exceed the capability of the power supply.

kw
 
On Wednesday, 17 November 2021 at 18:11:48 UTC-8, Ed Lee wrote:
....
> The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.

That is wrong.

the charger within the device will manage the charging current to not exceed the capability of the power supply.

kw
 
On Wednesday, 17 November 2021 at 18:11:48 UTC-8, Ed Lee wrote:
....
> The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.

That is wrong.

the charger within the device will manage the charging current to not exceed the capability of the power supply.

kw
 
On Wednesday, 17 November 2021 at 18:46:47 UTC-8, ke...@... wrote:
....
With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.
Click to expand...

https://www.embedded.com/usb-type-c-and-power-delivery-101-power-delivery-protocol/
 
On Wednesday, 17 November 2021 at 18:46:47 UTC-8, ke...@... wrote:
....
With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.
Click to expand...

https://www.embedded.com/usb-type-c-and-power-delivery-101-power-delivery-protocol/
 
On Wednesday, 17 November 2021 at 18:11:48 UTC-8, Ed Lee wrote:
....
> The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.

That is wrong.

the charger within the device will manage the charging current to not exceed the capability of the power supply.

kw
 
On 11/17/21 18:46, ke...@kjwdesigns.com wrote:
On Wednesday, 17 November 2021 at 17:18:47 UTC-8, T wrote:
...
As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?

With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.

kw
Click to expand...

Excellent explanation! Thank you!
 
On 11/17/21 18:46, ke...@kjwdesigns.com wrote:
On Wednesday, 17 November 2021 at 17:18:47 UTC-8, T wrote:
...
As for the battery, nothing wrong with 1.5C charging, although 1C is the optimized rate.


I am not following. How does the charging block
know what voltage and current is allowed? Is
the charging block a constant current device
that clips at 5V?

With USB-C there there is a wire in the cable that is used to communicate between the power supply and the device.
They negotiate what is the optimum voltage and current to use that is within both of their capabilities.

The power supply then provides that voltage and the device manages the charing current into its battery to not overload the power supply or overcharge the battery.

With the older USB there was a protocol for a device to negotiate up from 100mA to the maximum 500mA but that didn\'t suit charging so there were various other approaches either using resistors at the power supply end or a short between the two data lines that would give the device the information about how much power was available.

Again, the device would then manage the battery charging.

kw
Click to expand...

Excellent explanation! Thank you!
 
On Wednesday, November 17, 2021 at 6:48:51 PM UTC-8, ke...@kjwdesigns.com wrote:
On Wednesday, 17 November 2021 at 18:11:48 UTC-8, Ed Lee wrote:
...
The charging current is limited by the internal resistance of the battery. So, it\'s OK to hook up a 2A device to a 3A charger.
That is wrong.

the charger within the device will manage the charging current to not exceed the capability of the power supply.

kw
Click to expand...

The charger limits current to 3A. The device might not draw more than 2A due to internal resistance. A smart phone would likely have current limiting circuit anyway.
 
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