Battery Charger not very clear OUTPUT spec

[ConRAD]

I bought a new battery charger that features the following OUTPUT spec:

DC 3.6-6.5V/3A, 6.5-9V/2A, 9-12V/1,5A

I tested it either connected to a resistive load and to charge via USB interface my mobile phone and in both the cases I’ve measured 5V … so what does the above spec mean?

[Jdsk]

How is the output switched?

Can you add a URL or photo?

Jonathan

[thelawnet]

that seems not to be a battery charger so much as a USB power supply, which is not necessarily charging any battery.

it seems to be a usb power supply with quick charge 3, which is a proprietary charging protocol designed to overcome the limitations of older versions of USB, i.e. 5V and around 1.5A.


USB Power Delivery is the non-proprietary equivalent.


Anyway, without a chip telling it to do differently, it will default to 5V.

Depending on your actual charging protocols and QC/USBPD version then it may be easier or more difficult to override this, e.g.,

https://hackaday.com/2017/03/04/unlocki ... ower-bank/

http://blog.deconinck.info/post/2017/08 ... wer-supply

[ConRAD]

… how is the output switched? …

There’s no output switching, everything seems to be automatic (!)

… can you add a URL …

HER IT IS

… it seems to be a usb power supply with quick charge 3 …

... probably that’s the case, but I don’t know how it works …

[Jdsk]

What thelawnet says.

https://en.wikipedia.org/wiki/USB#Power-related_specifications

Jonathan

[RickH]

IIRC USB C can be multi voltage so it can be used for things like laptop charging that wouldn't have been possible with older variants of USB. I presume it "negotiates" between the charger & device in some manner to serve up the right power requirements.

[ConRAD]

... anyway, without a chip telling it to do differently, it will default to 5V ...

That's my conclusion too.

[ConRAD]

IIRC USB C can be multi voltage so it can be used for things like laptop charging that wouldn't have been possible with older variants of USB. I presume it "negotiates" between the charger & device in some manner to serve up the right power requirements.

Here below the specs of the PowerBank that comes with the A/M Power Charger, as you can see ALL the USB outputs (not only USB-C) are rated the same, i.e. DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A !!

TECHNICAL SPECIFICATIONS
Battery capacity: 20000mAh 74Wh
Micro-USB input: DC 5V, 2A
USB-C input: DC 5V, 3A - DC 9V, 2A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB-C output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
TOTAL OUTPUT (USB + USB-C): DC 5V, 3A

[thelawnet]

IIRC USB C can be multi voltage so it can be used for things like laptop charging that wouldn't have been possible with older variants of USB. I presume it "negotiates" between the charger & device in some manner to serve up the right power requirements.

Here below the specs of the PowerBank that comes with the A/M Power Charger, as you can see ALL the USB outputs (not only USB-C) are rated the same, i.e. DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A !!

TECHNICAL SPECIFICATIONS
Battery capacity: 20000mAh 74Wh
Micro-USB input: DC 5V, 2A
USB-C input: DC 5V, 3A - DC 9V, 2A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB-C output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
TOTAL OUTPUT (USB + USB-C): DC 5V, 3A

As I already explained this is not USB PD but Qualcomm QuickCharge. So it is not related specifically to usb c at all, since the goal was to get more power into mobile phones than usb could manage. This is linked to Qualcomm since Qualcomm make most mobile phone SoCs and support from the SoC is required to get a phone to charge at a negotiated higher power. Depending on the specific version of QuickCharge it might be compatible with USB PD as well.

If you follow and read the links I provided then it does explain.

https://en.wikipedia.org/wiki/Quick_Charge

[ConRAD]

Hopefully things start to appear much clearer now.
Indeed the two devices that I bought, the power charger and the battery pack, both implement Qualcomm QC 3.0 technology according to which the delivered higher power is managed via a “negotiated” higher voltage instead of a higher current, in this way avoiding wire overheating and possible detrimental effects on the batteries under charge.
The method is called Dual Charge (or Parallel Charging) using two PMCIs (Power management integrated circuit) to split the power into two separate streams.
Maybe supplying 9V/2A as 4.5V+4.5V to the two Li-ion power pack batteries. Is it something like that?

[axisofevil]

Isn't this pretty much the same as charging two batteries in series?
With (hopefully) some kind of voltage balancing.

[ConRAD]

Isn't this pretty much the same as charging two batteries in series?
With (hopefully) some kind of voltage balancing.

I don’t think so, each individual cell has its own DNA.
Charging two batteries in parallel with the same voltage assuming that each one of them takes the same current or two batteries in series with the same current assuming that each one of them at the end of the charging cycle reaches the same full-charge voltage … well all of that is not like to charge separately two different cells.

[thelawnet]

Hopefully things start to appear much clearer now.
Indeed the two devices that I bought, the power charger and the battery pack, both implement Qualcomm QC 3.0 technology according to which the delivered higher power is managed via a “negotiated” higher voltage instead of a higher current, in this way avoiding wire overheating and possible detrimental effects on the batteries under charge.
The method is called Dual Charge (or Parallel Charging) using two PMCIs (Power management integrated circuit) to split the power into two separate streams.
Maybe supplying 9V/2A as 4.5V+4.5V to the two Li-ion power pack batteries. Is it something like that?

This makes it sound very complicated, but typically a power bank would be multiple 3.7V 18650 cells connected in parallel.

This is a cheap QC3 board:



The PMIC is obviously a TI unit

https://www.ti.com/product/TPS61088

You put 3.7V in and you step it up to any variable number of volts between 5 and 12V.

Clearly the issue with a 20 Ah power bank is that you have six cells typically, so as they age it might be better to charge them separately; in terms of charging the cells then essentially you put 4.2V or less into them, and they charge but with age some cells might get damaged so if for example you put 4.2V into six cells at once, then that's not as good for the cells as if you charged all six separately.

Your powerbank is claiming to have two LiPo cells, instead of six Li-Ion cells, which is unusual, but if they are in fact charged independently that would be a good thing (they are still 3.7V btw, not 4.5V).

However none of this (how the power bank is charged) has anything to do with your output spec, which relates to the circuit board at the top, and where for instance if you want to charge a phone at say 24W, then 10V x 2.4A, or 12V x 2A is much better than 5V * 4.8A, since the resistance/heat in a wire relates only to current, not voltage, so where the wattage over a given cable/conductor has increased over time, it makes sense to increase voltage, which can only be done following the IC negotiating a safe higher voltage with another IC in the device being charged, failing which it will default to 5V.

[ConRAD]

... it makes sense to increase voltage, which can only be done following the IC negotiating a safe higher voltage with another IC in the device being charged, failing which it will default to 5V ...

Well, that appears to be indeed the real conclusion.

1. To “negotiate” the voltage both the “giver” and the “receiver” must be equipped with the same QC technology

2. To “negotiate” the voltage you need a full 4-wires USB cable, 2 wires #1&#4 used for power transmission, the other two #2&#3 used for voltage negotiating purposes

3. In all other cases, eg a normal/traditional smartphone or a 2-wires device like a lamp/light/resistor, well in all these cases the voltage settles by default at 5V-1to2A

4. In my test, see the picture below, either the charger and the power bank are equipped with QC 3.0 and so the voltage is correctly “negotiated” to 9V that, with 2A, makes a transfer power of 18W+