I have a speaker that the USB port is damaged. Im going to try and replace it on the PCB. I have a question about charging. I have always assumed that all the USB wall plugs were 5V. When I looked at the rechargable battery in the device its rated at 7.2V. I have being reading about how USB-C used something called USB Power Delivery that allows voltages all the way to 48V. How is this possible with just a regular USB wall wart
Thanks
Rick

 

A circuit inside the speaker boosts the voltage for charging the battery. It take in 5V and delivers up to 8.4V to the battery.

 

would that not increase the amount of current the power supply has to put out.

 

You lose current in the same ratio as you gain voltage.

So, when boosting 5V to 8.4V the current goes down to 5/8.4 if wgat you out in. Thus to charge at 1A it will need to draw 8.4/5 = 1.68A form the charger.

But you can charge a battery at any current less than what makes it catch fire.

 

Post #4 is the correct answer. And CORRECT short answer is NO!!! A charger circuit is constant current OR constant voltage, or some variable. IT IS NOT "Constant Power"!!!

AND some have decided that the USB connector is cheap enough that they will use it for other voltages. IF both the power receiver and the power delivery portions operate correctly every time that can be useful. But if they do not communicate correctly then your $1200 smart phone may get perhaps 16 volts, or 24 volts, or even more. THAT is a risk that I would choose to avoid.
The bad news is that while a lot of individuals are convinced that a cheap USB charger will never fail in a destructive mode, I have discovered that poor quality cheap consumer electronic products do sometimes fail.

 

Ok so I have a box with these USB power supplys. Every time I buy a phone or tablet or any other device they all come with a charger. So these chargers will put out different voltages depending on what the device calls for. Do they comunicate over the data wires in the USB cord

 

Pardon MisterBill, he is far behind on the technology.

"Standard" USB devices and supplies operate at 5 volts.

In order to supply greater power to devices, the USB-C PD (Power Delivery) standard was implemented in 2012, and has evolved since that time. A USB-C PD supply may supply up to 28 volts (or even higher) to deliver more power to a device (remember, power in watts = volts × amps and the number of amps that can be delivered depends on wire gauge).

A USB-C PD supply will only supply 5 volts unless and until a higher voltage is negotiated between the device and supply. The is zero danger plugging any USB device into a USB-C PD supply conforming to the standard.

That's not to say that bastardized supplies don't exist, but they are extremely rare. If a supply lists several output voltages and current ratings, it's almost certainly a proper supply.

 

Post #7 is correct, UNLESS PART OF THAT MULTI-VOLTAGE CHARGER FAILS!! Consider if it is used to power a 28 volt device and then the communication does not work right because a spec of dirt gets into the connector. POOF!! there goes your new $1800 smart phone. Not covered by the warranty because you used the wrong charger.

 

UNLESS PART OF THAT MULTI-VOLTAGE CHARGER FAILS!!

USB-C PD has been a standard and in use since 2012. It's supported and used by all cell phone manufacturers (including Apple) and many laptop computers use it for power.

The chances of a USB-C PD charger failing and destroying a device is less likely than a standard USB 5 volt charger failing and destroying a device because 5 volt supplies take little skill to make.

I challenge you to find any case where an actual USB-C PD charger destroyed a device, let alone any widespread rash of failures.

 

Post #7 is correct, UNLESS PART OF THAT MULTI-VOLTAGE CHARGER FAILS!! Consider if it is used to power a 28 volt device and then the communication does not work right because a spec of dirt gets into the connector. POOF!! there goes your new $1800 smart phone. Not covered by the warranty because you used the wrong charger.

Bill...

USB PD is a solidly established standard at this point. When dealing with a USB PD charger, it is almost impossible to imagine a practical scenario that would result un the delivery of a voltage higher than the device being charged can handle.

The process starts with the charger providing either 0V or 5V at 500mA (VSAFE5V as it is called in the standard). To increase the voltage and/or current, the device being charged must actively request it from the charger.

Chargers are built around dedicated chips that handle the protocol. There is nothing about them that could "break" in a way that would result in over-voltage. By design failure of communications will result in little or nothing at all from the charger.

There is a danger that a manufacturer will put a Type-C connector on a single voltage supply that produces one of the standard PD voltages but with no intelligence (e.g. 9V*, 12V). These supplies when combined with a device sporting a Type-C input only intended to be used with 5V (an error run design done to save costs) can result in a dead device.

$1200 smart phones are not such devices, and if they have a Type-C connector they are certainly PD compliant.

So your concern is misplaced. Unlike the USB A, mini, and micro USB Type-C is, from the beginning, designed to supply a variable voltage so using them with PD is completely safe.

 

OK, "Y" has delivered an excellent rebuttal indeed.
And certainly the products with adequate quality and design integrity, made with components of adequate reliability, will perform as intended.
My concern is those products that substitute features for any level of quality.
Understand that my definition of "product quality" is the ability of a product to be able to meet the implied specifications for an extended period of time. By "extended period of time", I mean several years, not just the warranty period.

 

OK, "Y" has delivered an excellent rebuttal indeed.
And certainly the products with adequate quality and design integrity, made with components of adequate reliability, will perform as intended.
My concern is those products that substitute features for any level of quality.
Understand that my definition of "product quality" is the ability of a product to be able to meet the implied specifications for an extended period of time. By "extended period of time", I mean several years, not just the warranty period.

Even the cheap junk electronics from China has the product quality (using locally produced devices) for USB-C energy selection to work flawlessly. You're more likely to get hit by lighting, while indoors, while sleeping, than to have an issue with USB PD.

https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=1745685365363
A Primer on USB Type-C® and USB Power Delivery Applications and Requirements

 

Even the cheap junk electronics from China has the product quality (using locally produced devices) for USB-C energy selection to work flawlessly. You're more likely to get hit by lighting, while indoors, while sleeping, than to have an issue with USB PD.

https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=1745685365363
A Primer on USB Type-C® and USB Power Delivery Applications and Requirements

BEEN HIT by lightning several times! And closely missed one additional time. Not directly hit, but certainkyaffected.

 

OK thanks guys.
I dont have a charger for my Bluetooth speaker it was lost. The rechargable battery is rated at 7.5V How do I find a replacemenet charger

 

How do I find a replacemenet charger

Does it have a USB connector? Full size B or micro B? Any USB charger should be fine.

Usually, devices operating on two LiIon batteries include a DC-DC boost converter for charging.

 

There is 2 batteries at 7.5 v each. There's a USB C outlet on the back.
So i could use any USB charger rated a 5v because there is a circuit in the speaker to raise the voltage

 

Thst's most likely true. Applying 5 volts from a standard charger with a USB-A connector using a USB-A to USB-C cable will probsbly work. Give it a try. It may not work but it won't harm anything.

If it does run from 5 volts, I don't recommend using a USB-C PD supply as some products that have changed from a micro-B to USB-C have overlooked a requirement to have resistors on the USB-C cc pins to signal the charger to supply 5 volts –:without these resistors, the supply will not provide power.

Your device may be a USB-C PD device requiring more than 5 volts. The device should be labeled if this is the case.

If you have a smart phone that uses USB-C PD, try its charger out. As I have said, PD will not supply greater than 5 volts unless and until a device asks for it. I am not sure why some people here remain so skeptical of this FACT.