Mains USB charger for small devices ???

Joined
11 Feb 2009
Messages
697
Reaction score
11
Location
London
Country
United Kingdom
Hi,

I have been looking for a quality mains USB charger/hub, and wishing to avoid the terrible chinese tat chargers found on Ebay - often designed and constructed not to UK Electrical Safety Standards (even though some say they are).

I took guidance from BigClive.com - who did a teardown on this Ikea SMAHAGEL charger - which he highly rated for quality:

The short version:
... and the full version:

However I have plugged in my rechargable headphones (these are cheap chinese ones) but afte a few charges the battery appears to expire within 10 minutes or so when used.

I once tried some cheap rechargable bicycle lights in a samsung mobile phone charger - and the lights stopped working straight after.

I had up until using these mains power USB chargers, charged the headphones and bike lights off my laptop.

I read in the below thread regarding over-supply to the device by the charger - is that happening here ? and does this charger rely on some circuitry on the device itself to limit current. Could one assume poorly designed chinese devices - lack such circuitry ??

Over charging devices

I'll watch the long version again over lunch, would i be correct to assume - the charger will feed what it thinks it can push into the device - even at the cost of it damaging the battery, and it is the devices task to limit that ?? So whilst the Ikea charger is well made and trustworthy, it cannot know what pull of charge is likely to be drawn from it - if the devide is 'dumb' in that respect.

In the worse case the device could catch fire whilst charging - yet the instructions for using the Ikea charger give absolutely no warning of this.

Do I understand this mostly correct, thoughts appreciated.
 
Just use an existing usb port off tv or pc.
I have a number of USB ports around the house on different devices that would be fine for charging low powered devices. That not an option?
 
I'll watch the long version again over lunch, would i be correct to assume - the charger will feed what it thinks it can push into the device - even at the cost of it damaging the battery, and it is the devices task to limit that ?? So whilst the Ikea charger is well made and trustworthy, it cannot know what pull of charge is likely to be drawn from it - if the devide is 'dumb' in that respect.

The charged device, and the charger, are supposed to negotiate between them, what each can support in the way of a maximum charge rate. The charged item, should then decide when it is fully charged.
 
The charged device, and the charger, are supposed to negotiate between them, what each can support in the way of a maximum charge rate. The charged item, should then decide when it is fully charged.
Does that not require specific functionality on the device?

Also, the charger needs to be "smart", and support USB-C PD (Power Delivery) standard and be a Programmable Power Supply (PPS) like the chargers for the new Google Pixel 10.

I think this is just a dumb charger and he is overloading dumb devices with too much power. Ikea Charger maximum output per USB port: 2.4A, 12W, compare to laptop USB-A 2.0 port, max current 0.5A, max power 2.5W.

He's basically smoking dumb devices with 4.8 times the power!!
 
I have been looking for a quality mains USB charger/hub, and wishing to avoid the terrible chinese tat chargers found on Ebay - often designed and constructed not to UK Electrical Safety Standards (even though some say they are).
What exactly are you intending to charge with this device? Any equipment you plan to connect must be fully compatible with the charger output voltage and failure to ensure this can result in damage or malfunction. Match the specifications, or don’t use it.
I took guidance from BigClive.com - who did a teardown on this Ikea SMAHAGEL charger - which he highly rated for quality:
What is the specification of it?
However I have plugged in my rechargable headphones (these are cheap chinese ones) but afte a few charges the battery appears to expire within 10 minutes or so when used.
What is the recommended voltage for the headphones to charge?
I once tried some cheap rechargable bicycle lights in a samsung mobile phone charger - and the lights stopped working straight after.
You must have damaged it, clearly the result of careless handling or ignoring the voltage requirements.
I read in the below thread regarding over-supply to the device by the charger - is that happening here ? and does this charger rely on some circuitry on the device itself to limit current. Could one assume poorly designed chinese devices - lack such circuitry ??
The output current of the charger is determined by the power drawn by the connected device, not the other way around. The device dictates the current it requires, provided the charger can supply it within its rated capacity
I'll watch the long version again over lunch, would i be correct to assume - the charger will feed what it thinks it can push into the device - even at the cost of it damaging the battery, and it is the devices task to limit that ?? So whilst the Ikea charger is well made and trustworthy, it cannot know what pull of charge is likely to be drawn from it - if the devide is 'dumb' in that respect.
For voltage yes.
Current no.
In the worse case the device could catch fire whilst charging - yet the instructions for using the Ikea charger give absolutely no warning of this.
If you irresponsibly use random chargers with mismatched voltage specifications on various devices, you're essentially inviting failure or permanent damage. Compatibility matters.
 
would i be correct to assume - the charger will feed what it thinks it can push into the device - even at the cost of it damaging the battery,

No.

The device you are calling a “charger” isn’t, despite that being what we often call them. It’s a power supply that converts 240V AC to 5V DC. It doesn’t have any battery-charging-specific circuitry in it.

The actual “charger” circuitry is built in to the device, likely right next to the battery. It is responsible for converting the 5V from the USB cable to whatever the actual battery needs and stopping when appropriate.

There is one complication that may cause some confusion: there is a limit on how much current a USB device can draw from its power supply, and this limit can be subject to negotiation between the power supply and the powered device. Some power supplies, e.g. laptop chargers, have much higher upper limits than others. But there is no way that this higher current can be “pushed” into a battery on charge.
 
I think this is just a dumb charger and he is overloading dumb devices with too much power. Ikea Charger maximum output per USB port: 2.4A, 12W, compare to laptop USB-A 2.0 port, max current 0.5A, max power 2.5W.

He's basically smoking dumb devices with 4.8 times the power!!

No, that’s not how it works.
 
1759413565778.png
 
So is he over-volting them then? The bike lights clearly don't have anything in them to prevent this damage.

No, he’s not “over-volting” anything. I don’t know what happened to his bike lights - not enough info to diagnose.
 
So is he over-volting them then? The bike lights clearly don't have anything in them to prevent this damage.

Nope, not possible - unless the bike lights simply have no charge control built into them, in which - case they do not meet the spec., for a USB device.
 

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Back
Top