AC/DC chargers

earth

I have a light that comes with an AC/DC charging plug. It's the second charger I have had, the first was replaced by the manufacturer when it broke. The replacement has broken now. I am thinking of getting a universal charger but I want to make sure I get the same electrical specifications as the manufacturers.

Input: 50/60Hz 100-240VAC 0.5A max
Output: DC 4.2V 1.5A

The chargers I have seen are
Output current 1500 mA max
4.5V

Looks like the voltage is slightly higher on the universal ones. Is this likely to cause damage or be a problem?

frisbee

A lithium ion battery needs a charger that monitors the voltage and stops charging when it reaches a certain level (or switches from charging at a constant current to a top up constant voltage mode). Or the battery goes pop. A random AC/DC converter won't work.

(Phones and tablets have the circuitry that does the monitoring and control of charging built in, so you can plug them into USB ports on PCs, random USB chargers etc..)

earth

frisbee wrote:

A lithium ion battery needs a charger that monitors the voltage and stops charging when it reaches a certain level (or switches from charging at a constant current to a top up constant voltage mode). Or the battery goes pop. A random AC/DC converter won't work.

(Phones and tablets have the circuitry that does the monitoring and control of charging built in, so you can plug them into USB ports on PCs, random USB chargers etc..)

Thanks, thats exactly the kind of disaster I wanted to avoid. Problem is I now have to go back to the manufacturer and ask for another charger again. It's not so bad but I know already the replacement will not work. The last one was dodgy from the outset. It made a high pitch whistling noise when charging.

sungod

google finds several, just search for 4.2v 1.5a charger

for instance

http://www.ebay.co.uk/itm/A-Intelligent ... 3641.l6368

why don't you say which light it's for?

earth

sungod wrote:

google finds several, just search for 4.2v 1.5a charger

for instance

http://www.ebay.co.uk/itm/A-Intelligent ... 3641.l6368

why don't you say which light it's for?

The charger in the link you posted looks identical to the one supplied by the manufacturer. I want something more reliable. I haven't mentioned the manufacturer in case they get word of it. A bit paranoid I know but I doubt they will honor any guarantee if they know I have been using a third party charger. Other than the charger, which is clearly a badged up generic product, they make a great light.

sungod

fwiw my light beginning with e has been going strong on the original charger for over two years, same as in the picture too, and i can also charge it off usb, which is 5v

tbh it's highly unlikely the light will care whether it's 4.2v or 4.5v or 5v, the charging circuitry is in the light itself and is likely to be tolerant over a fairly wide range

mr_evil

That one on ebay says "Automatic stop after full charged", suggesting that it is a proper charger, not just an AC/DC adpater, and that the light itself lacks any charging circuitry inside.

sungod

just a no load indicator on the led

these lights allow usb charging, usb has no automatic cutout, the charging circuitry is in the light

frisbee

sungod wrote:

just a no load indicator on the led

these lights allow usb charging, usb has no automatic cutout, the charging circuitry is in the light

The light that I, and I think the OP has, has a separate battery pack, you unplug the battery pack and plug it into the charger to charge it. The battery pack is just 4 18650 cells (probably recycled from a laptop).

I took the charger apart (after it went pop) and it has a charging circuit inside it, working how I described in a previous post.

sungod

mine is self contained, the charger plugs direct into the light, in the same socket that the usb adaptor cable does

peterbob

18650 or any lithium ion cell use a constant current constant voltage charging method. constant current puts the main charge in quickly while the battery is low the voltage is below 4v. when the voltage reaches to about 4v the constant voltage mode switches in and gently tops up the rest at a constant voltage of 4.2v and a low fixed current. This stage is accurately voltage controlled so as not to damage the cell, hence slowing down as the battery nears full.
Like filling a bucket and dumping the main bulk in with a fire hose to speed things up, then switching to a more delicate method near the end to avoid overfilling. Overvoltage quickly damages these cells and poses a fire risk, so it important to use cc-cv, but they are pretty universal interchangeable. boards can be got cheaply to solder your own with a little care.