Replacing a Chinese tablet charger

[VioletF]

I received my new toy just in time for Christmas. It's gorgeous and very responsive, so I was very happy with it for about 4 hours... until it started asking to be charged and I found out the charger doesn't work. The tablet doesn't offer USB charging so I now have an expensive paper weight on my desk.

Since it was ordered from a Chinese website, I don't have much hope that they'll send me a replacement (I have asked, but they haven't replied yet). Even if they do, it will take weeks to get here, so I've decided to look for one myself in the meantime.

I'm having a couple of problems, however.

Firstly the DC input connector is much smaller than any of the connectors available on the universal chargers I looked at (slightly larger than the newer Nokia charger connectors). One website calls it a 2.5mm something-or-other, but I'm not sure what that means.

Secondly - the charger itself has some chinese characters printed on it, with these lines next to them in English:
BY180951500C (charger model number? If I Google this, I get a lot of suggestions for chargers that can apparently replace it, except that they're all listed as 5V)
100-240V~50/60Hz (probably input)
12V - 2000mA (output, I'm guessing)

However: the tablet has "12V - 2000mA" printed on the back underneath the brand name, and "DC 5V" next to the power port.

Inside, it has 2 battery cells with 7.4V 7800mAh Li-ion printed on only one of them.

I'm utterly confused.

There are about 4 different variants of the same tablet (with minor differences apparently), so I'm not sure which one I have. This is what I ordered, but I received a version with an all-aluminium back: http://www.geekbuying.com/item/product-307944/

What kind of charger does this tablet need? What would be the repercussions if I used a 12V charger if it's supposed to be 5V (or vice versa)? The universal chargers I saw only went up to 1A. Would this be a problem? Also, where could I find a charger with a small connector like that, in Cape Town? I've been to several places already (including Zakspeed) and none of them have one with a connector this small.

I've received some suggestions, however: cut off the connector of the faulty charger and wire it onto a universal DC charger (if I can figure out which wire's positive) or a USB cable that I could then plug into a USB wall charger. Are these options feasible?

I've tried researching this online, but am getting lots of conflicting information and the seemingly reputable sites such as http://batteryuniversity.com/learn/article/all_about_chargers are very difficult to understand/apply. Can anyone explain this in simple English or point me to an "Electrical Engineering for Dummies" resource?

 

[ponder]

As long as the connector is the same you can use any 12V charger that supplies 2A or more of current.

 

[Rickster]

Which one of these does it look like:

 

[KhoisanX]

However: the tablet has "12V - 2000mA" printed on the back underneath the brand name, and "DC 5V" next to the power port.

Inside, it has 2 battery cells with 7.4V 7800mAh Li-ion printed on only one of them.

I've received some suggestions, however: cut off the connector of the faulty charger and wire it onto a universal DC charger (if I can figure out which wire's positive) or a USB cable that I could then plug into a USB wall charger. Are these options feasible?

What I would do: Cut off the connector and wire it into a universal power adapter.

Is the polarity stated on the charger or tablet(a little picture showing whether the inside/outside are +/- respectively)? Check this with a multimeter. Even though it states 12V I would first set the voltage to 5V and see what happens, 12V just seems a bit high, on the other hand the battery does state 7.4V. Better safe than sorry though.

If you can only find a 1A charger then the only side effect would be that it takes longer to charge.

 

[rodga]

Where are you based?
I have a USB cable that might work
I got it for my huawei s7 tab that also didn't charge through USB
I have since sold the tab but still have the cable, I can send it to you when I get back home in the 2nd week of Jan
It might work for u ...

With the s7 u could charge through USB when it was powered off though' maybe try that also

 

[Esquire]

This is unit looks similar to the Geeko Premium Tablet PC’s that we import, we do have extra AC/DC adaptors in stock, you can contact our Cape Town branch and speak to Graham and ask him to order one from Midrand, however the Unit should be able to charge from the Micro USB port or using any Blackberry Charger, try it first from the USB port

 

[VioletF]

Thanks for the replies, everyone.

As long as the connector is the same you can use any 12V charger that supplies 2A or more of current.

Regardless of what kind of battery it is, or just for the Li-ion type? They seem to use different battery chemistries for different types of batteries.

Which one of these does it look like:

View attachment 33512

It looks most like the first one in the pic, just with a black tip.

Is the polarity stated on the charger or tablet(a little picture showing whether the inside/outside are +/- respectively)?

Both of them show the polarity, yes, and they match. Inside's positive.

Check this with a multimeter.

Do you mean that if I re-wire the connector to a universal adapter, I can check the polarity with a multi-meter?

Even though it states 12V I would first set the voltage to 5V and see what happens

See, this is what concerns me. If it needs 12V and I give it 5V, what would happen? Could I damage the unit or the battery?

This is unit looks similar to the Geeko Premium Tablet PC’s that we import, we do have extra AC/DC adaptors in stock, you can contact our Cape Town branch and speak to Graham and ask him to order one from Midrand, however the Unit should be able to charge from the Micro USB port or using any Blackberry Charger, try it first from the USB port

Thanks, it does look similar, although yours has a Lithium polymer 8000mAh battery.

When I plug in a USB cable, nothing happens, regardless of whether it's on or not. Not even when using a USB wall charger. Online info is conflicting: some say it can, some say it can't charge from USB. The many variants with the same name also confuse things.

Someone tested the charger with a multi-meter for me and confirmed that it is dead, but I suppose it's possible that the circuit that's in charge of charging the battery (heh heh) is itself faulty?