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Chinese Batteries, NOT a good idea

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Beware Chinese batteries

Here is a tale of caution about buying cellphone and other portable appliance batteries from Chinese sources,  this example is of a built in Lithium/Polymer pack fitted to a satellite navigation device.

At first this battery would power the GPS unit for about 3 hours on a full charge, within one month it was incapable of sustaining power for more than 30 minutes, within one year, it would last barely 10 minutes and now at 18 months has insufficient capacity to retain the display alone for more than a few seconds.

The latest episode which is the most disturbing from a safety point of view is the potential explosion threat.  I heard a crack while driving that seemed to come from the dashboard,  suddenly the GPS unit flew out of the cradle and burst into two halves,  it had been split apart by the balooning of the battery pack, the 4 captive screws holding the back ripped out of their pillars and left the GPS in two parts lying on the dashboard.

Nasty happening while driving

This picture was taken back at home after I had cut the connecting leads to the battery,  prior to removing the offending pack to replace with a genuine cellphone spare.

Written by nandinium

August 30, 2010 at 12:53 pm

Posted in Danger

Tagged with

DANGEROUS Power supplies on eBay

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Destruction of switched mode power supply supplied with HD docking station

(from eBay)

Here is my hypothesis on the destruction of this small dual voltage switched mode PSU

These PSU’s are constructed cheaply in the far east, they have inadequate fusing protection
and no EMC noise filtering. The main active device, a power FET device is mounted on a small
aluminium plate internal to the printed circuit board, it has no outward facing faces so all
heat created by the power FET is retained in the plate, none is radiated to the outside which
is a minimum requirement to keep the device temperature to a safe working level.

It is obvious to me from the melted solder on the connection pins of this device, that far
too much heat built up within the device causing it to fail, this failure short circuited the
250V DC on the 47uF capacitor and resulted in the destruction of the 4 diode rectifier bridge
this put the full AC mains across the capacitor and resulted in the vaporisation of the PCB
tracks from the mains connector to the diode bridge, it also destroyed the fuse which should
have been the first fail safe device, since there was no evidence of any wire left within the
shattered fuse body, it is not possible to gauge its current rating. 1 Amp is normal in this
type of PSU. Certainly, judging by the thickness of the destroyed copper tracks, this fuse was
not of a suitable rating.

I have included some pictures of the device (1) and some of the internals (3-6) described above,
also a picture of the illegal plug (2) supplied by an eBay seller with the docking station
and (7) the web site advert for one supplier of these items showing another suspect PSU
and clearly showing the illegal plug.

1.    PSU Picture

2.    Illegal Plug

3.    Burnt Casing

4.    Burnt PCB

5.    PCB Top View

6.    PCB Damage

Be WARNED if you use similar power supply units,  supplied by sellers in the far east.

Sorry the image hosting location seems to have gone offline with all my pictures I’ve loaded them up directly now.

Written by nandinium

November 9, 2009 at 7:38 pm

Posted in Danger