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biwecity Li-Ion charger on E-Bay

Started by legg June 7, 2018
biwecity currently has multiple listings for a 36V Li-Ion battery 
charger. One example is item 322458751129. All have the same 
listing illustration and description as a 42V 2A charger for 
110-240VAC input:

http://ve3ute.ca/query/JC4202_charger_correct.jpg

An observant purchaser could probably note irregularities in the 
product's labeling, but this is not unusual in off-shore sourced 
product.

Unfortunately, the items shipped may not even resemble the image 
being evaluated:

http://ve3ute.ca/query/szYB-100W-42V2A_charger_error.jpg

The shipped device is actually a ~27W charger built around a 
typical applications circuit using the Kintago KTG7838 off-
line controller IC:

http://ve3ute.ca/query/szYB-100W-42V2A_off-line_converter_Kintago_KTG7838.pdf
 
Actual load profile is characteristic of the application circuit:

http://ve3ute.ca/query/szYB-100W-42V2A_Output_VA_Profile.pdf
http://ve3ute.ca/query/szYB-100W-42V2A_Output_VA_Profile.xls

As constructed, it cannot even be guaranteed to start up 
below about 140V, due to the device's start-up current spec 
and the selection of trickle-feed resistor value.

The unit tested here actually failed during the record (the 
zeros in the table and graph), with the chip assuming a low 
fixed impedance on it's supply pin.

If what you need is an ~80W device, don't bother with this one.

I'm sure that the seller, biwecity offers some excellent deals 
on other components, but they are unable to deliver on this one.

RL