Recently we ordered a batch of Battery Medic knock-off's. Hobby City was out of stock (though they are back in stock now) so we went to Ebay. As we were about to close the deal - my Chinese vendor warned me that I was buying the "poor quality" version
For a dollar more I was offered the "high quality" version -> so of course this sparked our interest. We ordered 29pcs of the high quality and 1pcs of the low quality.
Yes there is a difference
Yes one is better than the other - both in design and accuracy
THE GOOD ONE:
Green tinted LCD with sharp characters that are easy to read
Good spacing on the shunt resistors
Dead on accurate
THE BAD ONE:
Yellow Green PCB
Grey tinted LCD with weak character display
Shunt resistors are packed in - clearly the layout guy did not know what he was doing
Pretty poor accuracy, +/-30mV on a quick test
Flux on the PCB
That is about all you need to know. I expect someone to chime in and tell us what version Hobby King is carrying. We of course will be using and selling the quality version here at MethTek. They will be available just as soon as we characterize them and figure out what sort of "value added" modifications we want to do.
I did a quick test with a 4S pack.
4.15 Perfect (rounded up)
4.16 Perfect (rounded up)
4.16 Good (3mV error then rounded up)
4.07 OK (rounded down, so off by 10mV)
4.19 BAD (High by 30mV)
4.12 BAD (Low by 30mV)
That was by no means scientific - but that is all I need to see. Exactly what I expected to see from what I have read. If you have one - its fine... just understand its limitations.
Also realize that precision was not measured here (accuracy is how close it reads, precision is how constantly it reads). Both accuracy and precision are affected greatly by heat... but that is a test for another time. For the record - those (quite beautiful) results were not engineered in any way. I literally grabbed the top two units out of the box, grabbed a battery off the shelf, grabbed two DMM's, plugged in and wrote down numbers. (i.e. I did not pick a reading that would make the bad one look bad... or try to find worst case)
Here is some pRoN for you
MethTek at your service.... buying crappy stuff so you don't have to