Nov 23, 2010

Final remarks

Although I have managed to get the battery working, it will not be used. The work was performed for test purposes. I was just curious to understand what was wrong.

Somebody is going to say that two hours of work is too much and I could earn money to buy original battery in that time. And that somebody would be right.

Now as this blog is published every person who reads it and plans to buy replacement battery knows what is inside battery. Your replacement battery will or will not work. But, I have put both photos of original and replacement with comments - decision is yours what to buy.

I know I will never save money again on laptop batteries.

Crap working

The charging was performed with setup in presented in Figure1.
I have used the source with current limiter, and connected the cells via crocodile connectors.
The voltage raise was controlled and each cell was charged to 3.5V.
Each contact of power supply was resoldered with Weller machine.
After charging in laptop to nominal voltage battery is holding for about two hours of average work.
Obviously, the battery was in stock for too long and the cells discharged.

Nov 18, 2010

Force crap to work

Let's see if there are more issues.
Following steps will be:
  1. Charge cell by cell each cell to less then 3.6V (Limit the current below 0.5A-1A obligatory, I will go with 10-50mA first, monitor both current and voltage during charging)
  2. Rebuild the contacts where necessary.
  3. Hope the chip is working.
Fix the battery together to test it. 

Finally results of the HP battery test

The HP battery was tested in electromagnetic laboratory.

Original HP battery (blue ellipse) and onestockusa replacement are presented in Picture 1. below.

Picture 1. Comparison of original and replacement battery.

HP original battery is manufactured in a quality way. (Although the cells are poor, that is why
I have to replace the original).

Each cell is 3.6V, and there are 3 pairs of cells connected in series, resulting with 3x3.6=10.8V voltage.

Voltage was measured on onestockusa replacement  battery with multimeter on each pair of cells.

The measured voltages on cells was:
  1. 2 V on first pair
  2. 1.2 V on second pair
  3. 0.6V on third pair
Total voltage was less than 4V, and minimum voltage for battery to work properly is about 9V.

Picture 2. Measured voltage on the first pair of cells less then 2V.

The far worse part is that contacts on the replacement battery are very poorly manufactured.
That fact can result in overheating and consequentially fireworks.

Think twice before purchasing this onestockusa crap.!!!

Nov 16, 2010

Why I've decided to start this blog

I've bought battery on ebay  for my HP laptop, and as you guess, it is not working.
What I am aware from onestockusa conditions is that I have to pay for return shipment.
What is not clear is who will pay resending of shipment?
Shipment in one direction itself is more expensive than the battery.

After several mails sent to onestockusa with no answer I realized that the dead end is reached.
I have decided not to send the battery back. It is too expensive and there is no guarantee that I will get the replacement battery that works.
Onestockusa did actually send email trying to buy positive feedback for US$3.
We would like to thank you for purchasing an item from us on eBay. We would
appreciate if you leave us a positive feedback with 5 stars rating.  If you
feel any part of your experience with us was less than five stars, please
contact us and we will do our best to satisfy you.  As a limited time offer,
we are offering $3.00 CASH BACK to our customers who leave a positive feedback
with 5 star rating on all categories.

Buying votes on feedback - not with me.
The battery will be instead opened and tested part by part in our university labs.
Results and report with methods and pictures will be published in this blog.