Laptop Batteries: E-Bike Blog #3
- Tim Ellsworth
- Mar 5, 2017
- 2 min read
Source
My source so far for 18650 cells has been new replacement laptop batteries. The model battery that I have been using is linked in the picture below. The types of cells that I have pulled from the batteries has been inconsistent in make and mAh rating. The cells types have been:
INR18650H 15A15
JNICR18650 3.7V 2200MAH 161125
FP 18650 2000MAH 161205
INR18650HE 2200MAH 3.7 16E28
The majority of the cells were the FP 18650 types and they have an average capacity of 2000mAh. The INR and ICR cells had a capacity slightly over 2300mAh. I don’t think that this will be an issue as long as I balance the layout and placement of the cells in the battery.
Salvaging
If I was to make another electric bicycle after this one I think that I will find a source for brand new cells. The amount of work that goes into salvaging and testing the cells one by one is extensive. There are probably ways to make this process more efficient but my goal is to make a electric bicycle not a laptop battery salvage system. Maybe a later project. The steps I needed to take to salvage a battery were:
Carefully pry the seam on the terminal side of the battery until the two halves can be opened by hand
Remove the battery
Cut the PCM leads without shorting
Cut the nickel between each cell
Cut the negative nickel strip between each 2P group (I cut the negative side to prevent shorting the nickel from the positive terminal across the negative casing)
Remove the nickel strip from each cell by pulling it gently with needle nose pliers
At this point the cells are ready for testing. I thought that the salvage process would require cutting to remove the cells but prying with a small screw driver is relatively easy and if care is put into the process the PC or cells do not get damaged. I am sure that it depends on the design of the laptop battery. I take my time removing the nickel. One of the first batteries that I salvaged I momentarily shorted the positive nickel lead across the negative casing. The nickel can easily cut through the plastic shrink wrap. I always make sure that the nickel strip or PCM leads are not touching the negative case even if there is shrink wrap on the cell. Below is a picture of the battery case after I opened it. The pry marks show the locations that I found were best for opening.
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