# Laptop battery pack rebuild; what cell discharge rate?

Currently I am looking for eight new 18650 battery cells to rebuild my iBook G4 (A1055) battery pack. Because I can't find for what discharge rate the original cells are rated, I'm not sure which cells to pick. The original cells are Panasonic CGR18650CA (datasheet is for a slightly different type, I know), but in the datasheet is not specifically described what the maximum discharge rate can be. There is a mention of actual capacity vs discharge rate, the highest being 4080mA given as an example. Is there a general 'safe' rating for laptop battery pack cells?

The cell type I am planning to buy is the Samsung ICR18650-26H. This cell can have a discharge rate of 5200mA.

Here is a schematic of the cells as connected in the iBook G4 battery:

simulate this circuit – Schematic created using CircuitLab

• What is the capacity and how long does the battery last (when new). Average discharge rate is capacity / battery life. Commented Jul 24, 2016 at 20:28
• Thank you! The capacity is 61Wh @ 14.4V = 4236.1mAh or 4.2361Ah. The battery life as stated by Apple is 6 hours. That would make the discharge rate 706mA or 0.706A. This would mean the usage is well below the rating of the Samsung cell. The battery pack has some cells connected in series and others in parallel. Does this have any effect on the discharge rate per cell? Commented Jul 24, 2016 at 20:58
• No, that number is the discharge rate and you will be had pressed to find an 18650 which can't support that current. Commented Jul 24, 2016 at 22:55
• Average discharge rate has nothing to do with the peak discharge rate, which is what you are after. If you have some decent instrumentation and a bench power supply you can measure the peak current consumption, add some safety margin and start from there. 0.7A for a 4Ah battery is ridiculously low, a modern 4Ah battery can easily provide 10A. Commented Jul 24, 2016 at 23:21
• How many cells total are there? Since it is 14.4V, that means the series voltage is equivalent to 4 cells in series. I am guessing the number is a multiple of 4. Maybe 8? So it is 4 series, 2 parallel (4s2p). Is that correct? Commented Jul 25, 2016 at 2:22