Rebuilding a "smart" battery pack with higher capacity cells

[japlytic]

Many laptop batteries have a microcontroller connected to the SMBus (therefore being a "smart" battery), which is an industry standard interface.
Placing 3Ah cells in a 2.2Ah "smart" battery would only result in getting 2.2Ah out of the 3Ah cells, because the battery microcontroller connected to the SMBus needs to be reprogrammed (if you can do it - a rarity) to fully charge 3Ah cells.
I learned this the easy way by reading the Smart Battery Data specification.
Most (if not all) higher capacity non-OEM batteries will still be able to be charged to their rated capacity is because the capacity of the battery microcontroller can be programmed (rarely, if ever by the user) from 0 to 65,535 mAh (a very long way to go before the SMBus specification needs a major revision!) and the charge rate (and various other parameters) are also programmable (again, rarely, if ever by the user) to suit the particular AC adaptor.

[b700029]

Re: Rebuilding a "smart" battery pack with higher capacity cells

From my experience, battery controllers for lion cells are mostly adaptive, and the only important programmable setting is charge current (putting 3Ah cells in a 2.2Ah pack will just result in them charging slower than they could be, but it's not a big problem). Capacity is automatically calculated by integrating cv until the battery is full. The "design capacity" is not exact, as real cells will, due to statistical reasons, vary in their actual capacity even if never used. Usually 1 full charge + discharge cycle is enough to get the controller to recognize and calibrate to the new capacity.

[japlytic]

Re: Rebuilding a "smart" battery pack with higher capacity cells

It is a bit hard to tell if the battery controller (on the battery) is adaptive.

[kc8adu]

Re: Rebuilding a "smart" battery pack with higher capacity cells

if the pack is useless open it up and google the bmc.most reset and thus "forget" about the old cells when disconnected.