4 ms·
It's a safety issue to replace some, but not all of the cells in a Li-ion battery with cells that are not the same age and condition. Since smartphone batteries
by Zak 5y ago
It's a safety issue to replace some, but not all of the cells in a Li-ion battery with cells that are not the same age and condition. Since smartphone batteries are almost always a single cell, it's a non-issue.
Another scenario I can imagine is a charge controller reducing the maximum charging current as the battery ages based on information stored in the controller's memory, which would be incorrect if the cell is replaced. Of course, it would be unusual to replace a cell with one in worse condition, so it would also be surprising for that to be a safety concern.
- gambiting 5y agoKeep in mind that the check done inside an iPhone doesn't prevent the failure mode you describe. After all the phone only checks the microcontroller attached to the battery, not the actual cells(if that's even possible in any way).
- Zak 5y ago> not the actual cells(if that's even possible in any way). It isn't, but there are some controller circuits that switch off permanently if the voltage falls out of range, making changing cells more difficult.