Why do
batteries seem to get hotter when you charge them with more current? Is there no limit?
Any idea why that battery exploded when plugged into the iPad charger?
ANY
batteries will get hot if charged at higher than the max charging current designated in their specifications. There are limits, each different depending on the application.
For a 18650 mod type battery the charger itself controls the maximum amperage used to charge, the better chargers can be adjusted for your desired maximum amps.
Specs from a popular 18650 battery....
Minimum charging current: 0.6A (600mA)
Rapid Charging current: 1.35A (1350mA)
These minimums and maximum are controlled by the charger.
For an eGo, cig-a-like, MVP, and such the control is either in the electronics of the device OR the charger is designed to only provide a properly low amperage. When you plug into a wall socket in your home, the circuit is capable of providing 15 - 20 amps normally. The charger used reduces the voltage and the available amperage for a
particular specified battery. Some rechargeable mods can have electronics that control the voltage and amperage available to charge the actual battery contained within, depends on the model and manufacturer.
The battery plugged into the iPad charger was relying on the charger to limit the amperage, the iPad charger was relying on the battery to be able to handle the amperage it was providing. It's like two children pointing fingers at each other going "it's their fault"
The problem using a mix and match charger - battery combination is knowing which is responsible for the regulation, and if the battery is capable of accepting the maximum amperage the charger is "regulating" to.
Batteries are greedy, they will take all the available charging current even if they can't handle it.
Hopefully that at least as "clear as mud".....
