The mod itself may have it's own amp limit in order to protect the chip and this amp limit is calculated based on ohm's law.
So if the resistance is too low and the wattage is too high it will reach this limit the mod would lower the wattage to accommodate.
At the same time the amp draw on the battery itself would be different and is calculated as follows:
(Wattage/current battery voltage/number of batteries)/mod efficiency %
So for example running a 2 battery mod at 200W with a 0.5 coil with batteries at 3.2V with 90% efficiency would mean:
20A at the chip and 34A at the batteries.