Honestly? When you end up with a 1.5 ohm coil on these things you need to use a mechanical or a higher end VW box mod.
Forget eGo
batteries - 1.8 ohms is even pushing the limits of any eGo class battery. Below 1.8 ohms you risk frying the protection circuit, killing the battery. Low end VV/VW devices like an MVP2, VV V3, Vamo etc. will not fire anything below 1.8 ohms without the protection kicking in and either dumbing down the experience of turning the device off.