I just stared a thread asking about doing the exact opposite. I wanted to try the 510 LR attys. Maybe the 401 batts run to low?
Joe
Not recommended. Will shorten lifespan of your battery.
However, i do use my 401 atty with eGo battery and i like it so much, that i use it more that 510 atty! This setup keeps full flavor of 401, has an advantage of slightly higher voltage of eGo, longer cutoff time (10sec IIRC) for nice loooong drags, and removes worst 401 design flaw: leakage through airhole into battery. In fact, it still sometimes leaks, but the liquid comes out through adapter holes, and if leaks through adapter down to the battery, no big deal, its sealed. eGo battery w/ adapter is a big improvement for my 401
Don´t get me wrong, i still like that 510 atty too, but it´s LR so i keep it moist (read: flooded) so it´s more hassle than 401 atty yet.