You may have damaged your battery's protection circuits and after that it may start not holding charge as well or may even be dangerous to charge. The dual coil should never have been put on a slim battery. Slim batteries should be using things that are 2.5 to 3 ohms single coils (a 2.5 ohm dual coil won't work either because it's 2 5 ohm coils and works on high voltage mods.)
In general, anything under 2.5 ohms belongs on a fat battery model or mods. And even the mass manufactured fat battery models (Ego etc) are occasionally damaged by 1.5ohms. Some people will only go that low on mods.
If you want something with a big battery and 901 connection (901 connection with work with KR808D-1 cartos only IF the socket provides appropriate airflow for KR808D-1. In general I think the threaded end of the battery to have a slotted post to let air in?). You are also used to using 3.7v so you probably don't want a 3.4v big battery. Ones you can research (as to how well they work with KR808D-1 cartos and what their real voltage is) are the Kanger Vgo version that is KR808D-1 threaded (there is also a 510-threaded version), Igo, the Riva 901's at Liberty-Flights.com (I believe they have a slotted post but don't know if they are 3.7v), the CigEasy Elegant Easy. And any of these would need that own charger which will put of more mA and is not to be used to charge slim KR8 batteries.
Read about the KR808D-1 threaded Vgo version here
http://www.e-cigarette-forum.com/fo...ger-vgo-650-kit-kr808-little-fat-battery.html
Alternately you can get a more flexible 510-threaded 3.7v model like the Riva 510 kits at Liberty-Flights.com (their kits are 3.7v because they are new stock from the one Riva manufacturer who now makes the 3.7v ones). The Kgos may also me 3.7v. Or get a 3.7v mod. You can use a 510 to 808 adapter to put KR808D-1 cartos on them and can also use 510-threaded stuff on them. With Riva or Kgo or small battery mods, 1.5 ohms may still be pushing the edge a bit. Some recommend large battery mods (like ones that use 18350 or 18650) for 1.5 ohm vaping.