Anyone know which is the best battery to use for a provari. I run the prover at 5. to 6.0 and use either a 2.5 or 3.0 dul cart with a tank. The batteries I use are the Provari power 2500 may 3.7v li-ion protected 18650 and the trust fire 2400 may 3.7v li-ion. Both batteries last about two hours and then begin to loose power. Unscrewing the cap and screwing it back on helps for a while but not long. I have only been using the batteries for two months. ANy suggestions?