Are they LiFePO4 or voltage bucked protected LiCo cells? Tenergy offers both. The 750mAH cells are not protected, but are safe chemistry (LiFePO4) with a true capacity of ~400mAH. They should be pretty safe for use in an
ecig if properly cared for. The 900mAH rated "protected" cells (true capacity closer to 600mAH) are actually probably less safe in this application because an ecig will discharge them faster than the chemistry is really designed to handle.
Eric
