They only had about 4 or 5 cycles on them, but it usually got drained until it doesnt light up anymore, I never noticed any dimming, it just stops working after about 20 minutes and they recharged and work again fine for several more cycles, until now. The lamp works with 4 primary cells. Both the 17670s will work in my L4. I dont have any way of testing them other than putting them in the DSD charger, I've done them separately and they should both be fully charged. Theyre both protected, one of them is from several months ago, and AW just replaced one of the two for me thinking that would fix the problem. One battery must be a little different than the other in some way, thats got to be the reason they wont work together?