Hi
I’d like to give a second life to my Mag-Lite Mag Charger - old one with 11w halogen and Ni-Cd / Ni-Mh battery. My idea is to put 2x32700 LiFePO4 batteries in series + protective PCB for 6,4v LFP. I know LFP batteries should be charged with CC/CV protocol, but can they be safely charged with factory Maglite DC charger? I don’t really care about longevity of this setup - even 10 cycles will be plenty enough 
Charger output is just 360mA, 32700 has about 6200mAh capacity - that’s below 0.1C.
As far as I can remember mag charger has battery pack consist of serial 5 NiCD cells so it will charge it to about 7.5 volts on full state.
For 2 LifePO4 charging is max 2 x 3.65 volts and they can tolerate a slightly higher voltage for short time.
But with that small current I think that charging will last about 24 hours and critical voltage wouldn’t be go over limits of cell if you stop charging with time limit for example - 20 hours.
With good PCB I think that there wouldn’t be problems and it will last much more than 10 cycles 
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Yes, there are 5xNi-Cd or newer 5xNi-Mh. I measured the voltage at Mag’s charging pins when in charging cradle - reads just over 8,0v (8,1v if I remember correctly) - should be enough to fully charge 2xLFP in series at it’s 7,3v 
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