Originally Posted by JackJ
NiMH do have a lower nominal voltage than alkalines, but like lithium cells they maintain voltage much better over time and under load......
This is what I've noticed using NiMH rechargeables in my headlights. When the light gets noticably dimmer, in the time it takes me to pull over, stop, and dig my spare headlight out, the first one is completely dead. It happens that fast.
Which is one reason I run multiple headlights and taillights.
However, I've never had this happen with a taillight, since all the ones I have are LED and the batteries last much longer than the monthly recharge cycle they get.