Are there batteries of the same standard type (type 18650) as the one supplied but of other brands? I tried with a Nitecore 18650 3500mAh NL1835r: impossible to insert. The part of the battery that corresponds to the negative pole is slightly narrower than the rest of the battery. This corresponds to the case in which the battery is housed but does not allow the use of standard batteries of the same type from other brands. What about it?