Why does SB-900 indicate low battery when using a set of new lithium batteries and with the thermal cut-off function turn off?

Why does SB-900 indicate low battery when using a set of new lithium batteries and with the thermal cut-off function turn off?

Some Lithium batteries are equipped with an internal safety mechanism which controls output voltage when the battery temperature rises. When the temperature reaches a certain level, the SB-900 determines that the battery power is low. The low battery power indicator is displayed in the rear LCD panel, and the SB-900 stops working.

To solve this problem, when taking pictures consecutively using lithium batteries, leave the SB-900 unit to cool after several shots. The use of Ni-MH batteries or battery pack SD-9 is recommended when using the SB-900 to capture images consecutively.