It is best not to power directly, because a 1W lamp bead can provide power as long as it has 2.5V if two lithium batteries are connected in series, if not There is no low voltage protection, if the battery is. If it is not charged in time after being used for a period of time, the battery will be over-discharged. This is a troublesome aspect of lithium batteries
Approximately 5.3 hours.
The calculation is as follows:
The charging and discharging efficiency of the battery is approximately η1=0.85 (the efficiency of new batteries is higher than 0.85 and the efficiency of old batteries is less than 0.85, take the average value)
The efficiency of the constant current driver board of the lamp bead is about eta2 =0.85,
The power of the battery is Ep=V* C=3.7*2*1=7.4 (Wh), (C is the capacity of the battery, C= 2000mAh=2Ah)
The electrical energy obtained by the lamp bead is EL=Ep*η1*η2= Pt (P is the power of the lamp bead, t is the lighting time of the lamp bead)
The solution is t=Ep*η1 *η2/P=7.4*0.85*0.85/1=5.3(h).
The calculation above is unreliable and does not take efficiency into account. Can the equation t=V*I*t/P be solved for t? The original poster actually accepted it!