With the continued development of solar street lamps, solar street lamp batteries slowly changed from lead-acid batteries to lithium batteries. Therefore, many manufacturers use 20AH lithium batteries with a false capacity to impersonate 80AH to customers, access to large profits, 2014 to 2016, many manufacturers earn a lot of profit by lithium batteries a year.
12V 60Ah lithium battery, for example: the normal use of 3.7V 2Ah cells, 60Ah ÷ 2Ah × 3 = 90 section. When you learn that a 90-section cell has a 12V 60AH capacity, cutting corners requires another upgrade. Yes, the battery cells give you 90 knot cells, but quietly give you 3.7V 1AH instead. At this point the capacity is only 30AH, all of a sudden a lot of cost reduction, for dishonest businesses, this could be profit, or a nuclear weapon to seize the market.
So it is very important to know how to calculate the solar street light battery capacity, sometimes you can avoid being cheated.
How do you calculate the configuration of lithium-ion battery solar street lights?
Let’s take 40W LED light source as an example: the customer requires 8 hours of lighting per day, and 3 days for rainy days.
Let’s take the 18650 lithium ternary battery as an example.
Known conditions: the nominal voltage of a lithium-ion secondary battery is 3.7V; the system voltage of a 40W LED light source is 12V; the platform voltage of three lithium-ion batteries combined in series is 11.1V, and the standard charging voltage of the battery plate is 17.5V.
First, let’s popularize the conversion of Ah (amp-hours) to Wh (watt-hours) units.
Wh (watt-hours) and Ah (amp-hours) are both ways to measure battery capacityAH is a measure of the capacity of an electrical storage device, meaning that the product of current (amperes) and discharge time (hours) in units of capacity [AH] can be satisfied by conforming to the discharge curve (a similar inverse proportional curve).
We often see a number in Wh next to the mAh.
The work done by the battery W = UIt = voltage (V) * current (A) * time (h).
Voltage U*Current I=Power P (Watt, letter “W”)
Therefore, the work done by the battery W=P*t, the unit is Wh.
Ah = Work (W)/Voltage (U)
Daily power required by 40W LED light source = 40W*8H=320Wh
Solar street light design needs to take into account the day’s rainy weather conditions, for example, 3 days in Nanjing design.
Then 3 days 40W LED light source needs total power = 320Wh * (3 + 1) days = 1280Wh
Then lithium battery capacity = work (W) / voltage (U) = 1280Wh/11.1V = 115AH
Through the calculation of solar street lamp battery capacity, the next time we buy solar street lamps, we can better identify whether the manufacturers deceive us, so as to buy a good price, more suitable for our products.