13
Angle adjustment to light source
with voltage measurement:
Angle adjustment to light source,
measuring charge current:
5V
0.5mA
0.5mA
Minimum parts, measuring
charge current:
USB charging
Your rechargeable battery (
B4
) will need to be recharged often; it can be
charged with a USB connection or with solar light using any of these circuits.
The USB POWER light on
B4
comes on when it is charging through the USB.
For solar charging, place the solar cell in sunlight or about 12 inches from an
incandescent light bulb of 60W or more. It takes a few hours to charge the
battery. LED, CFL, and fluorescent lights do not work well with solar cells.
When measuring charge current, the current will often be too high to measure
on the
0.5mA
setting but too low to measure on the
50mA
setting (you can
use either). The current will get lower as the battery approaches full charge.
You can’t hurt the battery by overcharging.
Minimum parts:
Although the battery is rated as 3.6V, it may charge
to as high as 4.0V. If you are monitoring the voltage
using the meter, you may see the voltage quickly
reach 3.6V, but this does not mean that the battery
is fully charged. When the battery is discharging to
power something, the voltage is nearly steady for
a long while then drops off quickly. The same thing
occurs when it is charging. Recharging the battery will
quickly reach around 3.6V but it needs much more
charging to avoid a quick drop-off when discharging.
Recharge the battery for several hours.
PROJECT 3
• Best Charging Circuits
ASSEMBLING PIVOT STAND
Place base on
flat level surface.
Snap ball on pivot post
into pivot top.
Insert post
into base.
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