allows the battery to hold its charge longer when not in use.
The battery is charged in this design only when the reed switch
is on (i.e. no magnet present).
You will get noticeably more power delivered to the motors, but
battery drain will occur more rapidly. Because the DC-DC con-
verter accepts a wide range for input, and regulates the output,
the voltage delivered will remain relatively constant whether
powered from the rails, or from the battery directly throughout
its 3-4.2-volt range. It’s quite something to see the locomotive
go over dirty track, switch frogs, and uneven rails without miss-
ing a beat. Take a look at all the models in operation:
Even though this version provides more power, I am not happy
with it. The battery manager used here allows a very high
charging current, only limited by the 5-volt switching regula-
tor’s current limit. Fast recharging in these models is not nec-
essary. As such, this still performs within the limits of the LiPo
battery specification. A better design would have used a spe-
cial charging circuit specifically for LiPo batteries, rather than
the 4.4-volt circuit. Moreover, to my thinking, the slow speed
of the locomotive at 5 volts is a benefit, not a weakness. In my
own modeling, I have more confidence in the previous design,
and will prefer its use.
32. Controller comparison: Moteino (left) & ProMini.
32
