Powering Arduino from Lipo batt

Hey Guys,

I’m planning on building a project using a 7.4V Lipo to control a few motors, and I’d like to power my Arduino Uno with it as well. I know 7.4 V is acceptable for the Uno, but I’m a little worried about the potential for current spikes, especially when the motors start up.

Any advice?

You can use a current-limiting resistor from the positive end of the battery and connect it on to the Vin pin and complete the circuit attaching it to ground. Btw, how big spikes are you talking about?

A simple current-limiting resistor in series with the battery will not help much and may actually make the problem worse in the case of negative going spikes. Those occur every time a motor starts up.

However, a diode followed by a capacitor is commonly used, and is especially helpful in the case of negative-going spikes. For a severe case of positive going spikes, an additional RC filter (100 Ohm/100 uF) can be added, after the capacitor.

diode_isolator.png

diode_isolator.png

C1 (47uF) is already on the Uno board, and so is D1 (between DC socket and V-in).

Just connect battery to the motors and the DC socket.
Leo…

Ikram101: You can use a current-limiting resistor from the positive end of the battery and connect it on to the Vin pin and complete the circuit attaching it to ground. Btw, how big spikes are you talking about?

There are three motors wired up to the system, so about 85 amps total, with 55 amps on one path. The arduino would be in parallel, but it still worries me.

What size resistor would you recommend?