I'm looking for my robotics project to draw its power from one of 3 rechargeable batteries; basically whichever has the most "juice" in it. From the initial research I've already done, I believe I could connect each rechargeable battery (probably LiPo) to a diode, and then wire each of the 3 diodes in series.

However, being so new to robotics/electronics, I guess I wanted to bounce this off the community as a sanity check, or to see if there is a better way of achieving this. Again, what I am looking for is a way for the circuit to automagically detect that battery #1 has more power than battery #2, and so it "decides" to draw power from #1. The instant #1 is depleted or deemed "less powerful" than #2, the #2 battery takes over. Thoughts/criticisms?


Is there a need to draw from the batteries sequentially? If you wire the batteries in parallel you drain them all at the same time, so you don't need to worry about swapping dead batteries for fresh.

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  • $\begingroup$ Hey smart thinking @Chuck (+1) - do the descriptions in that link give me what I need to actually implement this parallel solution? Any diodes/voltage regulators/etc. needed to actually build this?!? Thanks again! $\endgroup$ – smeeb Jun 12 '15 at 20:40
  • $\begingroup$ Yes - from the article, "The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner. The final voltage remains unchanged while the capacity of the bank is the sum of the capacities of the individual batteries of this connection." All (+) connections together, all (-) connections together. IMPORTANT TO NOTE you don't need any diode protection as long as you don't mix charged and discharged batteries. If you're concerned you might accidentally put a dead battery on with 2 fully charged then add diodes. $\endgroup$ – Chuck Jun 12 '15 at 20:45

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