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Power regulation on 24V system

I need some ideas for deriving power for the electronics and servos on Yard Gnome. YD has a single large 24V motor that is powered by two 12V batteries in series.

Ideas:

  1. Power the electronics and servos from a separate LIPO or other battery; (Disadvantage: extra batteries, more weight, separate charging, etc.)
  2. Use power regulation from one of the two 12V batteries; (Disadvantage: existing charging system for 24V may not like unequally discharaged batteries, unequal long-term wear on the two batteries)
  3. User power regulation from the existing 24V rail; (Disadvantage: Need to step down from 24V to 5-6V with resulting power loss)
  4. Use the power from the existing on-board controller (originally from a mobility chair); (Disadvantage: I don't know how much current it can supply and might overdraw on it; Danger of damaging the controller, which I cannot easily replace)

Any thoughts on the best way? Othe ideas?

I do have one other idea, which is to connect the two 12V batteries in parallel, keeping them isolated via large power diodes so that I'm not shorting the mid-point between the batteries with ground. I have no idea if this would work. The advantage would be that I get even power draw from the batteries as in idea 3 above while only having to step down from 12V as in idea 2 above.

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Go with a DC-DC converter. You won't be wasting nearly as much power as a regulator, won't have to worry about unevenly discharging the batteries, and it is adjustable. Look for step down DC-DC converters.

You could also use a 5VDC regulator, but you would need a decent heat sink to help dissipate the extra heat.

I didn't think of a DC-DC step down converter. Thanks rik and Krumlink!

I'm looking at this one:

http://www.current-logic.com/shop/index.php?main_page=product_info&cPath=5&products_id=15

It is weatherproof and steps down from 12V or 24V to 5V at 5A.

Input Rage: 10 - 30VDC
Output: 5 VDC
Output Current: 5A
Size: 66*58*23(mm)