nuckolls.bob(at)aeroelect Guest
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Posted: Sun Dec 13, 2009 10:48 am Post subject: Center-tapped batteries . . . |
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At 12:06 PM 12/13/2009, you wrote:
Quote: | I'm planning a center-tap system to supply intermittent 12V loads
such as a trim motor and hydraulic pump for raising my gear on my
Velocity. Due to the high load imposed by the hydraulic pump, using
a voltage converter was prohibitively expensive (I looked at
swapping out the hydraulic pump for a 24V model, but the control
electronics are all set up for 12V as well).
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Rethink this decision. What's in the control electronics?
If it's nothing more than relays and contactors, those are
easy to change too.
Quote: | My understanding is that by using a reasonably inexpensive
battery equalizer, the negative effects of center-tapping can be
mitigated. Because the hydraulic pump only operates twice per
flight, I can get away with a reasonably low amperage equalizer (I
think I got 2 or 5 amp capacity). Any thoughts on these equalizers out there?
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If your equalizer is a 5A device, then it cannot
"equalize" effects on a series pair of batteries
wherein the bottom battery is sourcing 40+ amps
of pump loads simultaneously with the top battery
getting a 40+ amp overcharge event.
Running your 100 mA trim actuators from a tapped
battery is no big deal. But much more than that
directly affects battery service life.
If you must center tap two batteries as proposed,
I swap upper an lower batteries every dozen flights
or so. I'd also cap and load-check the batteries
more aggressively.
Bob . . .
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