Originally Posted by
John_M_
Paul, just curious what servos are you using, they must be using HV servos... I would run A123's on the servo buss, but the servos I'm running are rated for 6 volts and I wouldn't push them at 6.6 volts... I won't use a regulator, so I'm stuck with NiMh. ...
John, I originally had the same concern. After some research, and what Baracuda points out, I am very comfortable using A123 packs on servos that have a 6 volt rating. I think it is safe to say that everyone using A123-based packs are using them with servos that have a 6 volt rating. If they were using HV servos they would be using 2-cell Lipos to take advantage spending the extra money.
In the end, especially since we are only talking about a fraction of a volt, AND we are typically driving servos at only a fraction of their rated output, even flying 3D, IMO and for many others, the issue is negligible. The slightly higher voltage will result in faster servo motion thereby consuming more power (producing more heat and wear) than with a lower voltage supplied to the servo. Splitting hairs, we can assume that this will cause some slight reduction in servo life (too many variables to quantify).
However, some people will include a forward biased diode on one power lead which results in a 0.6-0.7 volt drop. They are very cheap and very reliable.
Just to throw it out there, slightly off topic, additional advantages include the very high charge rates you can use on these batteries (10 amps on the most popular cells), safety, and very low self-discharge rates.
Paul