ORIGINAL: LSP972
ORIGINAL: rmh
We setup our expensive models with the same moderately priced radios -but pay lots of attention to rx placement and power delivery setup - NO regulators.
Got a question for you.
I'm a long-time 72 mHz user, finally getting onboard the 2.4 train with a new Futaba 12Z (purchased about a week before they discontinued the thing
).
It is my understanding that its best to use a five cell/6V receiver pack with 2.4, the better to prevent a voltage drop ''brown-out''. My problem here is that most of my servos are specifically NOT recommended for use with six volts (Futaba 9252). Yes, I know tons of folks say they do it with no issue, but I see no reason to tempt fate. My plan was to put a regulator inline between battery and receiver to drop the voltage down to 5V or so. But you seem to advise against this. Moot point so far, because I haven't been able to find a suitable regulator.
Here's my question: how much of a chance am I taking on flying with a four cell/4.8V pack? All my receiver packs are higher-capacity NiMH; 1650mAh on a Kougar, 3600mAh on an H9 27% Extra 260. These are the ''slimers'' I'm converting to 2.4; the other ones will likely be e-power, since I'm getting into that now as well with an E-Flite Pulse XT 25, with plans for other electric models.
There are some guys at my club flying lots of sport planks on 2.4 with 4.8V packs, but they crash a lot too. Still, as you alluded to, that might have more to do with their generally sloppy approach to the hobby in general.
Anyway... I'm asking you because you have always seemed to know what you're talking about (I've been on this board a bloody loooong time), and I have been unable to get a straight answer out of certain industry 'experts'.
Thanks for your time... I feel like a frigging noob all over again...[&o]
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4.8 volt servos MAY actually operated just fine on 6 volts - but that is another story.
A reliable 4.8 volt power source is the problem-
Knowing just the battery size -doesn't really help-
you need to know what the "C" rating is on the pack -
Most 4.8 setup run at about 5.1 volts in use-and this is typically the output of BEC-in the ESC used on electric power types.
NIMH batts designed for powering electric cars ar a good source for a 4 cell "4.8" pack.
NOBS Batteries and others sell these packs in various sizes and C ratings.
You can't skimp on this stuff - Futaba will fail as easily as any others- if power droops under load.
As a generalization- the short stubby cells have higher "C" capabilities
buy the largest of these your model can use and then, get a volt/amp meter which plugs into rx/battery harness and test ALL battery setups
If all is OK- the voltage your rx sees - when system is ON but no servo loadings - will be - typically 5..1 or more.
Just sit back and cycle ll th servos and watch the meter - for say - 3-4 minutes .
this isn't a speed test just keep em going .
watch for voltage drop and droop.
sudden small drops reflect a load which is higher than others. find the offender and fix it .
Droop is the voltage drop underloads being applied.
I prefer to never see a voltage droop in excess of ONE (1) volt during the test.
I think I have covered the basics -