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Does anyone know what the minimum battery level is for correct operation in volts. For example should a FRsky faast operate at 4.91v? Would a genuine Futaba work at the same level?What is fully charged value?At what voltage do you recharge.What happened on a 'dead' battery? Does it register a voltage at all or is the current supplying value limited. Is this determinable by the voltage?Thanks.
The reason i ask is i had a battery yesterday that died on me. I lost complete control. No response from surfaces. Anyway i checked the voltage and it registered 4.91V, which is one above caution on my led checker. Anyway i stuck in on charge and it still registers 4.91V.
If it was the low volatage though your throttle would have dropped well before loosing control.I remember setting up my cap with an old battery - the servos has so little power they were very slow - but the RX was still powered on.I did a low power test on the TX as the time and it still responded well beyond the recomended distance.The throttle cutoff was working well stillChris
Futaba have a low battery warning failsafe. The throttle goes to low, you then resett it by closing the throttle on the Tx, you can then reopen it and get another 30sec, before it closes again. Tom
It is on PCM 35- is it the same with 2.4?
...low volts is the same as switching it off
I can't think of any 2.4 rx which has a throttle cut off on low volts
As others have said, Futabas do, they give low rx volts warning by closing the throttle, but the value at which this happens is so low, you really shouldnt ever experience it CheersPhil
Sorry, have to disagree there. Digital & microprocessor circuitry doesnt switch off cleanly when the voltage is reduced slowly, as an example, pic chips have a brownout detect option which will reset the chip and a brownout detect flag which you can monitor in software. At the point of brownout, ie the point at which the absolute minimum working voltage is crossed, spurious events can happen such as eeprom corruption, clock cycle skips or bursts, RAM corruption, etc. Without a complete reset (reboot), voltage recovery from the point of brownout can leave the processor in an unpredictable state. This situation is typical of many digital systems. Low volts isn't the same as switching it off ;)As others have said, Futabas do, they give low rx volts warning by closing the throttle, but the value at which this happens is so low, you really shouldnt ever experience it CheersPhil
I was flying my 1/4 scale pup and the throttle went to idle. Scratching my head, I put the throttle down, and back up. It came back on. did it again. and again. Bit like that Really Useless Machine. I finally landed it, wondering what was up, and found the battery flat. I had been upping and downing that throttle for five minutes! It then dawned on me what had happened....
You sound like you're not convinced Bob, but yes really, the "Futaba battery failsafe" and the brief outline of how brownout affects digital circuitry are both fact.That is exactly how it is supposed to work Bob. Your receiver was warning you that the battery was low enough to engage 'throttle failsafe'. This voltage is a safe margin above the brownout voltage, although in any case with falling voltage a Futaba FASST rx will typically maintain the link long after your servos have stopped. This is easily proven with a variable psu and a scope monitoring the rx outputs If you do get a battery failsafe you're supposed to get it down ASAP though! CheersPhil
but it would have been nice for Futaba to tell us about it)
(but it would have been nice for Futaba to tell us about it)
Well they do in the 6EX manual. Page 30 "Battery Failsafe" The trip voltage is 3.8v.
I dont think they did back then (or maybe I didnt bother reading it!) It was a FF8, which had just come out- that dates it!
They did: Page 29 of manual Tom
FF7 had the feature as well.
It did, but you had to set the throttle on low on the Tx for it to work. Tom
Ok I see what you mean and realise that prolly a better way to measure life one I get my car battery charger working in the house with a suitable supply. What would be a good point until then? Stick at 5v. I know some are going down to 4.5 with telemetry.
With Telemetry they are measuring the voltage under load and have probably set the alarm at that level, it probably goes off when they have the Rx battery under load. I know a few years back I fitted a battery checker in a plane with a 4 servo wing and on a 2200 mah 4 cell AA Nimh Rx it would drop deep into the red when twiddling the sticks when the battery was fresh off charge, with a 1400 mah 4 cell Sub C cell pack it hardly moved off green.
I can measure my battery under load on the ground. Stick in the capacity checker and twiddle the sticks.