ozzieflyer

Just a quick question.

Most JR servos, and other brands are rated 4.8 to 6 v.
I have been running 5 cell packs for years. But had a bad crash (PCM went into total lockout), and now a comment from an experienced flyer, that I shouldn't use 5 cells without a regulator.

I had been told many times that 5 cells is fine, and in fact I have been using 5 cells for over 10 years.

Can we confirm what the specs really are?

To me, a regulator on top of a 5 cell pack is another link to go wrong,

Confirmation would be appreciated.

P47 Jug - Al

My Feedback: (1)

My from understanding from Danny, current JR receivers/servos run on both 4 and 5 cell packs unless otherwise stated and no regulator. I also noticed on a few items, JR has placed at least a few basic specs including a voltage range as displayed on the below receiver.

[link]http://www.horizonhobby.com/Products/Default.aspx?ProdID=JRPR610UL**[/link]

And there are many specs. beyound the basics that would "draw a better picture" as to the quality of a product. I too would like to see much more in this regard.

I am sure he will respond tomorrow with your answer.

dsnyder

There are a couple servos that are 4.8 only (retract servos, a mini servo, and for the most part any servo connected to a gyro), however the entire JR line (unless otherwise noted) is fine to use 4.8 or 6V battery systems. I personally do use regulators often as they provide constant power to the RX and make the performance of the model more consistant from flight to flight. However they are not required on 4 or 5 cell NiCd or NiMh batteries.

ozzieflyer

Thanks Danny
I feel relieved.

In what way is the model more constant from flight to flight?
Do you mean, say with a fully charged pack, the servo response is noticably quicker, than say after a couple of flights?

If that is the case, at my level, I wouldn't notice. I'm still trying to get that elusive 4 point roll that is consistant.

Aussie DOwn Under

dsnyder

Yes, what I mean is more consistant servo speed and power since the voltage remains constant, and hence the airplane flies more consistantly from flight to flight.

Piet Le Roux

Sorry to hear about your crash. If you use a regulator the battery voltage must be at least 0.7 volt higher than the voltage you need, so a 5 cell battery (1.2X5=6) can not be regulated at 6 volt. But remember the voltage for a 5 cell battery, when fully charged, will be 1.4X 5 = 7 volt, a bit too hi. I am thinking of using a small 6 cell battery (7.2 volt) with a LM7806 regulator to regulate it at 6 volt. Digital servos are too expensive and need a big battery, so I want to use 537’s on 6 volt; I had bad luck with 539 servos so I hope this setup will give me enough speed, torque and reliability.

dsnyder

Most regulators are simply bypassed when the voltage falls below the regulated voltage. Also, the higher the difference between input voltage and the regulated voltage, the more heat generated in the regulator and the higher the wasted battery capacity will be. The difference in input voltage and regulated voltage is simply dissipated in the form of heat, so that is wasted battery capacity.

Piet Le Roux

The regulator I referred to, the LM7806 is a series regulator and can not be bypassed when the voltage falls below the regulated voltage because there has to be at lease one semiconductor in series with the output and the voltage drop over a semiconductor is about 0.7 volt. I would like to learn more about regulators that can bypass it self, but I can not see how this can be done without adding hardware. This and the use of switch mode regulators is not part of the KISS principle. I would prefer that the regulator rather absorb any over voltage in the form of heat instead of the devices that are being powered. As far as the heat generated in the process: a normal system will draw on average less than 0.2 amps: 7.2 – 6 volt = 1.2 X0 .2 = 0.24 watt of heat, not enough to loose sleep over. Remember your JR receiver also uses a series 3.2 volt regulator (NJM7201-U32) and then current that is drawn at a voltage over 3.2 volts it’s also absorbed as heat, how many of these have you replaced? It comes down to that you can not eat your cake and have it, if you want a steady voltage source, it will cost some battery capacity.