Reciever pack with SV27 motor and SC?

[RandyatBBY]

I am running SV27 motor and SC in my OM26. I have been running with out a reciever pack but I was wondering is any one uses one?

[properchopper]

re :

I'm running the SV 27 SC & motor in the TS-2 using the built-in BEC & a LipoSaver. So far no issues with a Neu 30/60 4S 4100. Like to hear other opinions as well.

[Joe Friars]

I am curious too. I am asking around on ther threads. You put the idea in my head Randy!
Joe

[RandyatBBY]

Hi Joe I was hoping that I would get a better responce hear I will ask on RR. I did ask a question on RR about Black Jack motor and SC had a answer in 4 hours.

[Doby]

Well, then perhaps RR is where you should stay
Why would you want to use one when you don't have to?

[RandyatBBY]

Well, then perhaps RR is where you should stay
Why would you want to use one when you don't have to?

::

Well I said I had hoped, I had thought that there was more people on this board that use the SV motors and I could get a answer faster. I care more about the boats and people than politics and that is why I came hear.

[Bill-SOCAL]

Well, then perhaps RR is where you should stay
Why would you want to use one when you don't have to?

While I agree that I see no reason to use a separate RX pack on the SV set up, I am at a loss to understand your snide remark to Randy. What's the issue??

[RandyatBBY]

Bill Hi
It it has been the norm for a long while to run a reciever pack in a race boat. It is a lack of voltage at the reciever and something has to give in a turn. Uasally it is the motor on a large course ( that causes glitching).

[Bill-SOCAL]

I understand taht Randy, but with the SV you will not have that issue. All my larger boats (in fact, ALL my boats except the SV and TS2) have separate RX packs. Withe SV it is just not at all likely that you can draw the batteries down to the point where the BEC is not supplying enough voltage for the one servo and the RX. It is set for 5 volts and will supply that until the main pack voltage drops below 5 volts, then it will pass the voltage.

So if you get your 4S set up to less than 5 volts even under load, then you may have an issue. But with an SV set up I just don't see how that would be possible.

Oh, and one other thing, if you are getting glitches I can say that it is not the result of battery voltage. The RX voltage would have to be below 3.8 volts before that would even be noticed. Futaba for instance has used 3.8 volts as their battery failsafe setting for years. If your system crops below that on a PCM system it will drop the throttle to warn you. The new FASST systems have been shown to keep operating down to 3 volts or less, a point at which the servo will start to move very slowly.

[SweetAccord]

Bill Hi
It it has been the norm for a long while to run a reciever pack in a race boat. It is a lack of voltage at the reciever and something has to give in a turn. Uasally it is the motor on a large course ( that causes glitching).

Why use a separate RX battery?

An radio system consists of an ESC that powers everything off the main battery that runs the motor and everything else including the RX/servos (for steering) etc. Since a separate battery for the radio control receiver also may be used, it can be connected to a separate battery to power it and the devices connected to it, ie a servo. Most ESC have a low voltage cut out (BEC) meaning your motor will shut down but you will still have power to the RX and servos since the RX has it's own power. Often a disadvantage of this method is that the receiver battery may be low or dead not allowing for any throttle or control or servo response.

Since most ESC's have a battery eliminator circuit (BEC) which eliminates the need for these separate radio control receiver batteries, hence powering the RX and servo from the main battery is a typical easy setup these days. This has the advantage of removing one extra battery from the system, but has the potential to reduce or even degrade the effectiveness of the radio control system-depending on the issue and the system and other factors may be needed.

So what the reason to use a separate RX battery? Well that depends on the stability of the BEC and how well it may stabilize the voltage to the RX and servos which may be affected by other factors (RFI/battery voltage, etc). When a separate battery is utilized, you will eliminate the possibility of RFI as the RX and servo have their own power supply and are not dependent on the quality or the capability of the BEC or the main battery.

In the absence of any worldly noise, the BEC circuit ideally should provide a perfect, steady voltage to drive the radio control receiver and some are going to do a better job of this than others. What may happen is if the receiver pulls a little more current, or the BEC has hard time compensating for voltage spikes etc, the voltage will momentarily drop or increase and the BEC regulator should/will compensate for that and maintain the voltage at the required level if it's a decent BEC. While some are not, causing the dreaded "glitching", radio loss or range issues.

So when people incur different issues with the radio system, one method is to disconnect the power circuitry from the ESC and power the RX separately to eliminate all this noise from the receiver and electronics circuitry which is susceptible to the noise. In other words, not using the BEC within the ESC. This is one way to eliminate any other factors of common radio problems.

Also as Bill-SOCAL stated, "Withe SV it is just not at all likely that you can draw the batteries down to the point where the BEC is not supplying enough voltage for the one servo and the RX. It is set for 5 volts and will supply that until the main pack voltage drops below 5 volts, then it will pass the voltage." This is also correct.

Hope that helps.

[SweetAccord]

Oh and I forgot to mention that a separate receiver pack allows for a slightly faster servo response and holding strength . . . . .

[properchopper]

re :

One thing that hasn't been mentioned yet relates to ESC heat management. Since the internal BEC circuit in a SC has to convert input voltage [ usually 14 + volts] to 4.8 - 6.0 volts, and " energy can neither created or destroyed " the bleed-off voltage in the BEC during this conversion can contribute to excessive heat buildup in the BEC and the SC as a whole. The rigors of racing [ or fun running] can push ESC temp's up to the magic smoke level, so disabling the internal BEC might well provide an extra thermal safety factor. My experience with the SV system has shown that the SC doesn't get too hot with the internal BEC, but I'm experimenting with the Ammo motor & found more SC heat buildup running this motor. I've disabled the BEC with this setup & run a CC BEC, as I've done with all my other boats using Hydra 240's to be on the safe{er} side.

[SweetAccord]

Thank for your input properchopper, I agree with you 1000%.