Discussion Going FBL Crazy

[CSpaced]

Sorry, I misread, two 5S will give you 37v

When you plug the first 5S lipo in, you get your telemetry reading at 19.5, but when you plug the second battery in, with the way it is wired are you not doubling the voltage?

[CSpaced]

I'm a little fuzzy on the battery connection so I checked with a buddy and he confirms what you said about the voltage to the SPC. So, assuming that the receiver is functioning correctly (I would plug an SPC plug back in and check it with a servo or something) could it be an issue with the way the power is coming on to the skookum unit?

[Dpelletier]

Originally Posted by CSpaced

I'm a little fuzzy on the battery connection so I checked with a buddy and he confirms what you said about the voltage to the SPC. So, assuming that the receiver is functioning correctly (I would plug an SPC plug back in and check it with a servo or something) could it be an issue with the way the power is coming on to the skookum unit?

Using my other (spare) optima 7 and being careful to plug the spc first, everything works as advertised, telemetry on A9 shows 19.5 volts(voltage of one 5S).

If I place the jumper in the spc port, then telemetry shows, 8.3volts(voltage supplied by the BEC).

So everything works fine, but I'm afraid that if I inadvertently plug in the wrong 5S first (not the one supplying the SPC) that I will blow the receiver. If it is a risk, I may just leave the jumper in and not have flight pack telemetry.

[CSpaced]

Looking at your photo, if you plug in one battery first into the plug that doesn't have the SPC wire on it, it shouldn't do anything because the circuit is still open? It won't power up until you plug in the second battery.

[Dpelletier]

Originally Posted by CSpaced

Looking at your photo, if you plug in one battery first into the plug that doesn't have the SPC wire on it, it shouldn't do anything because the circuit is still open? It won't power up until you plug in the second battery.

You're right, so in theory that would be just like the set-up you have and I have on my Beam, in other words, it should be a simultaneous power up of the spc and the servo rail.

Maybe the weakness is due to the higher voltages I'm running, 8.3 on one side and up to 21volts on the other.

[CSpaced]

I think 8.3 is the max you can use for the servos, I wonder how close the tolerances are on the max voltage you can run? The 21 volts to the SPC shouldn't be an issue at all.

[Dpelletier]

Originally Posted by CSpaced

I think 8.3 is the max you can use for the servos, I wonder how close the tolerances are on the max voltage you can run? The 21 volts to the SPC shouldn't be an issue at all.

from AT on RCGroups...
Always power up the SPC port before the servo rail - this as unless SPC plug is in place or a signal from powered & booted up receiver side, there is no controlling servo signal until receiver has booted up and some servo may jitter causing damage to self or connected item.
8.3v is very high for the servo bus, leaves no margin of error.