UBEC major voltage fluctuations

[mgoza]

I just wanted to share some info with you guys. I recently got a FDR to check volts, amps, etc. while in flight. I also set it up to check Rx voltage. I've been using a UBEC for years without problems, but I don't think I will any more...

I logged some flights (4) and noticed that the Rx voltage was all over the place going as low as 4.22V! It seemed to be related to pack draw. Every time I pulled major amps, the UBEC dropped voltage. As a test, I then hooked up a FP800 2s1p pack and Duralite 5.3 regulator (flew 2). The graph DRAMATICALLY shows the result! The seperate RX pack and regulator gave consistent voltage. The gyro behaved better too. Just thought everyone might like to know what I found.

[OICU812]

Wow, never heard of that much drop off. Did you try another UBEC? If your avg is 37 volts in flight for example on main packs and your regulated is 5-6Volts out, how can your supply drop off enough to see that sag??, sounds like a faulty UBEC or something.... :dontknow

[mgoza]

I have not tried my other UBEC, but I was VERY surprised at the output of this one. It seems to be all over the place. I will probably try the other one just to be sure. Like I said, I haven't had any trouble out of UBEC in the past 2 years. Maybe I just got lucky and caught it before it died. Either way the FDR just paid for itself!

[skippy]

I think you defiantly have a problem with it. Here's a log of my Trex-600 and for the most part voltage only varies about .2v.

[Rickster]

I realy like the UBEC's on 3S and 4S but when you get up to the 8S and 10S I just do not trust them.. Haveing to scrubb off that mcuh voltage seems to make them very inconsistent on output and they also are more prone to failure when armedat that high of voltage...

I am really liking the Align seperate bec and 2S setup with the LED's and switch...Looks like a pretty relaible setup so far and should be a fairly inexpensive one as well...

Rick

[WillJames]

If you decide to go with the RX pack and Duralite Regulators all the time Mike, I have some RX packs coming in you might be interested in, they will hopefully be here today or tomorrow due to snow delay. Also I have some custom 3s1p 1500 packs made just for powering the UBEC. Jon Jennings had me make them up and said his UBEC's work best on them. (For the record - Mike is a fully sponsored FP Pilot and competitor)

I found the Align BEC setup to momentarily cut out at times using 9252's and 611. I went to a FP 1800 RX Li-Po and Duralite Regulator and no more cutouts.

[skippy]

Hi Rick,

I'm with Will on the Align regulator, cuts out and gets way to hot. Keep in mind the Align is not a BEC, it's a regulator.

[Rickster]

So it is a regulator style BEC like CC use in their smaller ESC's.. Interesting.. Either way I am staying with my 1500Mah Nicad pack. I can get 4 7Minute flights out of it then I throw it on my Triton. Time it is done I have a fresh 4600 LiPo pack ready and can start the cycle over again...

Rick

[PDC]

I have experienced problems with the UBEC on 10S, but not with 8S. If it is due to voltage fluctuations or radio noise I don´t know....maybe a tiny receiver akku mounted as a buffer between the UBEC output and the receiver could solve any fluctuation problem?

[OICU812]

What kind of problems Paul? I have ran multiple 10S setups with Koolflight UBEC and never had an issue.

[PDC]

The Futaba PCM receiver have gone to failsafe for a short period more than once and with different heli´s on 10S.....

I had a e-raptor with a 10s 4000ma thunderpower battery which I have flown for a long time with no major issues as long as I was alone, but with small glitches when there was a lot of transmitters around. The TP battery was not performing as good as the flightpower I use now.

Some few weeks ago I mounted the ubec on one of my T-REX600 with 10S and the neu 1515 2.0Y motor, fantastic power, but already on the first flight I lost control.
I have had no problems with 8S/UBEC so far.

Until now I have suspected it was radio noise, but actually I might just have had the problem described in this thread?

Would like to try a small rx NmHd battery as a buffer, alternative a double UBEC to see if that can isolate the problem.