General T-rex 800 Battery Connection.

[Tony Mitchell]

Hi all,
I recently bought a T-Rex 800E DFC Pro combo kit. Have been busy building it for the last couple of days.
The combo kit comes with the Castle Edge HV 160 ESC and in the user guide it shows wiring for connecting the two 6S lipos in series to the ESC.
This kit also uses a third battery, a 2S lipo to power the Rx.
In the user guide for the ESC, they give an example of use of an external BEC, which has to have it's ground wire commoned with that of the 6S pair.
Now, I'm not using an external BEC, just the 2S lipo to power the Rx and servos, but does the ground wire from the 2S need to be commoned with that of the 6S pair?
ESC: Castle Edge HV 160
Rx: Spectrum AR620
FBL: BeastX Plus

Any help very much appreciated.

 

[Smoggie]

No, you dont need to connect common grounds, just make a harness that takes the power from the 2S LiPo and splits into two heavy duty servo leads. These two leads connect into the FBL and/or receiver directly.. assuming you are using HV servos?

PS.. the AR 620 is not really suitable for a large heli. it's a 'sports' receiver intended for small to medium 'foamy' type planes. You really should use a receiver that has antenna diversity and support for a satellite. Also a receiver with single line SRXL output will make wiring much neater.

The ideal receiver is the Spektrum AR7700 . Unfortunately it's been discontinued but you can still find it in stock in some dealers.

Receiver choice with the Microbeat is a pain because Spektrum moved to SRXL2 on all their new receivers but BeastX havent yet implemented support for that protocol, so there are no receivers in the current Spektrum range that are ideal.

 

[Tony Mitchell]

Many thanks for that Smoggie. Looks like I'll be shopping for a new RX then. I kept the same setup on both the 470 and 500 with the AR620 and BeastX Pro.

The 450 is a flybar one, that has the Spectrum AR610 that I bought along with the DX6e transmitter when I bought the 450. I was hoping to follow the same pattern with the 800 as I have a spare AR620, but I'll take your advice.

As I said, any help is appreciated as I'm a relative newbie to helis and it's been a very long time since I originally started with RC and that was with a bungee launched Keil-Kraft glider with 27MHz radio gear.

 

[Smoggie]

Yes, the AR620 will be ok for a smaller heli but the big ones tend to fly further away, and the big solid lumps of metal and carbon can easily block signals, so it's strongly advised to have antenna diversity on the big helis.

I'll do a bit of digging and find out what Spektrum receiver people are using with the Microbeast these days and let you know (assuming you cant find the AR7700)

 

[Smoggie]

I found an AR7700 in stock: Servo Shop

Here's a video of how to set it up in single wire 'SRXL' mode:

 

[Smoggie]

Alternatively you could use the new AR8010T which has telemetry built in. But you would then need a standard multi wire connection between receiver and FBL.

either option is good

 

[Tony Mitchell]

Great. Thanks again for that. It looks like the AR8010T is going to be the one. Just need to see if it will be happily driven by my DX6e, or to go for the full DX8/AR8010T combo.
Perhaps my 500 would be better served by the AR8010T too.

 

[Smoggie]

I just found out that the AR8010T does have SRXL, so it will work on single wire. That makes it ideal

 

[fran11784]

Smoggie that is great info. The discontinued AR7700 was killing me cause Im mostly a BeastX guy...
Cheers

 

[Tony Mitchell]

Thanks again Smoggie. I ordered the AR8010T this afternoon after speaking to Trevor at Midland Helicopters. That will be with me tomorrow morning. I was tempted to go for the full 8 channel TX/RX with the Spectrum DX8/AR8010T combination, but he said that would be wasting money as my DX6e is be quite capable of driving the AR8010T, just not using all the available channels.

 

[Smoggie]

That's right, very honest of Trevor as it would have been easy to push you into spending more. The DX6 will be enough to get the heli in the air, no problem. You can always upgrade down the line if you feel the need.

 

[Tony Mitchell]

This thing is driving me nuts. The Edge ESC refuses to power up the motor. I did everything that the user guide said for the initialisation sequence, I get the 12 beeps when I connect battery power, but don't get the beep when I return the throttle stick to lowest position.
To check out the motor/radio etc, I took out the Edge ESC and put in the one from my T-Rex 500. Everything worked perfectly. So what am I missing with the Edge ESC?
I don't have the Castle link USB adaptor etc. so can't attempt any programming. Leaving it with default factory settings, surely it should just be plug and go.

 

[fran11784]

Humm, usually because the Microbeast doesn't see low throttle. Your using SRXL? You have the ESC throttle wire to Channel 5 on the Microbeast?

 

[Tony Mitchell]

I'm not using the SRXL, just the bog standard Rx/BeastX setup. I just read a report on another forum saying that Spectrum SRXL is incompatible with BeastX unless you use Studio X to update the BeastX to be able to work with the AR8010T
Edit:
Scratch that incompatibility. I just received an email from Castle Creations who pointed me to a link on the BeastX website. In their WIKI pages there is loads of info on how to set up the Microbeast Plus. The one that came with my T-Rex 800 kit has V5.0 firmware and the notes say it is compatible with the AR8010T SRXL. I've just got to get my head around the programming instructions for the beast now and hopefully see some action by tomorrow.

 

[fran11784]

ah interesting. Does it have to be updated to V5 did it say? I had a issue once where I had to use studox to do the programming after updating to V5. Still thinking its a low throttle signal its not seeing but someone else might have other ideas.

 

[Tony Mitchell]

Out of the box, it's V5. The lights on the beast indicate that the firmware is V5.1. Here's the link to the BeastX WIKI pages.... Main Page - BEASTX Wiki
I've got some serious reading to do here, plus download the latest version of the Microbeast Plus manual. Looks like I need to get me the USB interfaces for both the BeastX and the Castle Edge ESC.
The attached pic shows my current wiring.

 

[fran11784]

That looks right to me. If your new to the Beastx and you read and follow the V5 setup youl be ok. There are a few steps out of order and different then the V4 and earlier setups. Ive been using the microbeast since 2013 and the V5 was a new learning experience. The USB dongle is always a good investment for both.

 

[Smoggie]

Using a Castle with the ESC in 'heli' mode you need to do the fixed endpoint calibration routine. You really need the uSB programming link, it's not 'plug and play' by any stretch:

Note that unlike shown in the video, sometimes it wont be possible to spin the motor up until AFTER you have calibrated the end points, so my recommendation would be to do that first.

 

[Smoggie]

PS.. if you need to borrow a Castle USB link dongle let me know. The one i have is out on loan to a friend but i'm sure he would be happy to forward it on to you to use and return.

 

[Tony Mitchell]

Sorted, without having to go the SRXL route. Following the guidance in the BeastX WIKI article, the bit entitled 'Transmitter setup (endpoint adjustment). Seems that my +/- 100% on the throttle travel wasn't enough for the ESC to detect the lower endpoint. It came right down to -120 before the ESC bleeped for me. Disconnected battery, reconnected and all worked perfectly.
So your comment on the microbeast not seeing the low throttle was spot on Fran. I would never have imagined that it would need such a large offset. The BeastX article also advised giving an extra 2% at either end as a safety margin, so now my throttle runs from +102 to -122.
Thanks for all the help guys.