Anyone ever done this? - RC-Monster Forums

JOHNNYMAXXIMA · 11:53 PM

Are there any issues in running a 2 cell LiPo in my receiver instead of my UBEC (or receiver pack for that matter)?
Thanks.

Serum · 06.15.2006, 04:45 AM

It's 7.4-8.4 instead of 6V.. check if your receiver/servo's can handle it.

Bmr4life · 06.15.2006, 12:36 PM

Most equipment would fry with that setup.

squeeforever · 06.15.2006, 01:24 PM

Use the ubec to regulate the voltage from the lipo. I found out the other day that you can do that....

Bmr4life · 01:37 PM

Quote:

Originally Posted by squeeforever

Use the ubec to regulate the voltage from the lipo. I found out the other day that you can do that....

Why use the lipo at all then. Just continue to run the ubec off of the main packs.

OP: Are you looking to extend your runtime or make your servos move faster/stronger?

Nick · 06.15.2006, 02:01 PM

Quote:

Originally Posted by Bmr4life

Why use the lipo at all then. Just continue to run the ubec off of the main packs.

OP: Are you looking to extend your runtime or make your servos move faster/stronger?

He means use the UBEC to make the 7.4v Lipo run like a 6v. Seems a good idea to me!

Bmr4life · 02:15 PM

Quote:

Originally Posted by Nick

He means use the UBEC to make the 7.4v Lipo run like a 6v. Seems a good idea to me!

I got that from the post eariler. :rolleyes: What I don't understand is why you'd run an extra battery pack if you don't need to. Only reasons I could see wanting to run the 7.4v lipo are to gain extra runtime by having the servos run off a seperate battery pack (instead of having a ubec feed off the main pack) or are trying to get extra speed/torque by giving the servos more then 6v (which is the reason I think the OP made this thread).

The suggestion of running the ubec off the lipo could theoretically help runtime, but I doubt it would be worth the effort.

If I'm missing a reason (other than the OP's truck possibly being nitro/gas), please let me know.

JOHNNYMAXXIMA · 06.15.2006, 02:15 PM

I fried my UBEC so I was looking to use the LiPo instead because I've got it laying around. I'm using the stock Traxxas receiver, I'm guessing it would fry that fairly quick? I drove it around allready for about 5 minutes like that, did I just get lucky?

Bmr4life · 06.15.2006, 02:22 PM

Quote:

Originally Posted by JOHNNYMAXXIMA

I fried my UBEC so I was looking to use the LiPo instead because I've got it laying around. I'm using the stock Traxxas receiver, I'm guessing it would fry that fairly quick? I drove it around allready for about 5 minutes like that, did I just get lucky?

I've used 7.2v battery packs are RX packs when I was testing equipment and didn't have a rx pack handy. But I wouldn't want to run like that for extended periods of time. I have no reason to think they'd die other than almost every servo manufacturer saying not to feed their servos over 6v. Just don't think they have a reason to lie about that.

How did your ubec die?

Batfish · 06.15.2006, 02:24 PM

I've read in several places about people who are using a 2s lipo pack as a receiver pack with no voltage regulation. I'm pretty sure there's a thread on UE's forum about it, and it's been brought up on the Nomadio forum as well. From what I've read, there doesn't seem to be a problem with it.

Just remember: it's your receiver and servos, so make sure you're aware of the risks.

There's a very good chance that the receiver can handle the voltage. Check the specs on your servo(s) and see what their operating range is. Most servos list what voltage(s) they can operate at.

squeeforever · 06.15.2006, 03:12 PM

Maybe adding a capacitor to the third channel will help?

BrianG · 06.15.2006, 04:20 PM

I don't see why it wouldn't work. Your typical 5 cell receiver pack is supposed to be 6v, but it's actually closer to 7v at a full charge. That said, isn't a Lipo over 4v per cell at full charge? That would make it over 8v total. I personally wouldn't go quite that high. Even if nothing blows right away, there may some components (mainly capacitors and ICs) that may be stressed and blow sooner. The added voltage will give servos more power and stress their driver circuits a bit more.

If anything, a capacitor will help keep the voltage up during brief relatively heavy current draws, but won't reduce the voltage at all. You could use a small linear regulator since the voltage difference is low, but there still might be a bit of heat depending how much current your servos pull.

Serum · 06.15.2006, 05:38 PM

Quote:

That said, isn't a Lipo over 4v per cell at full charge?

That's what i said..

Yeh, 8V and up..