Running dedicated accessory/servo Lipo

[RCSid]

Hi All, just wanted to ask if there is any thing special that needs to happen to run a dedicated small Lipo for cooling fans (x2 @ 8V) and Promodeler servo? Is there a real need to do so? and if so, anything special that would need to be done? I do have a bunch of small 3s Lipo's that I use to run my 1/16 E-revo.

 

[ZooKeeper]

I run a dedicated 3s battery for my cooling fans on my DBXL. The only reason I do this is because the fans are 12v. I could run the fans off the ESC BEC, but then they'd only get 6, 7, or 8 volts depending upon the ESC BEC settings. Under-volting them is no problem and has no negative impact, the fans just won't run at full speed, causing them to push less air.

Keep in mind that adding a dedicated battery also adds weight which could negatively affect the performance of your vehicle.

To run my fans, I use a 2200 mah 3s battery connected to a remote switch which is then connected to my RX (receiver). This allows me to turn the fans on and off from my TX (transmitter).

My RX also has a voltage sensor that I connect to the balance lead of the battery, which sends the overall battery voltage to my TX. On my TX, I have an alarm configured so that I'm alerted when the battery reaches LVC (low voltage cutoff) so I can swap the battery out with a fresh one. Having a way to monitor the extra battery is going to be super important, otherwise you risk trashing the battery by running it flat.

 

[RCSid]

I run a dedicated 3s battery for my cooling fans on my DBXL. The only reason I do this is because the fans are 12v. I could run the fans off the ESC BEC, but then they'd only get 6, 7, or 8 volts depending upon the ESC BEC settings. Under-volting them is no problem and has no negative impact, the fans just won't run at full speed, causing them to push less air.

Keep in mind that adding a dedicated battery also adds weight which could negatively affect the performance of your vehicle.

To run my fans, I use a 2200 mah 3s battery connected to a remote switch which is then connected to my RX (receiver). This allows me to turn the fans on and off from my TX (transmitter).

My RX also has a voltage sensor that I connect to the balance lead of the battery, which sends the overall battery voltage to my TX. On my TX, I have an alarm configured so that I'm alerted when the battery reaches LVC (low voltage cutoff) so I can swap the battery out with a fresh one. Having a way to monitor the extra battery is going to be super important, otherwise you risk trashing the battery by running it flat.

Awesome, Thanks!
Just what I was looking for.

 

[Dan B.]

Hi All, just wanted to ask if there is any thing special that needs to happen to run a dedicated small Lipo for cooling fans (x2 @ 8V) and Promodeler servo? Is there a real need to do so? and if so, anything special that would need to be done? I do have a bunch of small 3s Lipo's that I use to run my 1/16 E-revo.

It’s definitely better.

Awesome, Thanks!
Just what I was looking for.

There are a few ways to do this. ProModeler has a harness that powers the servo independently of the receiver. That’s what I use on my 1/5 buggy. If you take that route, the built in BEC in the ESC can easily handle a couple fans and lights because it’s not feeding an amp-hungry servo, so everything but the servo can plug right into the receiver. This is the easiest way to do it, IMO. Another way is to disconnect the power wire from the ESC going to receiver and power the receiver (and everything connected to it like lights, fans, servo, etc.) with a dedicated LiPo or LiIon. Just make sure the voltage you choose (2s or 3s) doesn’t over-volt any components. And as @ZooKeeper said, voltage telemetry is key in any case, especially if you’re powering the receiver independently. I will say though, even small LiIons have lasted more than one run for me, sometimes several runs. And they don’t need an LVC. I prefer to use those for independent power sources, not LiPo’s usually.

 

[RCSid]

It’s definitely better.

There are a few ways to do this. ProModeler has a harness that powers the servo independently of the receiver. That’s what I use on my 1/5 buggy. If you take that route, the built in BEC in the ESC can easily handle a couple fans and lights because it’s not feeding an amp-hungry servo, so everything but the servo can plug right into the receiver. This is the easiest way to do it, IMO. Another way is to disconnect the power wire from the ESC going to receiver and power the receiver (and everything connected to it like lights, fans, servo, etc.) with a dedicated LiPo or LiIon. Just make sure the voltage you choose (2s or 3s) doesn’t over-volt any components. And as @ZooKeeper said, voltage telemetry is key in any case, especially if you’re powering the receiver independently. I will say though, even small LiIons have lasted more than one run for me, sometimes several runs. And they don’t need an LVC. I prefer to use those for independent power sources, not LiPo’s usually.

Thanks for pointing out the alternative. I was going to do that at first, then decided to focus on using the lipos that I have. The lipos that I have are GenAce 3s 1400/60c 15.54Wh, they're very small batteries. That should be good for my Infraction, yeah?

 

[Dan B.]

Thanks for pointing out the alternative. I was going to do that at first, then decided to focus on using the lipos that I have. The lipos that I have are GenAce 3s 1400/60c 15.54Wh, they're very small batteries. That should be good for my Infraction, yeah?

Yeah, 1400 MAh should be fine for long runs. If your using a radio setup that supports telemetry the you could put a lead on your battery and see it on your radio. The RadioLinks have that, and it even comes with a plug and play jumper but it’s set up for XT60’s, so I just build my own harness.
Make sure your servo and your fans are rated for 11.1 volts! Most aren’t, and the the majority of the HV servos I’ve seen are only good for 8.4v.

 

[RCSid]

So I guess my Lipo's won't work then, as the RCP fans and Servo are 8v.

 

[Dan B.]

So I guess my Lipo's won't work then, as the RCP fans and Servo are 8v.

Well, that could have turned out badly! I actually bought 12v fans a few builds ago because I wanted to use a 3s LiPo I had. As for servos, some of the 1/5 HV servos I’ve seen got up to 3s or more, but most standard sized HV ones I’ve seen max out at 8.4. There could have been some Magic Smoke released, and once that happens it’s really difficult to get it back into the servo.

 

[RCSid]

Well, that could have turned out badly! I actually bought 12v fans a few builds ago because I wanted to use a 3s LiPo I had. As for servos, some of the 1/5 HV servos I’ve seen got up to 3s or more, but most standard sized HV ones I’ve seen max out at 8.4. There could have been some Magic Smoke released, and once that happens it’s really difficult to get it back into the servo.

Thanks again. So I have a clear plan now. Promodeler Crew probably laughing as they see my lineage of orders come through, probably have a money line when this next one was going to hit...

I have to do some reading on the RC8X, but is there a way via a harness/TX/RX to set the motor fans to come on when the motor hits a specific temperature? And the ESC fan too for that matter?

If I just read this stuff, I don't have an easy time comprehending the info. When I am forced to relate and understand it, it makes sense?.?.

 

[Dan B.]

Thanks again. So I have a clear plan now. Promodeler Crew probably laughing as they see my lineage of orders come through, probably have a money line when this next one was going to hit...

Thanks for helping put John’s kids through college. It’s working out well for his family. I think I already paid off his house

If I just read this stuff, I don't have an easy time comprehending the info. When I am forced to relate and understand it, it makes sense?.?.

Totally understandable. Some of this stuff can be really confusing and nobody is born knowing everything.

I have to do some reading on the RC8X, but is there a way via a harness/TX/RX to set the motor fans to come on when the motor hits a specific temperature? And the ESC fan too for that matter?

What setup do you have? Both of several Castle and HobbyWing systems offer motor heat logging/protection as well as ESC heat.
I did read a way back that a guy installed external motor can sensors running to a controller, but I can’t find the thread.
Most just use a temp gun and shoot temps every so often. As far as the ESC goes, even the Spektrum stuff has ESC overheat shutdown.

 

[RCSid]

What setup do you have? Both of several Castle and HobbyWing systems offer motor heat logging/protection as well as ESC heat.

I am using the CC XLX2 & 1721/1260 in my Infraction and my K6s has the OEM Spektrum in it. IIRC, the XLX2 will shut down if you set the safety motor temp feature? Wondering if it has that capability, then maybe someone somewhere makes a harness to trigger the fans on at a specific motor temp? I have no clue if that exists, but I guess that its reasonable and maybe so? As far as the Spektrum, absolutely no clue.