Can Lipos be run on a EVX? - RC-Monster Forums

JThiessen · **Can Lipos be run on a EVX? -** 12.11.2008, 11:43 PM

A buddy is wanting to use his 4S lipos with his stock EVX. I have a LVC from a HV-Maxx. Could we wire it up and run it similar to how you do it on a HV? I personally don't see any reason why not....

Unsullied_Spy · 12.12.2008, 01:25 AM

The old Orange EVX could handle the voltage, but you will probably want to run a fan on it.

The new EVX-2 handles voltage better, but I don't trust their reliability.

E-Revonut · 12.12.2008, 01:47 AM

If you do it run a 2s cut off on the battery lead that has the bec circuit attached to it. If you just use a 4s cut off it may allow the bec side pack to drop to low.

JThiessen · 12.12.2008, 09:42 AM

I was going to set it up with a jumper across one of the battery leads, and run it on a single battery, with the LVC soldered into to deans on the side that I have the battery attached to (similar to the instructions on the HV for setting it up for a single battery application). So I think that takes the BEC side out of play.

Unsullied_Spy · 12.13.2008, 02:19 AM

I wouldn't run 4s on the BEC side, you'll most likely fry it. That little device has to cut the voltage down from ~7.4v to 6v or so and creates a bit of heat doing so. Having to bring 14+ volts down to 6 would fry it.

BrianG · 12.13.2008, 02:28 AM

As long as he removes the red wire in the throttle cable and uses an external BEC, it should be ok. Regulators generate heat with a combination of current and voltage. If voltage is high, but current is low (the brains don't pull much at all), losses are minimal.

The formula for wasted BEC power is (Vbat-Vbec)*amps. If the battery is 14.8v, but the amperage is, say, 50mA, lost power is (14.8v-5v)*0.05=0.49w. The BEC is only powering the brains, which don't take much current at all. Even on 2s, the losses can be high depending on the servo. For a typical setup with a servo that draws 1A average, the power loss at 2s would be (7.4v-5v)*1A=2.4w. So really, a BEC should be used even when only 2s is used on the BEC. Obviously, I'm assuming a 5v bec voltage here.

Futhermore, the BEC in the EVX is the same type as in a MM - linear. And we all know the MM runs all day long on 4s as long as the red wire is pulled.

Unsullied_Spy · 12.13.2008, 02:35 AM

Quote:

Originally Posted by BrianG

As long as he removes the red wire in the throttle cable and uses an external BEC, it should be ok. Regulators generate heat with a combination of current and voltage. If voltage is high, but current is low (the brains don't pull much at all), losses are minimal.

The formula for wasted BEC power is (Vbat-Vbec)*amps. If the battery is 14.8v, but the amperage is, say, 50mA, lost power is (14.8v-5v)*0.05=0.49w. The BEC is only powering the brains, which don't take much current at all. Even on 2s, the losses can be high depending on the servo. For a typical setup with a servo that draws 1A average, the power loss at 2s would be (7.4v-5v)*1A=2.4w. So really, a BEC should be used even when only 2s is used on the BEC. Obviously, I'm assuming a 5v bec voltage here.

Futhermore, the BEC in the EVX is the same type as in a MM - linear. And we all know the MM runs all day long on 4s as long as the red wire is pulled.

Yeah, that's what I meant to say