Lipo- TX/RX - RC-Monster Forums

Papa · **Lipo- TX/RX -** 03.10.2006, 08:59 AM

LIPO GURUU- I want to run lipo in both my Z-1 transmitter, and as a receiver pack. What are your thoughts on the proper setup for this sort of application?

coolhandcountry · 03.10.2006, 05:26 PM

are you worried about it going under the voltage. I don't know of a lvc for it.

03.10.2006, 05:36 PM

im pretty sure the Z-1 tells the voltage of the batteries.

Papa · 03.10.2006, 06:08 PM

The Z-1 will monitor the voltage of the TX battery. I am more concerned with the RX. I amlooking for a recomendation for a voltage regulator, cut voltage back to 6V , save the servo's. My other concern is with cell balancing. Both low voltage indicator I have seen offer visible, little light , warnings. What kind of "ratings should I be looking for on cells? Any body else done this done this. What issues should I be contemplating?

MetalMan · 03.10.2006, 06:24 PM

You could use very inexpensive cells for the TX, like 2C cells. For the RX, anything that can handle about 4amps continuous is fine.

IMO, don't use a Lipo pack for the RX, unless you can find something that will cut off at 6V (which could be disastrous, as the receiver would lose its signal). The TX Lipo pack should be fine, as long as you do keep the cells above 3V.

Papa · 03.16.2006, 07:16 AM

WEll looks like the UBEC comes through once again. I will use it as a voltage regulator for the RX. I found this info on their web-sight.

"How can the UBEC be used in glow and gas powered applications? Since the UBEC is much more efficient than a linear regulator, it is a perfect match to use with lithium batteries to power a receiver. The UBEC runs at better than 90% efficiencies when run within specs. What does this mean? You will get significantly more usuable energy from the lithium battery pack to power your receiver than if you used a linear regulator. We only reccomend 3-cell packs in this application. the higher your input voltage....the more efficient your system will be. When using a 3-cell pack for your source power, the current draw from the battery pack will be almost half of what a 4-cell nicad pack would require. Here's an example:

A 3-cell lithium pack that is 840 mah in capacity would power your receiver and servos for about the same amount of time as a 1500 mah 4-cell nicad pack. If the radio system draws 4 amps a 5 volts (20 watts)...the 4-cell nicad pack will have to drain at 4 amps. However...the 3-cell lithium pack will only have to dump about 2 amps to deliver the 20 watts thru the UBEC.

Now, I am in the hunt for some quality lipo packs that will fit in the rx / box.

MetalMan · 03.16.2006, 08:32 AM

What are you going to do about low voltage situations? The cells can become unstable below 3V/cell.

Papa · 03.16.2006, 09:17 AM

That is one I have not figured out yet. I suspect I will have to be cautious and recharge on a regular basis and avoid over discharge. I have seen some low voltage monitors with either audible or visual warning.

MetalMan · 03.16.2006, 09:43 PM

You could do the audible low voltage unit. But, you would have to make sure that it would be loud enough and placed where it could be heard.

Papa · 03.16.2006, 10:05 PM

I think an audible will not be heard do to the "noise". I am thinking:

lipo--voltage regulator--receiver-- steering
lvc--failsafe--throttle

lvc between rx and failsafe.

or no lvc at all and being cautious not to run it dwon to low.

MetalMan · 03.16.2006, 10:09 PM

If those ideas don't work out, there's always the Nomadio :eek:. I think it can monitor the voltage of the RX battery via telemetry. This would be a nice feature if you can afford the Nomadio.

Papa · 03.16.2006, 10:10 PM

Yes it can.I like the NOmadio but the pockets are only so ...deep.

MetalMan · 03.16.2006, 10:14 PM

Tell me about it...

Another idea would be to just get a LVC with a hard cutoff (that would cut the power to an electric motor) and hook it up to the throttle servo like you would if you were hooking it up to an ESC.

Papa · 03.16.2006, 10:22 PM

That was my thought. Just concerned about getting the servo back to idle. Hence the fail-safe after the lvc ?

MetalMan · 03.16.2006, 10:49 PM

I'm not sure how the failsafe would be set so that it would keep the engine at idle. With the LVC, as soon as the voltage returns to normal, it will allow throttle to be applied. But, in this case, the servos would still be dragging the battery down, so the voltage won't return to normal. Hmmm... This is a tough situation.