[stuntman]

I have just bought a Zippy 2S 2500 mah 11.1 V battery for my Futaba 9 CAPS transmitter. Since this is my first lipo battery, I am looking for guidance on the following issues

-what is the amp charge rate that I should use to charge this battery.

-should I charge it in the transmitter or remove it.

-how low should I let the voltage go before charging it

I have a Triton EQ charger

[stuntman]

Correction- the battery is a 3S

[Jeff_D]

Originally Posted by stuntman

I have just bought a Zippy 2S 2500 mah 11.1 V battery for my Futaba 9 CAPS transmitter. Since this is my first lipo battery, I am looking for guidance on the following issues

-what is the amp charge rate that I should use to charge this battery.

-should I charge it in the transmitter or remove it.

-how low should I let the voltage go before charging it

I have a Triton EQ charger

If you charge at 1C, in your case 2.5 amps, you won't have any trouble at all. A li-po cell should not be discharged below 3volts, That is 9 volts total on your 3 cell pack.
Let me say this however. You will find many people using li-po 3-cell packs for thier TX, but if the Pack does not have some sort of voltage regulation or reduction, you run the risk of component failure in your TX. It might not happen right away, but the 12.6 volts coming from a 3s li-po is going to drive up operating temperatures of some of the electronic components. I have seen increases of 25 degreesC. A simple fix is to run 3 diodes in series. This will drop the voltage from the battery to a safe operating level for your TX.

[kwm]

With the lipo pack you will probably go all summer before you have to charge again, depending on how much you fly, just keep an eye on the voltage reading on you tx an do not go below 9.6 volts.

[Rod]

There are four members of our club as well as myself that are using 3S LiPo packs in our transmitters without any additional electronics, ( that I know of). A 3S Lipo will give you about 11.4 volts under the load of a transmitter. All of the members I have mentioned are very happy with the LiPo/transmitter combinations. The main advantage is that the LiPo has a very low self discharge and will hold it's charge.
We all charge the battery at a 1C rate ouside of the transmitter.

[Jeff_D]

All I wanted to do is make people aware that they could be damaging thier TX and won't know it until it is too late. Also, the higher the 'C' rating of the li-po will will result in a higher voltage output while the pack is under the load of the TX. A fully charged 3s 20C pack can easily have over 12 volts while under load from your TX. I have done tests using a calibrated Fluke meter

Originally Posted by Rod

There are four members of our club as well as myself that are using 3S LiPo packs in our transmitters without any additional electronics, ( that I know of). A 3S Lipo will give you about 11.4 volts under the load of a transmitter. All of the members I have mentioned are very happy with the LiPo/transmitter combinations. The main advantage is that the LiPo has a very low self discharge and will hold it's charge.
We all charge the battery at a 1C rate ouside of the transmitter.

[S1Pitts]

Originally Posted by Jeff_D

A simple fix is to run 3 diodes in series. This will drop the voltage from the battery to a safe operating level for your TX.

A value or part # for said diodes would be great. I'm contemplating switching over my JR 10X & would like to take the correct precautions.
Cheers
KR

[IAR 80]

I'm using 3s LiPo in 2 tx's , a Hitec Optic, and a Spektrum DX6.I dont use any diodes, which btw are 1N 4001,...4005.The Hitec ( 72 Mhz) becomes warm, Spectrum not at all.I'm contemplating the diode way, for Hitec.
Untill then, I charge the bttery at storage settings, always outside of Tx.
As stated before, keep an eye on the voltage, as the default alarm for low voltage is to low for LiPo.

[Jeff_D]

The 1N400X series of diodes work fine. They can handle a 1 amp load with no problem. I haven't found a TX that would exceed that load. Another benefit of the diode is that you can rely on your TX low voltage alarm and protect your battery from over discharge.

Eg. My Futaba will sound an alarm at 8.4 volts. The voltage at the battery pack would be around 10.5 volts. Each diode has a voltage drop of .7 volts.

I am going to make a bunch of these up and in the near future, I will have Jeff at thunderboltrc.com carry the adapter with the diodes.

[Jeff_D]

I set up a meter along with my TX to show how much the diodes will drop the voltage. You can see with a battery voltage of 12.57 volts the TX is only seeing 10.2 volts. Any one interested in a pre-made atapter as in the photo, send me a PM.