RX LiFe Battery Question

[Triple-D TJ]

So I've been building my T-Rex 600N for 9 months, gathering upgrades and buying components to fly this thing.. I charged my RX flight pack to 3.46 volts per cell with the new dual port Thunder Power Charger.. The LiFe Pack is a 6.6 V 2100 mAh pack.. Its attached to an Align 2 in..

Now to the question. How does it only last for 1 flight before needing to be rechaged? Is there not enough charge within each cell in the Pack?

Nothing horrible happend aside from the heli lifted during spool up and spanked brand new CYB FBL blades.. I realize it could have been worse...

This is my first Nitro, I'm used to flying electrics where EVERYTHING was powered off the main pack..

[fastflyer20]

Hello from N Tonawanda - Not real clear on what happened. It crashed due to loosing power?

A 2 cell LiFe fully charged is 7.2 volt, so 6.92 checked a period of time after charge sounds reasonable. The real test is the mah you put back into it, in my experience you will usually put 80% of the capacity back in when the voltage is around 6.2-6.4 volts.

600's use around 200-300 mah per flight depending on the heli and the pilot, so a 2100 should last for many flights.

You also don't need a regulator with a LiFe pack if using 6v servos.

[Triple-D TJ]

I'm using Savox & Futaba RX with Microbeast FBL.. Servos are rated for 6 Volts, however I read someplace the reciever cant handle over 6 V. I'm no expert at Nitros so the 2 in 1 was a last min addition just in case.

When I use my TP charger/balancer, it wont allow me to select or charge to a voltage over 3.8 Volts for LiFe packs... Unless im missing something..

[Triple-D TJ]

One last thing, This would have been the third tank of fuel through the engine.. Hover only, havent even take it out of Idle mode 1 yet.

[fastflyer20]

A 7.2 end voltage for a 2 cell RX would be a termination voltage of 3.6 per cell.

Savox and MB should be fine on 6v.
Not sure on the Futaba Rx, I use JR.

So what happened, did it crash, did you loose power?
It is good to check the battery can you cycle it on the charger?
The Align 2 in 1 have a worse reputation than LiFe packs, hence I have never used them.

[Triple-D TJ]

Luckily I was only spooling up, heli started to tip froward with minimal lift... Resulting in a blade strike. Not serious, aside for smoking a brand new set of FBL blades..

I just tossed it on the charger while at work, before charging I maxed out the final voltage @ 3.8 Volts.. Thats all the Thunder Power charger will allow me to charge to in a 2 cell 2100 mHA LiFe pack.. Now with lipos I can charge to 4.2-4.3 volts all day long..

Before Charging I read the cells at 2.6V....

[kevinl7778]

The glow ignitor can also suck up some power, i think the fact that it is fbl also adds a lot of servo movement as it is managig to keep level.

How many times are you trying to start it for every run.

How long was your flight.

Did you do a preflight check prior to the malfunction.

[Triple-D TJ]

Well I ended up calling Hobbico's customer service about the LiFe packs.. They said the the battery at the rate's I was carged to should last for at least an hour.

I made the mistake of assuming the RX pack would last long than an hour or so... I fly planks all the time and a RX NiMH pack will last all day.. Well needless to say, I should have checked the voltage during preflight. So its my fault, which I hate to admit but its true. I now have 3 RX packs that I will be rotating every three flights.

[bronicabill]

The LiFe pack has a lower voltage per cell than a LiPo, which is what the 2-in-1 is calibrated for, so if you're going by the voltage level meter on it, it's gonna show a need to recharge much sooner than if you were running a LiPo pack! This is also why you can't choose a higher voltage level in your TP charger/balancer; doing so would overcharge the pack and ruin it!

I have a 3200mAh LiFe pack on my T-Rex 600 and I get around 10 flights safely per charge. I wouldn't think a 2100 should provide less than at least half of that unless you have other issues causing a serious load on the pack!

[nick.m]

well just as a guideline i run the standard align battery on my fbl 600 with the 2 in 1 and ill get 3 flights b4 i change it,,it would prob make 4 but i never risk it

[popokatepetl]

I personaly fly this 2S LiFe 2100mAh and use it on my 700E. The best way is to have it directly unregulated and each flit is around 200-300mAh so you have enough power for many flights.

Don't worry about your servos running 6.6V!

[Triple-D TJ]

Somewhere on HF there is a thread about using Life & regulators. Something to the tune that it wasnt a good combo.. I dont know for sure but that is what was told to me.

I'm actually eliminating the Align 2 in 1 and converting to Push Glow and runing the LiFe pack direct to the RX. No need to have a compent thats not really needed..

[bronicabill]

While your servos may be fine with 6.6V (I know mine are), your gyro or Rx may not be! Maybe you want to check the specs on what you're flying before you draw any conclusions. The manual for my Futaba GY520 recommends against using voltages that high, so I run a regulator on the rudder (tail rotor) channel; all others receive full voltage from my LiFe pack without problems.

[michael503]

The manual for the 2 in 1 specifically states 2 cell lipo only.

The align 2 in 1 is calibrated for a 2 cell lipo, not LIfe. Not only will it not read right as to charge status, the regulator in it needs a certain amount of overhead to work. With a LIFE pack, you may not be getting full power to your electronics and you risk a brownout, which is bad on an electric model, but worse on a Nitro since you can't shut the motor down if it fails.

My advice is to make sure your equipment is 6V capable (RXs usually are, and your servos might be) Then run the Life pack straight, without the 2 in 1, which is notorious for failing anyway due to the micro switch and then if you want an onboard glow, get a Pushglo.

[texasclouds]

Are you guys running one or two servo power leads from the LiFe battery to the receiver? Two would require two switches, right? Would any basic R/C power switch work fine?

[bronicabill]

I'm running one power lead on mine with no issues so far. I'm not a HARD 3D pilot and only use DS610's on cyclic, so I'm probably not drawing the load others may, so don't take my word as "gospel truth"!

Personally I don't use a "basic" power switch on mine, which may be part of my success with my setup. I use the JR Heavy Duty power harness which of course means a heavy-duty switch also. Been running it for several years now with zero problems! YMMV

[fastflyer20]

Originally Posted by texasclouds

Are you guys running one or two servo power leads from the LiFe battery to the receiver? Two would require two switches, right? Would any basic R/C power switch work fine?

2 servo extensions

The battery connection/switch is a Deans, I used 2 servo extensions and soldered to the Deans. Now the receiver has 2 connectors for redundancy and added current capacity. A few layers of heat shrink protect the small diameter wires.
Cheap and simple.

[Triple-D TJ]

I switched over to a PushGlo. The LiFe batteries have have Four leads. (1 Deans, 1 Balance, 2 Futaba J's) Now running two independant switches from the 2 Futaba J battery leads direct.. No need for a regulator since my Tail servo is rated for a higher voltage..

[texasclouds]

Any of you guys use a deans arming plug for an unregulated setup?

I walked up to my crashed heli to find my plug missing...not sure if it ejected in normal flight or during the crash

[fastflyer20]

I rigidly mounted a Deans on a T600N and much to my surprise, it vibrated out in flight. If they are not mounted, they stay connected.