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03-31-2005 04:44 PM  13 years agoPost 1
helicopterMark

rrKey Veteran

Rumson, NJ

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Hi, I am getting concerned, I have begun loosing power on my Trex to the point where I cant recover and wind up crashing, I'm trying to determine if it is my battery, esc, or motor. Here is what I am running.

Relatively stock mechanical mixing T-rex, Align 400S motor, Align 25amp ESC, TP 2100 battery.

A little history on the battery, it has maybe 40 cycles, on about the 10th cycle in a crash without the canopy it sustained a blade strike, I thought it was going to blow, left it outside for 2 hours and it seemed fine, cycled it, seemed fine, so I continued to use it, recently I have noticed somewhat shorter flight times and a little less power, it is getting to the point that where I give it full stick while descending I can barely stock the descent. I also purchased a TP1320 3S which seemed incredible at first, but now after maybe 5 cycles I'm not sure, it could just be my imagination but it seems like the same thing might be starting to happen to my second smaller pack.

My initial thought was that the esc was draining the battery beyond the safe point, I have noticed in the past the heli begin to slow down and slowly sink and start cutting out, and I just dont know how much I can trust that align esc, I am planning on buying a CC35, but in the meantime this is what I have.

The other factor I was considering is my charger, I am charging my batteries on a cheaper 45 dollar eflight celectra lipo charger. I do plan on getting a triton soon to replace this charger. I am becoming afraid to fly the heli now because I dont know when I might start to loose power out of nowhere and wind up getting into a crash(which happened yesterday). I just am not sure what to do, she was running so nice just a few weeks ago, significant power and pretty good run times. If anyone has any ideas please let me know, I do plan on getting a cc35 and triton charger, but I'm afraid it might be too late for my tp2100, I'm going to try not to use the 1320 in the meantime, I'd hate to destroy that battery as well...

One last thing I noticed which might be useful, attaching a voltmeter when charging I see the voltage climb to 12.55, when the charger is done, the TP1320(new) falls slightly to 12.45-12.48 or so, while the 2100 drops a good bit to 12.29-12.33 not sure if that is a sign of wear or a cell out of balance? Thanks for any help you might have to offer,

Mark

Mark Schneider
Team Heli Wholesaler; Rotor Rage; YS; Perfect Regulators
www.helimark.com

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03-31-2005 07:09 PM  13 years agoPost 2
thunder21

rrApprentice

College Park, MD

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I would not recommend using a TP1320 3s pack on a T-Rex!!! It has nowhere near the current carrying capability needed to power the T-Rex.

When dealing with lipos you have to remember that heat is your enemy. External temps over 140F will result in damage to the lipo pack. I find it quite interesting to walk up to someone who just finished flying out a lipo pack with my IR temperature gauge. I'll ask the guy how hot he thinks the pack is. I usually get a response of 120 degrees F. They just about crap themselves when I tell them the pack is 150F on the outside. Just think about how hot it is on the inside! And they wonder why their packs are not lasting very long. Must be faulty manufacturing, right... I've found that you can hold on to a 140F pack loosely and not think it's very hot. Check you temps with a gauge.

I've also started to charge my packs at 1 amp. It takes longer but they seem to like it better and I haven't had to balance the packs that have taps on the. If your charger doesn't display the amps delivered to the battery, you can set a fixed charge and time how long until the charge stops.

My lipos usually drop to 12.53 volts immediately after a charge. After a few days or so they drop to 12.46 or so. If yours drops to 12.33 after charging the pack is probably toast. It's got a bad cell.

If you're not running a heat sink on the motor you could also damage the magnets. Temps over 200F can demagnetize the magnets.

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03-31-2005 08:18 PM  13 years agoPost 3
SRH990

rrKey Veteran

Birmingham, UK

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I had similar with a pack on a plank, started off fine then the pack dropped off really rapidly, cost me the plane I had previously over discharged the pack but had managed to recover it, or so I thought, I'd even cycled it twice and it seemed okay but a 2500 pack only took 1450 to recharge. Ended up with one cell being duff so a new pack replaced it. It does seem that when lipo's go bad they seem okay but the voltage drops off really fast - try a new 2100 pack and see if its better, the 1320 is really not going to cut it as you'll be pushing it much too hard on a T-Rex.

Steve -Trex 700N, Trex 600N, Raptor 550E, 450SE, Mini Titan, Logo 5003D, Beam E4

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03-31-2005 09:36 PM  13 years agoPost 4
helicopterMark

rrKey Veteran

Rumson, NJ

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thanks for your help guys, I think I will need to get a new 2100, is it true that if you send a bad pack to TP they will replace it for half cost if it isn't under waranty? I have noticed the pack does get warm, around 135 with my temp gun at the end of the flight, I think it could have definitely been over 140 as I didn't have a whole in the canopy for airflow like I do now. The motor is normally around 145 now that I have the heatsink on, it would get up around 175 180 without the heatsink! I agree that the 1320 would be pushing it, although I think it should be ok for just hovering in the yard. We'll see what happens... I do feel it is the battery though at this point, but I will try to limit my flying until I can aquire a cc35. Thanks again for the help,

Mark

Mark Schneider
Team Heli Wholesaler; Rotor Rage; YS; Perfect Regulators
www.helimark.com

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03-31-2005 09:57 PM  13 years agoPost 5
Jarod

rrVeteran

USA

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yes its true. I have sent them packs that were deffinately over the 1 year mark. Come to think of it I sent in an early Generation 1 pack. It didnt have a date on it at all. It was probably close to 3 years old when I sent it in. I told them it was getting very hot when attempting to use it. Im sure they dont mind if your willing to pay to replace it. It's cheaper then buying a new one for full price.

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