Trex 600 CF - Battery

[Rotor Ruiner]

I was wondering if anybody had any expirence or issues with running 2, FlightPower 3S1P 2150 mah batteries in series to power a Trex 600. I have 3 of these batteries that I use to power my Trex SE. I was planning on charging and balancing the batteries seperately, and making a series 'Y' harness out of some decent gauge (can't remember size) wire that has 500 strands and is rated for 300 volts. The wire itself is about 5/32" diameter without the insulation and is very flexible. Any thoughts on this would help. It would be handy as I wouldn't need to buy a $300 battery and a new charger + power supply.

[blax1]

This may help, scroll almost to the bottom of the page :)

http://www.tech-mp.com/bat_charge.php

I'd suggest email them and discussing this project with them, they should have some qualified answers for you :cool:

[Rotor Ruiner]

I am more concerned with causing undo stress to the batteries than building the harness. I should have been more clear about my question. I want to know if seperately charging and balancing the batteries, then running them in series to make them a 6S1P pack will damage the batteries, or even worse cause a fire.

[WiscHeli]

Its not the 2x 11.1v 3S1P batteries in series I worry about that should work fine. what I worry about is 2150 mah . the Trex is rated for a 4600-5000 mah pack. Even with that run time is not that long either. You can get packs as low as 15C that are cheaper 15C X 5000 mah = 75A and at 20C burst thats 100A

[AaronS]

The pack you are talking about running is nowhere near large enough for a TREX 600. You might be able to get away with 6S 2P, but not 1P. The original pack that Align put out for the heli was a 4200 mAh 6s2p pack of their 18c 2100mAh cells. Those packs proved to be boarder-line in the 600 and did not last long. Even if you could run a 1P (6S 2100 mAh) pack, it would be tail heavy, and your flight times would be about 2 minutes. Depending how much you demand of the heli (power) you may be fine with low cost packs. But, if you want to do 3D, you won't be happy with 15C packs.

[Rotor Ruiner]

Thanks for the info. I was thinking of picking up a couple of the new FlightPower 3S1P, 2500 mah, 25c packs. That way I could use them in either 'rex. I have heard good things about these packs. They are a little heavier than the 2150's, but with the Futaba 9650 I have on the tail it should make the little 'rex easier to balance out. Do you think this would be acceptable ? Or should I bite the bullit and buy a 6S2P 5000mah pack and a new charger ?

[cbflys]

The TRex 600 typically uses a 6S2P pack for two reasons. If the packs are made up of 20C cells, you'll be able to safely pull 40C from the pack. By just having a 6S1P setup, you'll most likely exceed their current rating. Not only that, at 2070 mAh, you won't have much run time.

[WiscHeli]

I plan on 6S2P 5000mah 20C in mine ,.... but i planed ahead getting my charger for my 450 I got a TP 1010 and 210Bal ..... batterys are coming down in price too ,,,,, but never fast enou :( gh

[blax1]

http://cgi.ebay.com/MEGA-POWER-Li-Po-Battery-5000mAH-20C-6S2P-T-rex-600_W0QQitemZ290170076106QQihZ019QQcategoryZ34056QQtcZphotoQQcmdZViewItem

[WiscHeli]

You found my Battery supply LOL ,,, i got one 2 weeks ago for $126 have not gone for less then $145 sence ,,,,,, i have time to watch and get a deal :D

[Ots]

I run two Trex 450 packs in series in my Hurricane 550 and it has OK performance - but it's lighter than a Trex 600. The battery packs are fine after flying and they are far from new. They have had lots of flights in my 450.

[RotorDoc]

Those batteries would definitely not work.

The battery packs supply the energy required to fly the heli. The longer the blades (in this case 600mm, a lot longer then the 320mm or so an the mini electrics like the t-rex 450) the more the energy required to swing them. Also the heavier the heli the more energy is required (I understand the T600 weighs in close to 8lbs!!! - that is more then 3 times that of the 450|). Also the higher the head speed the more energy required.

So if you gear your T600 for a decent head speed (at least 1800), then you will find those 600mm blades will require a guestimate of at least 1000 watts. (Turning 560mm blades at 2100 on my 6 lb.Swift in hard 3D takes an average of 1250 watts for a 6 minute flight and turning smaller 515 on 4 cells at 5 lb. 4 oz. takes only about 550 watts - at 1800 would be less)

So you must figure what wattage (amps x volts) that your cells are capable of delivering long term. That is where the "C" rating is now so important.

For example. If your 3 cell (11.1V) battery pack has a 2100 mah & 15C rating and you hook them in series, you will have a battery pack that has a 22.V/2100/15C rating. Hooking them up in parallel will give you a pack of 11.1V/4200mah/15C capacity. But both are only capable of delivering the same wattage.

The C rating tells you how many amps can be drawn from the cells without the voltage dropping excessively. So we usually try to set the system so that it will only require half of the C ratting - in this case 7.5C.

Now check the heli's requirements of a lower head speed (sport flying) of 1800 and 600mm blades and 8 lb. heli. Your wattage requirement may be 1000. With a 22.2V pack that would mean the current draw would be 1000/22.2 = 45 amps. A 2100mah at 7.5C would only comfortably deliver 2.1A (2100 ma) x 7.5 = 15.75 amps for a delivery of 22.2 x 15.5 = 350 watts - only about 1/3 of what is required. Even if geared to give the head speed on 11.1 volt in parallel with the 4200 mah rating you would still comfortably only get 350 watts (11.1 x 4.2 x 7.5).

This is why, in a heli of this size, you will need a battery pack that can at least comfortably deliver 1000 watts. e.g. a 5000mah / 20C / 6 cell. (22.2 x 5 x 10 = 1110). Even then you will have the performance of a smaller heli (e.g. Swift 16) on 4 cells.

This is why all the hot thumb flyers are flying the 515 size heli's on 6S/5000 cells and the bigger T600's on 10 or 12 cell 5000 mah / 20C packs.

Unfortunately, there is a BIG difference in the cost of a these packs.