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T-REX 500 › T-rex 500 battery choices ?
08-05-2011 08:14 AM  6 years agoPost 1
T-heli

rrApprentice

South-Africa

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Ok please help me out,

What battery did the t-rex 500 originally fly with when they first hit the shelves ? (what did they originally suggest)

i know people will say it's up to own preference so let me say the following:

i want to only do circuits, stall turns, maybe just maybe some FFF or mild ff,

i feel that a 6s battery is pretty big for this little machine am i correct in saying so (overpowered) i don't need these insane head speeds and am definately not going to do those angry 3d moves.

can i use a 3s 4s or 5s on this bird ?

(it's actually a hybrid copterx/trex 500 )

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08-05-2011 08:18 AM  6 years agoPost 2
OLROY

rrKey Veteran

Wichita Ks

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I use a scorpion 5S on mine and using 3000mah battery
You can always lower head speed and with this size battery means longer flight times in your case.

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08-05-2011 01:00 PM  6 years agoPost 3
design engnr

rrApprentice

Smyrna, TN

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6S is the way to go... You can tame down the headspeed by using a smaller pinion (11 tooth) on the motor. 6s will also be more efficient as it will take less amps to make the same power (P = V*I). I flew 6s 2650s in my original trex 500 and could routinely get 6-7 minute flights.

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08-05-2011 01:22 PM  6 years agoPost 4
Jerry K

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Houston Area

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design engnr has it correct

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08-05-2011 02:07 PM  6 years agoPost 5
davehour

rrElite Veteran

Guayama, Puerto Rico 00785

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What 6S batteries capacities will be the best bet for 3D?

Thanks.

David

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08-05-2011 02:22 PM  6 years agoPost 6
jsenicka

rrProfessor

Eagle River, WI

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Turnigy 6s 3000 40c if you want to beat on it. 6s 3300 30c will give you a load of flight time if you back the head speed down.

Jim Senicka
Team Manager, GrandRC Flight Team

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08-05-2011 02:33 PM  6 years agoPost 7
design engnr

rrApprentice

Smyrna, TN

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Anywhere from 2650mAh to 3000mAh will work..Provided you can fit it under the canopy. Lighter is better for 3d as it takes loading off of the rotor disk, giving a better power to weight ratio. However, flight times will be less.

Dave

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08-05-2011 07:38 PM  6 years agoPost 8
T-heli

rrApprentice

South-Africa

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It's just my t-rex 600 runs on 6s ! and that heli is way bigger than the 500.

Just doesn't feel right or maybe it's just me ? The upper limit that has been suggested for a battery pack on this heli is 500 grams.

I got 20c turnigy's 3000 mahs 6s and i think they weigh in at 487 grams according to the specs, now that's very close to the upper limit of the suggested weight range.

Again did i mention the battery looks huge compared to the tiny heli ?

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08-05-2011 07:44 PM  6 years agoPost 9
T-heli

rrApprentice

South-Africa

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"I use a scorpion 5S on mine and using 3000mah battery
You can always lower head speed and with this size battery means longer flight times in your case."

I like what Olroy says, seems to me that even with 5s one can bring down the headspeed so to me that means the heli has plenty of grunt on 5s, maybe i'll swop out my 6s for 5s then, should lower the weight much lower than the near upper limit of the 6s packs.

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08-05-2011 07:55 PM  6 years agoPost 10
HeliDawg

rrNovice

Spokane, WA United States

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My view on batteries
I just finished building my Trex 500e. All stock Align servos and the 500MX motor.
I did some reading on best batteries for this bird. Well with the new radio, I am 1100 into this heli and at the end of my budget. I wanted decent batteries for the price.
Found out about Gens Ace batteries and did some research, they looked great for the best bang for my buck.

So I bought 4 - 6S 2600 25c batteries. (BTW they cost me 36.00 ea)I figured I would get 4 1/2 minutes flight time like I do with my 450. I am happy to report that I flew 2 batteries last night and flew them for 5 1/2 mins each. Motor was not hot nor the BEC. Voltage came down to 3.83 and only took 1200 mah to replenish. I plan on kicking my timer up to 6 1/2 min and see what happens with that.

Dale

Dang I am upside down!

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08-05-2011 10:24 PM  6 years agoPost 11
design engnr

rrApprentice

Smyrna, TN

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T,
Your heli will fly fine on 5s provided it is geared properly, but you will have higher amp draw on the components. This generally means more heat, which electronics do not like,hence they will have a shorter life span.

Also, it is a widely accepted that 6s is too little voltage for a 600 size heli. Most go 8s or better. As a matter of fact the new 600e from align is setup to go 12s from the factory (as far as I know someone step in to correct me).

The choice is yours, but as for me I will stay 6s.

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08-06-2011 01:54 PM  6 years agoPost 12
davehour

rrElite Veteran

Guayama, Puerto Rico 00785

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design engnr,

Yes, the new T-rex 600EFL Pro is 12S.

In my first flights, where I have flown my 600EFL Pro with care, it has logged peak current demands of about 70 amps. I can imagine how the current demand is when using a 6S setup, having the equivalent power the new 600EFL Pro motor has.

BTW, thanks for answering my question.

David

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08-06-2011 03:31 PM  6 years agoPost 13
design engnr

rrApprentice

Smyrna, TN

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Thanks for the confirmation davehour. Glad I could help.

Dave

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08-06-2011 10:02 PM  6 years agoPost 14
T-heli

rrApprentice

South-Africa

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Thanks guys, i think then it's either a 5s 3000-4000 mah or a 6s 2300-2650, i think i might put the 6s 3000 mah's up for trade.

"Also, it is a widely accepted that 6s is too little voltage for a 600 size heli. Most go 8s or better. As a matter of fact the new 600e from align is setup to go 12s from the factory (as far as I know someone step in to correct me)."

My 80 amp feigao esc is mild after flight on 6s, and i my heli flies just fine with 6s no vibes, and i don't have any worn out parts due to high stress. thast's while i stay with 6s, like mentioned i'm not into 3d, i get satisfaction out of seeing the heli fly like a heli should fly.

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08-08-2011 06:24 PM  6 years agoPost 15
T-heli

rrApprentice

South-Africa

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I just about made up my choice with a 5s because i'd like to save weight when this guy mailed me with the following (is this a valid reason to stay with 6s 3000 mah) i'm just not comfortable with it being at nearly the max weight a 500 is made for ie 500 grams of battery. the 3s 3000 turnigy 20c weighs 487 grams a mere 13 grams from max recommended weight:
(and i'm flying a 6s on my t-rex 600 for about 3 years now and having no problems) So this is what the guy said:

***"It's all to do with the amps.

3000mAh * 20C = 60A which is what is required for a stock Trex 500 going to 2200mah would mean nothing less than 30C else the Trex would be underpowered and you WILL damage the battery!!! [-X [-X [-X [-X
60A is max the motor will consume according to motor specs.
Then you KV rating * the Volts = max rpm by motor. (Trex 500 = 1600 * 22.2v) and then gearing

5000mah *20C = 100A which is a stock Trex 600's power
Trex 600 = 1100kv * 22.2v and then gearing

RESULTS ON A 5s 20c with a 10T calculation
Result for calculation:
Estimated lowest voltage during flight: 16,35
Lowest RPM (due to voltage and efficiency) : 1372

Throttle 70%: 1524
Throttle 75%: 1570
Throttle 80%: 1616

DAMN 1616 is very very low for a Trex 500 and would surely wobble.

6S 20C 10T
Result for calculation:
Estimated lowest voltage during flight: 19,62
Lowest RPM (due to voltage and efficiency) : 1647

Throttle 70%: 1829
Throttle 75%: 1884
Throttle 80%: 1940

And that is well within the govenor range. ( set the throttle on 82% and you have a nice stable headspead @ roughly 1950 rpm)

6s 20C 11T
Result for calculation:
Estimated lowest voltage during flight: 19,62
Lowest RPM (due to voltage and efficiency) : 1811

Throttle 70%: 2012
Throttle 75%: 2073
Throttle 80%: 2134

My basic flight would be the above setup 75% nice for hovering (in gov mode) and if I want to do sport flying boost the curve to 85% .

1. the slowest headspead achievable for the heli to simply not wobble in flight and in a hover = Linear throtlle curve where you are comforatable with the head speed.
2. Weight = Stability. (Hence the reason why people put flybar weights on)
3. Lower mAH = shorter flight times losing 500mAH = like shaving a 0.5 - 1 minute of your flying time.
4. Rather keep the 3000mAH, run a 60-65% rpm range with a linear throttle curve and increase your flying time with more then a minute or 2. Since you will only be hovering you don't even need to be in govenor mode - only when you do climbout and pitch pumping will you need the govenor "***

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08-08-2011 06:47 PM  6 years agoPost 16
design engnr

rrApprentice

Smyrna, TN

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There is alot wrong with what you were told regarding the 500 size. No time to get in depth, but for starters.

1.) It is all to do about Watts not amps - I will elaborate later.

2.) Headspeed: 2000 rpm is still too low for a 500. 2600-2800 rpm is a nice sweet spot. due to their weight 500's have a high disk loading, because of this they need a higher head speed for stability.

More later. Ignore what you were told from what you posted. You can do fine with 5s, it just needs to be geared properly.

Dave

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08-08-2011 07:03 PM  6 years agoPost 17
Heli-on

rrVeteran

Southern Cali, CA - USA

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8S 4000 gives about 10 minute flight time in a scale setup. Take off headpeed is 1900, and you can see some slight wobble. Flight HS is 2200. My disk size is appx 10% larger, if you want to split hairs.

You probably could do a 10-minute flight with 6S, but the motor would be begging for mercy. My pod & boom comes down pretty warm on 6S, so for that reason alone I wouldn't run it anything less than 6S. 2650 is the ideal 6S for the 500 - gives about 4 mins hard flight time.

Have to disagree with your 2600-2800 RPM's there, chief. Align 425D blades are rated to run no higher than 2600. I've seen them launch the weight out of the end at 2600, so run them higher at your own risk.

Watch at YouTube

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08-08-2011 08:29 PM  6 years agoPost 18
design engnr

rrApprentice

Smyrna, TN

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Disagree if you want to "chief". But Mine and many other 500's run in the 2700 rpm range all day long with out issue, with or without align blades. 10% increase in disk area will make a difference in required headspeed (splitting hairs or not).

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08-08-2011 08:37 PM  6 years agoPost 19
Heli-on

rrVeteran

Southern Cali, CA - USA

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I'm not saying you can't, its just not recommended. And you can clearly see its not a requisite to the thing flying properly. Just making sure the person asking the question is seeing more than 'your side' of it. We won't add that extra battery or fuse weight into your 10% equation so it looks like you sorta know what you're talking about.

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08-08-2011 08:57 PM  6 years agoPost 20
design engnr

rrApprentice

Smyrna, TN

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Not trying to offend. Just going on past experience. I have had several 500's and each exhibited wobble below 2500 rpm.

I did not take flying style into perspective as that clearly has an impact. A smooth relaxed style such as yours will clearly not require as much from the heli. I can admit when I am wrong, I did not take the extra weight with Heli-on's scale bird into consideration, so disregard the 10% comment.

T-Heli,
As my credibility has been questioned, take this for what you will. What ever size pack you decide to go with I recommend that you not run your throttle less than 80%. Brushless motor and ESC's are at their most efficient at 100% throttle. Therefore, if geared properly you will maximize your flight time. Since you already have your motor and have decided on a 5s pack, choose your pinion size so you get the most out of you components.

Dave

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