Turnigy packs C rating?

[trillian]

I have been flying the Outrage 550 a few months now and spent a bit of time tweaking the governor and stuff so now I am starting to wonder something.

I just get the feeling sometimes it could be a bit punchier in terms of power and I'm not running a huge pitch range or doing anything very demanding. I'm also running at a very conservative headspeed (about 1950 in idle-up1).

The power setup is;
Castle Ice 100
Hacker A40 10L ET (1100kv)
Outrage Fusion mod 0.8 gears, 129 tooth main and 12 tooth pinion

So I'm wondering if the Lipos I have might be where the bottleneck is. I have Turnigy 6s 5000mah rated at '30 -40 c'. If they really did output 30c that's 150 amps (correct me if I'm wrong on this).

I have never seen a peak in the logs greater than 100 amps.

Do you think these Lipos are actually delivering something more like 20c ?

[cjcj1949]

The C rating of lipos is an almost, no it is, nonsense. If you suspect the lipos you can either borrow some good ones to try out or do some measurements. The limiting factor with current draw is the drop in volts at the current you are using and this is caused by the ir or internal resistance of the battery. High C rating batteries should be better, but there is no standard way of measuring this. You can measure the internal resistance of a lipo and good lipos have lower irs. ir does drop as temperature goes up and you should get an improvement if you warm up the batteries. 30 degrees C should give you some punch.

I can be more technically accurate if you want, but basically you need to look at the voltage drops when you are taking 100 amps. You need very thick wires and good connectors to keep volts drops down at that current. Power loss due to resistance varies with the square of the current, so going from a 450 25amp setup to 100 amps will lose you 16 times the power for the same resistance. Possibly why people tend to go for higher voltage setups. Its also why power lines work at very high voltages.

[p4ddy]

I have found the 25C packs to be far better than the 30C packs. The wires & connectors though are larger on the 30C so if you tried 25C you'll have to make an adaptor. I always thought that if your log shows a maximum spike of 100amps that is because your flying only demanded 100amps although the pack could of delivered more. I'm sure if you flew some hard pitch pumping moves it would go up. I dunno? However if more 'punch' is what your after then i'd try an optipower lipo as every flight i've seen on them always looks punchier & crisper than my Turnigy flights.

[stanley1]

Thunder power 65c lipos rule without a doubt

[Goto]

Hi

I've been running Turnigy 5000MAH 25C packs in a Logo, Scorpion 1100kv motor, 100amp LV ESC, 553 Edge or NHP Razors on a V-bar setup. I have never felt it under-powered, though I don't have the power logging that the Castle gives you to objectively back-up that feeling.

I haven't used higher C-rated Turnigy packs, though there is quite a lot of anecdotal support for the theory the higher-rated packs are a bit generously rated, but the 25C packs work great (if not always for many cycles).

What I would say is that you may not be demanding enough of them to really push them. A bit more pitch, or a bit more headspeed would show up any real performance, or lack of it. Also worth observing that in a 6S configuration you're probably working near the limits of what the setup has to offer reliably. a "fifty" size electric on 6S with a "performance" setup (pitch/headspeed set up for punchy pullouts and bog-free aeros) is quite capable of pulling more than 120amp peaks which may exceed the rating of the ESC and/or the motor.


Everyone is making good noises about the Gens Ace packs which are sensibly priced (I just don't see the advantages in buying overpriced 65C packs from premium brands).

[steve_b]

As posted earlier the C rating on packs is just a number on a sticker and doesn't seem to be based on anything realistic.

From memory there was a thread about the Opti Power packs where Andy said that he tested a number of packs and none of the met their alleged C rating. As a result he went for a 20 - 30C rating as this is a realistic value that packs he tested produced, even though there are 65C packs allegedly available, so he could have put a higher rating on, but again it just comes down to a number on a label.

[sacko]

Andy was talking about it on the Helination podcast too.

The difference in power between Opti 30c (which is a proven 30c) and Turnigy 30c is night and day IME; so definitely makes you wonder what C Rating Turnigy packs really are.

[stanley1]

The 65c tp's are rated for 600 cycles with no loss of performance. So although they seem overpriced they are actually very very good value for money. Add that to their superior performance and its a win win situation. Buy cheap buy twice is my motto and its proven here

[sacko]

That's not what the OP is interested in though.

Have TP got any data logs available to prove this out of interest?

[stanley1]

Yes plenty from pilots in the states, turnigy are expensive rubbish is my point
Sorry to go off topic slightly

[ChrisB]

I don't think the Turnigys are true rated personally but have found the 30c ones to have plenty of grunt for me used in a 6s and 12s config,not the best packs for sure but I would never say I have found them lacking really.

Gens Ace is also on my list to try as will be one Opti pack.

[trillian]

Thanks for all the comments. The Turnigy 6s 2650 packs I have been using on the 500 work very well (and on that heli there is virtually no difference from the Gens Ace and Opti I have) as do the 3s 2200 packs I have used on a 450 so my experience with Turnigy in general has been good.

The other possibilities are that the motor simply doesn't produce any more grunt than that or possibly it could be the headspeed change setting in the ESC which I'll have a look at.

Basically I am not unhappy with the performance in general it would just be nice to have that tiny bit more torque sometimes. The motor is rated as 'max 2000 watts' so I'm not sure what kind of duration it is supposed to be capable of that or what the peak amp draws might be. 2000 watts seems like plenty of power on a .30 size heli and that's only 90 amps at 22.2 volts.

[steve_b]

There seems to be a bit of a mystic black art with gearing and speed controller throttle settings as well to consider, if you not running the motor at the rpm then this seems to cause an issue, likewise if you're too high or low on the throttle curves then that can also seem to affect performance.

Unfortunately I do not know how to do this magic so I've just gone with what I think is a reasonable setup on my helis and it seems to work for me.

[trillian]

There seems to be a bit of a mystic black art with gearing and speed controller throttle settings as well to consider, if you not running the motor at the rpm then this seems to cause an issue, likewise if you're too high or low on the throttle curves then that can also seem to affect performance.

Unfortunately I do not know how to do this magic so I've just gone with what I think is a reasonable setup on my helis and it seems to work for me.

Yeah, on previous smaller electrics it has always been just set the gearing for the headspeed you want, flatline throttle settings in idle-up
and Bob's your uncle. With this Castle Ice there are several governor modes and all sorts of other parameters. I have it set to the switching frequency Hacker says (8khz) and timing (between 8 and 15 degrees). I played around with the governor gain a bit and realised how to tell when it was too high, etc.

I have it geared right now for max torque at my highest headspeed, so although it cannot go much higher than my target headspeed, it should be able to hold that speed much better than if it was geared steeper. (unless there's a max rev curve creeping in somewhere, which I really doubt).

[bolders]

Hi Trilian

It may be the case that opti packs can deliver more power than your Turnigys etc but if you are not placing the demand on the packs (which is obviously dependant on flying style) then this is a non issue. This can be determined by a little bit of analysis and there are a couple of possible approaches.

You can stuff an opti pack in there and just go by what your mind tells you which is a simple way of doing it but you have to be wary of the placebo effect.

Alternatively you can use the castle logs. There are 3 things you are looking for which are head speed, the recovery time of the headspeed when you load the head, and the throttle percentage.
Ultimately if you are maintaining a constant headspeed throughout your flight then you are achieving the full available power for that setup, for a given pitch (regardless of pack etc). However the reality is the headspeed will change to some degree thoughout the flight and this variation in headspeed and how quickly it recovers are your indicators of whether or not the pack is holding back your performance.

The first thing to check is that your throttle percentage does not hit 100% when running at your target HS (I am happy to hit 100% throttle at teh tail end of the flight though - say last 20 to 30 seconds). If you are hitting 100% throttle then the HS can not be governed properly and so your available power may drop. The solution is to go up a tooth on the pinion or try a stronger pack that does not have such a large voltage drop under load.

IF this is fine then look at the logs (the higher the sample rate the better). Look at the maximum and minimum HS (excluding spoolup etc) and when you identify the minimums look at how quickly the head speed recovers ( note governor gain will also effect HS recovery time). You can use your judgement as to whether the min HS and recovery times are adequate or you can do a test with another pack. At this point getting hold of an Opti pack to test would be a good idea as it would give you a baseline for comparison but this is done in a measurable way and not by guessing.


To almost contradict what I have said, in theory at least, if you are below 100% throttle, pack delivery should not effect HS recovery. The ESC should just be able to ramp up the throttle (thus increase voltage) to compensate for any deficiencies and it is the governor gain that controls the rate at which this ramp up occurs.