Why did my pack come down so hot? Eagle Tree Data incl.

[Thrasymedes]

EDIT: Heli model Trex 600E

I'm finally making some good progress on my flying, but my 6S packs are coming down HOT, HOT, HOT....around 150-154 degrees F.

But here is the thing, I'm not sure I know why, other than to know an 8S to 10S would be more efficient, but at least by looking at the data I'm a little perplexed.

A little pre-data, my HS is around 2100 spool, 2000 running according to RH calulator, so it is an approximate. The batteries are 6S 4900mah 25C EVO FP's, the speed control is an 80A FlighTech, and the motor is a Hacker C50-11XL. My throttle curve is 100-96-94-92-94-96-100 which is a linear v-curve when using the Futaba 10C.

Looking at the data tells me a couple of things. One is my motor is a little puny for the job, and I'm feeling it in flight. It is rated for 1700W maximum but the most I have gotten it to push is 1600W which isn't cutting it anymore. On a full speed FFF, and full collective sweeping turns it just doesn't have what I want......but, motor temps are 120-125 running 130 hovering, so it's not getting scalding hot by any means.

The internal resistance for the whole packs are usually between 90 and 150mohms depeninding on temp and use. BTW- this sounds really high to me.

Also, looking at the data tells me in this flight that, (1)...I never got the cells below 3.33v per cell at any time, and (2) I stayed within the 80% rule. Also, my peak amps was around 76A, well within it's 25C rating. Also each pack has about 30 runs a piece.

In addition, the speed control is coming down just warm to the touch, not hot at all.

Help me to understand what is happening here, is there something I'm missing? Is this a case of poorly soldered battery at the Dean's connector? Is it the V-curve biting me? Is the internal resistance trying to tell me something, my hunch is this is what it is but I'm not 100% sure? Did I solder it poorly thereby increasing the internal resistance causing my packs to overwork and overheat? The connectors are not getting hot though?

Also.....I really want to jump start the power a little, but I need to understand the HV systems better. I'm currently looking at an 8S or a 10S setup, leaning toward 10S. How do I figure or plan for run times? How does a 10S 3300mah battery as compared to a 6S 4900mah correlate to run times? I want to make sure I understand it well as I'm looking at a new motor, speedy, and batt, and want the setup to be good for a long while.

Thanks all.

[skigolfmike]

I'm betting your packs are dying. I had a couple of set of FPs for my Gaui 550, and they were my worst batts. My 25C Outrage packs of similar mAh had way more punch and headspeed.

The reason packs get hot is the I^2R losses due to internal resistance in the packs. If a pack is getting hot, there is more current going through the pack than it can handle. Also, as a pack discharges, the internal resistance goes up. Especially at the end of a discharge.

Try a new pack of a different manufacturer and/or of a higher C rating.

[LoveMyTrex]

looking at that data the pack looks like it is doing OK, not great, but it doesn't look like it is dropping to much voltage.

for a 600E I would not do a 10s setup, 8s is plenty and keeps it nice and light. an outrage 8s 3700 or 4200 pack is the way to go. also look into THIS motor, and a castle creations HV-85 amp esc.

[Thrasymedes]

I'm definitely looking at the CC HV85 for sure. I also think 8S would probably be plenty for me too, just some motors I've seen, like the Hacker A50 12L turbine use 10S, is why I was thinking of it. I have also been considering the Neu 1910.

The temps on my current 6S packs used to come down 95-100 degrees or so when I was just learning to fly it and mostly hovering, but here in the last week the temps have gone really high, doing loops - backflips - stalled hammerheads - FFF - and some other goofy stuff. If I do a hover session though they come down pretty good temps, give it some goose though and the temps start getting crazy.

[wren1702]

Norman, you may want to re-gear your current set up and try governor mode with the motor running close to 100% That may help.

As far as HV goes, go for it and you'll never ever look back! A 12S 2500 pack will basically give the same flight time as a 6S 5000 pack! The great thing is that everything comes down cool.....

Wesley's 8S Phazor would bring the packs in at 145 degrees as well, the same set up and flying on 12S would bring the packs in at 90-95 degrees!

[wren1702]

Forgot to add, sorry about the slow response time!

Here's my week of work:
12 hours Monday
10 hours Tuesday
12 hours Wednesday
15 hours Thursday
only 11 today!

Anyway, I have a spare 1910/1Y/H and a spare 1907/1Y/H and a HV-85 if you would like to experiment at Huntsville!

[Thrasymedes]

Thanks Alan, I have been researching all day and also referencing some of your older posts on HV stuff.

I'm definitely going for 10S and a little overkill on the motor. The reason is that I'm finding for FAI style passes, you are really on the collective and power for a long time. To do those hammerhead stalls and swing by at full spead I'm in the collective hard for a good duration. I think this is what's killing my current packs.

That's something I had never really thought about in that whole "go for speed passes FAI style" type flying I'm going for. 6S is just not going to even come close to being enough. Thursday I was doing a long hard full on power and collective turn sweeping around the field and I had to let up. It seriously felt like I was hitting the system hard. The motor being an in-runner probably doesn't help.

8S is a step up, but I figure 10S will take me a long long way into the future, so this is the motor I just ordered.....



I will have to cut the frames slightly to get it to fit, but this motor should comfortably run 2300Watts at 45 amps with a peak of 3000Watts on a 10S, not exceeding 80 peak amps. I have had REALLY good luck with Hacker so far, so I hope it continues. I will start this one off on a 15T (6mm shaft) pinion and get a batt in the 10S 3700-4200mah range. If it adds afew grams I don't mind and with FAI light is not always priority to get it to cut through the air at speed.

We'll see what happens, but it will be a few weeks before I get it all together, in the meantime I'll cut my flights down to 4 minutes and keep a carefull eye on the 6S packs.

[Thrasymedes]

Originally Posted by wren1702

Forgot to add, sorry about the slow response time!

Here's my week of work:
12 hours Monday
10 hours Tuesday
12 hours Wednesday
15 hours Thursday
only 11 today!

Anyway, I have a spare 1910/1Y/H and a spare 1907/1Y/H and a HV-85 if you would like to experiment at Huntsville!

Holy Cow Alan!!!!! At that rate, you must be saving for that Tazer!!!....

[wren1702]

Originally Posted by Thrasymedes

Holy Cow Alan!!!!! At that rate, you must be saving for that Tazer!!!....

[Thrasymedes]

Here is a vid of Matt flyng his Logo on one of these. Not that I will ever fly anyhting like that, but the relevance is the fact he helped develop this motor, and as we have seen in the Sernergy N5, he helps develop some good stuff.

I don't think I'll have a problem with speed anymore.......

[WillJames]

What was the max voltage difference between cells after the pack came down hot.

[Thrasymedes]

Originally Posted by WillJames

What was the max voltage difference between cells after the pack came down hot.

.056V

[Thrasymedes]

Just an update. I flew it today limiting my flight to 5 minutes and taking it easier than I was Thursday. I still did a couple of full on flybys and some hammerheads but I cut down on loops and stuff. Pack came down 130F. Still not ideal nor will it let me grow like I want but at least I can fly it this way until I get the 10S system up and running as quickly as possible. I will cut flight time on down to 4 minutes to let me push some new tricks and more speed. I'm giving the whole power system to my father so it's a win/win. I get 10S and he gets a 30 minute or more run time power system on his new Cub project (10 years in the making) without having to drop a dime of his retirement funds. Gotta love flying RC...

[nasukaren]

How hot is too hot? My 2200 mAh packs come down around 37-38°C (98-100°F). They feel quite warm, but is this normal?

This is for my 450 size birds.

Karen

[aucmax]

Originally Posted by Thrasymedes

Here is a vid of Matt flyng his Logo on one of these. Not that I will ever fly anyhting like that, but the relevance is the fact he helped develop this motor, and as we have seen in the Sernergy N5, he helps develop some good stuff.

I don't think I'll have a problem with speed anymore.......

Was battery was he using? A FP 3300? Not sure as this is the battery mentioned in your conversion sig?