much warmer lipos

[dogbiscuit]

i have been flying the blade 400 (gently) for a while now using my eight 2200 packs .after a flight they come of the heli mildly warmer than when they went on .
i have had the trex 500 for a week or so and have been hovering in the garden. about 6 batteries used. the packs come off this really quite warm just after the hover . i am using 2 align packs that came with it and also using the 3s packs doubled up (only the same age/type pairs). they are all coming off puffy/squidgy also, which then goes away as they cool.
i am not used to this level of heat with the 400 and so wondered if this is normal with the 500 or is there a problem?

[st200ol]

What 'C' rating are the 2200mah packs? The ususal 20C 2200mah packs when put in series on a 500 sized Heli are not really up to the job.
You could try lowering the headspeed with a smaller pinion, or a change to the TX pitch curve. Anything you can do to lower the current draw will help.

[dogbiscuit]

the 3s packs are 25c. the aligns (6s) 2100mah is 20c, the 2600mah is 25c. am i damaging the packs or is it ok to still fly/hover gently, or do i need to address the issue before any further flights

[coptermanic]

What triggers you to land after a flight??

[dogbiscuit]

about 20% left in the battery. 4 mins on the timer while working out how long they will fly for. making a point not to overdrain them

[coptermanic]

That's a good %, and they will get warmer the older they get, I believe. Hovering is quite battery demanding as there is no translational lift from fwd flight.

[Vic.P]

Heat build up in Lipos is mostly due to the internal resistance of the cells and anodes although obviously the levels of current draw will affect the temperature. As the battery gets older, the coatings on the anodes deteriorate causing higher resistance and more heat generation and less efficient current supply. Higher C rated packs effectively have a lower internal resistance which allows for the higher current demands without damaging the cells or overheating them.
As Mike says, hovering will generaly place higher demands on the battery than flying circuits and if you start to move the heli in normal flight the temperatures should drop and you should be able to increase flight times by about 1/2 to 1 minute.
When you get round to looking for replacement batteries try going for packs rated at 40C and higher and you'll find they'll come off the heli no warmer than they went on even with hovering, unless of course you have it maxed out for full on 3D in which case they'll get warm but shouldn't get hot or puffy.
The answer to your current problem with overheating is to fly gentle circuits or reduce the head speed or pitch if you are only going to hover. I would avoid using your packs with your current set up on the 500 as using them like this will invariably lead to cell damage even if the pack percentage is within a safe tollerance like 20% and especialy if they are starting to puff. Warm but not hot is what you should aim for.
Keep using the packs on your 400 which they work fine with and get some higher C rated packs for the 500.

[bolders]

Heat build up in Lipos is mostly due to the internal resistance of the cells and anodes although obviously the levels of current draw will affect the temperature. As the battery gets older, the coatings on the anodes deteriorate causing higher resistance and more heat generation and less efficient current supply. Higher C rated packs effectively have a lower internal resistance which allows for the higher current demands without damaging the cells or overheating them.

To add a little bit more info to this. I was on the FMA website the other day having a bit of a read about IR and volt drop etc when I came accross a small section which explained something quite obvious when you think about it but it was nonetheless something I had not considered before (that a lipo also dissipates power due to its IR). Basically what it stated was a battery with a higher IR is less efficient that one with a lower IR (or C rating if you like). Which is completely obvious when you consider that lipos with a higher IR come off the heli hotter than those with a lower IR.

if anyone is interested here is the link
FMA Direct : LiPo Handbook - Section 2

As Mike says, hovering will generaly place higher demands on the battery than flying circuits and if you start to move the heli in normal flight the temperatures should drop and you should be able to increase flight times by about 1/2 to 1 minute.
When you get round to looking for replacement batteries try going for packs rated at 40C and higher and you'll find they'll come off the heli no warmer than they went on even with hovering, unless of course you have it maxed out for full on 3D in which case they'll get warm but shouldn't get hot or puffy.
The answer to your current problem with overheating is to fly gentle circuits or reduce the head speed or pitch if you are only going to hover. I would avoid using your packs with your current set up on the 500 as using them like this will invariably lead to cell damage even if the pack percentage is within a safe tollerance like 20% and especialy if they are starting to puff. Warm but not hot is what you should aim for.
Keep using the packs on your 400 which they work fine with and get some higher C rated packs for the 500.

I was also of this opinion i.e. FF is more efficient due to the translational lift. However, the logs I have obtained from my ICE 100 tell a different story.
Im running 3300mAh 6S lipos in my 500 with a fairly sedate HS.
In the hover I can get somewhere around 10-12mins whilst still having approx. +20% left in the lipo. Current draw is fairly consistent around 15Amps.
When I start to do a bit of gentle flight with a few rolls flips and pitch pumps flight time drops to approx. 6mins (I might be able to get 6.5+mins out of it though). Current has a base line of approx 15 amps with peaks of between 20 - 40Amps occurring regularly.

[dogbiscuit]

i was under the impression that the trex 500 was designed to use your existing 3s packs to keep costs down, having eight of them that arnt much use is a little frustrating. i guess if i had bought 30 to 40c they would have been ok. the trouble is when you buy a blade 400 after an msr, you still dont realise that shortly in the future you will have to buy a trex 500 aswell! your ability at the time means that you are wasting money on high c packs. now i know what this hobby is like!

i flew it this afternoon and the temperatures with forward flight were less. it was a bit windy so i only flew the two align packs before stopping as i was a bit scared of crashing. i will try the 3s doubled again with foreward flight to see if they are ok when its less windy. at least the 500 does what it says on the tin with regard to wind resistance. it is far better than the blade. the blade was gone in the wind at one point.i recovered and landed and put it away

on the 500, the throttle curve normal is 0-40-80-80-80, pitch normal 32-40-70-80-88. i am only flying in normal mode, and the curves give me a hover at centre stick which i prefer to 3/4 stick. what should i do to these to help the heat situation, but not lose the centre stick hover

[st200ol]

500 sized Helicopters, when using a 6s setup are really designed to use a 2600mah pack, I use 3000mah 25C packs for my style of flying.

I have seen 450 sized helicopters using a 2650mah pack, two of those would make a better combination on the 500

Your series connected 3s packs are equal to 2200mah 6s packs, so the flying time will be reduced and the pack temp will go higher. Try a 2 or 3 min hover and see how hot the packs are. Trouble is then the flight times are so short its not worth the hassle.

Remember under load at the end of the flight you may be pulling the cell voltage very close, if not below the min recommended 3v

[Vic.P]

on the 500, the throttle curve normal is 0-40-80-80-80, pitch normal 32-40-70-80-88. i am only flying in normal mode, and the curves give me a hover at centre stick which i prefer to 3/4 stick. what should i do to these to help the heat situation, but not lose the centre stick hover

OK, first i think you could drop the mid throttle setting by at least 10% which should get the heli airborn at your mid pitch setting and will definately reduce the load on your lipos.
Unfortunately the percentage values you've quoted for pitch are pretty meaningless What we need to know is the actual degrees on the pitch guage at each of these points to be able to see if the curve is giving you the correct pitch at mid stick to match an appropriate throttle value.

However, i would actualy set a pitch to throttle curve that gives hover nearer 3/4 stick and the reason for this is that if later, when you feel confident enough to switch from normal to idle 1 during flight then there will be a marked difference in pitch when you throw the switch, ie, with your current settings for 1/2 stick hover in normal, switching to idle 1 will suddenly reduce your pitch from around say 6.5 degrees to zero degrees giving the heli a tendancy to suddenly lose hight.
With the normal curve set up for near 3/4 stick, the transition to idle 1 will be at or near the same pitch setting resulting in a much more even and comfortable transition without so much tendancy to lose hight.

My curves on my Trex 600e for normal would be

pitch: -2, +3, +5, +7, +9
Throttle: 0, 40, 70, 87, 100

and for For idle 1:

pitch: -9, -5, 0, +5, +9
Throttle: 100, 95, 90, 95, 100

The two figures in red are the transition points from normal to idle when the flight mode switch is thrown during flight and although they are not the same pitch values, the extra head speed in idle 1 compensates for slightly less pitch which makes the transition pretty smooth.

EDIT I reckon a normal curve similar tp the one i use for the 600 will give you a more efficient set up which should place less loading on your current set of lipos......at least until you get some higher C rated lipos
Hope this helps

[spunkmyer]

Down at the high wycombe compos last summer Tim a experienced member at our club was flying his delta wing with a 3 or 4s lipo. When it finally landed the lipo was so hot you could just hold it.

When I said that must be duff he said nope works fine.

My blade 400 Eflight lipos got quite hot towards the end of the life and I used then in my 400 size f/w before they went to lipo god.

[Vic.P]

Down at the high wycombe compos last summer Tim a experienced member at our club was flying his delta wing with a 3 or 4s lipo. When it finally landed the lipo was so hot you could just hold it.

When I said that must be duff he said nope works fine.

My blade 400 Eflight lipos got quite hot towards the end of the life and I used then in my 400 size f/w before they went to lipo god.

Yep, they will work fine if they get very hot, BUT, the cycle life will be drasticaly reduced and they will be on their way to lipo heaven well before their time

[spunkmyer]

Yep, they will work fine if they get very hot, BUT, the cycle life will be drasticaly reduced and they will be on their way to lipo heaven well before their time

Couldn't agree more.