Voltage drop (lipos natural behaviour during flight) equals RPM drop.

Governor can solve this issue. Disadvantage of governor on some setups can be poor tail behaviour due to abrupt changes in power compensating RPM drops at hard 3D manouvers.

Heating lipos before flight or during the flight (high load causes them to heat up) can compensate sometimes a little if lipos are pretty weak.

I prefer no governor, simple throttle curves.

Power headroom also helps with maintaining constant RPM but there is weight penalty.

Many good pilots like to fly at 80-90% of throttle and prefer governors. It requires proper gearing. Wrong gearing can cause fire (motor or ESC).

 

Thank you. I tried the governor but throttle curves hold my tail better. Flying my birds on 85%.

 

Best governors are at FBL units. Vbar has good one (not all Kbar gyros have governor, Fubar had one). Using mini bar gov is quite problematic due to unusuall wiring. It is doable but wróg wiring can burn bar gyro.

YEP governor is not bad. Many do not like Castle govs.

I noticed that motors with higher kV let you increase RPM but lack torque. For no gov setup lover motor kV helps in keeping close to constant RPM.

 

I have a feeling your battery packs are suffering or old and not up to the job..

A good pack will deliver close to the same performance most of the way through the flight - you do of course suffer some voltage drop but if running 85% this should mask a lot of that. So you probably need new packs..

you can do a test - say you fly at 70% - see how long your packs sustain that performance level constantly.. if they sustain it longer than the original 30 sec then you have advanced and are asking too much from your packs.

Try a higher "C" rating in your packs or if already high (ie: 65C), then try slightly larger capacity (as long as weight is ok) or a better brand.

What brand, capacity and C-rating are your current packs and how many flights have they done ?

 

Hi @jockstrap

I have poly express 3300mah 30C packs for my 500 DFC Pro. They have all about 60 flights noticed.

The C rate may be not enough anymore for my advanced flying style. I think they are still in good condition.

Kind regards

 

I don't know that brand personally - but hopefully someone else may and can add some opinion on them..
If you know anyone else with them, see how they are going - as now days they can put very fancy labels on them but that doesn't mean they deliver the goods..

Dare I say, 30C is probably the starting point on a 500 - However, I have a 30C pack on my gaui X4 II and it goes quite ok all the way to the end..

60 flights is getting up there, I've seen many packs die around that amount so possible your best bet is to buy yourself a new pack and compare... Aim for 45C or higher if possible so it will grow with you..

Also - the obvious question - you hav't let your packs drain below 20% have you at all ? as that will kill them quickly.. and the Higher the C rating you get, the kinder your flying will be on the pack.

 

Rule of thumb: never ever drain below 3.8V per cell.

 

Hi there

I had sometimes 14% on them to be honest. But in most cases I land around 30% to avoid damage.

What happens if they "die" haha? I hope the heli will not switch off in the air once....

 

Signs are obvious:
- hot lipos after flight
- cell puffing
- increase of internat resistance
- decrease in power delivered

You can still fly but less power and shorter flights will make you buy new ones and stick to 3.8V rule.

 

Yep - exactly what utrinque says..

Everyone on most of the forums say never go below 20% and that's what I always used to follow, but when you check the battery voltage - that's around 3.75V per cell and personally I fully agree with utrinque that 3.8V per cell is WAY friendlier on your lipos.. that's about 30% left..

You only loose about 30sec of flight and 30% means you have less chance of stressing your packs out, they will stay cooler and puff less as a result and give you more cycles in the long run so that 30sec you loose you will get back with extra!!!

Going to 14% is not the end of the world - good packs will bounce back from that easily - i've accidentally gone lower than that on some packs and they have survived - I tend to charge then a least to "storage charge" straight away if that happens thou - don't leave them in that low state.

The more often you go below 20% the more damage you do..

If your packs are old and can't handle it - they will go below voltage threshold of your ESC and the heli will start to loose power and shutdown so you have usually about 10-15sec to land.

However, that's if your ESC has that option set - don't set your low voltage cutout to "stop" or else your heli will simply fall from the sky and force an auto. Make sure it's set on "reduce power" mode or the equivalent for your esc.

 

Simple experiment can help. Fly hard as usual but 30 second sporter and compare by touch temperature of lipos after flight.

They actually get hot in last minute of flight.

 

Thanks a lot guys.

I have programmed a soft cutoff on my esc. But this never really happened. And I store my lipos always on 34% (storage mode on the charger).

My packs are getting warm. But I wouldnt say hot.

Its not what we want to hear but these expensive packs are just expendable items.

 

I store charge to 60% ( default % on hyperion charger) leaving them at the low charge wouldnt be helping ?

 

No. Storage voltage is around 3.8V for a reason.

It is related to chemistry of lipos.

Power reduction in freezing conditions also is related to chemistry.

Fortunatelly it is probably not a big problem in Australia. : )