G'day from down under!

First time poster here and a regular reader, but now I have a problem I can't find the answer to...

I need some help with a strange (to me anyway) problem I have with my Gaui Hurricane 550.
I initially had her running with the stock 550W motor, stock ESC and 2 EVO 3S 2500 paks, that gave me a 5-6 minute flight time.

Recently I upgraged to the 1500W motor, stayed with the stock ESC for the time being, and decided to purchase 2 TP 3S 3850 paks. I did the usual half discharge five times with the new lipos before increasing the flight time, but I found that the stock ESC would cut power after only 4 minutes!

After experimenting on the weekend I have found that...with the 2 x EVO 3S 2500, I get a 5 min flight, cells down to 3.7V each. With 2 x Kong 3S 2200, I get 4.5 mins, cells down to 3.7 each.(makes sense)......But with the new TP 3S 3850's, I only get a 4 min flight before the ESC drops power!!! AND, the cells are reading 3.95 Volts?!#[email protected]?

Can anyone shed some light on what is going on here?
Thx in advance!

JP

What is the C rating of your new cells. If you are exceeding the max current your ESC may be tripping because of the voltage drop due to excessive internal impedance on the cells. It could also be that the ESC is getting to hot and cutting out. Are you sure you are not exceeding either the current rating of the batteries or ESC and that you have adequate cooling provided for the ESC?

Thanks for the reply Rodney.

The new packs are 25c Thunder Power. But these new packs are considerably bigger and heavier with 3850Mah each. I expected the ESC and motor to be working harder, but thought that the ESC would do the usual cut to 75% power at 3.7 volts/cell. I knew it would possibly over-heat and risk burning out all together, but didn’t expect it to cut to 75% at 3.95 volts/cell. There’s something there I’m not understanding I think.

The stock ESC is rated at 50amps and is limited in it’s programming. You can only toggle between Lipo/NiMh and governor/no-governor modes.

I guess an upgrade to a 60amp ESC would fix the issue?? Or maybe a 75 amp, or would that be overkill?

Appreciate your time, thx.

JP

JP.

Rodney ask you if you have adequate cooling provided for the ESC or lipo. I don't think you answer him, this is very important question. I bet it is not enogh cooling since your sistem it's running hotter than before. You need to provide more air flow to them, thats why your ESC it's shutting you down after a few minutes. I did had a very similar problem with my ESC shutting me down after a few minutes and a few time I was force to a hard landing. So I move the ESC closer to the nose and open a bigger hole in the cowl for the air to flow to the lipo and problem solve. Try that first before going bigger in the rest of your sistem. Check also your amp draw of the new motor it may be over amping the ESC like Rodney said and just need to throttel manegament. If this the case then maybe you need a bigger one but try this options first.


Fernando

Thx Fernando,

Yes I’ll cut a hole right over the ESC. The only opening in the pretty fibreglass canopy is at the nose, so I’ll dig out an old canopy and see what difference there is to flight times.

Weather is awful here at the moment, hoping it will clear for the weekend.
I’ll do some trials and let you know how it turns out.
Thx again for the input!

JP

Any time JP,

I hope it work. No need to make a hole on the canopy to test it just try it with out it. If it work maybe you can make some nice vents on the canopy that will look cool and still functional.

Fernando

Just cutting a hole won't help necessarily. You need to create airflow. Small hole in the front, a second hole 1.5 times as large in the rear for an exit. This is to facilitate the expansion of the hot air.

A larger ESC won't solve your problem if this is a LVC cutoff issue. The bigger ESC will still cut off because the draw on the batteries is the same, and they will still suffer the same voltage depression.

There's nothing saying here that you didn't get a dud cell or pack. Unlikely, but not unheard of.

If you could do a Whattmeter pull on each of the three batteries, just to see what happens, that would tell us pretty much everything. You would be looking for the voltage on the TP3850 pack to drop off dramatically very quickly, much more quickly than your other two packs.

One possibility here is that the added weight of the batteries and the requried power to keep your heli in the air is offsetting the additional duration you have.