Endurance - again!

For a start the fin area has been reduced by 10%.
I don't think it will have much impact on the CofG at the cut off bit of Depron weighs 0.3g!

As a back up I have made the bits for another slightly larger, lighter V tail!

Another 64 minute flight this morning (before the rain!).
The ruduced fin area seems to have limited its tendency to 'tighten' in a turn or was it just the rather calm conditions.
Anyway 1050mAh to recharge for a 64 minute flight gives a 0.98A average.
I would like another sub 1A flight just to confirm it is repeatable but they are really boring to do. :pinch:

66 minute flight this morning in very pleasant but slightly bumpy conditions.
It used 1030 MAh which gives an average current of 0.94A.
It appears a sub 1A flight is repeatable.

Standing still in the middle of a field with a Tx for long periods seems to agitate the dogs (presumably its something strange so they tend to bark) but today a friendly one dropped its ball at my feet presumably on the basis that as it appeared I was doing nothing useful could I throw it please?
The owner duly retrieved the ball and threw it but the dog obviously felt that was "not the idea at all" and brought it straight back to my feet! :lol:

Perhaps the dog wanted to make sure you were still alive! :woohoo:

I noticed that HK were selling this multi copter "low C" battery ridiculously cheap - 6000 mAh 4S for just £10.47. :woohoo:
Its 2C rating is no problem for the Endurance as it will only take that at full power and less than 0.2C when cruising.
I only need a 2S so with a bit of work I could end up with two batteries!
According to the figures the 6000 mAh as a 2S will actually weigh a bit less than the 5000 mAh I am currently using.

This all sounds to good to be true - cheaper, bigger capacity but lighter - so I have bought one to find out.

The 6Ah 4S 2C 'Multi star' battery.

It weighs 358 g
A 2S version should weigh 179g maybe a bit less as it will have a much lighter wires and a tiny JST battery connector rather than an XT60.
My 5Ah 2S 15C battery weighs 209 g
So the Multi Star is 15% lighter and has 20% more capacity!
We shall see.

With a bit of "Don't do this at home" the 6Ah 4S has changed into two 6Ah 2S.

The 4S battery was supposed to weigh 364 g but it was actually 372!
So a 'half' would nominally weigh 186 g.
As I used much thinner wires and a smaller connector my conversions came out at 174 g each.

That's 17% lighter than the 5000 mAh I have used up to now and that showed the Endurance II could fly using just 1 A.
The lighter battery should give a bit more lea way so 6 hours duration is on the cards. :woohoo:

Put 1000mAh in the 6Ah 2S and flew the Endurance this afternoon.
A bit of a breeze but very turbulent, not really 'cruising' conditions.
Tacked side to side for about 20 minutes and only turned turned down wind once - to land!
I suspect I will have to extend the nose to move the lighter battery forward by 5 mm..

Flew it again this morning in much calmer conditions which showed it can manage with the slightly aft CofG due to the lighter battery. Stayed up for 32 minutes but came down through a mixture of boredom and cold although the thermals were beginning to bubble up nicely!

Whilst the Multistar battery flies the Endurance OK I do wonder about its claimed 6Ah capacity.
First my charger considers the cells 'full' at 4.10 V (exactly and both cells!) rather than the normal 4.2.
Second the charge rate (despite what is set on the charger) is very low no more than 1A and quickly drop further.
Giving a full 6Ah charge could take a very long time! :woohoo:

I assume these Multistar batteries have a higher internal resistance than a normal LiPo which causes the charger both to limit the charge current and the final voltage.

You should do a thread on doing that, It's brill :whistle: :woohoo:

one tenor
Do you mean a thread on cutting up a LiPo?

It appears these Multi Star batteries need a bit of 'conditioning' before they start to work fully.
After 2 cycles from full to storage (but each cycle takes close to twelve hours on the charger!) the start charge is now running at over 2A and it also gets to 4.19V at 'full' - eventually!
Still can't confirm whether it has 6Ah or not. After a 4 hour discharge at 1/2A (2Ah) one cell was down to 3.4 Volts the other to 3.6 so I stopped. Unless it gets a lot better at accepting a charge it is hard to imagine it will ever show the full 6 Ah!

I think I can now confirm that this particular 6Ah 4S Multi Star battery is a real "lemon", no disrespect intended to Lemon RC!

Other have found that it has nowhere near its claimed 6Ah capacity at a 2C (12A) discharge. It appears to actually be no more than 2Ah at even a 1C (6A) discharge which makes it virtually useless for almost any sort of normal RC plane, let alone a multi copter!
My own results are actually a bit worse than even that! :woohoo:

It appears HK UK warehouse is selling of their remaining stock cheap. It is no longer available at the other warehouses.

Thanks for the research and the warning Q, It IS appreciated mate

Garry

If HK are selling them off cheap why bother as surely they are only going to get refund claims. Or are they banking on peeps just dismissing them as crap and carrying the loss Hmmmm!