Mystic C5000 run time

[jjrctech]

what would be the run of this setup

Mystic C5000 with 2 neu 1527 1250kv motors

2 x 7s 5000mah



also how can I calculate this my self?

Thanks

[jjrctech]

2 min is what I would thing at 150amp?? is the correct?
thanks

[jjrctech]

also the motor would draw more or less amp when the volt go up

22.2v amp draw?
29.6v amp draw?

[drwayne]

1527 rated to 4500 W peak
V x A = W .... A=V/W
running motor at peak on 6S 22.2V 4500/22.2 = 202A
running motor at peak on 7S 25.9V 4500/25.9 = 173A
More cells = more total available power by VxA=Watts

however heat is a product of Watts through the motor.


runtime depends a lot on props and setup .. light load = low Amp = long run time

[Himalaya]

My HPR115 would run about 6 minutes with 4x 6S 5000mAh before the LVC kicks in, some speed runs plus slow cornering and pauses, not sure on the C5000 though. Just FYI.

But that highly depends on your finger. I am pretty much a hard trigger puller.

Tried calculate the amperage and I was impressed, over 200A of AVERAGE current, 4KW average power.

[ManuelW]

@ Himalaya:

You run 6S2P 5000mAh cells per engine and can run about 6min before the LCV kicks in at a speed of 142km/h? Then I have to admit respect to the Leopards and 180A ESC's who can hold this.
IMHO you need too much power for those speeds. Even with a single 6S 5000mAh per motor a runtime of 4-5min should be possible.

This is me and Christian playing a bit around:

http://www.youtube.com/watch?v=P64s8aKVsZg

I use "old fashioned" Kokam 5000 and when I drive till LCV I can recharge approx. 3800mAh so with effective around 3500mAh I get a runtime of about 4min.

Maybe you've got a video of your boat. Personally I think 2x 8S 5000mAh is the absolute max. which makes sense in a HPR06. Maybe you could post a video of yours, I think with just 6S1P per engine it will make way much for fun and also has the same performance.

Best regards,
Manuel

[Himalaya]

ManuelW do you really think I can CONTINIOUSLY run @ 142km/h？ Thank you but I am really not a superman.

Also did you read my post that clearly says 4X 6S5000mAh packs ?


Richard

PS: If you can put only 3800mAh back after the LVC kick I think you either set your LVC threshold too high or the packs were really old. a Eagletree may help figure the problem out.
I can always charge more than 4500mAh back into my Turnigies.

[ManuelW]

Hello Richard,

well I forgot to write you run 6min with a "top speed" of 142km/h but I thought it was obvious. And yes I clearly read your post, but when you run 4x 6S5000mAh in a twin engine cat this is 6S2P 5000mAh per engine for me, giving 10.000mAh per engine. You could also run 12S1P 5000mAh on each motor when you connect them in series, but as far as I know your motor has around 2000kv, so I neglected this option. And with 10.000mAh per engine and these top speeds the runtime of 6min is too short I think.

Best regards,
Manuel

PS: These are Kokam 5000, cell was developed 4 years ago. With these cells and the current I need in the HPR I'll never come close to the 5000mAh before the LCV kicks in. And as I use these packs now for more than 200cycles I think the threshold set was just fine. I also have the complete UniLog System from SM-Modellbau and checked it, everything in the setup is just fine. For todays lipos you can expect due to the dramatically lower inner resistance and overall performance that you can nearly use the capacity printed on the cell.

[Himalaya]

That's the point, Manuel. Light loaded boats and heavy ones have BIG difference in performance. I was surprised too of how huge the diff is. When I ran 2X packs(10Ah total) in my cat it ran approx. 5 minutes. I then added two more packs into the head of the hull for better stability at high speeds and expect a nealy doubled runtime but actually got only 20% longer. The added 1.5kg of weight greatly increased water resistance. And since the two packs were added into the head of the hull it runs more flat, no more nose up tendency, this further increased resistance. All these wasted energy are an expense of stability.

I was thinking how if we put all the wasted energy into pushing the boat to a higher forward speed, but this just can't be easily approched for stability become a big problem @high speeds when the boat gets significantly lighter. A critical balance point in the trade offs of both directions is so hard to be located. Anyway I thought this is where the fun is for boating.

Richard

[DISAR]

what would be the run of this setup

Mystic C5000 with 2 neu 1527 1250kv motors

2 x 7s 5000mah
also how can I calculate this my self?

Thanks

It all depends on the props that you will use. I have compared my amps readings from my twin sprintcat with fecalc and I concluded:

a) The actual max-peak amps will be about the same, with fecalc with option hydro and performance, fecalc gives about 10 amps less. So, my max amps were 138A and fecalc showed 126A.
b) My average amps were 80A, by calculating the mah used with run time. So average 80 max 138.

So,for your setup my estimations are:

7s with 447 L&R
max 110-115A, speed 60 mph, runtime with average 70A: 4 mins

8s with 447 L&R
max 130-140A, speed 70 mph, runtime with average 80A: 3.3 mins