run time

[Gen]

im new to the brushless scence and have a 32inch cat running 2 of 2s 5000mah ,with feigo 2074 kv now i was suprised my run time was so short only 2.5 mins ,,

and in reading around this seems to be the norm ,

now will my packs give me more after a few charges since there new or do i need to buy a lot more batterys ??

[Jeff Wohlt]

Prop is the real key here. Pretty hot motor. That is a 8T. I suspect it is an XL?

If you want run time you need to prop down a little. Also, is this wide open constant or playing?

What prop??

[Gen]

X444 2 blade prop , (or it could be a 44 by 1.4 ) XL whats that ?? can size is 35 by 74 ..

thats wide open , and on and off in corners a bit ,,,i just expected 5 mins ,,,,hell i get 15 mins easy in my brushless cars with 14.8v 5200 mah ..

and i dont want a slower boat ,speed is good ,not too fast ,not too slow 72kms hr




also can i ask since your the prop man ,i went to your site and since i have an x type prop can i remove some material from the tounge area as explained ,do you need experience here ,or can i cut resharpen polish and balance ??

as i can sharpen and polish and balance ..,,also will this take load off the motor as theres less water the props pushing ,,?? so will i get more runtime or less or same ...thnx ..

[Fluid]

Hi Gen:

There is no x444 prop, probably an x445 instead. If you are only getting 2.5 minutes of run time until LVC you are pulling an average of around 100 amps. For 45 mph that's not out of bounds by any means. Changing the prop alone will do little to extend run time, maybe adding less than a minute while decreasing speed. You cannot expect any boat to have near the run time of a car - boats pull a lot more amps.

You can almost double run time by adding 2 more packs for 4S2P - just watch for heat buildup in your warm December weather. Freeing the boat up more and detonguing the prop will help a little, but not a lot.

Your motor is an 8XL, meaning the longest motor in that series - a good choice. It is not a good idea to routinely run the packs down to the LVC (low voltage cutoff) as that may cause cumulative damage as well as overheating. Using a timer can prevent that, as can setting the LVC higher, 3.3-3.4volts for example.



.

[Jeff Wohlt]

Here is mine running the same set up but with a X442. I can get about 4 minutes race time and a lot more with just straight shots. This was really the first run.

http://www.youtube.com/watch?v=RM8keupHaHw

[sailr]

Cars don't draw anywhere near the amps that boats do. The motors are geared. 2.5 minutes is not unusual in race trim.

[Gen]

is there a difference with running 2 of 4s in parrallel as i want to do this but the guy i purchased boat off ,who i assume knows what hes talkin about cause hes got a fleet or 2 ,says it reduces lifespan ,, and lifespan of what motor ,batterys ?...heres hes email to me



Dear caputi007,

Boat is set up perfect for prop on 4 cell, motor gets warm but not hot.I run feigaos in 2 other boats and as long as you don't oversize the prop they are really good I started putting 2 x 14.8 3000 mah batteries in parellel but this reduces the lifespan, series is safer as well always put 2 x batteries in as it keeps the boat balanced. Don't buy the cheap winpro batteries on ebay they are crap....go to hobbyking.com and look at the turnigy nanotechs or the blue 30 to 40 C discharge they will give you your desired run time...thanks

?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ???????????????????

[andym]

Well by running two 2s 5000mah packs in series you are basically making 1 4s pack, 14.8v 5000mah. By running 2 4s 5000mah packs parallel you still have 14.8v but 10000 mah with the same c rating. As long as the motor and esc can handle the longer run time without over heating 2 x 4s packs is the better option. I do not know what life span he is talking about ? Not the packs as say 30c 10000mah is 300amps and 30c 5000mah is 150 amps.The esc could be the issue, what type ??

[Gen]

seaking 180 esc.......

I want to run 2 of 14.8 v 4000 mah 40 c in parallell .

Whats the amp draw there

[andym]

40x 4 Ah = 160 amps x 2 = 320. so what you have is 8000mah at 40c, do the math 8Ah x 40= 320. So a boat set up to run around the 100amp mark would not even bother that set up.

[Gen]

what does that 320 mean is that how much my boat can give if i have a high power system sucking more than 100 amps ,

also here is reply i got from saying batterys discharge unequally ,i dont want to buy 6 batterys then find that there all swelling puffin and poppin ,whats your guys experience with batterys in parallel ..


Dear caputi007,

I have run batteries in parralell but as soon as you connect them together the batteries equalise very quickly and you will find when you put a balancer on them they are way out. Then you will notice that the batteries start to swell. I'm not a fan of parralleling batteries.
_ _ _ _ _ _ _

[egneg]

I ran a pair of Turnigy 4S 5000mah 30C packs in parallel all season in my P-mono with out any problems.

P.S. Here is a pic of the adapters

[eboat]

4000mah lipos at 40C discharge rate means you can draw up to (4 X40 = 160)
160 amps from each of those lipos
If you run 2 packs in parallel you then can draw up to 320 amps (160+160)