Amp Draw?

[Fruity]

Guys, I run a 9XL on 6S in my SV27 and have had good success with a 100amp speed controller until i nearly sank the boat and drowned it. Prop is a 440/3.

How do I calculate the amp draw, reason for asking is - I have purchased a H&M Maritimo and some hardware, I have also just purchased 2 x 9XL motors, I want to run 6S each side counter rotating, so I would like to make an informed decision on speedies and not get ones that are too small.

Props will start at 40mm diameter x 1.4 Pitch and go to 42 x 1.4 then 45 x 1.4 if it will push it.

Any help will be greatly appreciated.

Thanks....Tim.

[NorthernBoater]

The best way is to buy a data logger like an Eagle Tree.

[Fruity]

Yep, the Datalogger is something I would like to invest in longer term, but for now, whilst still at set up stage, do I buy 120amp, 180amp, 200amp or 240amp speedies?

And Why go for a particular size apart from -- it's bigger?

Thanks...Tim

[ED66677]

9XL on 6S will pull many many amp so you'll need a big one, also the bigger has the less internal resistance so better performance.

[Simon.O.]

Guys, I run a 9XL on 6S in my SV27 and have had good success with a 100amp speed controller until i nearly sank the boat and drowned it. Prop is a 440/3.
Thanks....Tim.

Tim,
I ran the #'s through FECalc, it is not the best program but it gives ballpark figures to work with and compare setups.
It says you are at
141A , I am sure you are not !
34,300 rpm, a good place to be.
2811W. This is very high but if your temps are normal then this figure is well off
53mph. Are you there yet ??

As a few have said, it may be a good idea to get/borrow a data logger and see what you really have.

I use FECalc to estimate my setups and compare component changes.
On water testing with a gps and my finger "temp gauge" gives me the rest of my data. It is often different from FEcalc but I still use it as a tool, not as a "bible"

Keep us posted.

[Fruity]

Simon,
Thanks, I have heard of FE Calc but never seen or used it. Interesting info as the speed is nearly spot on, just over 80k's an hour, too fast for an SV, hence the crash that killed it and drowned the speedie.

The speedie I was using was a HELI one, Dualsky 100 amp and temps were fine, so I agree that I don't think it was 140 amps, my feel is around 100amps, but that's a guess, not based on any facts.

I am contemplating the Himodel 200 amp speedies, with my own cooling, I do have a couple of Hextronic 120amp ones from hobby city that I will watercool also, don't know which ones I will end up with.......?

Thanks for the info....Tim.

[Simon.O.]

Simon,
Thanks, I have heard of FE Calc but never seen or used it. Interesting info as the speed is nearly spot on,
Interesting, and noted.
The speedie I was using was a HELI one, Dualsky 100 amp and temps were fine, so I agree that I don't think it was 140 amps, my feel is around 100amps, but that's a guess, not based on any facts.
I use the feel a lot
I am contemplating the Himodel 200 amp speedies, with my own cooling, I do have a couple of Hextronic 120amp ones from hobby city that I will watercool also, don't know which ones I will end up with.......?

Thanks for the info....Tim.

Tim
If you have run a hull on a 100A speedie and it died because the boat crashed then your speedie is thus far fine.
Yes the previous one got wet and died, I have done a bit of that too.
If a 100A was fine untill the crash then a 120A should be good to go.

Do not get too hung up on watercooling esc's. There are many folk who do not cool the esc at all. If the esc is rated well above what is drawn then you are fine.

At 50mph (80kmh) you are really pushing a SV27 hull.
The DF29 or copy may maybe a good replacement.

There is a lot of info on either of those hulls here.

[ED66677]

At 50mph (80kmh) you are really pushing a SV27 hull.

yes but that was on 6S

The DF29 or copy may maybe a good replacement.

4S is enough and take mine somewhere around the same speed with a 8XL!

[Fluid]

What few seem to realize is that the advantage of 6S in a small boat like the SV27 is to run the same speeds as a 4S system with few amps and longer run time. You only need 2/3rds that amps to reach the same speed - easier on equipment and a longer period between charges. Pushing the speed up with 6S may be fun but not practical since the hull can't take it.

I would not be surprised to find out that the OP is pulling well over 150 amps in spikes as his boat skips across the pond. If we knew the exact run time and how much charge he put back in the packs we'd have an idea of his average draw.



.

[DISAR]

Guys, I run a 9XL on 6S in my SV27 and have had good success with a 100amp speed controller until i nearly sank the boat and drowned it. Prop is a 440/3.

How do I calculate the amp draw, reason for asking is - I have purchased a H&M Maritimo and some hardware, I have also just purchased 2 x 9XL motors, I want to run 6S each side counter rotating, so I would like to make an informed decision on speedies and not get ones that are too small.

Props will start at 40mm diameter x 1.4 Pitch and go to 42 x 1.4 then 45 x 1.4 if it will push it.

Any help will be greatly appreciated.

Thanks....Tim.

Just for reference in this page with the HPR 06 (45" inch long) setups one setup is

Frank, 2x Feigao XL8, 2x YGE 120 Navy, 2x 4500 5s1p

No Fear Andy Brown x442, 4,75mm Flexwellen, 107 kmh

http://hpr06.speedtoy.com/setup.htm

The feigao 8XL on 5s is about the same with the 9XL on 6s, so you might be OK with 120 Amps ESC for 6s, however the bigger the safer.