Power question

[nitrolouie2142]

I have a Whiplash sport 20 hull. swapping over to electric. got a Gool rc 4800kv motor and 70a esc. I was told to get a castle 15151y, that's 2200kv.
1. I know I'm losing torque, but will this be enough to get me going.
2. if I decide to upgrade will the 70a esc handle the 15151y.
oh yeah, running 4s lipo, 2-2s packs.

thanks in advance

[robstercraws]

That hull would work great with a p-limited setup. And I’m sure the 70amp esc is not going to handle the 1515 1y. Unless your using a super small prop that 4800kv will most likely burn up the esc too unless your running it on 2s.

[nitrolouie2142]

ok, got it cheap as a combo, the esc says 2-6s but goolrc, who knows? new to electric boats. just figured it was a way to get going in electric. I used to race in FL, but since moving to NH haven't done much of anything. I guess I'll go with the Castle setup. what's a good esc for the 1515 1y and 4s.
Thanks for your input

[Fluid]

We have no clue as to the size of the OP’s motor, but regardless a 4800 Kv motor is not appropriate for the Whiplash. The 1515/1Y is not really an “upgrade”, it is a mandatory replacement. Unfortunately a 70 amp ESC is a firestarter waiting to ignite with either motor. A minimum of 150 amps like the OSE Raider would be a better ESC choice, but even then more is usually better.

Exactly what packs is the OP running? Inadequate packs will likely fail with this or any setup.


.

[NativePaul]

Do you run the boat with nitro now? Let me try to explain the problem in terms a nitro user is used to.

What size prop is on the boat, and what RPM can your Nitro engine spin it?

A motor's KV is the RPM it wants to spin per volt, with 4800KV and 4s (16.8v) it is going to try to spin at 80,640 RPM.

Amps times volts is watts, and there are 746 watts to the horsepower, so pushing a 70A ESC to its limits on 4s, it can produce 1.5 BHP. 1.5bhp is not enough to spin a decent size prop at 80,000+ RPM. Half that prop speed or under will allow you to spin a prop that will actually push the boat.

Unlike a nitro that will fairly happily bog down and get nowhere near its RPM potential if over propped, an electric will get fairly close to its RPM potential when over propped, producing more power than is sustainable in doing so and will overheat. eg if it takes 15 bhp to swing a 45mm prop at 80,000, an electric will put 15bhp into swinging it, and might make it to 60,000, but that 70A ESC wont last long with 700A flowing through it and will burn up real quick.

[nitrolouie2142]

The packs are 5200mah 30c 2s x 2 packs.

[nitrolouie2142]

Thanks for the input. Any suggestions on a decent combo. And I have no props yet, that was going to be the next question lol. I understand the Kv per volt and have a good knowledge of electrical. I work in electronics. Just trying to get a good power to weight setup.

[CraigP]

Your batts are woefully inadequate. You need a minimum of 50C batts, or they are going to puff and fail quickly. Many would be happy to tell you what a typical 30” Whiplash would run, but you need to say what kind of boating you will do. Sport, racing, SAW?

[nitrolouie2142]

We modded the CMB 21, that was in it. It was dynoed at 42,000 no load rpm. I forget the prop we ran

[CraigP]

What does the nitro motor have to do with your electrical setup?