Another Lipo question

[Eggbert01]

Hello all
I would like to run 9s 10000 mah
Can I achieve this by connecting two sets of 5s 5000 mah pack in series with a 4s 5000 mah pack and then connect the two sets together in parallel. Wanting to put this in a 51” inch victory cat with a single TP 5680 3Y 1070 KV MOTOR. AND what size esc would be best for this setup .

[CraigP]

I think you messed up your meaning, looks like you got 14s there by the way it’s written. What you want is a 2s, 2p pack configuration. A 5s and 4s pack in series, paralleled to another 5 and 4s pack in series. If they all are equal and 5000mah (and they should be), then you get the 9s at 10,000mah that I think you desire. I would try and get packs from the same manufacturer and they use the same cell in the packs, for good load sharing. Sounds like a nice boat!

[Eggbert01]

Yes that is what I was trying to say 5s and 4s in series and then paralleled. I am ordering all new packs so they will be exactly the same . Thank You again what size esc should I go with

[srislash]

Something like a Swordfish 240 or 300 would be good. Flier has some as well. Careful with props tho. Big gas props will pull a ton of amps at high RPM.

What are your expectations before you take the ESC reccomendations to heart?

Thank You again what size esc should I go with

[Eggbert01]

Something like a Swordfish 240 or 300 would be good. Flier has some as well. Careful with props tho. Big gas props will pull a ton of amps at high RPM.

What are your expectations before you take the ESC reccomendations to heart?

I was thinking 300 amp esc by what I’ve read it is better to go bigger than needed. I am thinking of getting the boat to run high 60s low 70s.as far as prop I was thinking to start with an octura m545 diameter is 1.77 total pitch 2.65

[Eggbert01]

9s. 1070 kv 20% slippage. 2.65 pitch prop. My calculation come up with 71mph

[CraigP]

The calculator says you'll need a M645 or equivalent to hit 70. I used 92% Motor EFF, because the low KV motors run with much less loss than high KV. That's screaming on a big boat! That will keep your attention...

[Eggbert01]

Yes I just need a starting point and then work my way up depending on motor temps

[Eggbert01]

Thank You again

[Fluid]

Don’t always believe prop/speed calculators, they ignore too many factors. That prop is far too small for a 51” boat, it’s efficiency will be very poor with its very small thrust cone and high slippage. A 20% slip estimate is way too optimistic. That prop is suitable for a 30”-36” boat, not a 20# cat over four feet long. The OP should have saved $$$ and purchased a much smaller motor for that tiny prop, that big motor needs a load to run efficiently.

Even a 25% larger 50 mm prop is pretty small. The loaded rpm with that motor and voltage will be around 30,000. Much more realistic performance figures would be:

X450 = 57 mph
X455 = 63 mph

These values assume high quality packs and a well trimmed boat, and are of course estimates. But they are based on plenty of experience with large, high voltage setups. A motor with a lower Kv would have allowed larger, more efficient props to be used, and run on 10S the amp draw would be lower for comparable speeds. Actually, since he has not yet purchased packs he should consider running 8S2P, the more efficient props would give more speed than 1S more voltage. If he has the motor already, that’s what I’d do.

The OP’s 9S setup can work for his speed requirements, but he will need to watch the heat in the motor, ESC and packs if he does much extended running.



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[Eggbert01]

I have not ordered the hull yet just trying to get info on best setup first is the TP 5680 1070 kv motor to much for an Aeromarine 42” sprint cat. I have this motor .

[Fluid]

That motor will work in an AM SprintCat, depending on its use. Highly experienced oval racers have used a similar size and Kv motor in that hull, but on 10S it is marginal even for them - things get hot fast. Unless you only want to run for less than two minutes, I recommend that either the motor Kv or voltage should be reduced. There is nothing worse than to try to tune a overpowered boat and burn up expensive equipment while learning how to run it.

What do do you want to do with the boat: Oval race, General sport running, SAW-type running? Run time expectations? Type of water: ocean or large lake, calm pond, windy pond, river?



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[srislash]

Thanks for chiming in Jay. I had notification and read the 545 prop part and went ‘WHOA’!! Too small.

[Eggbert01]

That motor will work in an AM SprintCat, depending on its use. Highly experienced oval racers have used a similar size and Kv motor in that hull, but on 10S it is marginal even for them - things get hot fast. Unless you only want to run for less than two minutes, I recommend that either the motor Kv or voltage should be reduced. There is nothing worse than to try to tune a overpowered boat and burn up expensive equipment while learning how to run it.

What do do you want to do with the boat: Oval race, General sport running, SAW-type running? Run time expectations? Type of water: ocean or large lake, calm pond, windy pond, river?



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Sorry for late response this is just for sport running it will be run on a large resovior on calm days light wind at most. 5 minute run times

[Eggbert01]

When you say lower kv do you mean in the 750 to 800 range on 10s