HK Genesis setup

[zhevers]

I’m new to the RC boat world and looking for some help on my current setup. I have a HK Genesis with the stock 2075kv Water-cooled Brushless Inrunner, Turnigy Aquastar 120A Water-cooled ESC, and 2x 4000 mAh 30c 3S Turnigy lipos running in series for 6S power.

My first run with this set up yielded OK results and ultimately broke the stock (plastic) prop after only 5 minutes of test runs. I have been doing some research to try and order a new prop and came across a lot of information stating that I may be over powering the boat and causing more damage than good. Is this the case? Should I change anything or just look for the right prop that won’t put too much stress on the motor that is already being over powered?

Any help would be appreciated.

Please no trolling. Thanks

[waterproof]

Hello. Welcome to a fun and nice hobby :)

6s on 2075kv is to mutch, if you calculate it then you got the rpm.

22,2v x2075kv= 46065rpm!
That could not be god for the motor or flex shaft. You could order a metal prop as the same size as the stock 38mm to not get to mutch more power, but i think your flex shaft would break instead of the plastic prop when you change to a metal prop. I would say a stock genesis only should run on 4s.
Bigger prop would give more amp draw and put a lot of stress to the boat, how big prop are we talking about? Never run it with a bigger prop than the stock.. Definitly not on 6s that already is overpowered like you said :)

How is your motor temp on 6s? And are you happy with the boat?
I have always wanted to try out the genesis boat :)
Have you try it on 4s with stock plastic prop? Someone say it would hit 30mph and someone say 40mph..

[martin]

Your 120a esc will not last long on the set up you have.

[SJFE]

If memory serves me correct with a cat that size you will want to turn no more than 30000 with a 40mm prop. Your setup will live a longer life.

[zhevers]

Thanks for the reply,

I have heard of people putting a Octura x440/3 prop on it and it sounds like it works pretty well. Im not sure if that is too big or small. like I said im still trying to get my head around the boat world and props and prop math is definatly something I need to figure out.

If I was to run my 3s in parallel instead of series would that be better? Im assuming it would because of less amps running through and less rpm.

The boat so far is awesome. I had a few problems with it initially like a bsattery mount that came un-glued and the servo mount installed backwards but after those issues were sorted its been exactly what I expected for a $200 boat w/motor.

Hello. Welcome to a fun and nice hobby :)

6s on 2075kv is to mutch, if you calculate it then you got the rpm.

22,2v x2075kv= 46065rpm!
That could not be god for the motor or flex shaft. You could order a metal prop as the same size as the stock 38mm to not get to mutch more power, but i think your flex shaft would break instead of the plastic prop when you change to a metal prop. I would say a stock genesis only should run on 4s.
Bigger prop would give more amp draw and put a lot of stress to the boat, how big prop are we talking about? Never run it with a bigger prop than the stock.. Definitly not on 6s that already is overpowered like you said :)

How is your motor temp on 6s? And are you happy with the boat?
I have always wanted to try out the genesis boat :)
Have you try it on 4s with stock plastic prop? Someone say it would hit 30mph and someone say 40mph..

[wiljm]

I was at the same point you are last summer. I know it's not recommended, but I ran 6s, x440/3 prop, with a HK 180 esc on the stock motor all last summer. This is the setup in the following video. My experience was that the motor held up fine, not sure about your ESC though. My guess is the motor rating is probably not very accurate. Also, it's probably not the most efficient motor.

I did break the stock flex shaft right away. I upgraded to a .187 shaft and haven't had an issue since. Upgrading requires a new stinger to convert to 3/16, coupler, flex shaft, drive dog, and prop nut. All can be found here. I also had all the motor mounts and battery trays come unglued and had to re-epoxy everything.

[zhevers]

Im not really looking to change the motor or ESC right now but I want to get the most out of the boat. I found a website that explained the math on lipo setups and how to compute total amps. Since im running 4000mAh 30c lipos in series, if I did the math right I would be trying to put 120a into my 120a esc which in my mind is a bad idea. If I am dead set on running the 6s setup, should I be looking at 180a+ ESC's?

[sapdforu]

A friend had stock motor and a t180 on a x642 and it went 63 mph, on 6s 5000mah turnigy batteries, it's not that hot of a setup. Will it be a race setup you can run every weekend for several years? I doubt it. But it had plenty of speed and didn't melt down the esc or batts,

[champion221elite]

Im not really looking to change the motor or ESC right now but I want to get the most out of the boat. I found a website that explained the math on lipo setups and how to compute total amps. Since im running 4000mAh 30c lipos in series, if I did the math right I would be trying to put 120a into my 120a esc which in my mind is a bad idea. If I am dead set on running the 6s setup, should I be looking at 180a+ ESC's?

I haven't taken the time to crunch your number, but lets assume your calculations are correct.

1. Pushing 120 amps constantly through a 120 amp controller is a recipe for a failure. There simply is no headroom for the unforeseen. This could be when the boat hops a wake and the prop re-enters the water at full throttle. An amp spike here will overload and already maxed out esc. Lets say your prop or rudder picks up a piece of aquatic vegetation, this will also boost the amp draw and overload the esc. A 37" cat such as the Genesis needs a minimum of a 180 amp controller.

2. 4000 mah, 30 C batteries are on the small side for boating. In series, you only have a total of 4000 mah on tap. Remember that Series doubles voltage while parallel doubles capacity. Think of voltage as horsepower while mah (capacity) is your fuel tank. If running your lipo's to 20% remaining, you really only have 3200 mah of actual run time before you risk damaging your packs. Also, 30 C is a low C rate for boating. 40C is the minimum to run for high amp draw applications such as boats. The batteries will run cooler and last longer with higher C packs.

3. 2075 KV is too high for 6s operation unless you are running a SAW setup. For recreational boating, 1400-1600 kv is perfect for 6s.

4. Be VERY CAREFUL when putting a metal prop on to replace a plastic prop. Even if the pitch and diameter are similar, the metal prop will pull more amps on an already marginal setup. Plastic props flex and do not keep their advertised pitch. Metal props keep a constant pitch under load and do not flex. Running an X440/ 3 prop on your already over worked 120 amp controller will not last long.

My advice: Ditch the stock motor and 120 amp esc. Sell them on the OSE classifieds section. Someone will snap them up for smaller boats and be happy. Use the cash to buy a motor/esc and drive components better suited for 6s running.

By way of example, I thought I could use the factory 80A esc that came with my Blackjack 29 when I swapped out the original motor for a Leopard 3650 rated at 1650 kv. I was running a sharpened, balanced and cupped Prather S215 prop. This setup lasted exactly 2.5 minutes before releasing the magic smoke from the 80A esc. Even though my calculated amp draw was below the 80A threshold, it simply did not provide any headroom. I did not account for the extra drain provided by the cupped prop which burned up my esc. Now I'm running a Leopard 3674 motor rated at 1400 kv. The esc is a SeaKing 180 and I'm swinging an Octura M545 prop. The SK180 esc has plenty of headroom for the unforeseen, and everything comes back cool. The 1400 kv motor has plenty of torque and lets me turn a bigger prop which in turn offsets the reduced rpms. It's all a balancing act, but this particular setup works great on my BJ29. High rpm's are cool, but breaking stuff sucks. I'd rather be a bit slower, and have my stuff come back nice and cool.

[zhevers]

The math I did was this,

4000mAh x 30c= 120,000 mAh =120a
Im not sure if that equation changes when you run the batteries in series. I know the voltage doubles but I'm not sure if that equation stays the same or doubles in some way?

Let's say I keep the stock 2075kv and 120a esc what would be the best battery and prop for that setup? I'm finding that it would be more cost effective right now to just change batteries rather change my entire drive train.

[zhevers]

http://www.hobbyking.com/hobbyking/s...dProduct=24287

This is the esc I have and it's rated up to a 6s setup so I think I'm just confused as to *!***!***!***!** can the motor or replace the batteries.. I think I ordered out of impulse and didn't do my research and all I want to do is run my boat and not have it melt or blow up lol

[champion221elite]

The math I did was this,

4000mAh x 30c= 120,000 mAh =120a
Im not sure if that equation changes when you run the batteries in series. I know the voltage doubles but I'm not sure if that equation stays the same or doubles in some way?

Let's say I keep the stock 2075kv and 120a esc what would be the best battery and prop for that setup? I'm finding that it would be more cost effective right now to just change batteries rather change my entire drive train.

Lets clarify what you're trying to do here. You have 4000 total mah on board and have 30 c packs, the resulting 120 amps is not your actual draw, but rather the total amount of amps board that are available to draw.

To better calculate your amp draw, it can be done two ways.

1. Fully charge your batteries and run them for exactly one minute at full throttle. Bring the boat back in and fully charge the batteries again. The resulting number of mah put back into the batteries can be computed into an amp draw formula and will provide your actual draw.

2. You can calculate your amp draw, but first you must know the wattage of your motor. Also keep in mind that your input voltage will effect the end amp draw result.

Here's an example:

3.7 volts per cell x 6s= 22.2 volts with a 1500 watt motor = 67 amps

3.3 volts per cell x 6s = 19.8 volts with a 1500 watt motor = 75 amps

3.0 volts per cell x 6s= 18 volts with a 1500 watt motor = 83 amps

As you can see, the lower you drain your batteries the more your amp draw will increase.


FE boating is rewarding, but it can be a vicious cycle if running mis-matched or poorly selected components. As a motor heats up, it draws more amps. This stresses the ESC which in turn runs hotter. The esc pulling more amps from the batteries causes them to heat up. Low C rated batteries cannot sustain high amp draws and they begin to puff and will eventually fail. If running a single loop cooling system, the cooling water from one component runs into the next before getting dumped overboard. If the esc gets water first, it's heat gets dumped into the cooling water which then flows into the motor. It's important to cool the motor first, and then cool the esc. Better still is to cool the esc and motor independently as the heat from one component is dumped overboard without heating up the other. HOWEVER, if a power system (motor and esc) are properly matched to your hull, independent cooling of each component is less of an issue. Keep things cool and your components will last longer.

[zhevers]

Champion221elite,

Thank you for the explanation and time to do so. I'm sure the boating world takes some time and mistakes before you understand it completely and a melted esc or motor arent the end of the world and can always be replaced. Nature of rc I have learned with cars and trucks.

I'm a sicker for speed and instant gratification so this is a challenge for me to work all the different components together and get the perfect match while being new to the boating hobby haha.
For right now I believe it is safest for me to switch to a 4s setup running my 120a esc and stock motor as well as a metal prop similar to the original. When the time is right I will upgrade the esc and motor to get into a 6s setup and really push the envelope.

Thanks again.

[olwarbirds]

One thing, go a bit smaller on prop size from the original plastic prop. The Genesis Hull has alot of potential, but needs a good bit of upgrading once you start running 6S or higher. There is alot of info here on the forum about all the upgrades you should do. One thing for sure to do is remove all the mounts and add carbon fiber cloth to as much of the interior hull you can get too. This hull is rather thin. Most important thing is HAVE FUN and be safe...welcome to our addiction..... DJ

[zhevers]

olwarbirds,

I have heard of the carbon fiber inlay that some have been doing and it is definatly on the list of future modifications. I think I have come to the point of lowering my batteries to a 4-5s setup until the major mods are done. Im looking for a 3/16 prop shaft kit to change out my 4mm that came stock. I have seen a nice kit for sale that with everything needed but its forever out of stock haha.

I know this is going to be a fun hobby and the addiction is already set in and I can feel my wallet getting lighter as we speek haha.

Thanks