Lets talk HV setups for a second - RC Groups
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Oct 06, 2012, 05:51 PM
RC Addict
Raydee's Avatar

Lets talk HV setups for a second

I dont hear much about High Voltage setups in boats. I think that is because most of the guys on the boat forums race and I know there is a limit on cells for racers. This season I have been flying my heli's more than I have in the past and have went to high voltage setups in them and have really liked the difference I have seen. So far my high voltage heli's have been easier on the controller's and the cells.

Now that leads me to the boats that I think may also benefit from high voltage....OR will they?

Right now some of my 6s hulls are pulling from 150 amps to 250 amps and I am running my cells in 2p like most others are to achieve more run time and to stress the cells less. I am wondering if going to a lower kv setup on 10s will alow me to run a 1p setup with amp ratings in the low 100's? Has anyone tried this switch on thier boats and have any data they can share?
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Oct 06, 2012, 07:10 PM
I feel the need for speed!
scorpion1's Avatar
Heli's are insaney powerful in power to weight ratio, planes can glide, cars can coast..........................boats need constant input of big power to keep them moving. There is a vast difference, and it has been proven time and again that boats need less amps/heat and more voltage.
Oct 06, 2012, 08:19 PM
Redneck Injuneer
bill34207's Avatar
There are a few of us here that run HV setups. Scorp is one of them, I'm another. You just can't push a large boat on a 4s or 6s setup. My old Thunderbolt "Goldfinger" being a bit of an exception as a twin running 6s 2p per motor with Castle 1717's. It was a 50" hul that weighed in around 23 lbs and 4 minutes was pretty much the limit for run time.

Even going to high voltage in a boat you still need to run 2p setups to keep your voltage from sagging and to get decent run times if you drive like we do. .

08 12 Falcon (2 min 55 sec)

That's a 41" 17-19 pound single that runs a little over 6000 watts peak.
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Oct 06, 2012, 08:33 PM
RC Addict
Raydee's Avatar
What I am talking about is running 10s in a 37" hull and 8s in my 30" hulls. If I would still have to run 2p then that won't work and I will stick with my 2p 4s and 6s setups with high amp draws.
Oct 06, 2012, 10:01 PM
Redneck Injuneer
bill34207's Avatar
For short blasts across the water (saw passes) you wouldn't have to run 2p. For extended running (race conditions) you would still need it though.
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Oct 06, 2012, 10:02 PM
RC Addict
Raydee's Avatar
Yeah then it wouldn't be worth it for me. My hope was that increasing the voltage would drop the amperage enough to only need 1p.
Oct 07, 2012, 02:05 AM
Registered User
CornelP's Avatar
Well, you are actually correct... given the same power needed to move the boat, up the voltage you lower the amps. We race under Naviga rules here and we have a limit in weight for the batteries, so 2p is out. We tried different combinations of V/mA for the batteries and almost everybody is going to the higher voltages. It's not really what you usually call HV, but it proves a point.
To get through a 6 minutes heat, on a mono 2 boat (around 30"), you have these options:
kV~2200; 4S minimum 5500mAh
kV~1900; 5S minimum 4000mAh
kV~1800; 6S minimum 3800mAh
Oct 07, 2012, 12:22 PM
I feel the need for speed!
scorpion1's Avatar
8s or 10s with 6000 mah or so would get you decent runtime with the lowish kv you are going to use.
Oct 07, 2012, 01:08 PM
Never Fast Enough

It seems to me the boating world is stuck on using high amp setups in high powered hulls.

Racing is one to blame. But that's not where it ends. I know for me, it greatly simplifies things if I were to recommend setups that are specific to one cell count for every range of hull length. Multiple cell counts for the exact same length may become confusing for the new comers to boating. In some cases it also pushes people over the border where a newer HV ESC is required. Most sport boaters, however, are not running a typical voltage setup at higher current levels. So the convenience here is excellent.

On the flip side, of course it would work to up the voltage and reduce current to maintain the same output wattage. I am in the process of converting both a 1/8th on road car, and low to mid 30" Boat to an 8s setup. I have a couple reasons for this that may differ from yours.

Rather then drawing 140A @ 14v, I wish to draw 70A @ 28v. Doing so would actually decrease the amount of cost in my ESC's. I am currently trying out some of the air ESC's I have which are half the cost for the exact same power level. I would still use 2 4s packs, except now they are in series vs parallel.

I must convert over from using high capacity > 5000mAh packs. I wish to be around the 4000mAh capacity on average. My reason for this requirement is I only wish to purchase 4s packs around that capacity, standardizing my entire RC lineup to these 4s packs.

This standard I have set for myself will be made to work for my planes, cars, boats and maybe soon helis. I'm engaged in all areas of RC and do not need stock piles of LiPo's specific to each RC. This is something that I've seen too much of.

However, because of this sometimes I need to go in the other direction where its a bit higher amps on less voltage. For example, since I only plan to run 4000 sizes 4s packs, looking at a 500e sized heli, they typically run 2600mAh 6s packs. I would have to twist things up a bit and run at an equal ratio of power using a 4s pack. This would be (2600*6/4) = 3900mAh 4s pack. This for example would work perfect for me.

I'm not quite there yet, but I'm sure the mCPx will get me there.
Oct 07, 2012, 01:26 PM
RC Addict
Raydee's Avatar
Ryan I am also using Castle airplane esc's in my boats and they are working perfect.

I am not so much concerned about standardizing my packs as I am interested in lowering my amp draws and letting everything run much cooler. I too am addicted to rc and have planes, cars, boats and heli's. I have been using all hv setups in my heli's and because the amp draws are so low I can get away with using cheaper packs and they don't even break a sweat.

If I can go to low amp 1p setups in my boats and not kill my cells I will def make the switch.
Oct 07, 2012, 02:57 PM
Never Fast Enough
Why would you not think it would work?

You can manipulate any of the numbers to maintain the same output wattage.
Oct 07, 2012, 03:42 PM
RC Addict
Raydee's Avatar
I guess that I am just concerned that even though I am going to be lowering the amp output running a HV setup that it still may not be low enough to run 1P without voltage sag under load. Doubling my voltage in my heli's came out to be about a 40% less amp draw on my logs so I am wondering if it will be about the same in the boats or less? If I was starting to setup a new boat right now I would go HV right from the start but at this point for me to take out the setups that I am running right now and start over would be a major task.

If I could try 12s with a low KV motor on a Castle HV controller that would be the ticket for me since I already have the 6s Lipo's, I would just change the parallel adapter's out for series and I would be good to go but I am not certain Castle controllers are the best option to run on 12s....even though I do run 12s on my Trex 700 with no problems.

The only problem is right now I am running 6s2p at 8000mah to get about 2-3 min of run time running 200 amps at 60+ mph. If I run the 12 setup I would have to run 12s1p 4000mah so assuming that I am running at 40% less amp draw with 50% less mah to work with it looks like I am going to lose some run time no matter what. With the way my boats are setup its not possible to run higher mah packs in a 1p HV config.
Oct 07, 2012, 07:32 PM
Never Fast Enough
ESC's generally handle their spec'd max voltage better than they handle their spec'd max current. Voltage for an ESC is typically a yes or no question where current is much more vague and has many factors influencing its max for that particular day.

However, your packs would see the exact same 25C load in either case, since you are not changing their loading. There would be a similar voltage drop in terms of a percentage.

When you say about a 40% less amp draw, do you have all the voltage and current data including motor kv values? I would expect to see closer to 50% then that. I would not expect a 20% difference. That's a little much. Unless of course you gained this extra current consumption in more power. This would make sense.
Oct 08, 2012, 08:36 AM
RC Addict
Raydee's Avatar
I took a 3s helicopter that was running a 3400kv motor and changed it to 6s with a 1700 kv motor. My amp draw went from a average of 25-30 amps to 15-18 amps. This helicopter was a nice helicopter to test this on because everything stayed the same on the heli besides the voltage and the motor KV. The 6s packs I used were almost the exact same weight as the 3s packs I was using before (3s2200 vs. 6s1200).

I tried this on one of my other larger Heli's but there were to many different variable to get a good test. For one the motor KV went from 1100 to 560 so not really half and second the battery pack weight was different and it cause the heli to be sluggish on 12s with the 550mm blades I used. I am sure that made the amp draw go up as this heli saw about a 30% decrease in amps going from 6s to 12s. I ended up switching that heli back to 6s, but it probably would have worked great if I would have run larger blades to counteract the weight of the cells OR ran smaller cells to match the weight of the 6s packs.
Oct 08, 2012, 10:59 AM
Never Fast Enough
I'd imagine that if you are drawing more current on higher voltage you are making more power in watts. There are many factors and having a motor kv that is exactly half does not really mean that it is actually half. Motor KV does vary quite a bit depending on brand.

I don't think it would be a problem if you built your next boat on double the voltage or even converted. Run time should generally be the same otherwise you are making more power on one of the setups. If you are converned with the run time aspect, further analysis of the values would allow you to pick out where the extra consumption is coming from.

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