Conversion = Frustration

**Mich. Maniac** · 09-11-2008, 10:10 AM

The electronics setup and motor likes to run 4S1P... which in your tight fit hull you are best off using (2) 2 cell LiPo packs wired in series. equivelant of 4S. 4S mean 4 lipo cells, 1P means they are in series so you have equally a 4 cell pack. 4S2P would mean (2) 4 cell packs wired in parallel. on the mAh side you will prolly have room for some 4200 size packs and that should get you plenty of run time and cover you amp draw easily assuming you go with 20C discharge rate or higher. Cool boat looks like it will be fun!

On a side note as this forum has grown I see a need for a batteries and electronics section to the main page. maybe someday. Searching for this kind of thing can take a while.

**Darin Jordan** · 09-11-2008, 10:12 AM

Mike,

Pretty simple... You need to get yourself ONE 4S pack... No need to parallel ("P") on that setup, unless you need more run-time...

Get yourself a couple of 2S1P packs of 4500mah or larger and plan to wire them in series (+ of one pack to - of the other)... Each pack should be able to fit up under the deck where your pictures show the NiMH packs now...

I run the same motor in my 1/10th scale on 4S1P 4350mah cells and it works out great... It can be run hotter (5S or 6S), but I wouldn't recommend it for sport running...

Also, that prop isn't going to be big enough for that motor... It might work for starters... but you'll want something in the 45mm range, or even larger, eventually... I run 47 to 50mm sized props on my 1/10th with the same motor setup...

Hope this helps...

**ED66677** · 09-11-2008, 10:43 AM

As your motor has a KV of 1500rpm/V, you may want to use a 4S or 5S Lipo pack that allow you 50Amps draw (or more), 4S would give 22000 rpm unloaded while 5S would give 27750rpm.

**Mich. Maniac** · 09-11-2008, 11:04 AM

Originally posted by Mich. Maniac

The electronics setup and motor likes to run 4S1P... which in your tight fit hull you are best off using (2) 2 cell LiPo packs wired in series. equivelant of 4S.

Just ONCE, just ONCE can I get a single

??? Wow, I just dont get it sometimes. Or maybe I dont get it at all.

**ED66677** · 09-11-2008, 11:52 AM

Just ONCE, just ONCE can I get a single

Yes Sir, I was typing it then had to leave my keyboard for a while and got back to click "post"!

**Darin Jordan** · 09-11-2008, 12:38 PM

Originally posted by ED66677

As your motor has a KV of 1500rpm/V, you may want to use a 4S or 5S Lipo pack that allow you 50Amps draw (or more), 4S would give 22000 rpm unloaded while 5S would give 27750rpm.

This motor, while it's rated at 1500KV, is actually in practice closer to 1650KV or so... A 4S pack under those light loads is going to maintain around 3.9-4.0V/cell for a good part of it's discharge... so the voltage will stay right around 16V... so we're looking more like 26,400 RPM or so unloaded...

I believe you are correct that 5S might be a better voltage from an RPM standpoint, but we're looking at a sport setup here and runtime balanced with speed is important. Also, I'd be concerned about that stock ESC on more V than it's rated for... Even if it works... I imagine that it's running on borrowed time when pushed above it's ratings...

From what I can see... the real issue is going to be props... With the prop tucked up under the boat like that... it's going to have to be small in diameter, so the pitch is going to need to be increased to make use of this motor to it's fullest extent.... I'd look at the Grim 36x55 or something similiar... small diameter, higher pitch... That little purple plastic prop isn't going to cut it... It might work initially, but there is a lot of power there and a heavy hull to start with, so the blades are going to be flattening out considerably under load.... Even so... we run 45mm and even larger props behind these motors... My 1/10th scale uses a 45-50mm prop... Though, the 42x55's in our SV27s (I've been testing the BJ26 motor in mine...) seems to make them scoot right along...

Also, back to batteries... It's a little tougher to run saddle packs wired in series when trying to do 5S... I suppose you could run 3S on one side and 2S on the other... I'm not sure about running 6S... I haven't read anything about doing it, though I know many here have... Personally, I'd be leary about going outside of the ratings of the stock ESC....

**Mich. Maniac** · 09-11-2008, 01:06 PM

Originally posted by ED66677

Yes Sir, I was typing it then had to leave my keyboard for a while and got back to click "post"!

Thanks Ed! I was just messin around anyways though. Darin seems to have a good hold on this one. Alot of good points as to how to make it faster and dependable under a good sport setup.

**ED66677** · 09-11-2008, 01:39 PM

Darin always have good info to share!

**Darin Jordan** · 09-11-2008, 01:46 PM

Thanks Guys... but given the other expertise available on this site, I'd consider what I have posted, but take to heart anything that Jay Turner or any number of others here have to say... Everything I "know" was derived from info I got from guys like them...

I can only tell you what I'd do, and what I'd do, assuming I have to run the hull with the drive setup it currently has, is run it on 4S1P of saddled 4500mah Elite 2S1P packs, and then I'd get an X645 or maybe even something bigger, and cut it down and tweak it to work with this drive setup, maintaining plenty of blade area and pitch, but cutting down the diameter to fit onto the hull...

The later of this would take a bit of tinkering and may be beyond somes desire to tweak, but that's how I'd go about it...

**Eodman** · 09-11-2008, 01:47 PM

Hey onoffski, after you get that boat running, may I suggest you get the back issues of RC boat modeller Magazine --- there were some very informative articles for us Newbies concerning Lipo use and care!

I believe Fall issue 2007, Winter issue 2007 & Spring 2008 had articles on Lipo's written by "Jay Turner" who visits this forum often!

This magazine has all kinds of helpful info for all us of R/C boat guys ... its only published 4 times a year but back issues can be ordered!

**ED66677** · 09-11-2008, 01:59 PM

Hey onoffski, after you get that boat running, may I suggest you get the back issues of RC boat modeller Magazine --- there were some very informative articles for us Newbies concerning Lipo use and care

That could be the subject of one of these important thread in the "Tips and Info for building a Fast Electric Boat !!! " section!

**Eodman** · 09-11-2008, 02:02 PM

Yeah Ed and those articles are not that long if not the whole article perhaps just a link to RCBM

**j.m.** · 09-11-2008, 03:56 PM

I think the problem is the prop and shaft. There's no reason why that hull won't run with nimh packs.

You need this:
http://www.offshoreelectrics.com/pro...prod=sol-hydro
And a flex cable to go in that stuffing tube. (at least that's what it looks like, and i'm wondering why you are running a straight shaft in a stuffing tube also...)

**Darin Jordan** · 09-11-2008, 04:35 PM

Originally posted by j.m.

I think the problem is the prop and shaft. There's no reason why that hull won't run with nimh packs.

You'll need to step up the NiMH to 14 or even 16-cells to get the same voltage under load as a 4S pack... You'll need/want at least 4S voltage with that motor setup to get the RPMs... With that smaller prop limitation, even more so...

Conversion = Frustration

Conversion = Frustration

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment