How hot is too hot?

[Chop]

I was kinda bored this afternoon so at lunch time I went out to the pond and was going to run my Mini-V. I had not been too thrilled with it's performance on the stock battery pack and had juiced it up and put a 7 cell pack in it (GP1100's). Even with this it was mediocre.

As I was getting it ready, I noticed a Polyquest 1100mah (12c) 3s Lipo in the battery box. Hmmm...

I remember reading about someone using one in a stock Mini Rio and the only problem they had was that the wires going into the ESC got hot enough to melt some of the insulation. The wires in the Mini-V seemed a bit heavier (I still haven't gotten home to compare them). I paid $50 for the boat and about $14 for the Lipo. What the heck...

The boat was great with the 3s lipo! took off fairly quickly - the prop grabbed after about 4 feet. I ran it for about 5 minutes and brought it in. It was "a little hot" on the hatch. I opened it up, the ESC was about 115 deg. F, the motor was in the neighborhood of 140 deg, but the battery was 165 - 170 degrees.

I know you can cool the motor and esc. What causes heat in the battery: Rapid drain? I know that the electrical components and prop size matter. But I like how fast it ran because it was really stable. What can I do to keep the temperture's down?

[Ub Hauled]

it's the C rate on your batteries... way too low... you need 20-25C at least.
temps will drop.

[ED66677]

1100mAh 12C means you reasonnably can't pull more than 13Amp, and probably the same with the GP's but, the prop you were using with 7 cell (8.4V) is certainly too big for 3S (11.1V) causing higher amp and overheat! you m ay want to give it another try with a smaller prop if possible!
Use 20C or higher rated Lipo pack instead of 12C they can provide more amp and stay at reasonnable temp!

[Chop]

it's the C rate on your batteries... way too low... you need 20-25C at least.
temps will drop.

Really??? On a Mini-V???

The “C” rating… this is how quickly the battery will discharge(?). What determines if the ESC can handle it? I bought some lipo’s my Micro Hydro, by Mini Cat Racing, they are Elite 3s 2200 30c, and they said that I shouldn’t use anything higher than 25c.

You’re saying these should work in a Mini-V? They fit in the hull, but barely.

[Ub Hauled]

you still can use 1100's... just acquire a battery with higher discharge rate... but yes, technically you could use the 2200 cells in there. Sometimes bigger is not better, if your 2200 pack is too heavy for the little hull, it may throw off the whole setup... you actually may loose speed, specially on the tiny boats.
What determines what ESC should be used is the motor/prop combo... but you have no issue with that since the ESC is running luke warm. The motor was a liiiiitle bit on the warm side... not toooo bad, it could be due to the lack of power coming from the batteries or a prop that is a bit too big... hard to tell from here...
Who are "they"? The store?
Another helpful tip is, when you change things on your setup, do it one at a time so you can fix the problem w/o inadvertently creating another problem.

[Chop]

I bought some lipo’s my Micro Hydro, by Mini Cat Racing, they are Elite 3s 2200 30c, and they said that I shouldn’t use anything higher than 25c.

Jim at Mini Cat Racing. I had a small problem getting the ESC to arm.

By the way, I am using the stock prop on the Mini-V

Thanks for all the advice/help - you guy's are great.

[ED66677]

The “C” rating… this is how quickly the battery will discharge(?)

more or less yes, the xxC rating is the max amp a pack can deliver continuously or burst C being the capacity so a 1100mAh 10C pack can deliver 10x1.1=11A, if you pull more than the C rating you can damage the pack.

What determines if the ESC can handle it?

An ESC is designed to work under a certain voltage (typically 22V for standard ESC's and up to 60V or more for High Voltage ESC's) and is capable of having a current running through, number of Amp is the key thing, for example Hydra240 can handle 240Amp, if your motor can pull up to 80A, you have to have an ESC witch is at least capable of the same amp and same thing for the battery!
hope this helps

[n.h.schmidt]

Hot Cells

The guys are all giveing good advice.
One thing already mentioned is you need a different prop. Possibly smaller .I don't know what the stock prop is or how it mounts.
Another thing. Maybe your boat is too stable for its own good. A stable mono is almost always stuck to the water. Usually sucking too many amps doing so. Can you do anything to loosen it up on the water? Move weight around or change the prop angle? If you got it looser the amp draw would go down and the boat faster.
n.h.schmidt

[Chop]

Change one thing at a time, right?

Today's run consisted of the same set up as in the first post. The only thing I changed is the battery. I used a Zippy 2200mah (20-30c) 3s Lipo. The battery also has 8d on it - does anyone know what this is?

Anyhow, the temps after a 4 minute run were as follows: ESC: 84 degrees, battery: 87 degrees, and the motor: 180 degrees!!! YIKES!

The prop appears to be about 28mm.

[ED66677]

normal! your battery now can handle the amp you drain, but the motor doesn't like it!
next step is smaller prop!

[Ub Hauled]

I agree, next step is a smaller or less pitched prop... go to the next smaller size.
If you have a 1.6 pitch (x632) go to a 1.4 pitch and keep the same diameter (x432)
If you have a 1.4 series already go to the next smaller diameter

[ryan_t888]

Why are the components getting to excessive temperatures?

Monitor the temp by bringing in the hull after a couple minutes of running. Determine if the setup is too hot, if so make the neccessary changes.

Continuously over temping your components is not good practice, especially when you get in to the larger more expensive boats.
Over 140F on anything is too hot

Ryan

[ED66677]

even a couple of minute is sometimes too much, just go for 30 meters and come back, then check... and so on!
but in this case I guess it's even more difficult than on any other basic setup, I don't know anything about the Mini-V, but it looks like the original configuration is a brushed 380 right?
I don't think your gonna make any better with it! It reminds me when I started and was trying to speed up a 36" ABS mono with a pair of Speed600 Race under hummmm... as much cell as possible... 10cell! holly smoke is the best we did! but that was fun, not very fast but fun!

[n.h.schmidt]

Prop

Hi Chop
How does your prop mount? Is it screwed on? Likely 3mm or 4mm threads. There are only two props I know of under 28mm. One is the Octura X427 and the other is a Graupner 26mm. Both mount differently. You could try cooling the motor.
n.h.schmidt

[ryan_t888]

Review this thread for excellent detail on FE boating.

http://www.rcuniverse.com/forum/m_7603257/tm.htm

Ryan