49.9mph Using M440 Octura

[nate]

Are you serious..

[nate]

Maybe take more heat from 4s2p setup..but no faster..

[jcald2000]

Lower resistance from bigger plugs, equals less heat AND higher voltage to the motor.

[Capt. Crash]

Here is why I said 130 was pushing it.

Not really, good cells can handle 140F+ without damage - the internal resistance is lower at high temps. Over 160F is where good cells can start to go bad, although I prefer not to exceed 140F-145F personally. Heating the cells before running - or running them at an ambient of ~100F - is easier on the cells.


.

As quoted by Jason @ MaxAmps:

"120 amps is hot but with in 10 degrees of the max that a Li-Po should ever get which is 130 degrees. Chances are the issue of the pack puffing is due to the fact that your running it at or close to it's max rating for the whole run."

http://www.rcgroups.com/forums/showthread.php?t=1046645

After the smoke cleared in that thread, I'm not so sure about his knowledge on the subject nor do I think he makes a very good representative for MaxAmps. All I was trying to get was the minimum recommended temp to run my lipos at and was wondering if I puffed one due to running it too cold.

This is from the MaxAmps lipo care page:

"Lipo Battery Warming Devices/”Bumping” Lipo Packs:

Do not, under any circumstances, attempt to “heat up” your batteries or increase the voltage of a pack above 4.2V per cell using these devices or techniques. Some insidious lithium polymer retailers/distributors have suggested using these devices and techniques to increase the performance of your lithium polymer packs. THIS IS NOT SAFE AND IS LITERALLY PLAYING WITH FIRE!

Devices on the market that heat up lithium polymer batteries can increase the risk of a fire. Lithium polymer cell manufacturers suggest that exceeding 140 degrees is NOT a safe temperature for a lithium polymer cell. At 140 degrees, the pack can become unstable and very dangerous. The small increase in performance is not worth the risk of a fire. PLEASE STAY SMART AND SAFE BY NOT USING THESE PRODUCTS!

Some retailers/distributors of other brands of lithium polymer batteries have suggested that their customers and racers “bump” the voltage of their packs using settings other than the lithium polymer setting on their charger. The manufacturers of lithium polymer cells suggest a voltage range of 3V-4.2V. Increasing voltage above 4.2V per cell is not safe. You should never attempt to charge your packs beyond the voltage set for lithium polymer packs on your lithium polymer charger. Using other battery settings to “bump” the voltage beyond 4.2V per cell can cause fire and injury. The small increase in performance is not worth the risk of fire. PLEASE DO NOT USE THESE METHODS!"

http://www.maxamps.com/lipo-care.php

So as per usual there is a whole mess of opinions and conflicting information out here on the subject and this lipo newbie is trying to sort it all out!

[Grimracer]

thanks for the input

Please consider

If you are running high load props (like the 40X57/3-or other) you are taking the ESC to its limits.. This load will reduce the time you have to between SB and LVC..

Having said this it will be my pleasure to look into the shorter times between SB and LVC you are seeing.

Grim

[Fluid]

I prefer to listen to the ThunderPower and FlightPower techs, and to read their instruction sheets. Both have told me that 140F is okay. Both have told me that heating the packs can be a good thing. The fastest R/C boater in the world told me not to exceed 160F. Max who?

If higher temperatures scare you, then by all means run at 120F or less. It ruins all the fun if you are always worried about damaging your packs.



.

[Brushless55]

Please consider

If you are running high load props (like the 40X57/3-or other) you are taking the ESC to its limits.. This load will reduce the time you have to between SB and LVC..

Having said this it will be my pleasure to look into the shorter times between SB and LVC you are seeing.

Grim

I run a S220 and my esc temp is only in the upper 90s, and I only have about 3seconds after the SB kicks in..
Also the LVC kicks in to low.. Last time I ran my UL-1 I had 7.1v in one pack and 7.2v in the other.

[detox]

I've installed the 5mm bullet connectors on the motor/esc wires. I also installed two capacitors on the esc's pos/neg wires. I will also try adding lead to sponsons to make UL-1 more stable in rough water conditions.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK204&P=7

[detox]

Double post