RC-Monster Forums  

Go Back   RC-Monster Forums > RC-Monster Area > General Discussion

Reply
 
Thread Tools Rate Thread Display Modes
Old
  (#1)
nativepaul
RC-Monster Aluminum
 
nativepaul's Avatar
 
Offline
Posts: 522
Join Date: Jan 2007
Location: Sussex, England.
04.25.2010, 12:28 PM

Personally for me, Iam a basher not a racer so I can run a smaller lighter battery back in my cars and have a better performing and handling car at the expence of run time with higher "C" rated batteries, and for my boats I have a bunch of 240A controllers it would be nice to be able to pull 200A from the batteries although these will need a wire change to do so, also with a 450A burst rating I can run 2 motors and ESCs from 1 pack for a few seconds and hopefully get myself a record.

For car racers that need a 15 minute run time, the "actual C rating" doesnt matter, as a 15 minute run is only 4C average and even the first generation of LiPos would manage that, however there are 20C spikes that 4C batteries couldnt deal with and it wasnt till the 10C cells came out that LiPos were man enough for the task so you might say why not stick with 10C batteries and save a bunch of cash? The answer is that with every increase in "C" rating comes an increase in voltage under load which becomes even more apparent when used at less than its max "C" rating, a 10C pack would drop to about 2.8V under those spikes and only recover to about 3.2V between the spikes, wheras 45C cells will hold about 3.7v in the spikes and recover to full battery voltage in bewtween, a difference of 3.6v on a 4 cell pack which with a 100A peak is an extra 360Watts, or a whole 10th scale touring car more power than you had with 10C batteries. If 45c give a just couple of tenths of a volt under load more than 35C cells that is still 80Watts more power. As well as the power advantages the further under its rating you use a battery the cooler it will run and longer it will stay in good condition for, also I normally see an increase to my run time as well as extra power when I upgrade my cells for the same mAh rating which points to an increse in chemical efficiency.


Hot Bodies Lightning 2 Pro carbon, Mega 22/30/2, MMM, 4s3-5Ah.
Tamiya F201 carbon, Mamba 7700, MM, 2s A123 2.3ah.
Xray XT8, 1518, MMM, 4s5Ah.
Lots of boats.
fastelectrics.net

Last edited by nativepaul; 04.25.2010 at 12:39 PM.
   
Reply With Quote
Old
  (#2)
zeropointbug
Z-Pinch racer
 
zeropointbug's Avatar
 
Offline
Posts: 3,141
Join Date: Nov 2006
Location: SK, Canada
04.25.2010, 05:06 PM

That's exactly right Paul, every little bit of voltage makes a big difference in power, and to some, (me included) SYSTEM EFFICIENCY. The higher the voltage stays under load, the less power is wasted, and the more energy you have available to make a longer race, important for those longer 30 - 40 min mains where you want to size the pack just right... you want to only switch packs once in a race, so you want the smallest possible pack.

You may not EVER come near the 45C rate, but that's just the way they are rated.

You can use a pack like the 25C CX G3 lipo packs that have higher mah/g, but the voltage drops more, so that benefit is reduced, and IMO, I would rather have all the power you need, and have almost the same overall energy density. Plus, the lower rated packs, the higher rate you discharge them, the more mah capacity they lose, more so than packs like a 45C rated.

ThunderPower has 50C/100C packs if anyone didn't know too, but they are too expensive to make the difference worth it.


“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens
   
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump







Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2026, vBulletin Solutions Inc.
vBulletin Skin developed by: vBStyles.com