Go Back  R/C Tech Forums > General Forums > Electric On-Road
Mamba 7700 and 3s Lipos >

Mamba 7700 and 3s Lipos

Mamba 7700 and 3s Lipos

Old 02-28-2007, 07:40 AM
  #1  
Tech Initiate
Thread Starter
 
Join Date: Jun 2006
Posts: 22
Default Mamba 7700 and 3s Lipos

Hi guys, Ive been reading into this alot lately and was looking for some advice.

Basically what i have read

The Rotors are limted to 65000rpm hence why the motor is limited to a 2s lipo pack, however to me it doesnt make sense.

heres why

a 2s lipo is 7,4v x 7700kv = 56980rpm

however when charged, a lipo reads 8.4v

so 8.4 v x 7700 = 64680rpm which is the supposed limit of the rotor.

However CC say the 5700 is the quickest as it can actually run 3s

so 11.1v x 5700 = 63270rpm

And when full charged, is around 12.2v

12 x 5700 = 68400rpm which is over the safety threshold.

So my point is this. What is the real LOADED KV of the mamba motors, namely 7700. If this can be worked out then I can run a 7700 with a 3s lipo and run some resistors from the battery so that I can limit the voltage so that it maxes out at 65000rpm. This way I wouldnt have to buy another motor. Otherwise I could just use the software to peak the throttle curve at around 85%.

If this is not possible, then i guess I wil have to buy the 5700, but im pretty sure this would work fine.

So please let me know what u think.
Thanks
Dean
enricopalazzo is offline  
Old 02-28-2007, 08:43 AM
  #2  
Tech Master
iTrader: (1)
 
adamge's Avatar
 
Join Date: Sep 2006
Location: Saskatoon,SK Canada
Posts: 1,654
Trader Rating: 1 (100%+)
Default

A lipo at the load expected at full speed cruising will be around 3.9V/cell, and that's probably a high (safe) estimate.

Don't use resistors. Limiting the throttle throw after calibration is much better.

The interesting part is that Castle could fairly easily program in a rev limiter that is adjustable through the Castle Link. But, they haven't.

They also haven't got the ESC to work with other brushless motors.
adamge is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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 Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.