Go Back  R/C Tech Forums > General Forums > Radio and Electronics
Yes, another lipo question lol >

Yes, another lipo question lol

Yes, another lipo question lol

Reply

Old 02-23-2011, 01:58 AM
  #1  
Moderator
Thread Starter
iTrader: (128)
 
badaml's Avatar
 
Join Date: May 2007
Location: Mountain Home,TX
Posts: 2,668
Trader Rating: 128 (100%+)
Default Yes, another lipo question lol

Would running two lipo's in parallel also double the c rating?
As in, running two 2s 5000mah 30c in series would be the same as running two 4s 2500 30c in parallel? Both would provide 16.8v at 150 amps?

Looking to pick up some batts for my erevo and figure it seems like I can probably stick two 4s batts in and wire for parallel instead of two 2 s in series. Thanks in advance.
badaml is offline  
Reply With Quote
Old 02-23-2011, 02:16 AM
  #2  
Tech Master
iTrader: (3)
 
Join Date: Jul 2008
Location: Melbourne, Australia
Posts: 1,465
Trader Rating: 3 (100%+)
Default

Yes they would both provide the same available power

Parallel doesnt double the 'c' rate just the size in mah (just becomes a 4s 5000mah 30c pack)

If you fit parallel 4s 5000mah packs you will double your runtime and available power

Cheers
crusey_aus is offline  
Reply With Quote
Old 02-23-2011, 01:31 PM
  #3  
Tech Lord
iTrader: (21)
 
Join Date: Jul 2008
Location: Houston, TX
Posts: 11,530
Trader Rating: 21 (100%+)
Default

Originally Posted by badaml View Post
Would running two lipo's in parallel also double the c rating?
As in, running two 2s 5000mah 30c in series would be the same as running two 4s 2500 30c in parallel? Both would provide 16.8v at 150 amps?

Looking to pick up some batts for my erevo and figure it seems like I can probably stick two 4s batts in and wire for parallel instead of two 2 s in series. Thanks in advance.
Combining cells in parallel or series does not change the C rating of an individual cell. When you parallel a pair of lipos, that doubles the capacity, so paralleling 2 5000mah effectively become equivalent to a 10,000mah 2S lipo. Since capacity is part of discharge amps, the discharge amps doubles - but because the capacity doubled, not the C rate.

Two 2S 5000mah in series is the same thing as a 5000mah 4S. Two 2500mah 4S in parallel is the same thing as a 4S 5000mah. So yes, they are the same, the C rating does not change.

In parallel, capacity adds, voltage stays the same. In series, voltage adds, capacity stays the same. Neither changes the C rating. Since discharge amps = capacity(mah)/1000 X C rating, these two combinations have the same discharge amps. The series combo - 5000/1000 x 30 = 150amps, the parallel combo - 5000/1000 x 30 = 150amps.


I'm guessing you don't figure the capacity right for a parallel combination...
Duster_360 is offline  
Reply With Quote
Old 02-23-2011, 01:35 PM
  #4  
Moderator
Thread Starter
iTrader: (128)
 
badaml's Avatar
 
Join Date: May 2007
Location: Mountain Home,TX
Posts: 2,668
Trader Rating: 128 (100%+)
Default

Yeah, I didn't figure the c rating changed, mis wording on my part.

Not sure how you figure I didn't figure the discharge correctly though, as the example I provided was correct.

Anyways, just wanted to make sure my figuring was correct as it seems less expensive to order 2 4s lipos with a lower c rating and a lower mah than to order 2 2s lipos with a higher mah and c rating to get similar amperage and voltage.

Just to avoid confusion lol, I was planning on 2 x 2s 5000mah 25c, but am probably going to go with 2 x 4s 3000 20c. Only a 5a difference, and I should get slightly longer run time with the 2x4.

Thanks for the help.
badaml is offline  
Reply With Quote

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