E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

LiPo's in parallel

Reply

Old 12-02-2011, 05:47 PM
  #1  
AlphaOrion
Thread Starter
 
AlphaOrion's Avatar
 
Join Date: Sep 2002
Location: Houston, TX
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default LiPo's in parallel

I have been searching for information on the limiting factors for wiring LiPo's in parallel, to no avail.
Basically, I want to wire up to four (4) same brand, type, capacitybatteriestogether in parallel for my Senior Telemaster. Thunder Power 6G 3300, 6S
My electric motor will consume up to 59 Amps max, and Iplanto use a 77A speed control, but in reality I am assuming a continuous consumption of 25 Amps.
Am I misguided here? Can you wire more than 2 LiPo battery packs in parallel?
Maybe my problem has to do with weak understanding of advanced LiPo usage.
My project is to fit a Senior Telemaster with this much capacity to get between 1 and 2 hours of flight time. I picked this setup because the combined weight allows me to get as much capacity as possible for the least weight addition.
Any recommendations on how to accomplish this?
AlphaOrion is offline  
Reply With Quote
Old 12-02-2011, 06:10 PM
  #2  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo's in parallel

Any number of (same series cell) packs can be hooked in parallel for high capacity. This helps , maybe. http://www.scriptasylum.com/rc_speed/lipo.html
guver is offline  
Reply With Quote
Old 12-06-2011, 09:06 AM
  #3  
Glacier Girl
My Feedback: (4)
 
Glacier Girl's Avatar
 
Join Date: Jul 2004
Location: Lakeland, FL
Posts: 7,906
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo's in parallel

Yep no problem at all. Take a look over at Hobby Lobby they make a slick system for hooking up multiple parallel and/or series connections.
http://www.hobby-lobby.com/parallel_...ueryId=2418420
http://www.hobby-lobby.com/series_mo...ueryId=2418420

Of course they are out of stock [] But you get the idea, all you do is solder your esc to one of the sets of holes on the board, and simply plug in your packs and you are good to go.

I used them in one of my P-38s, used EIGHT 3S3700 packs, 4 to a side, wired in parallel and series connections to give me 6S2P7400 on each side.
Glacier Girl is offline  
Reply With Quote
Old 12-18-2011, 09:49 PM
  #4  
chuckk2
Senior Member
 
Join Date: Jul 2007
Location: Warner Robins, GA
Posts: 1,247
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo's in parallel

If the parallel cells are exactly the same chemistry - - and they were fully charged to the same voltage independently.
Under discharge, they will remain balanced unless and until they are discharged to an unsafe level. When reasonable discharge rates exist, the cells will stay in balance. A defective cell may discharge
the good cells. You can even charge them in parallel, as long as you used a safe charging current. Usually the limit is whatever 1C rate that applies to the lowest capacity cell.
The safe max current capability will reduce as lower capacity cells energy storage is exhausted.
there are some caveats, in that dissimilar cells will usually have differing internal resistance, which makes a difference in current capability.
At high discharge rates, lead length differences may have an effect.
In an ideal environment for protecting the cells, current limiting devices should be used between each cell. Automotive fuses may be a low cost possibility. Unfortunately this is often not practical in higher current usage, unless a complex and pricy power control scheme is used. (Yes you can buy such things)
chuckk2 is offline  
Reply With Quote
Old 12-20-2011, 11:47 PM
  #5  
chuckk2
Senior Member
 
Join Date: Jul 2007
Location: Warner Robins, GA
Posts: 1,247
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo's in parallel

Just remember that adding more cells increases weight, and will likely change balance. There is a limit if it's to get off the ground and fly well.
chuckk2 is offline  
Reply With Quote

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


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service