Notices
Ask the Expert Sal - Electric Airplane Advice Here is your chance to ASK SAL, the expert for all your electric flight related questions. If you are not Sal, please do not answer questions in this forum.

LI-PO Ballancing

Old 02-11-2007, 12:50 PM
  #1  
Junior Member
Thread Starter
 
Join Date: Feb 2007
Location: , UNITED ARAB EMIRATES
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default LI-PO Ballancing

Hi!!

I'm just about to take my first plunge into LI-PO/Brushless. I've got a Seb Art Katana 30E with the included Hacker s30 motor and ESC, and have some 2200 MAH LI-POs for power.

I've seen ballancers advertised. Could someone explain exactley how they work, how I use one, and the consequences if I try and get by without one?

Could someone also recommend what type of connectors would be best for this set-up?

Thanks guys!
Old 02-11-2007, 07:28 PM
  #2  
Senior Member
 
scoooper's Avatar
 
Join Date: Jun 2006
Location: crawfordville, FL
Posts: 279
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

RosscoW:: I've been do'in without a balancer for 22 charges on my 3c lipos , folks charged lipos for years before balancers were around with good results, but I too would love to here a good reply here as I'm a bit perplexed myself, your bub, scoooper
Attached Thumbnails Click image for larger version

Name:	Us53449.jpg
Views:	26
Size:	80.2 KB
ID:	619105  
Old 02-12-2007, 01:52 AM
  #3  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing


ORIGINAL: RosscoW

Hi!!

I'm just about to take my first plunge into LI-PO/Brushless. I've got a Seb Art Katana 30E with the included Hacker s30 motor and ESC, and have some 2200 MAH LI-POs for power.

I've seen ballancers advertised. Could someone explain exactley how they work, how I use one, and the consequences if I try and get by without one?

Could someone also recommend what type of connectors would be best for this set-up?

Thanks guys!
First the basics. The balancer brings the charge voltage of each individual cell to a predetermined voltage. Usually arround 4.1-4.2 volts. A balanced pack will charge all to the same voltage and discharge down to the same voltage. A charger reads the toatl voltage of the pack so for example, it will charge a 3 cell pack to 12.6 volts. If you have an unbalanced pack, say with three cells at partial dishcarge, one reading 12.1 volt, another at 12.3 volts and another at 11.9 volts. The charger will try to bring up the voltage to 12.6 volts tiotal. It will avarege charge so that the the low cell will be ok and so will the cell at 12.1 volt but the 12.3 volt cell will get a bit of overcharge starting to damage the cell. The opposite occurs while discharging. The better the balance the better the cells will work and the lobnger they will live. You can do the same thing as balancing simply by every slow charging 5-10 charges. To slow charge go to the 1/10th C rate.

Here are a few tips to keep you batteries in best shape and longest life.
Only dishcarge 75% of capacity. If you have a 2000 mah capacity only use 1500 mah...no more....
To do this you have to time you flights and see what you put back into the battery. For example if you have a 2000 mah pack and you fly for 10 minutes and have only used 1200 mah, you are safe. One your next flight you can try another minute more flight time or so and read the charge again. DO NOT RELY ON YOUR ESC! By the time your cutoff works you will have most probably damaged the battery. It only takes one over discharge to damage a battery
Store the batteries at less than 100% charge. You should store at 50-75%. I simply read the voltage as I am charging. In the case of the 3-cell pack I wait until I am at 12.4 volts and shut off.
Only go to approx 95% for a full charge. This will add many more charges to your battery pack. Most chargers start with constant current, then when the full voltage is acheived switch to constant voltage with a charge cutoff at 50 milliamps. Stop your charger when is reaches 150-100 milliamps.

More to follow...
Old 02-12-2007, 11:13 AM
  #4  
Senior Member
 
scoooper's Avatar
 
Join Date: Jun 2006
Location: crawfordville, FL
Posts: 279
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

salnsp::: I'm on my way to my LHS post-haste!!! thank you for your lipo for dummies exp, I've been read'in up on it but your simple reply was just the info I was look'in for!! thanks for your insightful an simple explanation that made it right through my thick hogg'in-box! your grateful bub, scoooper PS rossco, thanks for the thead your bub, scoooper
Attached Thumbnails Click image for larger version

Name:	Qo41212.jpg
Views:	23
Size:	71.0 KB
ID:	619611  
Old 02-12-2007, 05:37 PM
  #5  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

No problem! It can be very confusing. So many products, so many changes. Li-poly batteries are changing constantly and its hard for even companies like us to keep up.
Old 02-13-2007, 11:37 AM
  #6  
Junior Member
Thread Starter
 
Join Date: Feb 2007
Location: , UNITED ARAB EMIRATES
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

Thanks sal, that's great. My ballencer has been ordered.

WRT not over dis-charging the cells, how do you determine how much you've used on a particular flight? By the amount of charging the pack nedds next charge?

Regards

Ross
Old 02-15-2007, 10:15 AM
  #7  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

The best way to figure how much you can use for a particular airplane is to fly the aircraft for a certain amount of time, then charge it to see what you used. Be conservative! Lets say you have a 4000 mah battery pack and you fly for 10 minutes and you use 2500 mah. Now you only want to use 75% of the capacity max so that gives you 3000 mah to work with. 10 minutes flight time at 2500 mah is 250 mah per minute which means you could go to 12 minutes flight time.
Old 02-16-2007, 01:14 AM
  #8  
Junior Member
Thread Starter
 
Join Date: Feb 2007
Location: , UNITED ARAB EMIRATES
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

Thanks Sal,

All makes sense!!

Regards

Ross W
Old 02-17-2007, 12:53 AM
  #9  
Member
 
Join Date: Nov 2005
Location: Fairfield, IA
Posts: 40
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

I have two of these balancing chargers and I wouldn't use anything else on my expensive batteries.
http://www.fmadirect.com/products.htm?cat=45&nid=4
Perfect Lipo balancing charger for dummies.
And no, I do NOT work for these guys.
Happy Landings.
Old 02-17-2007, 04:43 AM
  #10  
Senior Member
 
Join Date: Sep 2004
Location: Bloomfield Hills, MI
Posts: 456
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing


ORIGINAL: Natch

I have two of these balancing chargers and I wouldn't use anything else on my expensive batteries.
http://www.fmadirect.com/products.htm?cat=45&nid=4
Perfect Lipo balancing charger for dummies.
And no, I do NOT work for these guys.
Happy Landings.
Ditto. The Cellpro just works....simple stupid. It will protect your Lipo investment.
Old 03-07-2007, 03:35 PM
  #11  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LI-PO Ballancing

You are most welcome. Actually I am finding this forum a lot of fun. I certainluy know how confusing the electric stuff can be. I like to help figure out motor systems for modelers. This hobby is all about having fun and I know that if I can get the right setup for your model or help with any of the problems that can crop up in this pretty technical hobby, it might put a smile on someones face. That's good enough for me.

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 Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.