Power in Flux
Likes Likes:  1
Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Leaf module: Top or Bottom Balance

              
   
   
  1. #1
    Senior Member JoeReal's Avatar
    Join Date
    Feb 2015
    Posts
    182
    Post Thanks / Like

    Leaf module: Top or Bottom Balance

    Hey guys,

    I have my 12 leaf modules bottom balance-
    I charge them to-
    Pack- 100v Max
    Highest cell - 4.185v
    Lowest cell - 4.142v
    Average - 4.166v

    The reason I charge to 100v is to not over charge any cell. I do not have a BMS (monitoring nor management).

    My question is-
    If I were to top balance- and get all the cells within 1/1000th of a vol. could I charge to
    Pack- 100.5v Max
    Highest cell - 4.19v
    Lowest cell ~ 4.19v
    Average ~ 4.19v

    I realize that the 0.5v pack may not seem like much, but it's more about having more cells in the 4.1-4.0 (the most energy dense volt) range for a longer period of time.

    I usually ride from 4.166v avg to 3.80 avg each day. I am noticing a large power drop off around 3.9v which is when I'm about to get onto the short highway part of my ride home from work. So the little bit extra power will mean a lot, everyday.

    Any input would be great.

    Thanks for the help guys,
    Joe

  2. #2
    Senior Member Athlon's Avatar
    Join Date
    Jul 2011
    Location
    Milan, Italy
    Posts
    380
    Post Thanks / Like

    My Social Networking


    Add Athlon on Linkedin
    4.190 looks a little too high to me for LEaf cell , for greater life you should charge them at 4.180 or 4.185

    also right now some of your cell charge above the last transition voltages 4.150 , other stay below so you actually unbalancing your pack by stressing differently the chemestry of your cell every cycle.

    bottom balancing is also really dangerous because in the event of a charger failure you will for sure overcharge some cell and have a fire or venting , a top balancing will at least make the pack more resistant to overcharging (high voltage will be shared on the cells instead of just one)

  3. #3
    Senior Member JoeReal's Avatar
    Join Date
    Feb 2015
    Posts
    182
    Post Thanks / Like
    Quote Originally Posted by Athlon View Post
    4.190 looks a little too high to me for LEaf cell , for greater life you should charge them at 4.180 or 4.185
    Thanks for the reply, Athlon.

    Ok, so I should top balance them to 4.185. Then set my charger to 100.44v (when fully charged, the pack will be closer to 100.32v, so 4.18v per cell)

    Correct?

  4. #4
    Senior Member Hugues's Avatar
    Join Date
    Jan 2012
    Location
    Switzerland
    Posts
    1,080
    Post Thanks / Like
    From this seller site:
    http://hybridautocenter.com/HAC4/ind...=72&Itemid=631

    "In many cases it is recommended limiting the charging to 4.1 - 4.15V, (especially if not using BMS)."

    I charge mine at 4.10, BMS on at all times, also when riding , to protect weakest cell, and I do have one that drops off the cliff before others.
    Regards from Switzerland
    My 2.5 Upgrade Thread

  5. Likes Athlon liked this post
  6. #5
    Senior Member DRZ400's Avatar
    Join Date
    Aug 2010
    Location
    New Jersey, USA
    Posts
    673
    Post Thanks / Like
    I have 11 modules, no BMS. Charge to 90v. Never go below 80v. Over 100 cycles and counting....all cells within .05v
    2003 Ninja 250EX, Agni #95R, 6:1 Gearing, 11 Leaf Modules.
    Alltrax SPM72400, 400 amp Controller, all LED lighting
    2014 CRF450X Supermoto
    http://www.evalbum.com/1955
    http://www.evalbum.com/3337

  7. #6
    Senior Member JoeReal's Avatar
    Join Date
    Feb 2015
    Posts
    182
    Post Thanks / Like
    Quote Originally Posted by Hugues View Post
    I charge mine at 4.10, BMS on at all times, also when riding , to protect weakest cell, and I do have one that drops off the cliff before others.
    Hughes, do you top or bottom balance?
    Which do you think I should do?
    I rarely get down even near the cells lower limit.

    Thanks

  8. #7
    Senior Member Athlon's Avatar
    Join Date
    Jul 2011
    Location
    Milan, Italy
    Posts
    380
    Post Thanks / Like

    My Social Networking


    Add Athlon on Linkedin
    Hugues uses an Orion BMS and top balance

  9. #8
    Senior Member JoeReal's Avatar
    Join Date
    Feb 2015
    Posts
    182
    Post Thanks / Like
    Quote Originally Posted by DRZ400 View Post
    I have 11 modules, no BMS. Charge to 90v. Never go below 80v. Over 100 cycles and counting....all cells within .05v
    Hey Phil,

    Wow, you bring them down to 3.3? Do you notice a large power drop off after 3.8?

    Also, how much energy do you have left after 3.8? In terms of distance per volt, I guess.

    I haven't installed my analyst yet, but I'm really curious to find out what my miles/volt is throughout the range of 4.2-3.2 v

    Right now it seems like I'm doing
    6.4 miles/10th volt from 4.1-3.9v and
    5.6 miles/10th volt from 3.9-3.7v

  10. #9
    Moderator Nuts & Volts's Avatar
    Join Date
    Aug 2010
    Location
    Columbus, OH
    Posts
    1,765
    Post Thanks / Like

    Leaf module: Top or Bottom Balance

    I take mine down to 3.4/3.5 most of the time. Been down to 3.0V under load at which point my controller LVC kicks in

    I have mine all top balanced at 4.165V using a PL8 charger. Bulk charge to ~116.5V on a 28s system, no BMS and no issues.


    Sent from my iPhone using Tapatalk
    Last edited by Nuts & Volts; 19 January 2016 at 1003.
    Whats under my tank may shock you!!! R6 Build, Blog/, [/URL] OSU Current webpage

  11. #10
    Senior Member DRZ400's Avatar
    Join Date
    Aug 2010
    Location
    New Jersey, USA
    Posts
    673
    Post Thanks / Like
    Not 3.3, (80/22)=3.63 volts The most I've ever pulled from my pack is 50ah. resting voltage was about 80v. Definitely loose about 2-3 mph off top end after 3.8 per cell. My LVC is at 72V. I almost never hit it, only in colder weather.
    2003 Ninja 250EX, Agni #95R, 6:1 Gearing, 11 Leaf Modules.
    Alltrax SPM72400, 400 amp Controller, all LED lighting
    2014 CRF450X Supermoto
    http://www.evalbum.com/1955
    http://www.evalbum.com/3337

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •