Results 1 to 14 of 14
  1. #1
    RC poster
    Join Date
    Oct 2013
    Posts
    17

    newbie with lipos

    I need some schooling on lipos I don't know much but I do now they are dangerous so if I can get some advice about lipos that would be great

    Thanks guys
    Last edited by Double G; 02-13-2014 at 07:56 AM. Reason: spelling

  2. #2
    RC Turnbuckle Jr.
    Join Date
    Dec 2004
    Posts
    3,656
    Drum roll please as we wait for JN.

  3. #3
    Marshal Double G's Avatar
    Join Date
    May 2008
    Location
    Putting the wet stuff on the hot stuff
    Posts
    9,763
    Quote Originally Posted by Jakey View Post
    Drum roll please as we wait for JN.


    Dangerous? IMHO, no more dangerous than carrying and storing dangerous gas in a one-gallon gas can in your garage.
    Take proper care and listen to the manufacturer and you'll be fine.
    The Super Derecho

  4. #4
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
    Join Date
    Oct 2009
    Location
    Alma, MI
    Posts
    12,283
    In my opinion, NiMH is more dangerous than LiPo. I have seen NiMH pop a cell without any warning... I have never seen a LiPo vent without warning. As a matter of fact, I have severely abused a LiPo trying to get it to do vent out in the spectacular fashion you see on YouTube. I over discharged it, I over charged it, I exceeded the maximum charge rate, I charged it in NiMH mode... everything I could think of. It didn't do anything out of the ordinary until I stabbed it repeatedly with a nail... and then it only swelled up (puffed) and let out some smoke. No flame. No explosion. No fire. Kind of a let down, really. lol

    I wrote this a while back so not all of it will apply here, however, I feel that it is important to have as much factual LiPo information as possible all in one location. Try not to get overwhelmed... just take it in bit by bit. Once you know the information below, using a LiPo is really not all that complicated. After a few months of using your LiPo powered RC most of this will become second nature.


    That being said...

    LiPo 101
    now in session


    Rules
    1) NEVER discharge below 3v/cell
    -- If your LVD/LVC is adjustable, set it no lower than 3.4v/cell.
    -- This also means to unplug your pack between runs.
    2) NEVER charge above 4.2v/cell
    -- This setting should be set in your charger.
    3) NEVER puncture your pack
    -- I suggest hard case packs in open chassis RC's.
    4) NEVER short out your pack
    -- When changing connectors, cut only one wire at a time and keep them covered.
    5) NEVER use a pack that has puffed
    -- It is a recipe for disaster!
    6) NEVER charge unattended
    -- If you are not there it will take longer to respond should something go awry.
    7) NEVER charge at a higher C rate than recommended
    -- Those limitations are there for a reason.
    8) NEVER use a pack that has been over charged/discharged
    -- Even 1 time is enough to damage a pack.
    9) ALWAYS check cell voltage before connecting your pack to anything
    -- A $5ish cell checker is available via eBay.
    10) ALWAYS keep your LiPo pack well balanced
    -- Most of the LiPo horror stories come from a time before balance chargers.

    To calculate the charge rate of your pack
    mAh x charge C rate / 1000 = charge amps
    For example:
    A 2200mah 20-40C pack that states a 2C charge rate.
    2,200 x 2 / 1000 = 4.4
    This battery pack can be charged at 4.4 amps.
    - Please note that if no charge C rate is stated, 1C is standard.

    To calculate the constant discharge rate of your pack
    mAh x minimum discharge C rate / 1,000 = available amps
    For example:
    The same 2200mah 20-40C pack.
    2,200 x 20 / 1000 = 44
    This battery pack can consistently provide up to 44 amps.

    To calculate the peak/burst discharge rate of your pack
    mAh x maximum discharge C rate / 1,000 = available amps
    For example:
    Again, the same 2200mah 20-40C pack.
    2,200 x 40 / 1000 = 88
    This battery pack can provide a peak discharge rate of up to 88 amps.
    Peak rates are limited in time... unfortunately, this amount of time does not have an industry standard. This is how a lot of inflated discharge ratings can be claimed. In my experience, honest retailers/manufactures of packs will list the constant discharge rating along with the burst discharge rating and not only the burst rating.

    Ratings
    When setting up your power system for your RC, make sure that the lower discharge C rate matches or beats the continuous amperage rating of the ESC. I try to beat it by at least 10-20%. This practice will provide you the most out of your system and it will also keep your batteries from working too hard. A LiPo should NEVER be hot... during use or charging. If it is exceeding recommended temperature limits, you are abusing the pack. Also, the less your pack has to work the longer it will last.
    LiPo's perform at their best once they are between 100F - 120F. Do not exceed these temperatures. This is yet another reason to have a temperature gun for this hobby.

    Parallel
    Running two LiPo's in parallel will double run time and also your available amperage... which is handy for high demand systems. Some misinformation I have read about the discharge C rating of packs in parallel is that the rating of the pack doubles. This is not the case. The C-rating of a battery pack is a fixed parameter of that pack; well actually it is the cells within the pack that have the C rating. Connecting two packs in parallel does not change either pack as they still have the same specifications, however it does create a battery "system" with twice the effective C rating. The packs are the same, but the parallel system is now theoretically capable of discharging at twice the amp rate. This is much like the cumulative capacity available when connecting two packs in parallel.
    The packs ran in parallel MUST be of the same cell count and should be the same age, capacity, and brand.

    Series
    Running two LiPo's in series will double voltage, therefore nearly doubling the speed of your RC. Capacity remains the same. The two packs ran in series MUST have the same capacity and discharge rate. Also, they should be of the same age and brand.
    Be prepared to gear down when increasing voltage on your power system.

    Charging
    There are many charging options out there... it can get really confusing really fast. The best advise I can give is to get the absolute best charger you can afford and to ask before you purchase. Your charge system is the backbone of your electric RC hobby, treat it as such. RC's will come and go, but your charge system will remain.

    The following features are what I consider to be the absolute bare minimum for a charger... balance charging and a storage charge/discharge feature. If the charger cannot perform these tasks, look for another charger. If you are going to be charging multiple LiPo's at the same time or 10th scale or larger packs, I recommend getting a charger that is capable of at least 10 amps or more. Also, ANY half-decent charger can charge multiple LiPo's at a time. It does not require a dual or multi-charger to perform such a task. It only requires the right support equipment... such as a ParaBoard (which I use), or a Traxxas dual charge board. The ParaBoard charges the packs in parallel and the Traxxas board charges them in series.

    Storage
    Storage voltage is 3.85v/cell. This voltage is the only voltage that is not super critical for LiPo. Anywhere between 3.5-4v/cell is considered to be acceptable for short term storage. If the pack is going to be stored for more than a few days, bring the pack closer to 3.85v/cell. I suggest putting a full pack to storage voltage if it is not going to be used within 30 hours or so. The longer a pack is at full capacity, the shorter its lifespan will be. I also suggest bringing a pack up to storage voltage shortly after a run. When a LiPo's voltage lowers to a certain point, they begin to loose their voltage quickly. I would hate to see you loose a pack (or more) due to not charging up within a few hours after a run.

    For long term storage; I bring my packs to storage voltage, seal them in an airtight container, and stick them in the refrigerator. As I type this, I have had my "speed" set of 3S packs in the fridge for over 8 months at storage voltage... I check them monthly and they are still at 3.85v/cell. Almost makes me regret buying them. lol

    Making your LiPo's last
    I will give an example of how much a small change in how a pack is taken care of can dramatically change how long the pack can be safely used: Two identical packs were both charged and discharged in the exact same matter.... except one pack was charged to 4.20v/cell and the other to 4.10v/cell. This was done in a very controlled environment... not in an RC. After 500 cycles, the pack that was charged to 4.20v/cell had reached its life expectancy... it would not take more than 65% of its original capacity; meaning the LiPo was no longer able to be used safely. The pack that was charged to 4.10v/cell was still at 70% capacity after 1,000 cycles... so the .10v/cell difference more than doubled the life expectancy.


    I hope this information helps!!
    Whatever it is I just said... I could be wrong.

  5. #5
    RC Qualifier
    Join Date
    Feb 2010
    Location
    Brewster ma.
    Posts
    701
    I myself am as green as green gets with electric . That being said , I have bought a mini revo , ez peak plus and 2 lipo 2200 traxxas power cells. Now I just need to re read your explanation again and ask some questions . Everything I have read is just plain jibrish to me As I sit in front of my charger and batteries I still am afraid of not charging things correctly . I know once I figure it out it's going to be simple but I've been a nitro guy forever this is a big step for me .
    Keep the shiny side up!

  6. #6
    RC Champion
    Join Date
    Feb 2013
    Location
    Montreal, Canada
    Posts
    1,838
    And always store and charge them in LiPo bags....
    Live life to the fullest

  7. #7
    RC Qualifier
    Join Date
    Feb 2010
    Location
    Brewster ma.
    Posts
    701
    Thanks , first I have got to figure out how to charge them . Lol
    Keep the shiny side up!

  8. #8
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
    Join Date
    Oct 2009
    Location
    Alma, MI
    Posts
    12,283
    You are on the right path with quality packs and charger!

    How to start charging:
    Flip through the menu until you see "Balance Charge"... then connect the main lead and balance lead to the charger and press start.
    Whatever it is I just said... I could be wrong.

  9. #9
    RC Qualifier
    Join Date
    Feb 2010
    Location
    Brewster ma.
    Posts
    701
    It's that easy ? The charger will know what to do ?
    Keep the shiny side up!

  10. #10
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
    Join Date
    Oct 2009
    Location
    Alma, MI
    Posts
    12,283
    Yup!
    That easy... the right charger takes a lot of "work" out of caring for LiPo's.

    When using, make sure the LED glows green for LiPo mode on the ESC.

    When finished and going to put it away for a bit, put the charger in storage mode and let it do its thing.

    When finished and want to keep driving, put the charger in balance mode and let it charge the pack up.
    Whatever it is I just said... I could be wrong.

  11. #11
    RC Qualifier
    Join Date
    Nov 2012
    Posts
    740
    All you need to know is the MAH, # of cells, put the charger on balance, then put on 2s or 3s ect. And like in "lipo 101" if its a 5000mah, it's 5 amps. 2200mah, 2.2amps. Easy as pie. BTW I was afraid at first, now, ill never look back

  12. #12
    RC Qualifier
    Join Date
    Feb 2010
    Location
    Brewster ma.
    Posts
    701
    Thanks guys , I'm in the city now but when I get home in a few hours I will play. Can I charge today for play tomorrow ?
    Keep the shiny side up!

  13. #13
    RC Qualifier
    Join Date
    Feb 2010
    Location
    Va
    Posts
    476
    Yes, just don't leave them fully charged for more then a day or two
    Twin Brushless Latrax Teton, .21TM Jato

  14. #14
    RC Competitor
    Join Date
    Jan 2014
    Location
    Melbourne Australia
    Posts
    65
    The bit that confused me with the ez peak plus 6 is that you don't use the "charge" mode to charge. You charge in "balance" mode.

    Putting your packs to storage is the process of not having them fully charged or fully discharged. They should be about 3.85v per cell.

    The storage mode on the ez peak only charges at max 2.0A so if your packs are 2000mah or higher just set to 2.0A and set the cell count as normal.

Posting Permissions

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