Results 1 to 10 of 10
  1. #1
    RC poster
    Join Date
    Jan 2012
    Posts
    11

    question about charging high MAH lipo's

    I know i have been asking a lot of questions on here since i joined just a few days ago and prolly becoming a pain, but i just try to get all the info I can before I do something .. lol. I am going to be taking the jump to lipo's here soon and i have a few questions about charging them. I would like to get one of those chargers capable of charging 4 batteries at once. I have been doing some research on them and i found one thing they all seem to have in common. When it comes to charging middle size batteries ( 4000 to 5000 mah ) they will do ok, but how do they do with charging high MAH ones. It says on all the chargers I checked it can safely do a charge rate of 5 amp per battery. They say to preferrably charge lipo's at a 1C charge ( 5000 MAH = 5 amp charge, 4500 MAH = 4.5 amp charge and so on ). So the way i see it, I would be able to charge 4 5000 MAH ( 20 amps total ) batteries at one time. Your not supposed to rack up more amps than the power supply puts out ( most are 25 amps ). So does that mean they have a MAX of 5 to 6 amps per channel or could i charge 2 batteries at say 8.2 amps as long as I dont go over what the power supply puts out. Any info on this this would be highly appreciated, preferrably someone that has one and charges high MAH batteries with it.

  2. #2
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    490
    As long as your power supply and charger can put it out your fine.
    But with charger that has 2 or more outputs (like the duos) each side is limited. Say you have a 20 amp charger, each side will generally be limited to 10 amps max.
    Batteries dont have to be charged at 1c either. They can be charged at 0.75c or 2c, as long as the cells are being ballanced. If a battery can be charged at 1c max, its not a quality pack or the manufactures are being overly precautious.

  3. #3
    RC poster
    Join Date
    Jan 2012
    Posts
    11
    Ok. Just to clarify I didnt mean they can only be charged at a max of 1C, it just seems to me thats what most people say they charge theres at. I take it that a battery will charge faster at 1C then it will at .5C correct? Yeah, about the chargers .. thats good to hear. Im planning on getting lipo's for my summit and i'm trying to get ones at least 8000 MAH. So as long as I dont go over what the power supply puts out then I should be good. Charging the higher MAH ones I will probably only just be able to charge 2 at a time instead of 3 or 4 ( charging them at 1C on 8000 MAH batteries would be 16 amps ). Is this statement correct? Thanks again for the info.

  4. #4
    RC Turnbuckle Jr. pavmentsurfer's Avatar
    Join Date
    Jul 2009
    Location
    Ontario, Canada
    Posts
    11,145
    You are correct about charging at 1C VS .5C... the higher the amps the faster the charge. the "C" charge rate number is simply a simplified way to explain that you charge the pack at 1 amp for every 1000mah of capacity. Or, 1C.

    The charger is limited by the power supply, the charger will not hurt the power supply by pulling too many amps. If the power supply doesnt have enough amp or watt output to charge at the rate your trying to charge it the charger itself will simply pull the amps back. For example, if your trying to charge 4 packs at 5 amps each (20 amps total) and you set all 4 channels to 5 amps, but your power supply is only 18 amps... your charger will automatically pull each channel back to 4.5 amps to compensate.

    The 4 port charger your looking at is, IMO, fine for smaller batteries but is EXTREMELY limiting for larger packs. You need to keep this in mind... charging at 1C typical takes 1 hour. When you charger at lower amp levels your charge times go up. So, if you have a 4 port, 5 amp per port charger and your trying to do 4X8000mah packs at 5 amps each you will be into more than 1.5 hours of charging. Not to mention this is not a super high end charger to start with so it will likely take extra time balancing.

    My suggestion is to go with a higher quality charger setup and get parallel balance and charge leads or a par aboard (that can parallel charge up to 6 packs at a time.

    Essentially when you parallel charge the charger "sees" one pack (even if 6 are connected) but it charges at the COMBINED rate of all packs connected. If you had 4 5000mah 2S packs connected the charger would see ONE 2S pack but it would see it as a 20 000mah pack and therefore could be charged at 20 amps.

    I use a para board and a I have a much simpler parallel balance and charge adapter setup. I only charge 2 packs at a time but on my charger I can do 2X 8200mah 2S SPC lipos at 2C (which is safe for the SPC pack). So, when I charge these 2 packs at a time I set the charger to 2S, set the rate to 32 amps (my charger can do that) and they are done in half an hour. Heres a pic so you can see what I'm talking about:
    Pede, Summit,
    ERBE, Rally,
    Motley Crew, 1SQ

  5. #5
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    490
    Quote Originally Posted by kaw_kx500 View Post
    charging them at 1C on 8000 MAH batteries would be 16 amps ). Is this statement correct? Thanks again for the info.
    If your charging the pair at the same time, yes.
    The higher the charge amps (or C) the faster it will charge.

    Opps Surfer beat me to it. I have the same charge coming in the mail, cant wait for 40 amps charge rate

  6. #6
    RC Turnbuckle Jr. pavmentsurfer's Avatar
    Join Date
    Jul 2009
    Location
    Ontario, Canada
    Posts
    11,145
    Your going to love it... and your going to need one BEEFY PSU to power it. The one I have is a 58 amp Dell 12v setup that was pre-converted for me. So far I havent been able to get it even warm... I guess thats a good sign.
    Pede, Summit,
    ERBE, Rally,
    Motley Crew, 1SQ

  7. #7
    RC poster
    Join Date
    Jan 2012
    Posts
    11
    Thanks guys. I really appreciate it. Lots of info for me to absorb. Thanks again.

  8. #8
    RC Champion
    Join Date
    Apr 2011
    Location
    woodstock .on.canada
    Posts
    2,194
    what other chargers can do a close to 50 amp charge?

    and couldent you wire up two psu in parellel to get more amps?

  9. #9
    RC Qualifier
    Join Date
    Jan 2011
    Posts
    490
    Most other chargers are limited to 30 amps. The powerlab 6 and 8 can do 40 amps.
    The hyperion 702 duo (I think) can do 20 amps per side.

  10. #10
    RC Champion
    Join Date
    Apr 2011
    Location
    woodstock .on.canada
    Posts
    2,194
    and the hyperion 720i net 3 ad can do 20amp charge(leist i think it can)

Posting Permissions

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