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  1. #1
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    New to RC and LiPo - Need help!!

    I just opened my new Summit as a complete newbie. It is the 5607L which came with two 5000 mah batteries. I bought an EZ Peak Plus to charge faster than stock wall chargers. I also bought the dual battery module. The problem I'm running into is that I am not an electrical engineer and the instructions are very difficult for me to understand. For example, how many amps do you set the charger to when charging. Is it the same for 2 batteries at once? What about the discharge feature? Can I use the discharge feature? If so, what are the proper settings? Is it okay to use the fast charge? Will the balance charge as fast as fast charge if I crank up the amps? (To 5, I think?). The instructions that came with the charger are vague or incomplete when it comes to these questions.

    Anyway, if there's somewhere someone can point me for a layman's set of instructions it would be much appreciated.

  2. #2
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Each battery can be charged at 5 amps. How to figure this out is explained below.

    If charging two in parallel, you can double the charge rate to 10 amps. How to figure this is explained below.

    You can discharge as fast as the charger you chose will allow.

    I advise against fast charging. I always balance charge... it only takes a few minutes longer and is safer.





    I know this is going to be a lot of info all at once, but take your time and go through it piece by piece.

    I wrote this a while back... but most of it applies here too:

    I apologize in advance for the length of this write up. However, I feel that it is important to have as much factual LiPo information as possible and to have it all in one location.
    That being said...

    LiPo 101
    now in session


    Rules
    1) NEVER discharge below 3v/cell
    2) NEVER charge above 4.2v/cell
    3) NEVER puncture your pack
    4) NEVER short out your pack
    5) NEVER use a pack that has puffed
    6) NEVER charge unattended
    7) NEVER charge at a higher C rate than recommended
    8) NEVER use a pack that has been over charged/discharged
    9) ALWAYS check cell voltage before connecting your pack to anything
    10) ALWAYS keep your LiPo pack well balanced

    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%. 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 warm... during use or charging. If it is, you are abusing the pack. Also, the less your pack has to work the longer it will last.


    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.

    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. They should be of the same brand as well as have the same amount of cycles on them.
    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... 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. Storage voltage is 3.85v/cell. 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. 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... I use a ParaBoard.



    Here is what I have done...
    this information might help with your decision

    I use inexpensive batteries.
    I have found them to be very reliable, extremely cost effective, and they have been proven to be under-rated; usually providing more mah and a higher discharge C rate than stated on the pack. SPC is a great brand that under promises and over delivers. There are others that claim extreme discharge ratings that are simply impossible with the technology that is available.

    I use an iCharger 206B.
    When I purchased the charger, I thought I would never use all 20 amps of its capability. Well, now I rarely charge at anything less than 20 amps lol. I have even considered selling it to get more amperage! I have performed hundreds of charge cycles with this charger and it handles the task without a single issue.
    I highly recommend any charger in the iCharger line.

    I built my own power supply.
    I have ~$30 into my 24v 75a 1800watt power supply.
    Sounds complicated, but it really is not that difficult. If you go this route, you are going to want a server power supply as they do not drop voltage when you are pulling amperage like a standard ATX PC power supply.
    You can also purchase these pre-built.

    I hope this information helps!!

    Here are some links to some more:
    http://traxxas.com/forums/showthread...rger-vs-cooker
    http://traxxas.com/forums/showthread...charging-setup
    http://traxxas.com/forums/showthread...ply-Conversion
    http://traxxas.com/forums/showthread...ply-Conversion
    Whatever it is I just said... I could be wrong.

  3. #3
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    I just got a new lipo in the mail. I tested the cells one has 4.2v and the other has 3.6v. I tried to balance charge them with my charger. I have a ez peak plus 6 amp charger. I get a low voltage alarm not long after i try to charge it. Any suggestions?

  4. #4
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    Quote Originally Posted by dennisp06 View Post
    I just got a new lipo in the mail. I tested the cells one has 4.2v and the other has 3.6v. I tried to balance charge them with my charger. I have a ez peak plus 6 amp charger. I get a low voltage alarm not long after i try to charge it. Any suggestions?
    Is it a traxxas battery ? If not try contacting the manufacture , If it is a Traxxas battery , I was told by TS that if one cell is more than .05v off the battery battery has to be balance charge with TRAXXAS LIPO Power cell BATTERY CHARGER 2-cell 3-cell TRA2935 If this don't work the battery is most likely bad .
    1 Rusty VXL

  5. #5
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    It is a traxxas battery. I noticed that the one high reading of 4.2 was for total voltage, not just one side. That means that they shipped me a battery with one side at .6v the other at 3.6v, defective battery? I've been reading up on lipo charging. I've seen some quick charge nimh to 5v or so to jump start them, not safe but it seems to have worked. I have let them balance charge to 4.2v on one cell and the other is at 4.08v. Is there a way to get them to even out? I have a ez peak plus 6 amp charger. Jimmie Neutron below suggests hooking the high cell to a load to drain it some.

  6. #6
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It does not have to be that specific charger... but it does take some knowledge of LiPo anatomy.

    More than likely, the 3.6v cell is dead/bad. LiPo's are supposed to be shipped out at storage voltage... if it is a two cell pack storage voltage for the pack would be around 7.7v. Since your pack is 7.8v, it was close so they probably did not pay attention (or did not care) that the cells where so far out of balance.

    If it where mine, I would hook up a small load to the one high cell and drain it to match the low one and then balance charge at .5C, watching it very closely.
    Whatever it is I just said... I could be wrong.

  7. #7
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    Quote Originally Posted by Jimmie Neutron View Post

    If it where mine, I would hook up a small load to the one high cell and drain it to match the low one and then balance charge at .5C, watching it very closely.
    How would i be able to hook a load to one cell to drain it?

  8. #8
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I would call Traxxas before you do something to the pack to cause them to not want to warranty it.
    In my opinion, this clearly is a defective pack that needs to be replaced. If the PACK voltage was 4.2 I would NOT charge, drain, use, or look at harshly.
    Whatever it is I just said... I could be wrong.

  9. #9
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    Ok Jimmie thanks for the input. Ill call traxxas on sunday to see what they have to say about the pack.

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