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  1. #1
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    Countertops, mini fridges, cinder blocks, and fire safes! New to LiPo questions.

    Hi, I loved RC cars as a kid, and have recently decided to get back into it. At the end of next week, I'll be picking up a Slash 4x4 and a Rustler VXL for the wife. I went with the LiPo battery packs due to what I'd read on them being a better battery. All will be 2 cells for now.

    I've searched for info in the forums and have found differing info. I'm gonna give it a shot here and see what I get.

    I live where temps are usually not much colder than 30 fahrenheit, and summers can get up to 110. As I've read all the horror stories, I'm trying to find out the best way to store the batteries. Due to extreme heat buildup in the shop during the hot months, I don't want to store them out there, unless in a mini fridge. However, I don't want to store them inside the house and burn the house down while we're at work, especially when our dog stays inside.

    Would lipo bags, and then storing them in a small fireproof safe be ok for inside, or should I put them in a mini fridge in the shop?

    We've got a couple of EZ Peak plus chargers, so getting them where they need to be shouldn't be an issue, but my wife (and therefore, I) have some concerns.

    Please provide your thoughts on my storage scenarios, and feel free to provide any other suggestions. I know I can't be the only person who has dealt with this.

    Also, do lipos provide their own fuel, or would having them in a fireproof safe, like a Sentry, starve them of oxygen if they were to flame up?

    Thank you in advance!

  2. #2
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I store mine in a plastic case in the fridge in the house... not a worry to be had.
    But I also monitor my packs very closely... I check voltages before they are connected to anything and after I disconnect them from anything. You will notice a weak cell by checking voltages before it even puffs... and they do puff before they vent.

    The fridge is a good idea, in my opinion. Stable cool temps help them last longer.

    Most all of the videos on YouTube (if not all) showing a venting LiPo are staged... meaning they are purposely mistreating the pack to make it flare out.
    Whatever it is I just said... I could be wrong.

  3. #3
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    So they really only have issues when charging or de-charging? Sorry for the wording, I'm out.

  4. #4
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    4 3S lipos here. I store em and charge em on the kitchen counter. I do keep em in a lipo bag when not in use.

  5. #5
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    There are not even issues while charging or using if they are used and charged properly.
    Whatever it is I just said... I could be wrong.

  6. #6
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    I don't foresee any issues then, as I'm pretty meticulous about things. Anyone know about them creating their own fuel vs. being able to starve them of oxygen?

  7. #7
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    Look around your house you actually may be surprised you may already have a lippo their.. Phones, cell phones, power tools, computers... Lipos have been in some of those things for years. When i checked i had a drill with lipo that is a few years old and i have beat the crap outa that thing

  8. #8
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Every YouTube fire I have seen LiPo's flare out and then smoke... they really don't burn.
    Whatever it is I just said... I could be wrong.

  9. #9
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    I appreciate the thoughts. I think I'm gonna go with lipo bags and a small fire and waterproof safe. At least that's what I'm looking at right now

  10. #10
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Nothing wrong with that!
    Whatever it is I just said... I could be wrong.

  11. #11
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    One last question....for now. Can you create false bottoms in lipos, or are they immune to that? I've read that to break them in it is best to not fully charge, and you can charge them to about 80% in a lot less than 80^ of the total charge time

  12. #12
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    LiPo's have no memory... at all. As long as you stay within the acceptable voltage range you can charge and discharge whenever you like.

    I have not heard of only partially charging during a break in period... I have heard of gently accelerating for the first few runs though.
    Whatever it is I just said... I could be wrong.

  13. #13
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    Ok, I feel that I understand this, but just want to confirm. The ex peak plus is a 6 amp charger, so on a 3300, I can charge at 3 amps, and then on a 7600, I can charge at 6, since it goes no higher, correct?

    Also, in storage mode, it says it sets it about 50%, and that in discharge mode there is a predetermined voltage cutoff based on the number of cells. The pic in the guide looks like it is 6.0v. Is that right? I thought I'd seen where people suggested 3.7 to 3.9.

    After you run it down, if it is near that range, do I need to do anything to it? Sorry, but I don't find this guide to be too easy to understand the processes other than "just do this".

  14. #14
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    3.3 amps would be 1C... 3 amps is fine though.

    You are correct on the 6 amps for the 7600.

    The picture may be incorrect... I would see what the voltage is when you use storage. I doubt it will really bring them down to 6v for a 2S pack.

    If you are done running and the pack is anywhere between 3.7v/cell and 3.9v/cell you don't have to do anything. Storage voltage is the only voltage that is not that critical.
    Whatever it is I just said... I could be wrong.

  15. #15
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    Ok. Charging a traxxas 2 cell 3300 mah on ex plus. Selected balance and hooked it up. It registered 2 cells and showed 7.4v. I started charging (this is a new battery) and it was almost immediately at each cell as 3.98 and a total of 7.96. I called traxxas and they said that it would actually hold a bit over 4v per cell and that the charger should shut off once battery is full. It's currently showing 4.2 per cell and hasn't stopped yet. Is that right? First time charging and just have ocd, so a bit concerned. Thanks

  16. #16
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It could still be balancing them... it should stop at 4.2v/cell though; not 4.21.
    Whatever it is I just said... I could be wrong.

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    Ok, as I was monitoring them, it looks like I found a spot where it says they will cut off at 8.4 volts. I stopped them short of that as we were ready to run them some before it got dark. Ran them in the yard with the dog for a while, and then ran them on the street. All in all, it was about an hour's time. Not wide open the whole time. Went to discharge and they both were still at 7.3.
    If we're going to run them tomorrow, do I need to discharge them?

    Why is it that we're supposed to discharge to 3.7? If the traxxas discharge stops at a number above that, then how do you discharge to less?

    Thanks again for helping someone new to all this. I just want to start out right so I don't learn bad habits.

  18. #18
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    3.85v/cell is storage.
    Anywhere between 3.6-4 is considered to be ok... storage is the only voltage that is not critical.
    Whatever it is I just said... I could be wrong.

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    Jimmie, thanks for your insight on this. I greatly appreciate it as someone just getting into lipos.

    Is there a small cell checking device that I can get so i can monitor them without getting the charger out and hooking the battery up to that and selecting a charge setting?

    Also, if these are supposed to operate between approx 3.5 - 4.2v per cell, what purpose do the first 3 volts serve if they're never used. Maybe that's kind of a dumb question, but I was just curious.

  20. #20
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    That is what keeps the cells active... not sure 100%, as I have not studied that far into the chemistry that is going on within LiPo cells. I just follow the guide lines. lol

    Cell checker:
    http://www.ebay.com/itm/250810360367...84.m1436.l2649


    Just in case you have not seen it... my LiPo guide:
    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. Try not to get overwhelmed... just take it in bit by bit.
    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.
    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.

    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 storage.
    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 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 just give an example of how much a small change in how a pack is taken care of can dramatically change how the pack behaves.
    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.



    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 at a very reasonable price.

    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
    Whatever it is I just said... I could be wrong.

  21. #21
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    cool, i'll print a copy of that or reference. Thanks again!

  22. #22
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    i will have to second that on using the icharger 206b jimmy has helped me threw my lipo issues and is a great teacher and tons of knowledge.if he sells his setup if i were you i would buy it from him.i have used the ez peak traxxas charger and a dynamite and the icharger 206b was a dream come true.don't forget to get a trx paraboard too

  23. #23
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    Ok, we ran them again this evening. Ran them until low voltage cutoff. Let them cool, and then put them on balance charge to bring them up to 3.8/cell. This doesn't seem as rough as it originally sounded. The only thing is that my wife's cells appeared to be .2 off when they started up, but shortly balanced out and showed balanced when I turned the charger off at 3.8

  24. #24
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    Ok, yet another question that may be stupid: I'm a bit confused by "storage mode". Is there a difference in that and just balance charging back to 3.7-3.85v after running? I've just been balance charging them, and then checking them every couple of days if I'm not able to run them. Am I doing something wrong? If I should be using the storage mode function, then what is the difference in it vs. balance charging to the 3.85 range?

    Based on the above info (thanks btw) it doesn't appear to be, but maybe the storage mode charges differently or something?
    Last edited by sbrc13; 03-11-2013 at 07:57 AM.

  25. #25
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Storage charging usually does not balance the cells... it really is not needed for storage due to the fact that storage voltage is not that critical.

    You can use the balance charge and then manually terminate at 3.85v/cell, but even then the charger probably did not balance the cells. Balancing usually only occurs near termination voltage... 4.2v/cell for most chargers unless you can adjust the termination voltage. For instance, I terminate at 4.17v/cell due to the studies that suggest a slightly lower termination voltage can allow packs to last double the amount of cycles while only loosing a few minutes of run time. This is a setting that is adjustable with my iCharger... not all chargers have this feature.

    If you are balance charger to full voltage to store, you are stressing out the cells and taking cycles off of them... the longer cells are stressed the more likely they are to go bad.
    Whatever it is I just said... I could be wrong.

  26. #26
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    Oh, I thought it balanced them as they charged. I've just been balance charging them back to about 3.85, then waiting for both cells to show the same, and then shutting off the charger.

    The only time I use the balance charge feature and run them close to full is when I'm going to be running them. Otherwise, I've been using the balance charge feature up to about 3.85 for storage.

  27. #27
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    It would take them forever to charge if they constantly balanced! The balance leads are only fed .2 amps or so.

    Doing what you are doing does not hurt anything, but that is really what the storage feature is for.
    Whatever it is I just said... I could be wrong.

  28. #28
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    To answer your original question... no you would not realistically be able to starve the fire of O2. I think you are referencing the super high temp fires invovlving combustible metals, where when water is applied, the fire is so hot that it can actually split the H2O into H and O and thus feed itself with the fresh Oxygen that you just added from the water molecule separating. A lipo fire is small and intense so a small fire resistant container is fine. Venom/Atomic just released a pretty smart device that combines charger and metal charging box in one, or the container separately.

    http://www.venom-group.com/Stronghol...ategory=119269

    I don't think your ambient temp in the summer is a problem, it's when the temp gets up there from actual heavy use that gets the chemistry upset. I would like to see Traxxas offer a similar charger/fire-resistant container like this one, instead of a simple lipos sack. If you already have that safe that is fine, but many people use Army/Navy surplus ammo containers for cheap. Even a simple metal file cabinet will work. A lipo fire is short lived so the object is to just contain it and NOT have it on a wood bench, on the carpet indoors etc. And like said before most Youtube vids involve purposely creating a Lipo fire, I don't think I have seen a legit fire in a vehicle on the net. I've seen pics of NiMH packs that completely burned up the host RC vehicle and cringed when someone in here posted pics of a burned up NiMH pack that was on his bed charging !

    Last edited by BTEMT; 03-12-2013 at 03:42 PM.
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