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Why the paranoia about charging?

Discussion in 'Pro/Adv Discussion' started by Dan Wells, Oct 8, 2015.

  1. Dan Wells

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    It seems like most Phantomers are really careful about charging their battery when they can watch it, not leaving it charged, etc. I just charged my first one, placing it on a completely non-flammable surface, watching very carefully to see if it heated up or did anything else strange. It didn't (stayed cooler than most lithium batteries I'm familiar with, in fact). Then it struck me "isn't this thing pretty much a laptop battery?" The ratings are very comparable (the Phantom 3 battery is 68 watt-hours, 4480 mAh 15.2 volts, while laptop batteries range from about 50 to 99 watt-hours, and they are all in the 15-20 volt, 3000-6000 mAh range), and the chemistry seems to be as well (modern laptop batteries are broadly described as LiPo, just like the Phantom battery). The only odd thing about it is the very high maximum discharge rate (it can give up all of its juice in 20 minutes, which is normal for an RC battery, but much faster than any other application I'm aware of, except some large video lights ).

    Given the description of what the battery does (monitoring charge rate, automatically balancing, monitoring remaining charge), it seems to be essentially a modern laptop battery (which is just a larger version of the smart battery in a digital camera). The charger is dumb, because the battery itself contains the important circuitry, which is also why it's a $150 battery.

    Even the Pro's 100 watt charger is not an extremely high rate charger for a battery of that size - plenty of workstation-class laptops use chargers in the 130-180 watt range for batteries only a little bigger, and 300 watt chargers are not unheard of on big gaming laptops. The 100 W Phantom charger has a charge rate only a little over 1C - again, solidly in the range of a high-performance laptop charger. Some big RC chargers put out 1000 watts, divided among several batteries, and can charge at rates up to 5C or so (people ARE very careful with these chargers, and probably rightfully so)

    The charging procedures people are describing are FAR more careful than anyone uses with laptop batteries, camera batteries, broadcast camcorder batteries two or three times the size, or frankly even the MUCH larger LiPo battery in my electric car(not a model car - I drive a Chevy Volt with a battery that holds 16.5 kWh of energy, approximately 250 Phantom batteries)! I walk away from my charging Volt all the time, and come back and get the car hours later, and it doesn't catch fire.Who doesn't leave their laptop plugged in overnight? Who hasn't left a camera battery on the charger for a week?

    I can think of a couple of reasons for this abundance of caution, and I'd love to know which one's right...

    1.) There's something odd about the Phantom's batteries that gives them their high discharge rate, and they really are more sensitive than garden-variety rechargeable lithiums.

    2. )People coming from an RC background are used to dealing with "dumb" batteries and chargers, along with extremely high charge rates, which are much less forgiving than modern smart batteries.

    3.) Since they only last 20 minutes on a charge (and may get charged and flown several times in a day), people are babying them more than they do laptop batteries - trying to squeeze out extra cycles.

    4.) Due to the high discharge rate, they get fewer cycles in a lifetime than ordinary laptop batteries, and people are charging them extra-carefully to try and get extra cycles.

    5.) The battery caution comes from previous versions of the Phantom, which may not have used smart batteries.

    Of course, if it really is a laptop-style smart battery, it will cut off the charge current when it's full, and you can't hurt it by leaving the darn thing on the charger. You might get a few extra cycles out of it by charging at 0.7C with the P3A charger instead of 1.2C with the P3P charger, but that's about it - smart batteries take care of their own charging.

    Similarly, smart batteries don't catch fire under ordinary circumstances. Charging a smart battery at 1C is not going to harm any ordinary, safe piece of furniture (and a smart battery won't let you charge it at "heat up" rates). When I felt mine, the battery didn't get hot at all (far less than my laptop or my iPhone), while the charger itself got about as hot as a laptop charger, which is safe on wooden furniture, or even on a rug or a couch, but perhaps not wrapped in very light drapes, tucked under the covers or sitting on a crate of 20 year old dynamite.

    Am I missing something here?


    Dan
     
  2. Michael Smith

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    Yes you are right that the battery is the same as a laptop battery except for (as you mentioned) it has a higher discharge rate and has a charge circuit built into the top of the battery.

    One thing to mention is that it is more exposed than a laptop battery. Laptop batteries normally have a hard case around the entire battery. A phantom battery has a hard shell, with parts cut out. the cut out parts only have a soft cover to protect the battery pouches. This might be another reason to take better care of the battery.

    Also you laptop battery is not changed as often, picked up, put down or flown through the air. Laptop batteries also pass a higher set of standard regulations to pass as safe for consumer use, Phantom batteries do not.

    As for charging, I think it improves the life of the battery like you said, if you charge it at a slower rate. But I think the reason that the phantom battery takes so long to charge is because of the limits of the small built in balancing circuit in the top of the battery. When I charge my large 16000mah 6S packs at 10amps my charger gets hot, even when I charge my smaller 6600mah 4s packs at 1-2C my charger gets hot. The small circuit in the top of the battery either a. cannot dissipate enough heat or b. has other limitations that prevent it from charging the battery at a higher amperage (thickness of the wires?)

    But having said all that, I stay in the house while my batteries are charging, and do it while I am awake, but beyond that, I do nothing else special, I just leave them next to my computer on my desk to charge.
     
    AirMan likes this.
  3. phn

    phn

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    Interesting topic, I'm pretty paranoid about batteries, and even store mine in a steel tin (Even when they are not charging ) but I was wondering if this is a bit too cautious! Guess I have been scared by too many YouTube video of lipos catching fire.
     
  4. GadgetGuy

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    I carefully store mine in the same ammo box with all my dynamite sticks.
    Is that wrong? :eek::D;):rolleyes:
     
    Man.Of.Kent likes this.
  5. adrian.ahonk

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    Yes if you all worry about charging phantom 3 batt u should worry to charge any electronic device like your phone, your tablet, ur laptop. Because now all device use a litium batt. And when you charging it, are you attended when charge it...??
     
  6. 4wd

    4wd

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    They do hold much more energy than a laptop.
    Incidents are rare but physical damage such as having been dropped or bumped against a hard corner *could* result in some kind of fire and it would be messy.
    If not nearby while it charges, I like to at least put them on a non-flammable surface such as sink draining board.
    Bear in mind the charger plug terminal will arc violently if they somehow touch a conductor while turned on.
    It's easy to get complacent over time - try to maintain a certain respect for the danger.
     
  7. GadgetGuy

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    OK. I'm convinced. I'll store my dynamite some where safer. Sounds like the batteries could ignite the dynamite, and then everything would go BOOM! :oops:
    That would be bad for both me and my P3P! :eek:
     
    Flyaware likes this.
  8. adrian.ahonk

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    If the battery has phisical damage and it's looks bad then you should has extran attendent for this batt.
    As long as the battery has good condition, it save to charge unattendent
     
  9. GadgetGuy

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    Any swollen battery or one with obvious damage should not be charged at all!
    That's where the fires and explosions come from!
     
  10. RoyVa

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    A nice 12x12 tile is cheep to put under the battery if you only have wooden surface to place it on to charge. Good cheep insurance in case of a flame up. Not likely but can happen if cell goes bad. Be mindful of what over it. Good ole common sence pays off.
     
  11. N017RW

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    While neither the LiPo or Li-ion contain metallic Lithium, there are a number of differences between them and thus the Li-ion in most portable devices is generally considered safer than the LiPo.
     
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  12. GadgetGuy

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    The extra precautions are likely as a result of some litigation and were recommended by their lawyers. However, even airlines are concerned about these batteries, and require that they be in your carry on luggage, where issues can be more easily dealt with and contained, instead of stored in checked luggage in the unmanned cargo hold.
     
  13. Dan Wells

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    In terms of stored energy, they're NOT more powerful than laptop batteries - they're right in the same range. Where they are more powerful is in terms of designed discharge rate - even my HP ZBook workstation, which has an 8 cell 4s2p battery with a very similar voltage to the Phantom, and about 25% more storage capacity - 83 wh vs 68, is designed to get over an hour out of the battery at high load (3 to 4 hours at low load). The Phantom battery gets only 20 minutes, so it's pushing a lot of power at once, from a relatively small total.

    By the way, all large lithium batteries are illegal in checked luggage. You technically can't check a MacBook Pro (I'm sure people do all the time), because it has a large, nonremovable lithium battery. My ZBook can be checked, but only if I take the battery out and carry it on, while checking the rest of the computer.

    Interestingly, lithium batteries larger than 99 watt hours require airline approval to carry on (this includes the extended battery for the Inspire 1 and some other large RC batteries, as well as large video batteries), and batteries larger than 160 watt hours can't go by air at all. That category includes a few VERY large RC batteries, some electric tool batteries (primarily for lawn equipment) and a small number of pro video batteries, but is probably primarily composed of electric car batteries, which range from ~10 kWh on up to 90 kWh, and are large enough that they're freight, but automakers occasionally want to fly a prototype electric car somewhere and discover that it HAS to go by sea.
     
  14. FunN4lo

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    90% of laptop batteries are literally a bunch of 18650 batteries in a hard plastic case. Same battery that goes in many high discharge or tactical flashlights. (among other things) Cut a laptop battery open some time. Or just look for the vids on YT. So there is a large physical construction difference between a laptop battery and an RC battery. Of course there is a large chemical difference also.

    You will never package enough 18650 batteries into a container the size of the P3 battery and get the P3 to fly. The discharge rate between the two chemistrys is why. That potential energy is what makes Li-Po chemistry more dangerous than Li-on chemistry
    http://www.amazon.com/NCR18650B-340...&qid=1444355412&sr=8-4&keywords=18650+battery
     
  15. acherman

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    Are you sure about the P3 batteries being non-protected in those plastic cutouts? Pretty sure I saw someone post photos of a disassembled battery on here, and those exposed parts are still protected by an aluminum sheet. Hardly damaged or punctured by "bumping" it. Then again, some people just "bump" the vehicle in front of them and cause thousands in damage. Haha I'm careful with my batteries, but certainly not in the paranoid crowd at all.
     
  16. John Locke

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    You're correct. Li-po or lithium polymer batteries are the most dangerous, and the least weight. They offer the best power to weight ratio. Li-fe-po or lithium iron phosphate are less dangerous, used in Tesla and other e-cars and e-bikes most the time, and they weigh more per watt. Li-ion or lithium ion is the safest lithium type battery, used in cellphones, but can still catch fire in rare cases.
     
    #16 John Locke, Oct 8, 2015
    Last edited: Oct 9, 2015