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Cheaper car charger?

Discussion in 'Phantom 2 Vision + Discussion' started by PaganLinuxGeek, Aug 24, 2015.

  1. PaganLinuxGeek

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  2. RoyVa

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    Looks to be workable in expensive charging source.Dont really like having to plug directly to battery. It is pulling 4amps so not a good idea to connect to cigarette lighter/12v charger. Probably would get to hot and could damage the wiring. Think I'll stick to the inverter. Built into my car so I just use my regular charger.
     
  3. CapnBob

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    You do NOT need a charger or inverter.. Each P2V+ battery has an integrated balance charger. What you need is a power supply, which your car's battery is. Read the label on the charging unit that came with your Phantom. It says "Power Supply". I have posted several times on this. Pick up a multi-charger board on ebay, and a cable with Cig Lighter to the coaxial power plug on the adapter, and you're good to go. I spent less than $18, and it works just fine..

    http://www.ebay.com/itm/Rapid-Batte...om-2-Vision-/231508174477?hash=item35e6f6668d

    adapter.jpg
     
  4. RoyVa

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    Some need regulated power supplies like laptop computers do. An unregulated power supply would not be good.
     
  5. CapnBob

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    The factory power supply is rated at 12.6VDC, which, handy enough, is the voltage of a fully charged automobile battery. The specs on the battery say 18V maximum input voltage. Your vehicles alternator does indeed have a voltage regulator and it is "regulated to" 13.8 to 14.3 VDC, which is well within the battery's specs. To use an inverter is just silly; you're taking pure 12.6VDC from a battery, converting it to high frequency AC, then reconverting it to 12.6VDC again. Not to mention feeding a LiPo Charger with another LiPo charger. Give the battery it's DC voltage and let the internal balance charger work. The average Cig. Lighter fuse is 10 Amps. The dji power supply is rated at 4 amps. Charging multiple batteries should be no problem at all, and I have not had any problems. D.C. is D.C. do matter how you slice it. If anyone has had any issues charging directly from a battery, please chime in here.
     
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  6. yorlik

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    CapnBob, please consider not doing this anymore; you are indeed harming your batteries...

    I too thought our 'smart charger' regulated the charge and the 12.6vdc@4amp switching PS from dji was just a crude supply.

    I did the testing a couple weeks ago and PROVED that our smart batteries HAVE NO CURRENT REGULATION IN THEM.

    They simply have mutliple FET switches that either turn on or off, no PWM control at all. So the results I published on here or the other forum was a chart of input voltage vs charge current.

    The chart showed clearly that even 12.6v will charge well over the battery 1C charge rating. Get to 13v input and you are near 15amps charge rate! Not only will that overheat the FET switches inside, doing that more than a few seconds is reducing the life of the battery cells which are only rated for 1C or 5.2amp max sustained charge rate.

    If you measure the actual charger voltage when your batt is on the dji charger, you will see the 12.6v no load rating drops to just a hair over 11.1vdc and it charges with 4 amps for the majority of the charge time. Until it approaches the 12.6v level, at which time the current the current is reducing until it is 0.1amp - that is the current level triggering my smart batts to shut off the FETS and say charged.

    The amount of charge current is simply I=V/R. Checking the internal resistance of my batts as well as lead resistance, my R is about 0.1ohm total. So hook your battery to your running car (my ford is always 14.3v when running) and you will charge at (14.3-11.1)/0.1 = 32 amps! Your battery won't last very long that way! Please reconsider my friend!.
     
  7. yorlik

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    some more info to help understand our p2 smart battery charging...

    each cell is absolute max voltage 4.2v, so all '3' make 12.6vdc. When thebatt gets used, this 4.2v goes down until it is around 3.6 or 3.7v minimum (no load - less under load while flying).

    Charge for lipos, including ours, is meant to be CC-CV (constant current then constant voltage at very end).The smart batt has no control other than counting the coloumbs going in and coming out for tracking purposes, and a big on/off switch to the outside world.

    Their internal resistance is low at about .030 ohms, but each is actually 2 in parallel, so each set is about .015ohms, and so 3 of em in series is about .05ohms. When charging, we have to put a very small amount more than terminal voltage across them to force current into that resistance.

    The current stays pretty constant while the batt charges; if you ever measured it, you would see for a 2 hour charge, about 1.9 hours is at constant 4amp, then the last few minutes, as it approachs it 4.2v per cell (12.6v total), the current drops off. Conceivably if you kept exactly 12.6 v across it, the current would go to zero and remain there, not overcharging. The smart batt watchs this current reduction and shuts off the charge at 0.1amp.

    But the lipo has a weird personality: you can leave 12.6 on it forever and current remains low, but go a few millivolts OVER than and the current again goes up thru the roof as explained in my previous post. Since our smart batts seem to shut of as fully charged when current reaches 100ma, I suspect that if left on a car charger at any voltage above 12.6 it will continue to pull that high current and never shut off. It should have to overheat and catch fire shortly thereafter. It MAY be that the smart batt just goes to 12.6v then sits there for a given timer amount of time and then pulls the plug, but that has not been my experience yet. I would not want to be one to test that either.
     
  8. CapnBob

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  9. CapnBob

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    Well, I can see your argument and the reasoning behind it, but I have 2 dji 5200mah batts and a LimeFuel 6000mah. At home I use the dji power supply for those, and an iMax B6AC for my other lipos (beacon, etc.). I am very familiar with LiPos and their voltage and current personalities. I have never run the batteries down in the bird, AAAMOF, I rarely go below 20%. I also check on them every few minutes while charging in the car, and I usually have 2 on the strip topping them off, sometimes all 3. I have yet to have a problem, and they never get hot while charging. Again, I don't use this setup as my primary, just to get extra flight time on the road. I guess I should not have presented this as a viable full-time charging setup but, properly used and monitored it works just fine for my purpose. Again, I have not experienced any problems thus far.
     
  10. dannytroy

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    If you are into r/c chances are you have a multi-charger that does different chemistry batteries. My multi-charger also charges PB batteries and that setting is how I charge my Phantom batteries. Of course, use the 12v setting. I'm conservative and usually not in a hurry, so I use the 1A setting. 2A if in a hurry. I believe it is safe to 4A, but not sure about that. BTW, I have a new car charger that I never used and probably never will, if anyone is interested in buying it. PM me if interested.
     
  11. RoyVa

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    Safety wise the stock charge and an inverter work great and is regulated. No damage to batteries that way.
     
  12. CapnBob

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    Yorlick's and other comments made me reread what had posted. In no way am I proposing this method as a primary charging solution. You will kill your batteries in short order if you use an unregulated current method. I have used this successfully in the field as a way to extend flying time in those times when three batteries are done before I am. I always have a voltmeter in parallel, and I watch them closely. In the field, I don't want to wait 2+ hours for a "proper" charge, so this works for me short-term. I am sorry if I was not clear in what I was trying to say.
     
  13. yorlik

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    Danny, why not use your lipo setting? That is how I charge now most of the time. That way I can document the exact mah put in, add it to the mah dji reports before the charge (after last flight), and verify that dji then reports the correct mah in assistant! I find I put in about 3% more than dji reports, which seems good to me - gotta charge a tad more mah than removed to fully charge - the small amount extra goes to heat. Verifies everything this way.

    But my point is twofold:

    1) the smart batt watches the voltage and current, so it is good to charge correctly if exactly 12.6vdc is applied to its terminals. So my using my ICE charger set to 3pc 4.2v cells, charges at the current I program, then goes to CV mode at exactly 12.6v - just like the dji PS. So it does NO HARM. In fact, I find most of the time MY charger stops the charge instead of the smart battery - probably a race of who stops first - of only a few minutes difference. That few minutes is at .2 to .1amp so not important. But at least I now have redundant chargers that cause zero problems AND I get good mah put in AND I get to set the charge current (I normally do 3amps (.6C)

    2) I FULLY charge the battery: your method only charges to 4.0v/cell, which according to my chart I am building and posted on another thread here, and most other charts on 4.2v lipos, is well below 100% charge. It is probably around 85% charge instead. Now, if you want to be sure to never overcharge, then that is a great plan. But I find that my cell temps are almost room temp at end of the real cc-cv charge since the current is dropping to zero, and the highest during 3amp charge is only about 10F above ambient, so I am convinced charging these to 4.2v/cell is a-ok.
     
  14. yorlik

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    Bob, Thanks for posting that to help prevent others from maybe popping their batt on cig lighter and leaving it unattended and maybe coming back to a vehicle fire!

    might you have a clamp on dc ammeter? If so, you should look at the current going into each battery to how hard you are hitting them for even your short time top off. I would be very interested in what you see. Keep in mind you cannot use your VOM IN SERIES with the batt since its current sense resistor is even bigger than the one in the phantom battery! I quickly found if I did that my charge current dropped from 4 amp to about 1 with 5 different meters I tested!
     
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  15. dannytroy

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    Interesting idea. I will do a test, charging one battery using PB mode and the other using Lipo mode. I'll check both voltages at the end of the charge. This will give me a rough idea of the higher capacity battery. As far as the charger cutting off before the battery's smart charger, mine always does. That might be an indication the battery wants more charge and can safely accept it.
     
  16. CapnBob

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    I have never used a VOM or Multimeter to measure current. I never understood why they even make that an option. I had a clamp-on current probe that read out my fluke, but it broke awhile ago. I'm looking for a replacement. Maybe an Extech MA120.
     
    #16 CapnBob, Aug 26, 2015
    Last edited: Aug 26, 2015
  17. dannytroy

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    This is the one I have. Works great for r/c: https://www.batterystuff.com/solar-chargers/t-01003.html
     
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  18. CapnBob

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    Thanks. Was looking for more of a multi-purpose solution. I just ordered the Extech MA120.
    CLAMP METER, MINI, AC/DC W/NCV
    Features
    • Measures 200A AC Current up to 100mA resolution
    • 3% basic ACA accuracy
    • 0.7" (18mm) jaw opening; 300MCM cable size
    • 2000 count LCD display
    • Non-contact AC Voltage detector (120/240VAC, 50/60Hz) via clamp tip
    • Built-in white LED flashlight
    • Measures Frequency up to 1kHz with 0.01Hz resolution
    • Autoranging with Auto Power Off and Data hold function
    • Extech MA120.jpg
     
  19. yorlik

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    nice one. mine is similar and cheapo, but I have checked it against our good flukes and it reads close enough for me. mine also has a 20amp scale which helps on resolution, altho if yours stays accurate down to 1-4amps on 200amp scale, great! In case you did not know, if you wrap the wire around the jaws 1x, it cuts the 200amp scale to 100amp, 2wraps makes it 50a, 3 wraps, etc. so if you make up a #12 or so feed wire to wrap around, if you leave it long enough to wrap 1-4 times, you can increase your resolution and accuracy then by that factor.
     
  20. CapnBob

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    And thus,....transformer theory!
    Great idea, never thought of that.

    Yeah, They want $350 for a replacement for my Fluke i1010.
    For $75, I can live with the accuracy delta. ;-)
     
    #20 CapnBob, Aug 26, 2015
    Last edited: Aug 26, 2015