Battery Pack Tech question
I have a question about the battery pack on the Emag. 650mA really isnt alot when playing tourneys. Maybe my pack is dying but I seem to use my battery very quick. I see that the pack is simply 14 AA NiMH Batteries in series with each other to provide the 16.8 volts. I found some 2000 mAh NiMH AA batteries at a couple battery sites online. Am I wrong in assuming that I could set these up the same way as the the original pack, and now have a battery that lasts alot longer? I see no reason why this wouldn't be possible, it's the circuits that determine the current loading, right? Anyway, I'd greatly appreciate some input on this subject. Thanks.
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well, you could, but it wouldnt fit...
the current pack is 14 AAA, not AA.
highest you will get is 720 mAh. if you want, i could build one for you. link's in sig..."The Fine Print: Discontinue use if your eyeballs suddenly get way smaller." -
Battery ?
Thanks man, you rock. I didnt even bother to look at the battery, I looked at the pic on the website. Teaches me. I guess 14 AA would be a bit big.
I may just get in touch with you for those.
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Im trying to learn about this, so when charging...how do you decide what charger to use when there is 14 in series??? I see most of the chargers charge on battery at a time in its own slot. I know that for a slow charge itys supposed to be 1/10 of the capacity so 75mA in this case, but what for a fast charge?Comment
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the number of batteries in series changes th voltage. number of cells x 1.2 = voltage of charger minus 2.
so, multiple the number of cells by 1.2, and then add ~ 2 volts for the charger voltage.
the normal charge rates are .1C, .2C, .5C, and 1C. Its just the number times the capacity (.5C in this case would be 360 mA).
anything higher than .1C generally needs some sort of overcharge protection. However, in this case, the stock charger would work fine. it just wont charge quite as fast. :P"The Fine Print: Discontinue use if your eyeballs suddenly get way smaller."Comment
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MighyJoe - Thanks for starting this thread, I was going to ask the same questions.
I have a decent battery charger (Integy 16X4 Pro) for my R/C cars and I'm hoping that I can use it to charge/discharge my EMag battery and have a few additional questions. Any help is appreciated.
Since there are 14 cells in series, does that mean that the charge voltage should be ~18.8V at the .1C, .2C, .5C and 1C rates? Can I charge at a lower voltage with a higher rate?
Should the Emag battery be discharged since its NiMH? What is the proper discharge rate and voltage?Comment
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You can charge actually up to about 21 volts safely is what I just read, but yeah once you start charging at those higher rates like .3 to .5c and up, then you need to start monitoring the time that they are on the charger. As you may know the reaction of charging a NiMh battery is heat, the opposite of Nicd. So you can either figure what your putting in (in mA)and multiply it by the capacity of your battery (in mA Hrs)to get the time required and stop charging at that point, or if you have on of those super duper chargers that monitor voltage and or battery temperature, you'd be golden. What I do is just leave it at .1c, which is 65mA for the Emag battery (out of 650mAhrs). At this rate you can plug it in and basically leave it safely plugged in for an extended period of time (easily a day or two) with no heat build up. I can tell you how to build a charger like this using the same emag charging block as the original charger (i burnt my original internals out)for about $10 and some electronic skills like soldering (dont even need to do this) and using a multimeter. Anyway, good luck.Comment
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MightyJoe - I'd like to see how you built the charger. Please post the details you have. Do you discharge your batties? In R/C racing, we never leave a NiMH battery with a charge for storage and I assume the same should hold true for the E-Mag battery. What do you do to discharge it? I have a revy running off of the battery that I could just leave on, but then I'd shorten it's life span.Comment
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Looks as though my $7 charger from radio shack will work (18v 120mah) just gotta keep an eye on it (i dont feel like cleaning up anyhting that could get burnt)
Andrew
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