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question about Volts

Old 09-21-2007, 12:06 PM
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matador_24
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Default question about Volts

Hi guys.... I just got a voltage indicator but I don't know what it means..... I have the batteries fully charged and this is what it reads.....

850mah fully charged = 8.2V (lama v3)
2200 mah = 4.1V
2100 mah = 4.0V

is it normal?????? what does it mean??? what should it read when the batteries are low in power?????
Old 09-21-2007, 02:09 PM
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rlsloan
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Default RE: question about Volts

Fully charged 3-cell lipo's peak out at 12+ volts at the end of a charge
Old 09-21-2007, 02:59 PM
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Philng
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Default RE: question about Volts

fully charged 3 cell will be 12.60 volts, making each cell 4.2 volts
Old 09-21-2007, 03:03 PM
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matador_24
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Default RE: question about Volts

Ok, I understand, so, if the tester reads 4.1V in my battery.... what is that???? that each cell has 4.1 x 3 = 12.X??? and it's fully charged???? or that it has 4.1V in total????? I plug the tester directly to the battery plug.
Old 09-21-2007, 03:06 PM
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Philng
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Default RE: question about Volts

4.1 is the voltage of one cell in your battery
Old 09-21-2007, 03:52 PM
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matador_24
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Default RE: question about Volts

thankssssssss
Old 09-21-2007, 04:12 PM
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Rafael23cc
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Default RE: question about Volts

Who said that this pack was a 3 cell pack?

He said that it was for a Lama V3, although I don't have one, I would guess that the heli uses a 2-cell pack 850mah. As stated in the original post:
850mah fully charged = 8.2V (lama v3)
If it was a 3-cell pack and fully charged it read 8.2 volts I would say it's toast.

Now being a 2-cell pack, 8.2 volts is very close to fullly charged. Actually I would call that fully charged.

The question is; What the #3!! are these readings? Without knowing what they are, we truly cannot answer this question.
2200 mah = 4.1V
2100 mah = 4.0V
Rafael
Old 09-21-2007, 07:39 PM
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W4RCF
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Default RE: question about Volts

One more thing. Sounds like to me you are plugging into the balancing plug and not the one that has both cells (if it's 2 cells) in series. Does that make sense? Please feel free to email me if not.
Old 09-22-2007, 04:23 PM
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matador_24
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Default RE: question about Volts

Yes, the battery of the lama is a 2-c 850mah, I plugged the tester to the plug that goes to the ESC because it doesn't read anything in the plug that goes to the charger...... it reads 8.2 V..... but, why the battery 1500mah of my DX7 Tx fully charged reads 10V???
Old 09-22-2007, 07:00 PM
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john_doe
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Default RE: question about Volts

Anyone please correct me if I'm wrong here as I'm not 100% sure in this area, but this is what I think is right.

First off... asuming you have the same tx pack in the dx7 as I got, that is two completly different battery technologies with different characteristics...

the one for the lama is lipo (lithium polymer), and the one in the dx7 is nimh (nickel metal hydride). the lipo's is suposed to be 3.7v per cell (a 3 cell lipo is also refered to as a 11.1v lipo (3x3.7v=11.1v)). I don't really know what they mean by 3.7v/cell, becouse fully charged the cells are 4.2v (3x4.2v=12.6v). I think mayby it's the average voltage on the cell for that specific battery tech (nominal voltage?).

The dx7 batt on the other hand, atleast in mine, is a nimh pack internally consisting of 8 aa size cells. the nimh batts is 1.2v per cell wich add up to 8x1.2=9.6v. again I think that the value of 9.6 is the average voltage, becouse my pack reach aprox 11.3v (1.4v per cell) when fully charged.

Hope this help explaining something.
Old 09-26-2007, 06:20 PM
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clutchbob
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Default RE: question about Volts

The voltage of your pack is dependant on the number and type of cells you have. In series, they are additive.
The Mah is the capacity of the pack ( how long it can provide the rated voltage ). You can have a battery that provides, for example, 8 volts, but some 8 volt batteries can provide that 8 volts for a longer time ( capacity ). As that capacity increases for any given voltage, the batteries will be larger and so will weigh more. Compare 12v. motorcycle batteries ( low capacity ) to 12v truck batteries ( high capacity ).
Anyone in this hobby should learn a little about the relationship between voltage, current, resistance, power etc., basic electronics is all just simple math. don't be intimidated.

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