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Old Apr 17, 2007, 07:37 PM
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BowerR64's Avatar
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Would NiMH be better if they had more voltage?

Do they have single cells that put out as much voltage as 1 lipo cell?

The thing i find good about lipos is since there are only 2 cells its easier to hook a few wires to them so that each cell can be charged independantly.

If a NiMH was in a single cell format and had the same voltage as 1 lipo cell would they be better? more durable? more stamina?
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Old Apr 17, 2007, 08:08 PM
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The 'problem' with NiMH cells, in motor vehicle use (especially airplanes and helicopters), is their gravimetric energy density. An airplane needs a certain amount of energy to fly for a decent amount of time. To get that energy with NiMH cells ends up adding a huge amount of weight to the vehicle. To overcome that weight you have to equip a larger motor, larger ESC, and more cells. The final result of this is poor aircraft performance relative to LiPo power.
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Old Apr 17, 2007, 08:16 PM
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Voltage is determined by cell chemistry, so there is no way to get Lipo voltage from NiMh

Pat MacKenzie
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Old Apr 18, 2007, 02:36 AM
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Letchworth, Great Britain (UK)
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Quote:
Originally Posted by BowerR64
The thing i find good about lipos is since there are only 2 cells its easier to hook a few wires to them so that each cell can be charged independantly.

If a NiMH was in a single cell format and had the same voltage as 1 lipo cell would they be better? more durable? more stamina?
The perceived wisdom is that LiPo battery packs need to have their cells balanced to avoid overcharging one or other of the cells, which in turn will reduce the life of that cell or, at worst, cause it to vent and flame

Most other mainstream types of battery are more tolerant of over charging, and are less prone to vent-and-flame type failure. So generally speaking they don't need balancing leads Having said that, I've installed a balancing lead halfway through a couple of my 12-cell NiMh packs because I read somewhere that the risk of cell imbalance in an Nixx pack increases significantly once you get above a certain number of cells. So from time to time I can check the voltage of each 6-cell half, and cycle them as 6-cell packs if necessary. Can't say I've noticed any difference in performance or life though

As Pat MacKenzie has said, it's the cell chemistry that determines the voltage of each cell. If you make the cell larger, all that does is increase the capacity of the cell and, probably, the amount of amps that it can deliver.
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