MaH flight time? how to tell??
08-04-2007, 10:27 AM
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MaH flight time? how to tell??
I am a new flier,t-rex 450, thunder power 11.1v 2070 mah batteries.I am still flying in normal mode just trying to get the perfect hover,when I am done flying(timer set at 8 minutes) and I charge the bats they take around 1100 or so mah to charge,so after flight I have around 970 mah left in battery.so is this normal? what would the average be for recharging a 2100 mah battery after flight? thanks for any info
08-04-2007, 06:57 PM
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RE: MaH flight time? how to tell??
it's not relative...this is why brand and quality matters.
mAH gives little indication of flight time. current (amp) draw changes in flight constantly. a 430XL trex motor is probably drawing between 15-20 amps in hover (there's no real way to tell unless you have a data recorder ie eagletree logger).
the mAH rating on a battery is pretty much the current you can get out of a the battery and be dead in exactly 1 hour. so 2200mAH means you can drain it at 2.2amps for 1 hour and it will be COMPLETELY or VERY dead (NOT CONSIDERING LIPO or MODEL CUTOFFS). Now to complicate matters worst, lipos have their 3.0/cell damage threshold cutoff and helicopters usually dont fly too as they start dying. Therefore, the USABLE mAH is actually more like 1500 for example. Some batteries don't hold up very well when high current is pulled from them and the capacity seems to be less. This is why C ratings make a big difference. So 20C in a 2200mAH lipo is 40amps MAX (the 430XL probably gets 50+amp spikes...i assume which is why the align battery puffs with it). 20C means nothing basically except HOW it is rated. this is why some batteries like TP extreme or Flightpower are better for some people depending on how you fly.
then there's battery efficiency...when load is applied, volts drop. The more load applied the more volts drop. cheap batteries will drop voltage Fast when current is applied (maybe even less than their C rating). They will start to degrade in this area a LOT and lose consistency. batteries get hot which increases the resistance and you lose even more efficiency it also damages the lipo cells (usually the middle cell which is the least airflow and you get lipo imbalance and eventual death.
mAH gives little indication of flight time. current (amp) draw changes in flight constantly. a 430XL trex motor is probably drawing between 15-20 amps in hover (there's no real way to tell unless you have a data recorder ie eagletree logger).
the mAH rating on a battery is pretty much the current you can get out of a the battery and be dead in exactly 1 hour. so 2200mAH means you can drain it at 2.2amps for 1 hour and it will be COMPLETELY or VERY dead (NOT CONSIDERING LIPO or MODEL CUTOFFS). Now to complicate matters worst, lipos have their 3.0/cell damage threshold cutoff and helicopters usually dont fly too as they start dying. Therefore, the USABLE mAH is actually more like 1500 for example. Some batteries don't hold up very well when high current is pulled from them and the capacity seems to be less. This is why C ratings make a big difference. So 20C in a 2200mAH lipo is 40amps MAX (the 430XL probably gets 50+amp spikes...i assume which is why the align battery puffs with it). 20C means nothing basically except HOW it is rated. this is why some batteries like TP extreme or Flightpower are better for some people depending on how you fly.
then there's battery efficiency...when load is applied, volts drop. The more load applied the more volts drop. cheap batteries will drop voltage Fast when current is applied (maybe even less than their C rating). They will start to degrade in this area a LOT and lose consistency. batteries get hot which increases the resistance and you lose even more efficiency it also damages the lipo cells (usually the middle cell which is the least airflow and you get lipo imbalance and eventual death.
08-05-2007, 12:08 AM
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RE: MaH flight time? how to tell??
yikes!!! large mammal confused.......just kidding,I do follow you,I'm basically just trying to get a "ball park" idea of flight times,or if I'm on the right track
as far as my timer setting.Thanks for the comprehensive info! appreciated.[sm=thumbup.gif]
as far as my timer setting.Thanks for the comprehensive info! appreciated.[sm=thumbup.gif]
