ORIGINAL: spitfire66
Hello Again! I have a question concerning battery duration. I have a 4.8 vot 1500 mah batter (new). How much flight time can I expect after the battery is fully charged? I was always told never to attempt a flight when the voltage drops to 4.8 on a loaded voltmeter. Another question I have is how long after a day of flying (maybe 30 minutes of flight time) should I leave my batteries charging? I have the standard jr charger with 50 mah of draw.
During normal flying, the amp draw is about 300ma. So for a fully charged 1500mah battery, you can expect to fly 1500mah/300ma = 5 hours.
When the voltage drops to 4.8 on a loaded voltmeter, for practical purposes, the pack is depleted and you should not fly.
After 30 min of flying at 300mah, you will have used up 150mah; just to replenish that, you need at least 150/50= 3hrs+ charge at 50ma; you might leave it on charge until you fly the next day or so.
To fully charge your 1500 pack at 50ma would take 1500/50 = 30 hrs + , but at 50ma, which is really a trickle charge, you may never get a full charge depending on the self-discharge characteristics of your battery.
Suggest you charge at 150ma (.1C) for 14 hrs for a good full charge.
Always charge at this rate the night before flying.
NOW HERE IS AN IDEA THAT MIGHT YOU MIGHT CONSIDER -
Charge your rec'vr pack from the JR tx output but make sure the polarity connection is right. The output from the tx into the rx might be anywhere from 100 to 130 or so. I just measured the output from my ACE tx-rx charger and I got 130ma charge into 4AA2500mah cells.
Thought you might be interested.
feihu