batteries how low on tx/rx/
05-31-2004, 02:26 AM
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batteries how low on tx/rx/
What is a good No. at which I should put a fast charge on tx and rx batteries when flying several planes all day long. Like, I take several planes out and fly, I fly one two or three times then go to 2nd plane, then 3rd and so on, then come back and fly them several more time ect ect. So on a 4.8 Rx battery, after a full charge at home, I will get a reading of around 5.2 volts, and on Tx I get a reading of say 10.3 volts. what would be the lowest safest reading to fly? say I change planes and test the Rx and get a reading of 4.5 volts, can I still be certain of being able to safely fly? I know there are a lot of vairables, hi tork servos, how many (4 to 7) ect , but just sport flying, with say average of 5 standerd servos what would be a general number not to fly before putting a charge on battery, both Rx and Tx? I am sure you have had this question before and some one will get sarcastic or what ever, but I really just would like to know, I think I may recharging my batteries to often when there is not a need to. ( I know, It never hurts to be on the safe side then sorry). I recharge my rx at around 4.5 Volts and Tx at around 9.9 or 9.8. Can I go quit a bit lower or not. Well, thanks anyhow for any rule of thum that you may recomend.
05-31-2004, 07:34 AM
#2
RE: batteries how low on tx/rx/
ORIGINAL: crashedagain
What is a good No. at which I should put a fast charge on tx and rx batteries when flying several planes all day long. Like, I take several planes out and fly, I fly one two or three times then go to 2nd plane, then 3rd and so on, then come back and fly them several more time ect ect. So on a 4.8 Rx battery, after a full charge at home, I will get a reading of around 5.2 volts, and on Tx I get a reading of say 10.3 volts. what would be the lowest safest reading to fly? say I change planes and test the Rx and get a reading of 4.5 volts, can I still be certain of being able to safely fly? I know there are a lot of vairables, hi tork servos, how many (4 to 7) ect , but just sport flying, with say average of 5 standerd servos what would be a general number not to fly before putting a charge on battery, both Rx and Tx? I am sure you have had this question before and some one will get sarcastic or what ever, but I really just would like to know, I think I may recharging my batteries to often when there is not a need to. ( I know, It never hurts to be on the safe side then sorry). I recharge my rx at around 4.5 Volts and Tx at around 9.9 or 9.8. Can I go quit a bit lower or not. Well, thanks anyhow for any rule of thum that you may recomend.
What is a good No. at which I should put a fast charge on tx and rx batteries when flying several planes all day long. Like, I take several planes out and fly, I fly one two or three times then go to 2nd plane, then 3rd and so on, then come back and fly them several more time ect ect. So on a 4.8 Rx battery, after a full charge at home, I will get a reading of around 5.2 volts, and on Tx I get a reading of say 10.3 volts. what would be the lowest safest reading to fly? say I change planes and test the Rx and get a reading of 4.5 volts, can I still be certain of being able to safely fly? I know there are a lot of vairables, hi tork servos, how many (4 to 7) ect , but just sport flying, with say average of 5 standerd servos what would be a general number not to fly before putting a charge on battery, both Rx and Tx? I am sure you have had this question before and some one will get sarcastic or what ever, but I really just would like to know, I think I may recharging my batteries to often when there is not a need to. ( I know, It never hurts to be on the safe side then sorry). I recharge my rx at around 4.5 Volts and Tx at around 9.9 or 9.8. Can I go quit a bit lower or not. Well, thanks anyhow for any rule of thum that you may recomend.
05-31-2004, 07:39 AM
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RE: batteries how low on tx/rx/
I re-charge my Rx packs at 4.8, never lower. (Some will say you can go to 4.6, but I won't risk a plane for an extra half flight. 
)
Tx packs I recharge at 9.6 minimum.
Keep in mind, NiCD's have a quick voltage drop when they start getting low, so I prefer to play it safe. I've never lost a plane to low voltage. (Well maybe one, but that was on a VERY cold day with a NiMH pack, and that's another story.)
Dennis-
)Tx packs I recharge at 9.6 minimum.
Keep in mind, NiCD's have a quick voltage drop when they start getting low, so I prefer to play it safe. I've never lost a plane to low voltage. (Well maybe one, but that was on a VERY cold day with a NiMH pack, and that's another story.)
Dennis-
05-31-2004, 08:27 AM
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RE: batteries how low on tx/rx/
I recharge my 4-cell packs when they get below 5 volts, 5-cell packs when they get below 6.2 volts. These readings MUST be obtained with a good Expanded Scale Volt Meter that puts a load on the batteries, not just a plain voltmeter. If you are waiting until they reach 4.5v you are risking battery failure and it will eventually bite you in the rear. The cells are 1.2v each. When the pack reaches 4.5v the cells are @ 1.125v each and falling quickly. Your 4-cell Rx packs should be achieving 5.3 volts at full charge and the Tx pack should be around 10.6 volts. As mentioned, charge the Tx when it gets below 9.6v for safe operation. I know there are some that will say these parameters are a bit conservative but IMO battery condition is for the most part under complete control of the pilot, so why not play it safe? 
05-31-2004, 08:43 AM
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RE: batteries how low on tx/rx/
NiCad's are, essentially, dead when the voltage reaches 1.1 volts per cell. 1.2 volts is where I will not initiate another flight. On a 4 cell pack (4x1.2) that is 4.8 volts, on a 5 cell pack (5X1.2) it is 6 volts. On an 8 cell Tx pack (8x1.2) it's 9.6 volts. I chicken out and recharge at a slightly higher value.
As Stick Jammer says, you MUST use a load when measuring. Whether it be automatic with an expanded scale voltmeter or a load that is inline with a digital voltmeter.
As Stick Jammer says, you MUST use a load when measuring. Whether it be automatic with an expanded scale voltmeter or a load that is inline with a digital voltmeter.
06-01-2004, 12:41 AM
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RE: batteries how low on tx/rx/
Thanks to al for you input!. Guess I have been doing it right. I thought that I was recharging them too often at too high a voltage , ie, 4 cell I would recharge at 4.8 and Tx at 9.8 But I guess it's not hurting them to do it this way and I would rather have the extra insurence of knowing that I won't lose a plane due to a low battery. Once again, I thank you all. Happy Flying. Bob
06-01-2004, 05:41 PM
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RE: batteries how low on tx/rx/
crashedagain,
You stated in the first post that you recharge the Rx pack when it reaches 4.5 volts. If that is the case, you were not doing it right. At any rate, charge it when/before it reaches 4.8 volts with an expanded scale voltmeter.
You stated in the first post that you recharge the Rx pack when it reaches 4.5 volts. If that is the case, you were not doing it right. At any rate, charge it when/before it reaches 4.8 volts with an expanded scale voltmeter.
06-01-2004, 06:18 PM
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RE: batteries how low on tx/rx/
I've gone as low as 9.3 volts on a transmitter, but glitches became evident and the plane was landed as soon as I could. Scary.
Anymore, I use the cell count nominal voltage tested under a load for the re-charge point. Haven't had a problem running out of juice in years this way.
Anymore, I use the cell count nominal voltage tested under a load for the re-charge point. Haven't had a problem running out of juice in years this way.
06-02-2004, 01:08 AM
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RE: batteries how low on tx/rx/
Thanks again for all your help. but stick jammer mistook my first post. perhaps I just did not write it clearly. I was useing 4.5 as an example. (I should have wrote, Example, if flying and then I test the rx volts and it read 4.5, is it ok to still use it) No problems tho. I never let them get that low. I check my batteries with a digital meter. That is not putting them on a load test however. But I should be O.K. as long as I keep charging them when they read 4.8, is that correct? I cycle them on a Hobbico recyler about every 2 months. I know proberly I should recycle them each month, but I only get to fly about 3 days a month due to my work. Thank you all again. As always you all have been so very helpfull to all us who do not know some things that are simple to most of others. Though it may be a "dumb question " for most of you, to us who do not know, unless we ask, we will not gain the knowlage that others have known for years. I just thank RCU for being here for us. Oh yeah by the way, that brings another question, what is an expanded scale voltmeter? Bob
06-02-2004, 11:09 AM
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RE: batteries how low on tx/rx/
I check my batteries with a digital meter. That is not putting them on a load test however.
06-02-2004, 06:00 PM
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RE: batteries how low on tx/rx/
Original: crashedagain
I recharge my rx at around 4.5 Volts and Tx at around 9.9 or 9.8.
I recharge my rx at around 4.5 Volts and Tx at around 9.9 or 9.8.
