NIMH Charging/LIPO for RX battery?
10-31-2007, 09:06 PM
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NIMH Charging/LIPO for RX battery?
Hi,
1. What is the correct 'c' rating to charge a RX NIMH pack at?
2. What should full charge/max volts be per cell after charging? (in my case a 4.8v NIMH 1100 mAh )
3. What is minimum voltage per cell (or 4.8V rx pack) that I should get down to before recharging?
4. Also, could you use small 1300mAh 2s 7.4v lipo with a UBEC, such as Castle's new one (5.1V output is default) as power for your RX/Servos?
Thanks!
Ken
1. What is the correct 'c' rating to charge a RX NIMH pack at?
2. What should full charge/max volts be per cell after charging? (in my case a 4.8v NIMH 1100 mAh )
3. What is minimum voltage per cell (or 4.8V rx pack) that I should get down to before recharging?
4. Also, could you use small 1300mAh 2s 7.4v lipo with a UBEC, such as Castle's new one (5.1V output is default) as power for your RX/Servos?
Thanks!
Ken
10-31-2007, 09:09 PM
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RE: NIMH Charging/LIPO for RX battery?
Most rx packs and smaller opacks should go for about c/4 or so and the max voltage is around 1.4 (resting) when charged. Not sure about the minimum , it will depend on the current being pulled at the time. My guess is 1-1.1 volt per cell.
10-31-2007, 10:36 PM
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RE: NIMH Charging/LIPO for RX battery?
It's best to re-charge when the pack is down to 4.8 volts under load. At 4.7 volts it's a must. The voltage drop is very fast, and capacity in nearly fully expended at 4.7.
This is critically important if you are flying one of the new 2.4 gig radios that will re-boot on low voltage.
This is critically important if you are flying one of the new 2.4 gig radios that will re-boot on low voltage.
11-01-2007, 12:16 AM
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RE: NIMH Charging/LIPO for RX battery?
yeah what they said =)
#4 yes, that is a good alternative. Lipo's have a more even discharge curve meaning you can predict approx capacity by measuring the voltage. When it gets down to nominal it's about 20%, so 4.2v is 100% and nominal is about 20%, so each 0.1v per cell is approximately 20%, so 3.8v for example would be about 40%. of course that is no load votlages and is just a ball park.
my 2cents would be max 1C min C/10 and C/4 like guver said would be a good middle point. Just watch the packs that they do not get over 100F (at the most internal spot in the pack), that's the guideline I go by
my packs are usually around 1.35v per cell or so after resting, hot off the charger they are usually 1.45 to 1.5v per cell
I would agree and say something around 1.2v per cell, or slightly under, in your case you would probably go for 4.7 to 4.8v under an equal load to what your plane uses inflight (usually 500mA to 2A).
#4 yes, that is a good alternative. Lipo's have a more even discharge curve meaning you can predict approx capacity by measuring the voltage. When it gets down to nominal it's about 20%, so 4.2v is 100% and nominal is about 20%, so each 0.1v per cell is approximately 20%, so 3.8v for example would be about 40%. of course that is no load votlages and is just a ball park.
my 2cents would be max 1C min C/10 and C/4 like guver said would be a good middle point. Just watch the packs that they do not get over 100F (at the most internal spot in the pack), that's the guideline I go by
my packs are usually around 1.35v per cell or so after resting, hot off the charger they are usually 1.45 to 1.5v per cell
I would agree and say something around 1.2v per cell, or slightly under, in your case you would probably go for 4.7 to 4.8v under an equal load to what your plane uses inflight (usually 500mA to 2A).
11-01-2007, 11:45 AM
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RE: NIMH Charging/LIPO for RX battery?
Lipo's are a great alternative to having a standard receiver pack. As you noted, you will need some sort of voltage regulator. This can either be a BEC or just a standard voltage regulator such as those available in the accessories page of our website.
Ryan Lefevre
www.CommonSenseRC.com
The Go To Guys For Electric Power
Ryan Lefevre
www.CommonSenseRC.com
The Go To Guys For Electric Power
