4.8V versus 6V for receiver battery?
10-09-2007, 12:18 PM
#27
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RE: 4.8V versus 6V for receiver battery?
No, I guess I wasn't talking about that conversation. I thought I heard you or somebody say that given the same mah--a 4.8v battery will last longer than a 6v. I have mostly 6v 2700 mah
10-09-2007, 01:38 PM
#28
RE: 4.8V versus 6V for receiver battery?
Depending on what you are using those batteries on, 2700 mah is a fairly good capacity.. 
I use 1200's myself and get at least four flights (conservative that I am) and won't go much further without a recharge.
To tell you the truth, I am somewhat reluctant to listen to the sort of predictions about 4.8 vs 6 volt and their charge longevity. I did my own research and talked to what I consider battery pro's both on-line and in person, and have come up with my own criteria for battery options on my planes.
Some of the guys at the field think I am sort of overboard, but what can I say. None of my glow planes are under-powered so I don't worry about weight. Electric powered aircraft are a totally different animal here, and out of the realm of this discussion (I had to throw that in as a disclaimer considering the scrutiny that seems to happen often here on RCU 
).
I also have dual battery setup(s) on my 'larger' and 'more expensive' aircraft (pattern planes) and also use the 6 volt 1200 mah's on those.
But, with that said, one of the guys in our club who flys pattern, uses a 72 MHz Futaba system, (said that because the Spektrum's seem to prefer 6 volt systems) and uses a 4.8 volt battery. He likes the slower response of those for his pattern flying, and spends a considerable amount of setup time and effort to keep any sort of servo bind out of the equation. I don't recall the capacity he uses, but he definitely swears by using the 4.8's in his pattern planes. I was sort of surprized to see that he had a 700 mah 4.8 volt pack in his pattern plane.. but what he said makes perfect sense. His flights last only about 5 minutes each and he monitors the batteries constantly (well, not during flight, but I'm sure you realize that and understand what I am saying here).
I use the 6 volt packs and if I want to slow things down, I just add varying levels of exponential or reduce the throw (or both).
CGr.
I use 1200's myself and get at least four flights (conservative that I am) and won't go much further without a recharge. To tell you the truth, I am somewhat reluctant to listen to the sort of predictions about 4.8 vs 6 volt and their charge longevity. I did my own research and talked to what I consider battery pro's both on-line and in person, and have come up with my own criteria for battery options on my planes.
Some of the guys at the field think I am sort of overboard, but what can I say. None of my glow planes are under-powered
so I don't worry about weight. Electric powered aircraft are a totally different animal here, and out of the realm of this discussion (I had to throw that in as a disclaimer considering the scrutiny that seems to happen often here on RCU ). I also have dual battery setup(s) on my 'larger' and 'more expensive' aircraft (pattern planes) and also use the 6 volt 1200 mah's on those.
But, with that said, one of the guys in our club who flys pattern, uses a 72 MHz Futaba system, (said that because the Spektrum's seem to prefer 6 volt systems) and uses a 4.8 volt battery. He likes the slower response of those for his pattern flying, and spends a considerable amount of setup time and effort to keep any sort of servo bind out of the equation. I don't recall the capacity he uses, but he definitely swears by using the 4.8's in his pattern planes. I was sort of surprized to see that he had a 700 mah 4.8 volt pack in his pattern plane.. but what he said makes perfect sense. His flights last only about 5 minutes each and he monitors the batteries constantly (well, not during flight, but I'm sure you realize that and understand what I am saying here).
I use the 6 volt packs and if I want to slow things down, I just add varying levels of exponential or reduce the throw (or both).
CGr.
10-09-2007, 03:19 PM
#29
RE: 4.8V versus 6V for receiver battery?
The nice part about 5 cell packs is if a cell dies it wont drag the system down to where the reciver will reset, you still have enough volts to fly safely.
The down side is some servos arent rated for it so the servos can fry. That applies mostly to high frame rate stuff used in gyros and governors in helis though.
The down side is some servos arent rated for it so the servos can fry. That applies mostly to high frame rate stuff used in gyros and governors in helis though.
10-09-2007, 03:31 PM
#31
RE: 4.8V versus 6V for receiver battery?
ORIGINAL: goirish
Barracuddahockey where you been--is the hockey season getting ready to start again.
Barracuddahockey where you been--is the hockey season getting ready to start again.
10-10-2007, 05:20 AM
#32
RE: 4.8V versus 6V for receiver battery?
In July, I was flying my Venus II with OS 1.20 AX engine and the Spektrum DX7 system. I have a pair of 1200 mah NiMH 5 cell packs on that plane.
After the second or third flight, I forget what one exactly, I wanted to check the battery condition. So, I did. What I found shocked me. One battery read about 1 volt. The other read about 6.2 volts. At first, I thought I read the first battery wrong, or my expanded scale voltmeter was acting up, so I borrowed one from one of the other flyers. That battery read the same thing, but as it loaded with the voltmeter load function, the voltage started to drop from 1 volt.
I removed that battery and put a spare that I had and then put both batteries on the charger. I also started to use Voltwatch after that flying day.
We then began to take a close look at that bad battery. It had a bad cell.. one bad cell. It would have caused me severe pain if I had not had setup that plane with two battery packs. So, I don't believe that if you lose one cell, you can fly on. That plane would have definitely have come down if I only had that one battery pack installed.
CGr.
After the second or third flight, I forget what one exactly, I wanted to check the battery condition. So, I did. What I found shocked me. One battery read about 1 volt. The other read about 6.2 volts. At first, I thought I read the first battery wrong, or my expanded scale voltmeter was acting up, so I borrowed one from one of the other flyers. That battery read the same thing, but as it loaded with the voltmeter load function, the voltage started to drop from 1 volt.
I removed that battery and put a spare that I had and then put both batteries on the charger. I also started to use Voltwatch after that flying day.
We then began to take a close look at that bad battery. It had a bad cell.. one bad cell. It would have caused me severe pain if I had not had setup that plane with two battery packs. So, I don't believe that if you lose one cell, you can fly on. That plane would have definitely have come down if I only had that one battery pack installed.
CGr.
10-10-2007, 08:30 AM
#33
RE: 4.8V versus 6V for receiver battery?
ORIGINAL: CGRetired
In July, I was flying my Venus II with OS 1.20 AX engine and the Spektrum DX7 system. I have a pair of 1200 mah NiMH 5 cell packs on that plane.
After the second or third flight, I forget what one exactly, I wanted to check the battery condition. So, I did. What I found shocked me. One battery read about 1 volt. The other read about 6.2 volts. At first, I thought I read the first battery wrong, or my expanded scale voltmeter was acting up, so I borrowed one from one of the other flyers. That battery read the same thing, but as it loaded with the voltmeter load function, the voltage started to drop from 1 volt.
I removed that battery and put a spare that I had and then put both batteries on the charger. I also started to use Voltwatch after that flying day.
We then began to take a close look at that bad battery. It had a bad cell.. one bad cell. It would have caused me severe pain if I had not had setup that plane with two battery packs. So, I don't believe that if you lose one cell, you can fly on. That plane would have definitely have come down if I only had that one battery pack installed.
CGr.
In July, I was flying my Venus II with OS 1.20 AX engine and the Spektrum DX7 system. I have a pair of 1200 mah NiMH 5 cell packs on that plane.
After the second or third flight, I forget what one exactly, I wanted to check the battery condition. So, I did. What I found shocked me. One battery read about 1 volt. The other read about 6.2 volts. At first, I thought I read the first battery wrong, or my expanded scale voltmeter was acting up, so I borrowed one from one of the other flyers. That battery read the same thing, but as it loaded with the voltmeter load function, the voltage started to drop from 1 volt.
I removed that battery and put a spare that I had and then put both batteries on the charger. I also started to use Voltwatch after that flying day.
We then began to take a close look at that bad battery. It had a bad cell.. one bad cell. It would have caused me severe pain if I had not had setup that plane with two battery packs. So, I don't believe that if you lose one cell, you can fly on. That plane would have definitely have come down if I only had that one battery pack installed.
CGr.
10-10-2007, 10:09 AM
#34
RE: 4.8V versus 6V for receiver battery?
Yeah, and it was a fairly new pack, not, by any stretch of the imagination, overused or overcharged. It just died in flight. Made a believer of me for dual battery packs. I can afford the added few ounces of weight for the added security of that second battery. And I check them frequently (always did, but make darned sure now).
10-10-2007, 10:51 AM
#36
RE: 4.8V versus 6V for receiver battery?
The best way to connect two batteries is to run each battery through it's own switch. And then each switch plugs into seperate channels in the receiver. If there are not enough open channel slots in the receiver you can put a Y-harness into a channel on the receiver, then plug the switch into one side of the Y-harness and the servo into the other side. This is the best way because a bad switch or bad connection will not kill the plane. Since the other battery is still plugged in and providing power to the receiver it will still operate.
A second way is to connect both batteries into a Y-harness and then plug that into the switch. Then the switch into the receiver. If you do it this way a switch going bad will result in no power to the receiver.
Ken
A second way is to connect both batteries into a Y-harness and then plug that into the switch. Then the switch into the receiver. If you do it this way a switch going bad will result in no power to the receiver.
Ken
10-10-2007, 11:06 AM
#37
RE: 4.8V versus 6V for receiver battery?
Should always use 2 switch harnesses BEFORE connecting to the Y-harness. Both for charging purposes and operational redundancy. Better yet to use 2 RX ports in some manner if you can.
10-10-2007, 11:47 AM
#38
RE: 4.8V versus 6V for receiver battery?
WWW.Smart-fly .com sells a battery combiner that draws from the strongest of the two batteries. It is installed after the switches.
"With the Smart-Fly BatShare, you can tolerate a single failure (open-circuit, short-circuit, low voltage) in either battery pack, or switch, or battery wiring, without losing radio control."
Regardless, individually switched batteries is always a good bet as a switch problem is a single-point-of-failure disaster. Smart-fly also sells HD Cermark switches with recharge ports built right in. They have double poles so even if one set of points fails you are OK. Can't be too careful. ;-)
"With the Smart-Fly BatShare, you can tolerate a single failure (open-circuit, short-circuit, low voltage) in either battery pack, or switch, or battery wiring, without losing radio control."
Regardless, individually switched batteries is always a good bet as a switch problem is a single-point-of-failure disaster. Smart-fly also sells HD Cermark switches with recharge ports built right in. They have double poles so even if one set of points fails you are OK. Can't be too careful. ;-)
10-10-2007, 12:24 PM
#39
10-10-2007, 01:32 PM
#44
RE: 4.8V versus 6V for receiver battery?
ORIGINAL: bruce88123
NHL started last Wednesday. 10/3/07
ORIGINAL: goirish
Barracuddahockey where you been--is the hockey season getting ready to start again.
Barracuddahockey where you been--is the hockey season getting ready to start again.
10-11-2007, 05:49 AM
#45
RE: 4.8V versus 6V for receiver battery?
Some pattern folks have a theory about points of failure and they claim that adding more components becomes more detrememtal to operation when a failure occurs. They claim that added devices, such as was pointed out by Charlie only adds to the potential failure points in a battery system. But, that device holds merit, as does the Voltwatch, but for obvioiusly different reasons.
Personally, I am not quite sure of that (points of failure), but it makes sense, but I am still somewhat dubious. Even the pattern folks will admit to a bit of paranoia there, but they have a rather large investment in those planes too.
What I see is that taking two batteries through a Y connector to one switch IS a potential problem because any one failure can cause problems.
With two batteries, connected as RCKen pointed out, (two separate systems - 2 batteries, 2 switchs connected to 2 separate receiver channels) provides definite redundancy and is the most reliable method. Proof of that is my post about what happened to me with my Venus II. I had no idea that a battery had failed until I landed and measured the voltage. The plane flew just fine.
I don't know what would have happened if one battery would short, for instance (most detremental I believe) in a dual setup to a Y cable. Would the short circuit draw down the good battery? Current flows through the path of least resistance.. so would that be the failed (shorted) battery? Open circuit is not a problem.. infinite resistance.. shorted switch.. well, isn't that the way they work? Open switch.. a big problem.
So, IMHO, double everything, battery, cable, switch, two separate RX channels.. is the way to go. And with this, you can, if you really wish, reduce weight by going to a pair of 700 mah's which will give you a 1400 mah supply.
CGr
Personally, I am not quite sure of that (points of failure), but it makes sense, but I am still somewhat dubious. Even the pattern folks will admit to a bit of paranoia there, but they have a rather large investment in those planes too.
What I see is that taking two batteries through a Y connector to one switch IS a potential problem because any one failure can cause problems.
With two batteries, connected as RCKen pointed out, (two separate systems - 2 batteries, 2 switchs connected to 2 separate receiver channels) provides definite redundancy and is the most reliable method. Proof of that is my post about what happened to me with my Venus II. I had no idea that a battery had failed until I landed and measured the voltage. The plane flew just fine.
I don't know what would have happened if one battery would short, for instance (most detremental I believe) in a dual setup to a Y cable. Would the short circuit draw down the good battery? Current flows through the path of least resistance.. so would that be the failed (shorted) battery? Open circuit is not a problem.. infinite resistance.. shorted switch.. well, isn't that the way they work? Open switch.. a big problem.
So, IMHO, double everything, battery, cable, switch, two separate RX channels.. is the way to go. And with this, you can, if you really wish, reduce weight by going to a pair of 700 mah's which will give you a 1400 mah supply.
CGr
10-11-2007, 08:25 AM
#46
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RE: 4.8V versus 6V for receiver battery?
Mr. RCKen
When I hook up two batteries you said I need two switches. If I am not using flaps or retracts do I plug the battery into one of those slots and the other battery in the battery slot on the rx.?
When I hook up two batteries you said I need two switches. If I am not using flaps or retracts do I plug the battery into one of those slots and the other battery in the battery slot on the rx.?
10-11-2007, 08:31 AM
#47
RE: 4.8V versus 6V for receiver battery?
Goirish,
Yes, you plug each seperate switch into the receiver. The first one goes into the battery connection of the receiver. The second one goes into any open slot in the receiver (i.e. gear, flaps, etc....). If you do not have any open slots in the receiver you would use a Y-harness. Plug the Y-harness into a slot on the receiver, for instance the gear slot. Then plug the gear servo into one side of the Y-harness and the battery into the other side of the Y-harness. You can plug the battery into any channel on the receiver and it will work.
Ken
Yes, you plug each seperate switch into the receiver. The first one goes into the battery connection of the receiver. The second one goes into any open slot in the receiver (i.e. gear, flaps, etc....). If you do not have any open slots in the receiver you would use a Y-harness. Plug the Y-harness into a slot on the receiver, for instance the gear slot. Then plug the gear servo into one side of the Y-harness and the battery into the other side of the Y-harness. You can plug the battery into any channel on the receiver and it will work.
Ken
10-11-2007, 08:38 AM
#48
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RE: 4.8V versus 6V for receiver battery?
Thank you Sir: Always great help at RCU--Are the moderators full time with RCU--you all seem to spend lots of hours on the old puter. Just my 2c. Thanks for being there
10-11-2007, 08:41 AM
#49
RE: 4.8V versus 6V for receiver battery?
ORIGINAL: goirish
Are the moderators full time with RCU--you all seem to spend lots of hours on the old puter.
Are the moderators full time with RCU--you all seem to spend lots of hours on the old puter.
Some moderators have more time here than others. Being self employed I get to do a lot of work from home. Plus, when I am at the office I pull up RCU there as well. Other moderators only have evenings and weekends here on RCU. The time they devote to RCU varies from moderator to moderator. But none of us are "full time".
Ken
10-11-2007, 08:42 AM
#50
RE: 4.8V versus 6V for receiver battery?
And that's a good point CGRetired, adding complication can increase Murphy's chances.
I just purchased the battery combiner to install in a 27% Ultimate that is $1,200 of airframe, engine and parts in the air at one time. The redundancy is a comfort, perhaps only imaginary, that I will get it back in one piece should one pack fall out of the circuit. Nothing I have that is glo-powered has ever had a dual battery system. I suppose if you have to add weight to balance a second battery as far back as the connector wiring allows or behind the firewall is a better idea than "dumb lead" near the tail.
Even with a switch with double-poles you could be flying on one pair of points damaged without knowing it, so if the second set also fails during a flight you're still kissing dirt.
When the gremlins want your plane they will find a way.
I just purchased the battery combiner to install in a 27% Ultimate that is $1,200 of airframe, engine and parts in the air at one time. The redundancy is a comfort, perhaps only imaginary, that I will get it back in one piece should one pack fall out of the circuit. Nothing I have that is glo-powered has ever had a dual battery system. I suppose if you have to add weight to balance a second battery as far back as the connector wiring allows or behind the firewall is a better idea than "dumb lead" near the tail.
Even with a switch with double-poles you could be flying on one pair of points damaged without knowing it, so if the second set also fails during a flight you're still kissing dirt.
When the gremlins want your plane they will find a way.