Ignition batteries.
12-25-2007, 06:50 PM
#1
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Ignition batteries.
I cannot see what all the problems are in selecting a Ignition battery pack.Why not just use a 4.8 volt NMHI psck 1000 MA ot more. Except on the Zenoah EI 1000 MA would not last long . Most Ignitions draw about 450 to 600 MA at 8000 RPM.
But Here are some figures I came up with ,for those that want to use some of the new batteries. They probably do not mean much and you will still have to make your own choice.
These tests were done on a CHRCXL module and a CH module they are the same circuit. The RCEXL module cannot be changed we can bias the CH module for any voltage from 3.7 to 12 volts.This was a version 2 RCEXL circuit.
Voltage In----------------------Currant drain turned on ------------------------Currant drain 7500 RPM---------------Voltage on Output cap ------------------------Temperature on Transistor
Engine not running
2.5 V--------------------------------25 MA---------------------------------------No spark Hall switch dead---------------75V---------------------------------------------75 F
3.2 V--------------------------------30MA----------------------------------------Trying to work would not run engine 100V--------------------------------------------80F
3.7V---------------------------------40MA----------------------------------------Engine runs fine--------------------------120V-------------------------------------------85F
4.8V---------------------------------45MA---------------------------------------375MA--------------------------------------150V-------------------------------------------95F
6V-----------------------------------60MA----------------------------------------500MA--------------------------------------200V------------------------------------------115F
7.2 V--------------------------------75MA----------------------------------------700MA--------------------------------------220--------------------------------------------150F
8 V----------------------------------80MA----------------------------------------775MA--------------------------------------240--------------------------------------------1.80F
9V-----------------------------------90 MA---------------------------------------850MA---------------------------------------260-------------------------------------------210F
10V----------------------------------120MA--------------------------------------Over 1 amp -------------------------------290V-------------------------------------------240F
Something smelling hot (no smoke yet). Transistor going into suicide mode would soon self destruct and then there would be smoke and ignition dead.
Again why use over 4.8 volts . 6 volts would probably not hurt the CHRCEXL or the CH ignition. You could probably use two A-123 cells with one or two diodes in line with pos battery lead. I have been flying the CHXL single systems on one Li Poly works fine and have not field charged one yet.Tried one A-123 and would not run very long and voltage got to low. Hall sensor quits at around 3.2 volts. We are using same Hall switch as RCEXL.I will switch back to NMHI next flying season.
Take these fiugres for what they are worth probably not much and I am not suggesting anything. But heat goesup very rapidly over 6 volts. Anything over 120 V on output cap is fine.
Ran engine First Place 2.4 from 3.7 to 6 volts and no change in top RPM. I do not no who came up with the story that 6 volts would let you turn better RPM.
I will be doing tests on 2.4 to see if it is immune t o all RFI noise. I already no that it isn"t. Will post.
BCCHI
But Here are some figures I came up with ,for those that want to use some of the new batteries. They probably do not mean much and you will still have to make your own choice.
These tests were done on a CHRCXL module and a CH module they are the same circuit. The RCEXL module cannot be changed we can bias the CH module for any voltage from 3.7 to 12 volts.This was a version 2 RCEXL circuit.
Voltage In----------------------Currant drain turned on ------------------------Currant drain 7500 RPM---------------Voltage on Output cap ------------------------Temperature on Transistor
Engine not running
2.5 V--------------------------------25 MA---------------------------------------No spark Hall switch dead---------------75V---------------------------------------------75 F
3.2 V--------------------------------30MA----------------------------------------Trying to work would not run engine 100V--------------------------------------------80F
3.7V---------------------------------40MA----------------------------------------Engine runs fine--------------------------120V-------------------------------------------85F
4.8V---------------------------------45MA---------------------------------------375MA--------------------------------------150V-------------------------------------------95F
6V-----------------------------------60MA----------------------------------------500MA--------------------------------------200V------------------------------------------115F
7.2 V--------------------------------75MA----------------------------------------700MA--------------------------------------220--------------------------------------------150F
8 V----------------------------------80MA----------------------------------------775MA--------------------------------------240--------------------------------------------1.80F
9V-----------------------------------90 MA---------------------------------------850MA---------------------------------------260-------------------------------------------210F
10V----------------------------------120MA--------------------------------------Over 1 amp -------------------------------290V-------------------------------------------240F
Something smelling hot (no smoke yet). Transistor going into suicide mode would soon self destruct and then there would be smoke and ignition dead.
Again why use over 4.8 volts . 6 volts would probably not hurt the CHRCEXL or the CH ignition. You could probably use two A-123 cells with one or two diodes in line with pos battery lead. I have been flying the CHXL single systems on one Li Poly works fine and have not field charged one yet.Tried one A-123 and would not run very long and voltage got to low. Hall sensor quits at around 3.2 volts. We are using same Hall switch as RCEXL.I will switch back to NMHI next flying season.
Take these fiugres for what they are worth probably not much and I am not suggesting anything. But heat goesup very rapidly over 6 volts. Anything over 120 V on output cap is fine.
Ran engine First Place 2.4 from 3.7 to 6 volts and no change in top RPM. I do not no who came up with the story that 6 volts would let you turn better RPM.
I will be doing tests on 2.4 to see if it is immune t o all RFI noise. I already no that it isn"t. Will post.
BCCHI
12-26-2007, 10:18 AM
#3
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RE: Ignition batteries.
Good post.
It should end the discussion about the need for 5 cells.
4 cells when empty, have 4 volts, with the ignition still going strong at low battery drain current.
It should end the discussion about the need for 5 cells.
4 cells when empty, have 4 volts, with the ignition still going strong at low battery drain current.
12-26-2007, 01:45 PM
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RE: Ignition batteries.
I cannot see what all the problems are in selecting a Ignition battery pack
Lion and 123s dont discharge while it sits so if I miss a weekend or get a call to go fly at the last minute ( which happens a lot) I can come home pickup the trailer and fly.
Nothin to do with capacity or voltage for me.
12-26-2007, 04:48 PM
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RE: Ignition batteries.
ORIGINAL: Panzlflyer
Because I dont want to charge the thing before I go to the field everytime.
Lion and 123s dont discharge while it sits so if I miss a weekend or get a call to go fly at the last minute ( which happens a lot) I can come home pickup the trailer and fly.
Nothin to do with capacity or voltage for me.
I cannot see what all the problems are in selecting a Ignition battery pack
Lion and 123s dont discharge while it sits so if I miss a weekend or get a call to go fly at the last minute ( which happens a lot) I can come home pickup the trailer and fly.
Nothin to do with capacity or voltage for me.
THAT is EXACTLY right. I'm getting lazier and lazier.... soon, I'll expect them to fuel themselves, then preflight, and self-start, then follow my mental program flight path.
But for right now, I'm happy with LONG storage/shelf life batteries that I don't have to worry about blowing up my house with....
