Bass1

Hi all, I have a 4 cell 1400mah Nicad ignition pack powering a CH ignition for a Brison 3.2. Is it safe to assume I need to recharge the ignition battery before I get it down to 4.8 volts? At what point/voltage, does the ignition start having problems? After 2 flights ( 10 minutes each) my fully charged pack reads about 4.8 volts with a digital voltmeter. Does this sound right? Thanks in advance

TLH101

My Feedback: (90)

Sounds like you may have a weak battery. The C&H ignition only uses about 200-400mah when running. You should be able to fly all day & more with a 1400mah. Not sure what voltage it will cut out at, but it will start "shooting ducks", when the battery gets low.

Don M.

My Feedback: (5)

I have a Brison 2.4 & a MVVS 1.6 I always use an 1100 - 4.8 volt pack and can easily fly 7 flights in 1 day no problem. I find my 4.8 battery packs will drop to 4.8 after only 1 or 2 flights but will only drop to 4.7 after 5 more. Neither ignition give me any problems at 4.7 volts.

Geistware

My Feedback: (16)

I usually have problems at about 4.4 volts.

SAL98

My Feedback: (6)

Don.M is correct, Nicad and Nimh do not drop there voltage in a linear fashion. they will always drop very fast at first even right off
f the charger and then settle in at around 4.8 for almost the entire discharge of the pack.

Diablo-RCU

My Feedback: (1)

The voltage you measure is also a function of the amp load on the meter and the capacity and internal resistance of the cells. My packs don't drop to 4.8 volts in a heartbeat.

Bass1

Well I'm feeling a little better about my ignition battery pack. It is less than a year old and it's from a trusted company. My voltmeter (Hobbico MK III) tests the pack under a 250 mah load. I would put the pack on a quick charge after the second flight for fear of inadequate voltage to power the ignition. I'll fly a third time and check the pack. Then if all goes well, I'll shoot for 4! Also, When I charge my 2700 mah 5 cell flight pack, I get close to 7 volts. By the time I get to the field the pack tests at about 6.70 volts. After 2 flights it is down to about 6.28. Being cautious, I also recharge the flight pack as I'm afraid the pack may drop below 6 volts on a third flight. Am I being overly cautious? Seems like I spend alot of valuable flying time charging my batteries. This is my most expensive plane and it's the most fun I've had flying R.C. in 30+ years. I would hate for it to go in because of depleted battery packs[X(]

Don M.

My Feedback: (5)

If you feel better charging after 2 flights then go for it, but I can tell you I have never charged a battery at the field in 20 years of flying, I don't even own a 12 volt charger. I have never lost a plane due to low battery voltage ( except one I forgot to charge before flying ). I have a 1/5 P-51 that has 10 servos and a 2700 - 5 cell pack and fly sometimes 5 or 6 flights and still have plenty left for 2 or 3 more ( according to my recycler ). I have a Balsa Nova 120 with 6 servos ( 3 digital ) and a 2000 - 5 cell pack and if it is the only one I take to the field I may fly 8 - 10 flights ( 10 min. ones ) and still have juice left.

After 5 flights I do however check voltage before each flight but once it gets to about 6.2 volts it just seems to stay there. I find the same thing with my transmitter it has an 1100 mah battery and will very quickly ( 2 or 3 flights ) drop to 9.8 volts and never go any farther even after 10 - 12 flights.

Someday I will lose an airplane I suppose and change my habits, but for now ( and the last 20 years ) "all is well that ends well".

Geistware

My Feedback: (16)

It is amazing how a thread migrates away from the topic at hand

I to would like to know the minimum voltage that the ignition can run. I have put 4-5 flights on a pack and see a decrease in max rpm. I measure the pack with a 1 amp load at 4.4 volts or there abouts. What have others seen?

Diablo-RCU

My Feedback: (1)

Try a 250 mA and enjoy the higher voltage reading....
I don't think the peak current draw on a CH single ignition is anywhere close to 1 amp.

Antique

My Feedback: (4)

RPM is not a function of ignition voltage on a gas engine.

Tired Old Man

My Feedback: (1)

According to Terry at C-H, the minimum recommended battery voltage is 4.8. That's pretty much the desired rated voltage for a given amp hour sized nicad battery pack. They are reputed to draw approximately 400 mAh per flight hour on a single cylinder engine. Very recent independant scientific lab testing noted that the above works very well and that the C-H system is extremely reliable for extremely long periods of time. Further specifics regarding the testing cannot be provided due to non-disclosure agreements.

More voltage input will have little additional benefit.

Geistware

My Feedback: (16)

Ralph,
I don't know about that.
My BME102 will idle OK with a measured ignition voltage of 4.5.
When I increase the RPM, the voltage drops to around 4.2 and the unit starts to cause the engine to miss. I have had the unit in for service and know it is working good. WHen I charge the pack the problems go away. This I KNOW.

If what you are saying is true (and I dojn't doubt you), then I would definately like to find out why my engine and ignition operates differently.

TLH101

My Feedback: (90)

I believe what Ralph is trying to say, is you will not gain RPM by using more voltage (ie: 6v pack). However you can definatley see a breakdown in ignition performance with too little voltage.

mglavin

My Feedback: (31)

I don't remember the specifics of this assertion, but the Engineer of the C&H Ignition design once told me the unit consumes 8 or 10 amps in gulps, I think he was suggesting this of the twin unit. I wish I could recall more but it was several years ago.

Antique

My Feedback: (4)

The Ignition will work down to 4.2, but like you say, will miss...If you're showing 4.5 you need to get a new battery pack....
Our circuits are slightly different in that mine takes about 180MA at idle and about 200MA wide open...That would explain the engine idling and missing at higher rpm, right on the borderline of too little voltage...

mglavin

My Feedback: (31)

According to those in the know:

"Brown out reset on the SS module is about 4.4V which is quite far into the down leg of the discharge curve on a 4.8V pack. When this occurs the engine will start to 4-stroke and you had better land."

tkg

My Feedback: (1)

A nicad or Nimh is considered discharged at 1.1v per cell. It may have the voltage to run an ignition but it does not have the current.
With a regulated 10 amp power supply we have run the ignitions to less than 4v.