I'm changing out engines on my Meister FW-190A, and the FPE 100 has a CH electronic CDI ignition. Looking at the CH website, it calls for a 4.8V battery of at least 800MaH. My question is, does it HAVE to be a 4.8V battery, or can I use a 6Volt battery?

Thanks,

Ed

I will use 4.8 2000mah

4.8 works better. The ignition consumes more current at higher voltages. Figure the engine will use rougly 450 ma/cylinder/hour of running time. You will not obtain longer running times with more voltage. Actually you get less.

Ed, A five cell pack is fine. Dan.

I've got 6 volt battery packs coming out of my ears, but no 4.8 volt packs. I'll give a 6 volt-1700 mah pack a try.

Thanks,

Ed

I'm really interested now in why you even bothered to ask the question...

Because the info I got from the CH website mentioned nothing about 6 volt packs... only 4.8 volt. I asked, because I only have 6 volt packs, and wanted to be sure I wasn't going to hurt the ignition system by going 6 volt.

The early CHEXL ignitions would not take anything over 6V and a 5 cell pack has more than 6V unless it is run down.

All the CH units ran satisfactory and drew less current if run on a 4 cell pack

Kinda what I was wondering also!

How much work is it to remove one cell from a 5 cell pack? Gee, I guess if it didn't come that way I can't change it for my requirements.

I guess it'd be more work than just using a 5-cell 6 volt pack, if it would work with the system, eh?

The CH is one of the best ignitions ever made and they will handle 6v, or more accurately 7.2v on a fresh charge for quite some time, but not forever. Unfortunately you cannot get another CH anymore so you might want to consider using it at the voltage they rated it at. There was a reason for that rating, and the reason is heat. Excess voltage is disposed of as heat. Heat is and always has been the enemy of electronics. Things don't happen over noght but eventually that ignition, run on 6v, is going to crap out on you. I know from a whole lot of personal experience the CH can last a few THOUSAND hours of running time if used at the rated voltage. Bill from CH posted some current draw numbers for their ignitions some time back. It was interesting to note how much more current was consumed at 6v over 4.8.

So yes, you can run it at 6v+. If I had to make a choice of running a $150.00, top of the line ignition at 6v to save buying an $18.00-$25.00 battery or run it at 4.8v and keep it forever my choice would be simple. I might run it one weekend at 6v but by the next I'd have a better battery for it. But that's just me. I've used hundreds of their ignitions and know how reliable they can be, and also know how to shorten their lifespan by a considerable amount.

I would say go get a 4 cell pack. C&H ignitions runs great and they run forever on a 4.8 pack. I have a C&H ignition on a old Brison 2.4 that have been running for years on a 4 cell 1100ma Nicad pack without a hiccup. The thing is, you can't go get a new C&H ignition module. I would not risk it and push it to 6v. You wont fully appreciate a good dependable ignition module until you've pulled out half your hair trying to figure out a bad one.

You can change a five cell pack to a four cell pack very easily. Unsolder either the red or black wire and solder it to the next inside cell. Just make sure you get the polarity right. The black wire goes to the end of the battery that is flat and the red wire goes to the side with the button on it. You can leave the unused cell in place. Make sure your charger can tell the difference or reprogram it. Dan.

Me to. LOL

It also say's nothing about not using a 2 or 3 cell lipo.

Milton

This 4.8 volt versus 6.0 volts for powering an ignition is a topic that has been beaten to death here almost as often as the OIL thing, and yet folks keep trying to reinvent the wheel by wanting to use a higher voltage than recommended, for absolutely no increase in performance whatsoever on ignitions that the manufacturer's rate at a specific voltage of 4.8v ..... sure beats me why they want to do it.

Karol

Thanks to Tired Old Man, Dan Reiss, w8ye, and On Final, for the pertinent and very helpful information.

And, if I had nothing but a box full of 2-3 cell Li-Po's, I probably would've asked the same question about them, too, in an effort to learn a bit more about what's good and not good for the ignition system.

Thanks for your input.

Ed

NOW HERE IS A QUESTION? It seems like you could use the packs you have...just place the correct voltage dropping resistor in place. There has got to be a simple way to drop the voltage to about 4.8-5 Volts! Right??? Capt,n

well, no actually, not that simple just to put in a resistor.
voltage drop over a resistor is proportional to the current - TOM estimates (and probably actually has measured carefully) that to be ~450ma per cylinder. E=IR. You could do the math and figure out a R value that would give you a voltage drop of 1.2v, (something like 2.5 ohms) but the actual drop would be dependent on instantaneous current draw, and dependent on the specific ignition system. If the draw were substantively different, the resistance would be wrong. I understand the interest in using what we have (6v, or lipos, or whatever), but in this situation it does seem simplest, and best, just to use a 4 cell pack. It is what the ignition system was designed to use. The other issue is that voltage drop across the resistor will generate a bit of heat, albeit not in the ignition.

A series resistor is counter productive in this application as the amount of voltage drop is dependent on the load. You would have the greatest voltage drop as the capacitor was charging and when the current draw is at a minimum the voltage would soar. The total internal resistance would make for a poor performing ignition system.

Well it was just a question. How about a voltage droping arrangement of diodes?
I guess the use of a voltage regulator may not work either. Too bad.....he had several packs...all to high voltage. Well it is a good learning curve for others too!

The diodes seem to work well

Greater initial voltage and a voltage regulator would be better. Maybe from a BEC?

I'm one that looks for simplicity. In adding optional electrical components you introduce new points of potential failure, not to mention the additional work involved. Unless your time is worth next to nothing the easiest and simplest way is just to use the correct battery. I'll venture there's more than a few people that have those 600 ma batteries that came supplied with their new radios. That handles a single cylinder engine for most average flying days.

Sometimes it's not about what we have. Shoot, I have a bunch of old glow engines but I'm not looking for a place to use them in place of a gasser. Also have a bunch of old 2-56 hardware laying about but the functionality is well beyond suspect in anything above about .60 size glow. It's all about personal choice. All we can do is inform of what might be the "best" method or product. The individual has to make their own choice from there.

K.I.S.S., 4.8v, NO diode, regulator, resistor.

w8ye, TOM, TKG....al real good informative postings...Thanks Capt,n &amp; others!</p>