[JKovats]

Hi Guys;

I have a 4.8 battery pack hooked up to a JR HD charging switch. I was originally going to set up an ignition system on the moyor and use the 4.8 pack.

I am considering going with glow now but want to use what I have set up and wired in. That way it will act like an onboard glow when I turn the switch on and I can recharge my pack thru the swithch. Is there some kind of diode or resister or something that I can wire inline so that can drop the battery pack output to 1.2-1.5 volts.

I am not interested in disassembling the battery pack etc.

[Sparkfarmer]

Sounds like you're looking for a simple voltage devider circuit. Lot's of info on google. Basically two series resistors with the proper wattage rating in series. You tap off one of the resistors. Or you could use a potentiometer and dial in whatever voltage you want. You'll want to lock it after setting it because vibrations could change your setting.

Most electronics stores will have what you need as the parts required are common. Even an old field box panel with a glow connection could do if it has a rotary knob to set the "temp" of your plug. The knob is most likely a potentiometer....it is on mine anyway.

One thing to remember is that the whole circuit is a load on your 4.8V battery. Don't be fooled into thinking you'll get prolonged life since you are only using 1.5V. The remaining 3.3V is being used as heat energy off the resistor you aren't tapped to.

Hope this gives you a little direction. If I have time I'll see what I have in my stock. Maybe I can make one up for you.

[bartman]

Best bet would be buy a onboard glow driver.

http://switchglo.com/shop/product_in...i8upebvrqfdl71

I have that one but there are other possibly cheaper models.

[Sparkfarmer]

Sometimes most of the fun to be had comes from taking the long way around!

[bartman]

Originally Posted by Sparkfarmer

Sometimes most of the fun to be had comes from taking the long way around!

Agreed but for me that equates to

Large effort + large time investment = failed experiment LOL

But seriously the best would be to dissasemble pack and set up in a parallel circ, should end up at 1.2v 1500mah or better.

Resistors will work but like having a toaster inline.(as Sparkfarmer pointed out) voltage will fluctuate as pack depleats as well

Diodes wont heat up but will require 4 or 5 inline and you cant set the voltage as precise.

How about a cheap inline voltage regulator? Just need to source one that goes as low as 1.2v. Most RC stuff bottoms out around 4.8v being Rx based.

[JKovats]

Thanks Guys. I'll keep waiting for the simple, reliable, practical answer. I already have the 2700 mah battery pack in place and the HD charging swithch in place. I may in fact go to ignition, but I may want to try this step down issue first and use glow.

I had the plane all set up for a twin os 160 that I was going to put on ignition. The 4.8 feeds the ignition module. I have converted 4 saitos to ignition, left them on glow fuel, and really love them. No kick back, easy start, better fuel economy, even power curve and low/scale reliable idle.

I ended up picking up a twin saito 182 with twin glow plugs. Now I have a new challenge, 4 glow plugs.

So saito says spark up 1 glow plug on each cylinder and the other 2 will spark up on their own. So what happens if I put a spark plug in each cylinder and get a twin ignition and leave a glow plug in each cylinder. The glow plug will probably ignite from the heat. Does that throw off combustion timing and will the glow plug conflict with the spark plug? Interesting question. There are lots of theories out there but who has some actual hands on experience with this question??? Right.

Few people have real ignition experience with glow conversions and continuing to run glow fuel. I have found this out over the years and I don't know if anyone has this experience.

Next option, add a spark plug to each cylinder and disable the remaining glow plug by removing the coil.

3rd option, get an ignition set up with 4 leads and put 2 spark plugs in each cylinder. Probably a waste of money, wouldn't run any better, however would be pretty cool looking.

4th option similar to above, is to get 2 twin ignition modules and run them parrallell.

Since I am putting it in a 1928 "racer" cool and overkill would be okay. My Heath Baby Bullet.

I thought I would start with the glow issue first. I want to keep what I have already done and put something inline from the switch to drop the voltage to spark up the glow plugs and keep my options open for the future.

[tallone66]

John, my 2c worth. I would not run spark and glow at the same time. the advantage if spark is the timing is set and fixed, glow is not, hence the reason for kicking back when flipping glow. My thoughts would be the glow would flash before the ignition, leaving little or no fuel to burn when the plugs fire. In the case of twin plugs, i would run single spark, and plug off the glow.

Cheers
Derrick

[Sparkfarmer]

So there you have it. Lot's of good suggestions! Definately no lack of ways to do it! If you are set on getting a simple circuit and aren't in any rush, I'm back to work on Monday.

Based on some quick calculations a 1 Ohm and 4.5 Ohm resistor would do the trick. I might have a few kicking around my tool box or in the hangar somewhere.. Otherwise there is an electronics store on my way to work that will definately have some. I'll put the circuit together and test it.

Originally Posted by bartman

Agreed but for me that equates to

Large effort + large time investment = failed experiment LOL

But seriously the best would be to dissasemble pack and set up in a parallel circ, should end up at 1.2v 1500mah or better.

Resistors will work but like having a toaster inline.(as Sparkfarmer pointed out) voltage will fluctuate as pack depleats as well

Diodes wont heat up but will require 4 or 5 inline and you cant set the voltage as precise.

How about a cheap inline voltage regulator? Just need to source one that goes as low as 1.2v. Most RC stuff bottoms out around 4.8v being Rx based.

Diodes inline is the "Red Green" way of doing it. As you mention is not a very good option. As far as heat dissipation, as long as you have the right wattage of resistor it should actually be fairly cool.

[Sparkfarmer]

By the way...any pics of your bullet??

[kip51035]

Each silicon diode drops the voltage .7V so if you put five in series you should end up with 1.3V. They have to be five amp diodes.