Simjet 75n converted to auto start
 

I have a Simjet 75n that was converted to an autostart by Simjet and last ran in 2010, I have dug it out and was looking to start it.
It has had the pump and solenoid valves checked and a new glow plug fitted. The propane/butane mix is old, but still ignites when ignited with a naked flame and seems to enter the turbine from the smell of gas. It never gets passed the start phase, i.e. although the red led is on for glow ignition during the start cycle, nothing happens, no ignition occurs. It used to be fine and would start very quickly.

The ECU is a FADEC 2002-D1 rated at 9.6 volts and so had a supplied 1300mah 2/3 cell 9.6v Sanyo NiCd, which although charges apparently correctly, fails to start the turbine and goes flat really quickly, not surprising for a 12 year old battery. I don't like using NiCd's so wanted to move over to preferable a Lipo as I use them all the time in my other models and drones.

If so would a 3s work? I know a fully charged 9.6v NiCd could be around 11.2v and a fully charged 3s lipo could be 12.6v, would that be acceptable or would I have to limit the voltage of the 3s Lipo?

Use a two cell LIPO, you could also use a flame in the back of the turbine during the starting sequence, it will ignite the propane, the old NICD doesn't have what it takes to start the engine anymore, the glow plug is there just to get the flame going, if you can get it to fire then you are one step forward.

Keep us informed.

Good luck.

Well it fired up today with the old NiCd, seems to have been a gas issue.

But I would still like to go to a lipo.

Is the 2s recommendation based on actual knowledge of the ECU or just as suggestion?

The two cell LIPO is an excellent replacement for the six cell NICD pack, it will not exceed the voltage recommendations ( @ 8.4 max ) for the FEDEC, I run my 20 years old TJT300 that has a Xicoy FEDEC with a two cell LIPO.

My first turbine was a 2300 Simjet, I run it with NICD packs, we used to run all of our turbines with six pack NICDs then we switched to 2 cell LIPO packs when they became available, we still do, I run 3 of my engines on a 2 cell LIPO pack.

Only problem is the original pack is an 8 cell NiCd 9.6v! A 2s would be too low a voltage I imagine.

Agreed, I was just re reading your post.

Let me see.

Ok then, a 3 cell LIFE pack is your best bet @ 9.9v min and 10.8v max.

The 3 cell LIPO maybe getting to close to the FEDEC's max rated voltage that may be 13v.

Thanks, I'll look into them. :)

How did it go with the battery ? I have 2002 fadec for my 1200 that i use a 3 cell lipo on , 2 cell did not work.

It worked with the original battery, but is away for service now. I will look into it further when it gets back.