So I was wondering if there was an alternator that would spin off of a gasser that would go in parallel with a 3s battery (~12V) so that the backup battery wouldn't discharge as much or could be recharged inflight? If there isn't, how would I go about making this? Also is this bad for the battery?

Take a look at Sullivan Products

The idea of gasser recharging/generating inflight has been brought up many times, and normally comes to the conclusion that adding a gas tank, alternator, and engine is bulkier, messier, and heavier than simply adding more battery.

As long as you keep voltage/current within the LiPo's limits, it shouldn't be very bad for the battery. You might need a charge controller in there to manage the lipo charging.

Yah I've looked at those. I guess if I broke down a small charge station it would work. This actually won't be for a gasser. I was trying to simplify it a bit. The objective is getting power from an autogyro back into the system for longer duration flights.

Hi,

A friend of mine used a brushless motor as a generator ... aboard a ~ 2m / twin engine RIVA boat model !

riva lagaffe (2 min 5 sec)

but the purpose is to power the electrical systems of the boat ( and spare the dedicated battery ) ... but the gassers are mainly used for propulsion !

Alain

Originally Posted by gearwolf

The objective is getting power from an autogyro back into the system for longer duration flights.

Sounds like an experiment to check that the 2nd law of thermodynamics still holds.

Originally Posted by john dee

Sounds like an experiment to check that the 2nd law of thermodynamics still holds.

Lol yah physics is a p.i.t.a. It gets in the way of everything. You're right but I don't want it to be right. Well anyway I'm still looking for a way to try this. A way to get a generator to act as a parallel battery to my main flight pack. I have seen 12v regulators and maybe I should add that after the converter from three phase to two. Does this sound right?

I'm not suggesting this is going to get you to your goal of improving flight times, but you could look into this generator that is used on gasser helis (usually for AP, and not as popular now with the proliferation of LiPo receiver batteries). This system puts out 5.4 volts, but that is just because they have selected a 5.4v regulator to use with radio systems. You could probably do something similar with a 12v regulator...
http://mysite.verizon.net/vze49gsg/

Originally Posted by aaronredbaron

I'm not suggesting this is going to get you to your goal of improving flight times, but you could look into this generator that is used on gasser helis (usually for AP, and not as popular now with the proliferation of LiPo receiver batteries). This system puts out 5.4 volts, but that is just because they have selected a 5.4v regulator to use with radio systems. You could probably do something similar with a 12v regulator...
http://mysite.verizon.net/vze49gsg/

I understand, this was wishful thinking for me. I remember seeing that and probably got deterred by the price but then again hopefully you get what you paid for. I will contact that person. Thank you for helping me find a system. If anything it will make a funny video.