prerotator

[walterex1@gmail.com]

can someone please advise me on the best starter motor for a pre rotator
thanks
Rex 0423100160

[mad max]

I've used many different types of starters. Any modern starter with a reduction seems to win with power to weight. My present craft has a petrol hilux N.D. unit. They seem indistructable and you can overhaul them easy. replacable solenoid contacts, ect. Cranks my 28ft. AK's up to 100 rpm (I use a soft start resistor circuit)

[walterex1@gmail.com]

thanks MM and should I use a lithium battery to minimise weight?
is your soft start similiar to this link
:
https://www.ebay.com.au/itm/30A-DC6-...0d78%7Ciid%3A1

[mad max]

I designed my own system. Absolutely simple (Like my brain) No electronics. Just a high wattage resister made from a few turns of nichrome wire. (Got the wire from the tip of an old 400 volt low tech gismo) Pass the motor current through the resistor for a few seconds and then use a universal solenoid to bridge out the resistor for max. speed. The solenoid can be used as a terminal block. Comes out neat. All I need now is one of you intellectuals to design a couple of blade tip rockets to finish off the job and push the blades up to 300rpm so I can get airborne by my front gate

[walterex1@gmail.com]

thanks MM

[mad max]

I use standard lead acid mower battery. It cranks my EJ25 engine and pre-rotator easy. Pick them up for $120. Little guy with a handle. Your alternator will assist with pre-rotator power These little batteries even start my Mitsubishu 4 cly. diesel slasher engine.

[walterex1@gmail.com]

thanks I thought I would have to buy a lithium, good info

[RossM]

I suppose that a pulse width module would be more efficient than a resistor wire.
Be interesting to see if those mosfets do handle the current/heat, otherwise you will have to put in bigger heat sinks.
I am not a tech, but for $8.25, give it a go

[walterex1@gmail.com]

I will let you know if it works

[mad max]

Who cares about a few watts lost in heat. You've got a good power supply. 100HP engine driving an alternator and a battery.

[RossM]

I turn the rotors by hand first, then hit the starter motor.

[mad max]

That works