Gas/electric progress and how to test a wacker

Discussion in 'General Questions' started by professor, Nov 6, 2009.

  1. professor

    professor Active Member

    The little Weedeater wouldn't spin the alternator, so I bought a Harbor freight 2.5 and made a mount on the back for it.

    In case you are wondering what I am doing- it is legal in NY to have an electric assist power bike (no gas jobs).
    So I thought, I know nothing about controlers and hi teck gizmos. How about making a genset to power it instead of batterys? Would need a small battery to energize the field circut of the alt. to make juice.
    Alternator needs to spin 2200 rpm to make the scooter motor's 24 volts and drive my bike.

    Final drive chain is not on so my basic test is to crank up the engine to full rpm and hit the field wire to energize the alt. (motors draw much more than normal load when starting).

    Here is a pic of the motor in the Mongoose- I raised the shock mount to fit the motor in there and the jackshaft is a rear freewheel hub adapted to the scooter sprocket.


    BIG bugaboo with the HF engine is weight, a real sweet runniing mill and looks like a quality item BUT, I went for a pedal ride down the street and it felt like the fat lady was riding on the tail of the bike.
    All up weight was 78# not including any last bits like rear sprocket and small battery for the field circut.
    Plenty of power though, the HF hardly flinched when I hit the field wire. Throttle would spin the electric motor up or down perfectly.

    Maybe mounted down in the frame it would be fine.

    Had another wacker that doesn't smoke much and is real snappy, but I didn't want to make parts for the v-belt drive and then find out it too wouldn't have the guts to drive the alternator.
    It came to me last night in bed, to couple the alternator shaft and the wacker lower end outputs together with some rubber hose. Looks like this:

    The Toro is hanging from a chainfall.
    Real good test! The clutch equipped wacker started nice and would spin the alt. like wild UNTIL I connected the field wire, then it loaded down holding 25 volts or a bit more. But this was just spinning the motor with no real load.

    Sooo, 25 ccs are just not going to cut it. I guess I will have to borrow the Techumseh off my 24 incher. It's half the weight of the HF, probably twice the power (won't use much of it). Or look for a chainsaw engine.
    Or try some batterys I just obtained and go full electric. I have 4 9ah 12volters sitting in the workshop.