professor
Active Member
Here is what didn't work- driving a dc motor (as a generator) to propel drive motor on the bike. Engine at full rpm and creeping down the road. Back to square one. Bike has a 250 watt electric motor driving the back wheel with a chain. Gearing 19 to one and battery power speed 13 mph.
Phase II >
Weighty HF 79cc (20#) on rack (6#) driving an alternator (9#) (non-regulated with a small battery to energize the field) making 37 volts at 3600rpm = it goes, but does not have the snap the battery alone had. Would get up to speed but was sluggish. Motor pulley was smaller than the one on the alternator.
Phase III >
Changed the motor pulley to run at a one to one ratio= 50 volts at full rpm and the drive motor now acts almost as snappy as the battery on initial take off. Have to throttle back to almost idle going down the road to keep from going faster than the battery powered formerly went.
Here is what I think- motors typically draw a multiple of running amps on start-up, and the battery would supply that extra juice. But the alternator doesn't have that deep reserve for starting, hence the high rpm and big voltage fills that need. But once going down the road, it is necessary to drop the rpm (volts) down to the motor's design voltage.
The next phase will be to remove the HF and replace it with a 50cc Techumseh which weighs 11 pounds less.
The current rack set-up is totally unusable but might be OK at the lower weight. (If the HF and alt. would fit in a cruiser or streched frame- I think it would be OK).
My question is, will the smaller engine start OK with the extra pulling effort of the alternator connected to it, the HF does fair in this regard. You definitely know the alternator is there- about double the pull effort- lots of inertia to overcome. This is with the field wire un-attached.
What I need to find is a regulator i can tap off of the big power output to charge the 12 volt field battery (remember the big power is connected directly to the drive motor- the battery that powers the field is separate).
So far-so good.
I have a pic but this new computer uses Linex and I can't figure out how to get the pic to photobucket!
Phase II >
Weighty HF 79cc (20#) on rack (6#) driving an alternator (9#) (non-regulated with a small battery to energize the field) making 37 volts at 3600rpm = it goes, but does not have the snap the battery alone had. Would get up to speed but was sluggish. Motor pulley was smaller than the one on the alternator.
Phase III >
Changed the motor pulley to run at a one to one ratio= 50 volts at full rpm and the drive motor now acts almost as snappy as the battery on initial take off. Have to throttle back to almost idle going down the road to keep from going faster than the battery powered formerly went.
Here is what I think- motors typically draw a multiple of running amps on start-up, and the battery would supply that extra juice. But the alternator doesn't have that deep reserve for starting, hence the high rpm and big voltage fills that need. But once going down the road, it is necessary to drop the rpm (volts) down to the motor's design voltage.
The next phase will be to remove the HF and replace it with a 50cc Techumseh which weighs 11 pounds less.
The current rack set-up is totally unusable but might be OK at the lower weight. (If the HF and alt. would fit in a cruiser or streched frame- I think it would be OK).
My question is, will the smaller engine start OK with the extra pulling effort of the alternator connected to it, the HF does fair in this regard. You definitely know the alternator is there- about double the pull effort- lots of inertia to overcome. This is with the field wire un-attached.
What I need to find is a regulator i can tap off of the big power output to charge the 12 volt field battery (remember the big power is connected directly to the drive motor- the battery that powers the field is separate).
So far-so good.
I have a pic but this new computer uses Linex and I can't figure out how to get the pic to photobucket!
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