Regen as a charger?

GoldenMotor.com

rocksalt27

Member
Oct 24, 2013
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15
18
Portland, ME
So I am also wanting to put an eMotor on my front wheel. What is the difference in the different Voltage models? What about the total Wattage differences? Can you use the regen brake to recharge when you switch to engine power?
 

BarelyAWake

New Member
Jul 21, 2009
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Wattage is the combination of voltage and amperage, higher the voltage the lower the amperage to achieve the same wattage, or vice versa.

http://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.htm

Yes, you can use the regenerative braking properties to increase the amount of current generated for recharging - however, when they say "regen brake" they're not kidding, the amount of drag is massive with an instantaneous engagement so it's not something I'd consider as a front wheel setup.
 

biknut

Well-Known Member
Sep 28, 2010
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I have a friend with a 72v 3500w motor on his front wheel. I wouldn't recommend that much power. It looks dangerous as heck to me. From a stop with a riders weight on the bike, the front wheel spins like a crazy fool when you gas it.

My advise is if you have a front wheel motor, keep the power down to about 1000w.
 

rocksalt27

Member
Oct 24, 2013
121
15
18
Portland, ME
So higher Voltage yields more speed while more Wattage yields higher torque and charge cap right? I just want a power boost here and there and I think the cheapest setup is the 24V/250W for $300.
 

BarelyAWake

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Jul 21, 2009
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So higher Voltage yields more speed while more Wattage yields higher torque and charge cap right? I just want a power boost here and there and I think the cheapest setup is the 24V/250W for $300.
"Charge cap(acity)" would be the AH (Amp Hours) of the battery pack, another unit of measurement entirely, essentially the size of the fuel tank. Wattage is again a combination of voltage & amperage, to carry your example amperage would be torque & voltage horsepower, wattage those combined - but it's not quite that clean cut as there's other variables in play.

Also, can I use the magneto accessory wire to charge the battery?
Depends what engine, if it's the typical two stroke in-frame kit - then no, not really as it doesn't actually have a proper lighting/charging coil. After regulator/rectifier conversion losses there'd not be enough to make a dent in an ebike's charge requirements.

I'm not sure I'd consider a 24V/250W for $300 worth the investment for a hybrid project, 250w = 0.3hp and that's peak, best case scenario.
 

miked826

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Aug 6, 2011
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So I am also wanting to put an eMotor on my front wheel. What is the difference in the different Voltage models? What about the total Wattage differences? Can you use the regen brake to recharge when you switch to engine power?
Brake Regen is nowhere near powerful enough to completely recharge any size battery pack. Brake Regen can, along with a gas motor propelling the bike, extend the range of the back, by a total of 300% on my bike, but that's about it. Brake Regen by it self adds 30% to the battery packs range. You need a gas motor that is much larger in watts than the battery pack is and is capable of propelling the bike at the same time it's charging the battery pack. It would need to be a big cc gas motor with a emphasis on the word "big". LOL

The McLaren P1 and Porsche 918 both have big big gas motors to accomplish that while driving.
 
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mew905

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Sep 24, 2012
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Brake Regen is nowhere near powerful enough to completely recharge any size battery pack. Brake Regen can, along with a gas motor propelling the bike, extend the range of the back, by a total of 300% on my bike, but that's about it. Brake Regen by it self adds 30% to the battery packs range. You need a gas motor that is much larger in watts than the battery pack is and is capable of propelling the bike at the same time it's charging the battery pack. It would need to be a big cc gas motor with a emphasis on the word "big". LOL

The McLaren P1 and Porsche 918 both have big big gas motors to accomplish that while driving.
The Fisker Karma is pure electric with a gas recharge, Porsche 918 and McLaren P1 (and La Ferrari) are all Hybrids in the sense of gas + electric to the wheels. The fisker uses a much smaller motor to recharge the batteries, but you're correct in saying you need a motor at least equivalent in watts (1 hp = about 750 watts), in fact to go WOT you need to overcome it at least by 10% to allow for efficiency issues. but 1000 watts (~1.3hp) is only half the advertised power of the 66cc china girl motor, but because all the power is available at the low end (starting at 0 rpm, and how high up that torque goes depends on the motor), it feels much, much more powerful than a gas motor of equal rating. But it only takes a car about 9hp to maintain 100kph, a speed which most normal people will maintain. Which means that aside from accelerating, you only need about a 6700 watt electric motor to meet that need. This of course excludes gearing and things most e-bikes wont worry about.

As for the ratings of electric bikes:
Wattage = total power, can be converted to hp @ 1.3hp per 1000 watts, or 750 watts per 1 hp. This can be calculated as volts x amps.
Voltage = Mostly depends on your accessories, a 1000 watt 24v motor will go just as fast as a 48v 1000 watt motor. Difference is higher amperage means hotter wires, so a 48v will be more efficient. But higher voltage is more likely to arc, arc-welding connections or annealing them, either way, it makes the motor unusable. Use only voltages within safe ranges for the motor.
Amperes = Volts x Amps = watts. More amperes are more vulnerable to resistance (wires). A motor will only ever draw X amps, no more. But you CAN force-feed more power by giving more voltage. You want the end result to be high watts, so increasing either of these will increase your watts. A battery will only ever give out Y amps (listed on car batteries, this can be CCA, that is how many amperes the battery can dish out for 30 seconds without overheating in -30 weather, or losing so much power that it becomes unsuitable for starting a car, most batteries average around 700 CCA) but it will always give Y volts. Doesnt matter if your motor wants 48 volts or not, if you have a 48 volt battery, your motor will get 48 volts of power, so match these within safe ranges.
Amp Hours (Ah) = This is the battery's capacity. That is how many amps you can draw, for how long. If you match the voltages, and have a 20Ah battery, and draw only 5 amps for a whole hour, that battery will last 4 hours. Generally speaking, the higher this number, the bigger and heavier the battery will physically be.
Charge cap = Usually rated in "C", which tells you the absolute maximum the battery can be charged within 1 hour. 1C on a 24v, 20Ah battery means you can feed the battery 24 volts and 20 amps (480 watts), and charge it within 1 hour safely. Any more quickly, and you risk incurring the rath of overcharging (leaks, dying batteries, even full-on acid explosions).
If you're rated at 0.8C, that means you can charge the battery 80% within an hour. Easy to calculate, it's Ah x C (hours cancel out, so you end up with 80% of the Ah rating, so with a 20Ah battery and 0.8C, you can recharge it with 16 amps).

There are numerous other ratings to look at too, but those are the ones you will find. Golden Motors has performance graphs, showing how much power the engine will give you based on voltage, and RPM, because an electric will dump all its power to get you going ASAP. they accelerate much faster than gas. a 500 watt motor will easily keep up with a 66cc china girl at 2.5hp, at least up until the gas motor gets into its power range, at about 25-30kph (20mph?) at which point electrics start losing out. It takes significantly more power to go faster and faster. In fact a 480 watt motor may max out at 50kph, but if you travel at 35, you might only use 120 watts. So full throttle is a huge waste of energy, the slower you go, the less energy it takes to get you moving, and keep you moving. With gas motors, milage follows a curve, because obviously moving 0 mph is still using gas (idling), whereas electrics don't have this issue, it's on-demand. So I'm not sure if they follow a similar curve.

When you see this graph, it'll help to know what RPM means what speed.

16 inch wheel is 21 RPM per one-MPH

26-inch tire
1 mph = 12.93 rpm
1 kph = 8.10 rpm

24-inch tire
1 mph = 14.00 rpm
1 kph = 8.80 rpm

20-inch tire
1 mph = 16.81 rpm
1 kph = 10.50 rpm
 
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miked826

New Member
Aug 6, 2011
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The Fisker Karma only accomplishes the charging with the small motor because that motor is not connected to the drivetrain. If it was connected it simply explode to pieces from the stress of trying to propel the car and charge batteries.

The P1 and 918 use the Brute Force Method to charging the batteries. That method is with huge high horsepower motors. Unlike the Fisker, The P1 and 918 never needs to be plugged in to recharge their batteries.......ever. No rocket science there. LOL



The Fisker Karma is pure electric with a gas recharge, Porsche 918 and McLaren P1 (and La Ferrari) are all Hybrids in the sense of gas + electric to the wheels. The fisker uses a much smaller motor to recharge the batteries, but you're correct in saying you need a motor at least equivalent in watts (1 hp = about 750 watts), in fact to go WOT you need to overcome it at least by 10% to allow for efficiency issues. but 1000 watts (~1.3hp) is only half the advertised power of the 66cc china girl motor, but because all the power is available at the low end (starting at 0 rpm, and how high up that torque goes depends on the motor), it feels much, much more powerful than a gas motor of equal rating. But it only takes a car about 9hp to maintain 100kph, a speed which most normal people will maintain. Which means that aside from accelerating, you only need about a 6700 watt electric motor to meet that need. This of course excludes gearing and things most e-bikes wont worry about.

As for the ratings of electric bikes:
Wattage = total power, can be converted to hp @ 1.3hp per 1000 watts, or 750 watts per 1 hp. This can be calculated as volts x amps.
Voltage = Mostly depends on your accessories, a 1000 watt 24v motor will go just as fast as a 48v 1000 watt motor. Difference is higher amperage means hotter wires, so a 48v will be more efficient. But higher voltage is more likely to arc, arc-welding connections or annealing them, either way, it makes the motor unusable. Use only voltages within safe ranges for the motor.
Amperes = Volts x Amps = watts. More amperes are more vulnerable to resistance (wires). A motor will only ever draw X amps, no more. But you CAN force-feed more power by giving more voltage. You want the end result to be high watts, so increasing either of these will increase your watts. A battery will only ever give out Y amps (listed on car batteries, this can be CCA, that is how many amperes the battery can dish out for 30 seconds without overheating in -30 weather, or losing so much power that it becomes unsuitable for starting a car, most batteries average around 700 CCA) but it will always give Y volts. Doesnt matter if your motor wants 48 volts or not, if you have a 48 volt battery, your motor will get 48 volts of power, so match these within safe ranges.
Amp Hours (Ah) = This is the battery's capacity. That is how many amps you can draw, for how long. If you match the voltages, and have a 20Ah battery, and draw only 5 amps for a whole hour, that battery will last 4 hours. Generally speaking, the higher this number, the bigger and heavier the battery will physically be.
Charge cap = Usually rated in "C", which tells you the absolute maximum the battery can be charged within 1 hour. 1C on a 24v, 20Ah battery means you can feed the battery 24 volts and 20 amps (480 watts), and charge it within 1 hour safely. Any more quickly, and you risk incurring the rath of overcharging (leaks, dying batteries, even full-on acid explosions).
If you're rated at 0.8C, that means you can charge the battery 80% within an hour. Easy to calculate, it's Ah x C (hours cancel out, so you end up with 80% of the Ah rating, so with a 20Ah battery and 0.8C, you can recharge it with 16 amps).

There are numerous other ratings to look at too, but those are the ones you will find. Golden Motors has performance graphs, showing how much power the engine will give you based on voltage, and RPM, because an electric will dump all its power to get you going ASAP. they accelerate much faster than gas. a 500 watt motor will easily keep up with a 66cc china girl at 2.5hp, at least up until the gas motor gets into its power range, at about 25-30kph (20mph?) at which point electrics start losing out. It takes significantly more power to go faster and faster. In fact a 480 watt motor may max out at 50kph, but if you travel at 35, you might only use 120 watts. So full throttle is a huge waste of energy, the slower you go, the less energy it takes to get you moving, and keep you moving. With gas motors, milage follows a curve, because obviously moving 0 mph is still using gas (idling), whereas electrics don't have this issue, it's on-demand. So I'm not sure if they follow a similar curve.

When you see this graph, it'll help to know what RPM means what speed.

16 inch wheel is 21 RPM per one-MPH

26-inch tire
1 mph = 12.93 rpm
1 kph = 8.10 rpm

24-inch tire
1 mph = 14.00 rpm
1 kph = 8.80 rpm

20-inch tire
1 mph = 16.81 rpm
1 kph = 10.50 rpm
 
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Sidewinder Jerry

Well-Known Member
Dec 19, 2011
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Rockwood, TN
Have you seen the new Staton gas electric gearbox?

http://www.staton-inc.com/store/pro...se_Tri_Hybrid_Gear_and_Chain_Drive-904-0.html

I plan to do a build with it soon. The bike will shift 5 gears automatically through a shiftkit. Self charge the battery when using gas only or coasting. It'll have an electric drive motor attached to the gearbox. A mid frame mounted alternator driven by a rim pulley and belt. This way the only time the battery gets used is when using the electric motor on level ground. A switch can be used to switch between alternator power and battery power. I'd wire a charger up to the alternator which will cut off when the battery is fully charged.
_____________
 
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miked826

New Member
Aug 6, 2011
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Have you seen the new Staton gas electric gearbox?

http://www.staton-inc.com/store/pro...se_Tri_Hybrid_Gear_and_Chain_Drive-904-0.html

I plan to do a build with it soon. The bike will shift 5 gears automatically through a shiftkit. Self charge the battery when using gas only or coasting. It'll have an electric drive motor attached to the gearbox. A mid frame mounted alternator driven by a rim pulley and belt. This way the only time the battery gets used is when using the electric motor on level ground. A switch can be used to switch between alternator power and battery power. I'd wire a charger up to the alternator which will cut off when the battery is fully charged.
_____________
Sounds like Heaven on Earth, except Stanton left out a few small details. The size of the gas motor used and the size of the battery pack being charged and how far you would actually have to ride on ONLY the gas only motor to keep the electric battery "fully charged", as they claim. The smaller (the slower) the gas motor, the longer you will have to ride to accomplish that feat. LOL
 
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Sidewinder Jerry

Well-Known Member
Dec 19, 2011
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Rockwood, TN
What I'm talking about doing is having an electric motor and an alternator. The alternator would provide power for the motor most of the time when coasting or using gas. A rim pulley like the one GEBE uses could be used to drive the alternator.
 
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miked826

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Aug 6, 2011
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What I'm talking about doing is having an electric motor and an alternator. The alternator would provide power for the motor most of the time when coasting or using gas. A rim pulley like the one GEBE uses could be used to drive the alternator.
Yeah the ole Alternator Plan crossed my mind long ago until I realized just how fast it would have to spin to "fully charge" the batteries. It can however prolong their eventual complete discharge, but as far as keeping them "fully charged" or charging a dead battery pack to 100% with it just does not add up. The electrical math (no matter how the Alternator is connected) just isn't there to prove it is possible to do (on a bicycle frame), even before you build it.

The McLaren P1 and Porsche 918 can only do it with massive gasoline motors.
 

miked826

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Aug 6, 2011
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What I'm talking about doing is having an electric motor and an alternator. The alternator would provide power for the motor most of the time when coasting or using gas. A rim pulley like the one GEBE uses could be used to drive the alternator.
Blaze a Tesla trail Jerry and maybe you can actually get it to work......if the battery pack is small enough (volts and amp hours wise).
 

miked826

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Aug 6, 2011
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If you're using a 10:1 ratio for every 300 turns of the wheel that's 3000 rpm in the alternator.
That would be the absolute minimum RPM's that would be needed. The you have to understand the maximum amp rate or speed that Lithium batteries chargers can charge a Lithium battery pack before it bursts into flames. It's a fine line between success and disaster. LOL
 

miked826

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Aug 6, 2011
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The easiest way to deal with battery range issues is to increase the capacity of the batteries being carried. Done. 96V and 40Ah solves all my problems, instantly. LMAO