Building a dual motor e-bike - can I get some input
Posted by el_myco_profesor@reddit | ebikes | View on Reddit | 34 comments
Ok so here’s my plan so far - Falcon frame with 26” wheels Dual motors - Q205 3000w rear motor and QS 1500w front motor 2 sine wave controllers (80amp for the rear) 70ah Amorge 72v battery packed strapped to the rear rack (the rear sack is steel and very durable)
Thoughts/feedback?
chuckwolf@reddit
Why? The Falcon is already dual 2500 watt motors with a 60 volt 60 amp controller as it is, you'd actually be going down in power to the front
el_myco_profesor@reddit (OP)
Immediate throttle response, 72v power plus 70ah battery instead of 32ah
chuckwolf@reddit
They already do 0-20 in 4 seconds, how much quicker do you want?
el_myco_profesor@reddit (OP)
Show me a video
gregoryofthehighgods@reddit
Why would he lie to you? There's no reason to
el_myco_profesor@reddit (OP)
I owned the bike for 400mi and got rid of it because of the throttle lag issue
chuckwolf@reddit
Also at 72 volts and a direct drive instead of the geared hub 60 volts the bike currently has the bike would have a higher top end but you would lose a ton of torque and might actually lose off the line accelleration. there's a reason the 60V Philodos are limited to \~40 mph, and that's the internal gear ratios needed to produce 105 Nm of torque each
chuckwolf@reddit
the soft start from a dead stop isn't an issue itr's to keep the front wheel from breaking traction from a dead stop. you can override it by stopping and then starting before the speedo reads 0. but even with the soft start dual motor 0-20 is still only about 6 seconds, if yours was slower you might have had one of the early defective controllers and should have contacted philodo customer service. anything over 10 seconds 0-20 is single motor performance
chuckwolf@reddit
On another note do you realize how big a 72 volt 70 amp hour battery pack is? Even with 21700 50e cells it would have to be 21s15p just to reach that capacity
el_myco_profesor@reddit (OP)
Yes, 6.25”x9.25”x14”
lcdroundsystem@reddit
It’s going to ride like shit. All that weight on the back
el_myco_profesor@reddit (OP)
I’m going to try to add as much weight as possible to the front (example using empty battery case filled with weight in downtime)
LargeNerdKid@reddit
Monster build! Nice, like to see that thing move once your finished 👍
BXRunner@reddit
VESC VESC VESC VESC VESC
Get ready to learn tuning. This is my only input.
timbodacious@reddit
you really don't want more than 1,000 watts on the front wheel due to spin out and burning rubber unless you always want to feather the throttle or lean over the handlebars from a dead stop.
chuckwolf@reddit
Just having good tires prevents this... At least on my ~2000 watt front motor on my Forester using Ultraverse tires and that's still being able to hit 0-20 in 4.29 seconds measured by the Dragger GPS based acceleration app, using the non-zero display launch trick
el_myco_profesor@reddit (OP)
What is non zero display launch trick?
chuckwolf@reddit
If you're stopped but the speedometer is still showing any number other than 0 the controller sends full power to both motors, disabling the soft launch. Basically if you stop and then take off right away.
Ill_Imagination986@reddit
Check the applicable laws where you live. I don't think that's going to be legally considered an ebike in any western nation, and in the United States, that's not even within the federal definition of a motor drive cycle and probably won't even be classified as a moped in most jurisdictions
alldaybekfast@reddit
It’s funny how nobody asked about that.
Ill_Imagination986@reddit
"Thoughts/feedback?"
Fletchx@reddit
I'd love to this this happen!
anzitus@reddit
Having battery pack on rear rack may shift the weight to the rear. Depending on how much you weigh, if there's too much in the weight in the rear, the bike would feel like it wants to help you do a wheelie.
ExaminationFeeling45@reddit
That rear motor's gonna do most of the work. Make sure your wiring can handle the load and consider a single controller if you can swing it simpler setup, less headache.
anzitus@reddit
I have a couple of dual motor - single controller eBikes and a couple of dual motor - dual controller eBikes. The ones with the dual controllers are a bit quicker when drag racing and have a higher top end speed.
LargeNerdKid@reddit
Sorry to hijack the OP.
I have a Duotts N26 dual 750 48w battery. They only unknown is the rating of the 2 controllers. I found a 45 amp controller online with a key for that can restrict output so it only goes 25kph with a press of the fob.
Do you think that controller can replace my 2 controllers in regards to the amperage? Any help would be appreciated. 👍
Significant-Pen-6049@reddit
It’s going to be too damn heavy. By first dual motor bike was two direct drive 1000 watt motors and two batteries. It was horrendous.
I ended up replacing it all. 500 watt geared hub front wheel and small battery pack for that one. Bbshd to power rear wheel. Now I could have ample climbing and use the front wheel when needed but have no resistance whenever not needed.
Suspicious_Desk_2365@reddit
That's gonna be a beast with that setup. Make sure your battery can handle the draw from both motors pulling max amps at once or you'll sag hard
chuckwolf@reddit
Actually he'd be taking a 1000 watt power loss to the front hub
el_myco_profesor@reddit (OP)
How so?
chuckwolf@reddit
The front motor on a falcon is 2500 watts peak, 2000 continuous, I know I own a forest which is the same bike on a mountain bike frame
el_myco_profesor@reddit (OP)
Have you measured the output of the Falcon on a dyno?
chuckwolf@reddit
Not a dyno, however GPS verified 1/8th mile acceleration in 17.66 seconds with a trap speed of 35.29 mph with a combined bike+rider weight of 150 kg should be good enough to estimate combined wattage, which is split evenly between both motors
chuckwolf@reddit
The front motor on a falcon is 2500 watts peak, 2000 continuous, I know I own a forest which is the same bike on a mountain bike frame