Safe to ride with no batteries

[magudaman]

I haven't posted a topic in a while and have what I feel is a simple question. I want to do a human powered bike ride with some friends and one doesn't have a bike. The only extra bike I have is my electric but I want to run it with no batteries. I have a 409 motor with 72v controller and just want to make sure it okay for it to run with no batteries attached? There seems to be less drag with no batteries what is up with that?

 

[CGameProgrammer]

Of course it's 100% safe.

 

[NickF23]

If it was my bike and I had a motor without a freewheel then i'd disconnect the phase wires and make sure they couldn't short, otherwise it wouldn't be very safe. I suppose you'd be ok without doing this as long as you didn't switch the controller on.

hopefully fechter will be along in a minute to give you a more qualified answer.

 

[magudaman]

Oh that's a simple great idea I just didn't think of that. I have power pole connectors on the motor so It is easy to disconnect. I just leave everything else on and just disconnect that to play it safe. Thanks guys...and if fechter want to give some input for future purpose that would be great!

 

[Miles]

Safe wouldn't get very far, with no batteries

 

[Ypedal]

Safe wouldn't get very far, with no batteries

I read that the same way !! lmao...

I"ve pedaled my hub motor bikes without a battery pack plenty ( with the dog ) .. no problems yet.. you can actually power your CycleAnalyst using the motor, as long asyou don't stop lol..

Only problem i could see, and i doubt this is a problem, if you force the motor to spin fast enough to generate high voltage over the controllers rated capacity.. etc.. but with a 72v unit that should never be an issue lol.

 

[xyster]

Safe wouldn't get very far, with no batteries

I read that the same way !! lmao...

:lol:

Safe to ride with no pedals either. Safe powered by just the wind and one big-ass spreadsheet.

 

[knightmb]

I"ve pedaled my hub motor bikes without a battery pack plenty ( with the dog ) .. no problems yet.. you can actually power your CycleAnalyst using the motor, as long asyou don't stop lol..

I was about to say that too. It's funny to watch the regen meter hit 999.9% percent regen when the batteries are disconnected. On mine, I have to be doing at least 13 MPH to power it up, afterwards it works really nice.

 

[Miles]

..... Safe powered by just the wind and one big-ass spreadsheet.

:lol:

 

[knoxie]

Yo

Yes its safe of course, Knight added a handlebar switch to his rig so he could disconnect the batteries whilst freewheeling, this is a good Idea if you like to peddle a lot as well as using the e-assist, the resistance is the motor acting as a generator in effect, doing this will will help big time.

Cheers

Knoxie

 

[safe]

Safe powered by just the wind and one big-ass spreadsheet.

MCL powered spreadsheet!!!

 

[fechter]

I've never figured out why disconnecting the batteries makes a difference. If the power switch on the controller is off, it should be the same as disconnecting the batteries until you try to exceed the no-load speed of the motor.

Are you going to make them pedal unpowered with the batteries still on the bike?

Disconnecting the phase wires is the most sure-fire way to prevent drag.

If you want to give them a real workout, short two phase wires together

 

[Drunkskunk]

I ride mine all the time with the power off. With the dual speed Xlyte there is a position on the switch that disconects the motor completely from the controller. when I remember I switch it there, but I forget often enough and it realy doen't produce enough drag to notice, even on 10 mile rides

 

[knightmb]

I've never figured out why disconnecting the batteries makes a difference. If the power switch on the controller is off, it should be the same as disconnecting the batteries until you try to exceed the no-load speed of the motor.

My controller doesn't have a power switch on it, so disconnecting the battery keeps the motor from trying to charge up the batteries. I can do fast down a steep hill and switching battery pack on and off makes a difference in the braking force I feel. Once the pack is disconnected, the bike feels more like a free fall then.

 

[knoxie]

I've never figured out why disconnecting the batteries makes a difference. If the power switch on the controller is off, it should be the same as disconnecting the batteries until you try to exceed the no-load speed of the motor.

Are you going to make them pedal unpowered with the batteries still on the bike?

Disconnecting the phase wires is the most sure-fire way to prevent drag.

If you want to give them a real workout, short two phase wires together

Yes!

DC Braking! well not really but yes! ha, shorting out 2 phases is a good test! I am not sure why the resistance is there when you switch the controller off either, maybe its the flywheel diodes in the fets? dumping out the back emf through to the battery maybe?

Knoxie

 

[xyster]

I sometimes ride my Xlyte for exercise with the batteries switched off via a relay. I've never noticed any difference in pedal effort between batteries engaged and batteries disengaged. But I've never looked for any difference either. Will do next ride, if I remember to.

 

[magudaman]

Well I plan on disconnecting the phase wires. My controller doesn't have an on off switch. It's the compact 20a 72v controller. It about 5 inches long by 4 inches wide by 2.5 high. Thanks for the help...and I'll short the phase wires if she ends up out in front of me. :lol:

 

[xyster]

Well I plan on disconnecting the phase wires. My controller doesn't have an on off switch. It's the compact 20a 72v controller. It about 5 inches long by 4 inches wide by 2.5 high. Thanks for the help...and I'll short the phase wires if she ends up out in front of me. :lol:

You could do that by remote controller pretty easily. Instead of shorting it, use a potentiometer to dial-in the drag as needed.

 

[knightmb]

I sometimes ride my Xlyte for exercise with the batteries switched off via a relay. I've never noticed any difference in pedal effort between batteries engaged and batteries disengaged. But I've never looked for any difference either. Will do next ride, if I remember to.

You won't notice until you hit a speed that exceeds the no load motor speed. I can take my NiMH out the back, hook up (3) 12 SLA bricks and find a steep hill to coast faster than about 32MPH (only because I have some hills around here that allow you to coast up to 55MPH). Once you get over that speed plus maybe an extra 2 or 3 MPH you feel the "braking" effect then. I can turn the switch on and off, it acts like a coaster brake all the way down the hill.

Using my 48 volt NiMH pack, I never encounter a hill (except maybe one) in which I'm going over 50MPH which is about the limit of the 48 volts on a 406 motor in my 700C wheel. Anything faster and I need a higher pack voltage to coast any faster. In theory, 72 volts would allow me to coast maybe 65MPH+ but I don't think I want to go down any hill steep enough to generate that much speed for me. :?

[edit: Stupid me, we are talking about with no batteries ]