How to do 60 KPH with no peddle (flat) with only 36V battery
- Thread starter qtipslea
- Start date
AussieJester
1 TW
I think you might be pushing it, if you mid-mounted it
And ran it through the bikes gears you might get close
With a tail wind...
KiM
And ran it through the bikes gears you might get close
With a tail wind...
KiM
60kph ~ 37mph. I was able to get my BMC V3 to go 28mph on flat, no wind on 36V at 30A (limited by the BMS) if I remember correctly. A123 LiFePo4 can handle a lot more current. Assuming you have to right BMS, I say it MIGHT, and that is a big might, get to 35mph. I mean it all depends on your setup and the weight the bike is pulling, etc. A lot of factors. Possible, Yes, Probably, Yes under ideal cases, i.e. super thick phase wires, only going for short distances at that speed, light weight to carry on the motor, super high speed winding for the motor.
I find I need around 1.8KW to sustain 37mph on flat on 51.8V Lipo battery. Assuming same efficiency and such, I would need at least 50A if not more to achieve and sustain that speed on 36V. However, 50A is pretty high for small 14G phase wire in my BMC V3. Moreover, the voltage sag is going to be pretty high meaning you will be losing effect torque.
I say go to at least 48V or more for higher speed.
I find I need around 1.8KW to sustain 37mph on flat on 51.8V Lipo battery. Assuming same efficiency and such, I would need at least 50A if not more to achieve and sustain that speed on 36V. However, 50A is pretty high for small 14G phase wire in my BMC V3. Moreover, the voltage sag is going to be pretty high meaning you will be losing effect torque.
I say go to at least 48V or more for higher speed.
DAND214
10 MW
I don't think so!
Not on 36v.
Down a big hill , with a strong tail wind! Oh no pedaling either.
Dan
Not on 36v.
Down a big hill , with a strong tail wind! Oh no pedaling either.
Dan
qtipslea said:Hm, I should have mentioned no peddling.
mvly, you were able to hit near 60KPH on the BMC V3 or is that another motor?
Cell_man Mac 1000W is basically a BMC V3 clone right?
http://www.emissions-free.com/catalog/i24.html
Yes almost 60KPH ~ 37mph. On flat I can sustain 35mph or so on 51.8V Lipo at 30A current limit with ~ 200lbs (150lbs for myself + 20 for battery + 30 for the rest like charger, water etc.) using the BMC V3 with NO PEDALING. The 1KW Mac from cellman should be the same as the BMC V3.
Just know that you can burn the motor up if you try to shove it power going uphill. That is how i fused the phase wires on the last BMC V3. Just know that if you getting the 1000W MAC, you can't really use it for hills unless you pedal assist it and drop the power input during the hill climb. Flats are fine.
General rule: If I am going up a hill and using full throttle, and my bike slows down to below 24mph, I immediately ease off the throttle such that I have only putting 1KW into the motor and pedal assist until I can go faster than 24mph without the assit.
You can read all about here:
http://endless-sphere.com/forums/viewtopic.php?f=4&t=29194
It is a bit dated since I have not updated to reflect the lipo battery and EV Falcon bag.
hjns
100 kW
mvly said:
On my rear DD hub (Clyte HT3525) I can get to 58km/h with 84V 30A (2.5kW). Now this is a slow motor, but the amounts of Watt are about right (around 2kW). So, with a fast motor (Clyte 5302), and 36V 70A you should theoretically get somewhere near that. Play around with the simulator here: http://ebike.ca/simulator/ , so you can try for yourself.
For 70A you would need nice thick wires (minimally 10AWG, preferably 8AWG), and the large connectors to go with it (+5.5mm). Better aim for a higher voltage. Any specific reason to stay at 36V?
AussieJester
1 TW
Nope, no need to dump them, just 'series' them..lots of speed
At 72v 8)
KiM
At 72v 8)
KiM
AussieJester said:
I'm afraid to open up the perfect black shrink wrapped they are in. Is it hard to _series_ them? I don't have any welding experience.
Worst part is I'm in Canada! It seems all the good merchants/tweakers are in US. That mean I can't just asked someone to series them for me.
Chalo
100 TW
qtipslea said:
Pick up the bike and jump off a high bridge.
Why not just use a motorcycle?
Chalo
nicobie
100 MW
Add a couple of 6s lipo packs in series with the a123 and most any motor/ 72v controller will get you there. You'll need to get a charger for the lipos too. A cheap $20 one will do.
MadRhino
100 GW
Even if you had a motor fast enough to ride 60 Kmh at 36v, your battery is not likely to have the C-rate to supply the power requirement.
Series another one, it is your only and easy solution if you want to keep your actual battery and go faster.
Series another one, it is your only and easy solution if you want to keep your actual battery and go faster.
crossbreak
1 MW
BAD idea mixing them!
I think what he meant was that battery voltage has very little to do with the price. A 36V system won't be cheaper than 48V one if you like going 60kph.
With a midmotor you can gain nearly any speed if you like, but that does'nt make much sense because of the high currents.
I think what he meant was that battery voltage has very little to do with the price. A 36V system won't be cheaper than 48V one if you like going 60kph.
With a midmotor you can gain nearly any speed if you like, but that does'nt make much sense because of the high currents.
DAND214
10 MW
Just double the A123 pack, that will give you your 72v and 60kmh you are looking for.
Maybe even with the motor you have.
Dan
Maybe even with the motor you have.
Dan
Sunder
10 MW
It's the old engineer's motto of:
I can build it cheap
I can build it fast
I can build it reliable
Choose any 2.
I can build it cheap
I can build it fast
I can build it reliable
Choose any 2.
Sunder
10 MW
I think that's unlikely, because there are laws of physics.
Frankly, a watt will only move a fixed weight a certain speed, when fighting against gravity and friction. Thems the laws of physics. And if you lower the voltage, you increase the current. Higher current will generate more heat as it goes through copper wires, and you have both the problems of higher loss, and needing to manage waste heat.
Unless we develop room temperature super conductors on the cheap, then I don't think we will ever get very powerful low voltage bikes.
Frankly, a watt will only move a fixed weight a certain speed, when fighting against gravity and friction. Thems the laws of physics. And if you lower the voltage, you increase the current. Higher current will generate more heat as it goes through copper wires, and you have both the problems of higher loss, and needing to manage waste heat.
Unless we develop room temperature super conductors on the cheap, then I don't think we will ever get very powerful low voltage bikes.
AussieJester
1 TW
Chalo said:
GoLD Chalo HAHAHA...
KiM
dogman dan
1 PW
Plenty of future for moderately fast ebikes at lowish voltages, such as 48v, but with the motor driving the chain, and using the shifter. Fast windings of hubmotors fall into the pick two of three trap. Make the motor go 60kph at 36v, and you have a poor climber unless you heap the amps to it. Most ebike hubmotors offered now are trying to pick all three, but by being moderately good at both climbing and speed. So they aren't so fast, or stellar on hills, but get by.
Direct drive hubmotors are pretty tolerant of overvolting, so adding another battery in series is not so bad an idea. No need to open the pack, but you may want to protect your bms's with diodes. Threads on that exist. Really easy to do a lipo boost for a short part of your ride, if you only need the speed for a short part of the route.
Direct drive hubmotors are pretty tolerant of overvolting, so adding another battery in series is not so bad an idea. No need to open the pack, but you may want to protect your bms's with diodes. Threads on that exist. Really easy to do a lipo boost for a short part of your ride, if you only need the speed for a short part of the route.
nicobie
100 MW
crossbreak said:
Really? I've done it for years:
sla + nicad
Ping + nicad
Ping + lipo
lipo + different C rate and Ah lipo
Just be carefull that your controller is up to it.
dogman dan
1 PW
Anything you want in series just about. It's paralelling different chemistires that gets tricky.
Chalo
100 TW
dogman said:
You'll want to use batteries of similar real-world AH capacity, or somewhere along the line you'll have cell reversal out the wazoo. A chain of batteries is only as good as its feeblest links.
Chalo
No geared hub motor will do what you're looking for.
No DD hub i know of will do what you're looking for.
Chain drive and very high amps at 36v ( 50-100 ) are going to do what you're looking for.
You just need higher voltage to get that speed on a regular hub.
And you can series any battery you like to another. You just need to make sure neither battery drops below it's low voltage point and you will have to disconnect them and charge them seperately. Not really a proper or trouble-free setup..
No DD hub i know of will do what you're looking for.
Chain drive and very high amps at 36v ( 50-100 ) are going to do what you're looking for.
You just need higher voltage to get that speed on a regular hub.
And you can series any battery you like to another. You just need to make sure neither battery drops below it's low voltage point and you will have to disconnect them and charge them seperately. Not really a proper or trouble-free setup..
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