Comparing 36v 250w to 500w Hub Motors

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chopper_elec
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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Mon, 11 Jun 2012, 02:00

Hey All,

I'll start by saying that i'm an enthusiast of life and whenever i'm out on the bike tracks i'm always careful on my peddle bike when around people.

I am currently debating whether to get a 36v 250w kit or a 500w 36v

Its actually going on a 24" Front wheel on a bicycle chopper.

I'll be likely to use 12ah or 18ah Lead Acid batteries at the moment, but long term i'll be using 36v 20ah lifepo4 battery.

Just going off some pros and cons

Also wondering what sort of run times i'm likely to get when comparing the 2 kits?

Would it be justifiable to go up to say 350w comparing to 250w?

I've done 25km an hour on an electric bike and know well into the current laws, so for this example i'll keep its use as offroad.

Thanks
Adrian
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Simon
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Comparing 36v 250w to 500w Hub Motors

Post by Simon » Mon, 11 Jun 2012, 04:45

The run times of the 36V 250W vs the 36V 500W would be pretty much the same if your cruising at constant speed with no hills and headwinds.
Lots of stop start riding and powering up hills will be a different story though (ie real world riding).

I have a 350W geared BLDC motor in a 26in wheel powered by a 24V pack and would not want any less power than that.
Soon I will have a 1000W Magic Pie III in a 26in rear wheel! (for offroad use only of course!   Image)

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Mon, 11 Jun 2012, 04:58

Thanks heaps for your comment

I may have a 1000w 48v in the mail but may find it a bit too much of an overkill haha

What sort of run times are you getting from the 36v 500w on general smooth roads? Just wondering what capacity battery you have too.

Thanks for your input :)

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Comparing 36v 250w to 500w Hub Motors

Post by jonescg » Mon, 11 Jun 2012, 05:12

Hey Chopper,

I have a 500 W direct drive hub in my bike (700c) and a 48 V LiFePO4 battery from Cell_Man (aka Paul Lynch from Emissions-free.com). I have a 12 FET infineon controller which has no difficulty dragging 100 amps from the battery, but the phase wires to the motor get a bit warm Image.

I ride everywhere full throttle without exception, and with the bike in it's highest gear possible I can just keep up with the pedalling - about 37 km/h. Unfortunately I can't use the smallest sprocket as the chain fouls the frame.

I can keep this pace up for about 30 km before the BMS cuts me off. With half throttle and dedicated pedalling I can push that figure to 40 km, but the throttle is too easy to open up Image.

My advice would be to avoid lead first up, unless you got lots of cheap stuff lying around. LiFePO4 is good, but a bit saggy. Hobby LiPo is awesome, but doesn't last as long cycle-wise (not usually a problem for e-bikes though). I build high-powered LiPo packs from individual cells into any configuration if you are interested, but they are a bit expensive (about $1.10 per W.h). Might be perfect for your 1000 W motor Image

Cheers,
Chris
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Comparing 36v 250w to 500w Hub Motors

Post by Simon » Mon, 11 Jun 2012, 05:19

The battery I have is a 24V 10Ah Lithium-Ion Manganese, controller is 350W and I can get 20km without any pedalling. With moderate pedalling it's more like 40km but I have never discharged the battery fully.

Make sure you use a torque arm with that 1000W motor.

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Mon, 11 Jun 2012, 15:43

Thanks for all the comments.

I'm still not sure what to get now haha. the 500w motor seems the way to go, then again with the 250w kit i'm likely to get only another 5-10km

Its mainly for the hills and to bring up speed or when I get tired haha, otherwise i'd be fine with pedal power for the majority.
The trick is to go slower for longer or faster for less time.

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Tue, 12 Jun 2012, 02:31

I am a bit worried now as i've ordered the 1000w kit in a 24" wheel. I've asked them to change it around to the 36v 500w kit instead. Bit worried after reading on youtube about requiring torque arms etc. I want it to be a safe ride and think the 500w kit will be more than enough

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Comparing 36v 250w to 500w Hub Motors

Post by Simon » Tue, 12 Jun 2012, 04:08

Torque arms are simple to install and good insurance.
http://www.ebikes.ca/torque_arms/ After reading this I think I am going to put a Torque arm on my Giant Revive as it has alloy forks and the axle bolts do not have a good seat on the dropouts either. Image

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Tue, 12 Jun 2012, 13:55

oh nice thats a nice kit there. I think i'm more worried about the torque placed on the drop outs even with the torque arm in place.

Would the 1000w kit be too much for the little chopper bicycle front?

I asked the company if they would change it around to a 500w but they say its a custom design, somehow it was magically made the second after I paid :(

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Comparing 36v 250w to 500w Hub Motors

Post by Simon » Tue, 12 Jun 2012, 21:24

Not sure if 1000W would be too much for your Chopper forks. What model is it?
The motor in the 1000W and 500W kits could well be the same motor and the only difference is a higher current limit on the motor controller.
You can always get a programmable motor controller that will let you lower the amps for less peak power or just get a lower power controller.

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Comparing 36v 250w to 500w Hub Motors

Post by Faz » Tue, 12 Jun 2012, 21:45

How much was your 1000W kit?

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Tue, 12 Jun 2012, 22:00

Simon wrote: Not sure if 1000W would be too much for your Chopper forks. What model is it?
The motor in the 1000W and 500W kits could well be the same motor and the only difference is a higher current limit on the motor controller.
You can always get a programmable motor controller that will let you lower the amps for less peak power or just get a lower power controller.


Thanks for the heads up. Its a Flight Dragster Chopper bike from Goldcross Cycles hehe Was around $400 mark.

That could work having a controlable motor controller actually. I may look into this :) Thanks
Faz wrote: How much was your 1000W kit?

The kit was just over $270 for the lot posted. Pretty good price.

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Comparing 36v 250w to 500w Hub Motors

Post by Faz » Tue, 12 Jun 2012, 22:38

Wow great price. Who did you buy it from?

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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Wed, 13 Jun 2012, 00:20

Thanks mate, got it from vpower off ebay
They are fantastic. If a 24" front wheel kit would suit you i'm happy to sell for $250 if you like?

You could easily rehub it to suit.

I wish I got the 36v kit. Would the 1000w motor really pull that much pressure on the forks themselves? I'd still use the kit if I could restrict it down. Its easier to downtune an engine than it is to increase power on a less powered motor.


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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Wed, 13 Jun 2012, 01:16

I am also debating whether I should go 350w over 250w. The difference is quite small but it could make a bit of a difference.

I am really looking for longetivity moreso

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Comparing 36v 250w to 500w Hub Motors

Post by jonescg » Wed, 13 Jun 2012, 02:20

Always go for more power if you can manage it Image

350 over 250 is a no-brainer. In my experience you won't need torque arms for anything under 500 W.
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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Wed, 13 Jun 2012, 02:35

That sounds good, I wonder if the extra 100w would justify the chances of getting caught and having to change it back again or having the bike confiscated.

I'm all up for following the rules, but 100w extra in this case will be lucky to have very little effect I would think.

Thanks for the heads up re torque arm

My other considerations were to run a bicycle trailer with 3 SLA 25-30ah batteries in the back as per below haha

Something about having a trailer and an electric bike has always been such a cool thing. I wonder if it would cost more to make one

Image


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Comparing 36v 250w to 500w Hub Motors

Post by electriker » Sun, 17 Jun 2012, 16:54

I built a couple of solar-trikes using Heinzemann 24volt 250Watt hub motors, and fitted with photovoltaic panels.

Image
Image

By not using a big motor (and being prepared to pedal a bit) I can use the trailer for carrying things other than batteries. This piccy shows the trailer carrying a fold-up bicycle.

In the 4 years I've had the PVs fitted, neither machine has taken any power from the grid.

The average speed for the red trike is about 18.5 km/h and the green one is about 19 km/h (over about 500 km each), including a very steep gradient about 5 km long on each long ride.

Joe
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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Sun, 17 Jun 2012, 22:02

Wow thats very impressive. How powerful are those solar panels?

I'm hoping to score one of those trailers similar to yours, but i'd want to convert it so I could mount it to the back of the seat.

I ended up going for a 48v 500w motor for the chopper. Hope it all works out haha. I did have one ride the other night and had only my phone light to guide me on my way. It was scary to say the least and a better light is on the way luckily.
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Comparing 36v 250w to 500w Hub Motors

Post by electriker » Sun, 17 Jun 2012, 22:41

chopper_elec wrote: Wow thats very impressive. How powerful are those solar panels?

I'm hoping to score one of those trailers similar to yours, but i'd want to convert it so I could mount it to the back of the seat.

I ended up going for a 48v 500w motor for the chopper. Hope it all works out haha. I did have one ride the other night and had only my phone light to guide me on my way. It was scary to say the least and a better light is on the way luckily.

DRAT - - I lost all my writing.

Better start again!!!!!!

Joe
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Comparing 36v 250w to 500w Hub Motors

Post by electriker » Sun, 17 Jun 2012, 22:50

The panels in the photos are my old ones which I've replaced with "concertina" ones:
Image
Image

Nominally, the panels are 20 volts and 20 watts, but in real life, under load I hook two of them up in series, and generate 24 volts. THe ammeter tells me I'm getting about .7 amps, which is about 14-17 watts.

Because I only use the motor for taking off from the lights and climbing hills, if I ride to Perth and back (about 25 km each way) the batteries are usually fully charged by the time I hit the bottom of Welshpool Road. However, if it's a sunny day, I'm able to just use the motor for a km or 2, knowing that the batteries will recharge in time.

Because of the different sized wheels the two trikes have different charactistics. The green one (26") will max at 26 km/h without me pedaling, while the red one will max at about 17 km/h. However, I know from bitter experience that the red trike will get me up Welshpool Road without pedaling. I broke the rear derailleur one day and had to come home from McCallum Park in South Perth with little or no pedaling.

However, it wasn't a total loss ... I met a very nice young lady in the park and we had lunch together.

Image

The trikes are great conversation starters.

Joe

I went for 24 volts rather than 36 because (a) to have 3 sets of panels instead of 2 would create a traffic hazard and (b) I couldn't find a small, inexpensive 36 volt regulator to prevent overcharging the batteries when I wasn't riding.

J
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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Mon, 18 Jun 2012, 21:19

Thanks so much for taking the time to write all that up.

I wonder if a mirror/lense system may work which may allow you to run an Octoganal shape tube with solar panels on the inside? Silly idea I know (not very well thought out). At least there wouldn't be any particular reflection unless you looked at it from the sky.

You mentioned that the batteries will recharge in time when using the motor for a few km or 2? Does this mean that for some of the trip you will just ride with the motor and the system will recharge by the time you finish your run? I'm really curious to see just how much solar panel is putting back into your system.

I wonder how big the panels would have to be to run off purely off solar panel with around 200-250w of power.

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Comparing 36v 250w to 500w Hub Motors

Post by electriker » Mon, 18 Jun 2012, 22:32

I wonder if a mirror/lense system may work which may allow you to run an Octoganal shape tube with solar panels on the inside? Silly idea I know (not very well thought out). At least there wouldn't be any particular reflection unless you looked at it from the sky.

Whilst it won't be portable in the sense of putting it onto your bike, I initially had a free standing set of PV panels which I used to charge the batteries on the green trike.

Image

To get a bit of extra power from them I experimented with building a reflector made from old CDs/DVDs, cut with a paper guillotine into hexagonal, rather than octagonal shape.

Image

As you can see the hexagon is the most efficient "packing" shape. Just this small reflector could give me between 8 and 10% increase in output from the panels.

After a while I took some of those panels and put them on the back of the trike.

You mentioned that the batteries will recharge in time when using the motor for a few km or 2? Does this mean that for some of the trip you will just ride with the motor and the system will recharge by the time you finish your run? I'm really curious to see just how much solar panel is putting back into your system.

Yes. I try and get the timing so that when I hit the bottom of the hill, the batteries are fully charged, so they won't go flat on the ascent. That's never actually happened on any day, although during summer I've had the thermistor on the green trike cut out because the air temperature is so high that the motor overheats. However, a few minutes to cool down and the motor started up again. (Heinzemanns are good like that from what I've heard.) This trike is much more likely to overheat because of the higher gearing of the bigger wheel.

I can't give you any solid figures on power in vs power out, I'm just happy when the ammeter drops back to zero. This means that the batteries are fully charged and the regulator has tripped.

I wonder how big the panels would have to be to run off purely off solar panel with around 200-250w of power.

I think the answer to that question would depend on so many variables, time of day, time of year, temperature, efficiency of PV panels, how much percentage of throttle is used, weight of the rider etc etc, one could only theorise about it. I suppose arithmetically, you could get a ball park figure by saying if you run the motor at half power ie 100 watts, then assuming the panels in my piccies put out their nominal maximum of 20 watts, then you'd need roughly 5 times the area of panel. That's where the batteries come in handy. If I run the motor at 100 watts for one minute then theoretically my 20 watt panels could replace the power consumed in 5 minutes.

The panels themselves measure 52 cm x 42 cm which is roughly 2100 sq cm, multiplied by 5 gives 10,500 sq cm. (I'm quite expecting to be shot down for my crappy arithmetic.)

However, the jigger factor here is that the Heinzemann motor is geared to a maximum of 193 rpm, before it "cuts out", so even though it may be possible to achieve the theoretical maximum speed, under different conditions of wind, steepness of gradient etc, eg if there's a tail wind the speed may not exceed 193 rpm, there'll be less power used, and so forth.
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Comparing 36v 250w to 500w Hub Motors

Post by woody » Wed, 20 Jun 2012, 16:18

chopper_elec wrote:Would the 1000w kit be too much for the little chopper bicycle front?

Torque arms are cheap insurance - if your motor "spins out" it will rip all the wires out.


The torque isn't that much - nothing like a disc brake stopping or going over a bump.

1000W @ 0rpm is inifinity Nm, but the motors don't work like that, they have a peak torque at 0rpm (you can measure / calculate it with a spring balance - tie a spring balance between your bike seat and a pole, and try to drive away - check the reading in Newtons and divide by tyre radius in metres).

cheers,
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Comparing 36v 250w to 500w Hub Motors

Post by chopper_elec » Wed, 20 Jun 2012, 18:19

Thanks for all the information. Truly awe inspiring innovation here. What would I be looking at for a similar solar power panel?

I wonder how big a 250w solar panel would be hehe.

Thanks for the info. I feel that for some reason the axle will still spinout even with the torque arm kit. I ended up going for a 48v 500w motor.

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