Newbie advice

Hello all. As the subject line suggests im new to the Electric bike world, and would like some advice/suggestions on how to tackle my needs.
Firtsly i would like to convert my Raleigh road bike to electric for my daily work commute of 36 miles. The round trip is getting too much for me now and would like to get at least one way with little or no pedalling. I have done some research and have more or less made my mind up to use the Currie USPD drive kit. However i dont think that this kit will give me the speed i am looking for as i would ideally like to get around 25-30mph, looking around at websites and emailing people it seems the way to do this with the currie is to change the motor for a kollmorgen and overvolt to 36 or 48volts, using nimh batteries.
Do you think this is a good viable option? i have asked a few people in the UK but thought there was no harm opening this subject to the broader spectrum.
Any help greatly appreciated.
Rgds
Barry
UK

well
that sounds like xysters battery pack! study his bike!

There are other folks here with lots of experience with the Currie USPD kit. I understand its no longer in production.
I know my ebike batteries pretty well though... 25-30 miles per hour for 20 miles (1/2 your trip + margin) is going to take some serious battery energy.

Let's figure out about how much....

First let's visit our venerable bicycle speed and power calculator and input your numbers:
http://www.kreuzotter.de/english/espeed.htm

Looks like you'll need about 750 watts to the pavement to sustain 30mph on level ground, no pedaling, without extra wind. But wait, we must correct for the fact efficiency is not 100% -- more like about 70-80% depending on the motor/controller. So...

750 watts / 0.75 = 1000 watts of input power to get 750 watts of output power.

At 30mph, you'll make a 20 mile trip in...

20 miles / 30 miles / hour = .667 hours = 40 minutes

And so the amount of energy you need to carry to make the trip is....

.667 hours X 1000 watts = 667 watt-hours.

With the controller/motor combos available, to sustain 30mph you'll need at minimum 48 volts.

So lets figure the energy required in amp-hours since that's how batteries are rated...

667 watt-hours / 48 volts = 14 amp hours (AH).

With the exception of the newest, expensive type lithium batteries, no other chemistry can be depleted 100% without risking serious damage. So let's correct for that...

14 amp-hours / 80% = you need to carry a 48 volt pack rated at 17-18 amp-hours .

What does this give us for options?

Well, lead (SLA) is out -- too heavy for that much battery.

You could:

1) Use NiMH. There's a well-regarded canadian vendor selling 24V, 18 AH, 15 pound packs for $360 and you'd need two wired in series:
http://www.ebikes.ca/store.shtml
This is the highest capacity nickel pack on the market I'm aware of. And you'd need all that capacity, so your choice here is very limited. You could wire smaller NiMH or Nicad packs in parallel to boost capacity, but there are serious issues charging Nickel batteries in parallel that must be addressed.

Serial/parallel battery pack primer:
http://www.batteryuniversity.com/partone-24.htm

2) Use lithium. Will weigh less than 1/2 as much as NiMH. There are major safety issues with lithium batteries to be aware of. Unless you're into a good month of solid research for a DIY lithium pack like mine, or a more expensive off-the-shelf lithium solution, I'd recommend sticking with Nickel batteries for now. If you have thousands of dollars to spend on a pack, you could use new generation lithium powertool batteries that don't have the serious safety concerns.

so i guess either he charges at work, or pedals 1 way.

Thankyou for your input.
I am quite happy to cycle one way plus i also have access to charge at work, so does that effect the amount of power i would need to carry in terms of battery packs? I would like to keep the weight down to a min, as i still intend to cycle at least 18 miles.

What are your thoughts on this?

Thanks again

Barry

Hi Barry;

I am quite happy to cycle one way plus i also have access to charge at work, so does that effect the amount of power i would need to carry in terms of battery packs?

Click to expand...

I assumed in the calculation showing you'd need the big 18ah batteries that, as you originally stated, you're planning to ride 18 miles one direction at up to 30mph. If you use the battery to get to work, plugging in at work certainly wouldn't hurt, but it's not going to change that equation.

I would like to keep the weight down to a min, as i still intend to cycle at least 18 miles.

Click to expand...

If you pedaled half the way there, and half the way back, whilst recharging at work, then you could probably get by with 48v and 12ah. Here's a pack like that for $700:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2538
or the
"48V 12Ah NiMH Battery, 2C Max Rate
10.08 kg (22.22 lbs)" $475
from
http://ebikes.ca/store/

Also, if you went 5-10mph slower while pedal-assisting the whole way, an ~12ah 48 volt pack should suffice.

I think folks here would agree the ebikes.ca packs are preferable as Justin, the vendor, is well known and trusted in ebike circles and tests all his packs pre-sale. To avoid whatever import fees and hassles, in the UK these guys are a well regarded vendor, though they don't currently advertise their battery pack selection:
http://www.teamhybrid.co.uk/index.htm
Team hybrid also sells much lighter 36 volt 15 ah lithium polymer packs like this one:
http://www.texaselectricbikes.com/catalog/lithium-polymer-battery-volt15-hour-p-165.html
and there's also I believe a 48 volt 20 ah model that would suit very nicely. With any lithium pack there are very serious safety concerns to be aware of, but so far no reports of fires with these pre-built packs.

Hopefully Knoxie can chime in here -- he lives in the UK too and probably knows more about UK vendors.

if u pedal with the batteries/motor u don't feel their weight so much.

u'd be way more tired with a too small pack, than with a bigger heavier pack with lots more AH.

also xy's assuming no hills or that u pedal up them.

joystix2 said:

WOW! When did BatterySpace raise their prices on the 48v13ah packs. I bought the same pack for $459 in February and its current price of $699 for the same pack is way too high in my opinion. Thats a $240 jump. I had to recheck my email receipt and do a doublecheck on my price. For that new price I would have to go another route and do lithiums......

Click to expand...

I feel your pain. Check this link below, we have an ongoing discussion about it right now.
http://endless-sphere.com/forums/viewtopic.php?t=588

This price jump is BS quite literally, they are making a false markup on these IMHO, the dealer price of NIMH and Lipoly is dropping, Batteryspace are taking the piss im annoyed about this.

The Chinese dealer prices are dropping? i smell a rat its nothing to do with Nickel prices, there isnt enough nickel in the batteries to make that kind of difference, at those prices you would all do much better to order lipos direct from China. or buy Saft NIMH packs.

Someone should drop them a line.

Knoxie

Dunno, using the default "mtb" bike setting from kreuzotter.de
Obviously, for the same effort one would go faster on a road bike.

20Kph = 85w - Average human can sustain this effort
25Kph = 143w - A regular cyclist
30Kph = 225w - A cyclist who's in shape
35Kph = 337w - Club cyclists well in the pain threshold, not enough to show.
40Kph = 483w - Fit cyclists in racing pain, plain to see on their faces.
45Kph = 668w
50Kph = 897w


For 50Km/h, ~30Mph
900w - 100w = 800w - Power needed - regular/fit cyclist not pedalling much.
800w / 0.75 = 1067w - Compounding efficiency
30Km / 50Km/h = 36m - Time to travel 30Km
1067w * 36m = 640wh - Power used to travel 30km
Around 30kg, 125$ in Lead
For NiMH, about 14Kg and 450$

For 40Km/h, ~25Mph
480w - 100w = 380w
380w / 0.75 = 507w
30Km / 40Km/h = 45m
507w * 45m = 380wh
Around 16Kg, 70$ in Lead
Around 8Kg, 300$ in NiMH

For 30Km/h, ~20Mph
225w - 100w = 125w
125w / 0.75 = 167w
30km / 30km/h = 1h
167w * 1h = 167wh
Around 7.5kg, 30$ in Lead
Just over 4kgs and 110$ in NiMH

Battery requirements, cost & weight, increase a lot with speed.

xyster said:

Team hybrid also sells much lighter 36 volt 15 ah lithium polymer packs like this one:
http://www.texaselectricbikes.com/catalog/lithium-polymer-battery-volt15-hour-p-165.html
and there's also I believe a 48 volt 20 ah model that would suit very nicely. With any lithium pack there are very serious safety concerns to be aware of, but so far no reports of fires with these pre-built packs.

Click to expand...

Wow, that's a sweet pack. I'm sold when you can buy two for the price of that one. And thanks to everyone for fleshing this stuff out. Even if these options can get a little redundant at times, it helps a lot more people than just the original poster.

You can get the 48v20ah Lithium pack from ForsenUSA. They are running at $1200 a set. Hopefully they will be half that within the next year or two.[/b]

this is an excellent write up.
It also makes me very concerned about the cost of batteries for my pushbike conversion :s

I'm going to need a 25klm x 2 plus safetey range (with some hills - rolling) ie about 60ks at aprox 40kph (when not in traffic)

- based on the texas electric pack i'd need two of them - to reiably get to and from uni (taking into account inefficency, and pack degridation over time) - one in each side of the panny.

I'd be very interested if we could sorce GOOD batteries direct from the manufacturer. would make things a lot less expensive.

This ebike is already getting expensive
teamhybrid puma motor kit $999 AUD plus delivery
2x texas battery packs $1820 AUD plus delivery
chargers other misc costs

Which way would the packs be best wired up for range? series or parallel? (or doesn't it matter)

$477, goes 80km for less than $1:

http://www2.singersl.com/singer/products/motor_bicycles/motor_bicycles.asp?pcode=LNC_LC-LX48Q

Batteries have a long long way to go before they can compete with the main stream 50cc stuff.

Lowell said:

$477, goes 80km for less than $1:

http://www2.singersl.com/singer/products/motor_bicycles/motor_bicycles.asp?pcode=LNC_LC-LX48Q

Batteries have a long long way to go before they can compete with the main stream 50cc stuff.

Click to expand...

Personally I think i would still rather spend the extra on the good batteries to get the distance over buying a 50cc motorbike. I have found some (haven't tried this one) motorbikes to be too small, or annoying to ride (ie kick start and you can't duck up onto bike trails), plus it doesn't let you get ANY exercise. While you might get a little (or a lot) on an ebike. But thats just me. - I'm planning upgrade paths for the bike(s) i'm planning on building - to allow majority use of electric bikes (with the car as a backup). I'm spending about $12AUD on petrol alone to get to work / uni. PER DAY I ride a racing bike some days to try to minimise it - but its very draining.

Those Firefly batteries about to enter the market also look extremely appealing, maybe more so than current NiMH -- based especially on price and temp range. For some reason these aren't being discussed as much on the forum, and real-world information itself is limited to press releases alone.

I read that these Carbon-Graphite Foam-based batteries were capable of delivering up to 40-50whr's more than typical lead acid, slightly better even than NiMH, and less than lithium. They also feature far less sulfation, faster-recharge times, better high-low temperature discharge times, and obviously weigh considerably less (50%?) than current lead-acid batteries.

http://www.fireflyenergy.com/index.php?option=com_content&task=view&id=204&Itemid=89

I've been following firefly for about a year and a half now. I agree that what they're doing has a good chance of maybe even outperforming Lithiums. Even if they can only match lithium performance, it should be a superior technology since the physical package should be smaller and they don't need BMS. They should also be cheaper. Nobody has been talking about them now because there are no firefly products! They've cut deals with electrolux to supply batteries for gardening equipment and also to supply batteries to the military but I haven't heard of any planned mass production for consumer products. One question I have about the technology is, how durable is that graphite foam matrix? If you dropped the battery, would this matrix crack???

Does anybody know where firefly performance specs are listed, such as energy density?

I found few quantitative claims in the qualitative description. The most interesting I posted below.

One problem with this technology is that it's still basically a lead battery. Lead has less than half the electrochemical potential of lithium -- which, if I recall, is the most chemically active metal. The info copied below the chart suggests these firefly lead matrix batteries have the potential for 1.5-1.75 times the energy density of typical lead batteries, whereas lithium-cobalt has 4 times the energy density.
From: http://www.batteryuniversity.com/images/partone-3.gif


From: http://www.fireflyenergy.com/images/stories/pdfs/White%20Paper%2010.30.06.pdf