Electric Basics

[twowheeledfox]

One of my drinking buddies is highly interested in an electric bike, so this question is for him:

What are the basics of building an electric motorbike? How much do the kits cost? What is the range? What's the average charging time, and life of battery? What abut speed at cruising?

I have little to no knowledge of electric motors and such but this is about what he requires/wants-

20mph cruising speed
at least 50m range at that speed (I have NO idea as to whether this is realistic or not; if it's not, would carrying an extra battery or two aid in this?)
Cost under $300 for the kit
Preferably not too DIYish in the sense of non-kit stuff.

He's thinking of building this otherwise on the cheap, something like an old cruiser or MTB frame, new brakes, install a lighting system and the drive system and that's that.

Thanks for the help all.

 

[SANGESF]

He's thinking of building this otherwise on the cheap, something like an old cruiser or MTB frame, new brakes, install a lighting system and the drive system and that's that.

We would all love to go 20mph and go for 50miles cheap.
Not gonna happen..... Especially if he doesn't want it too much DIY.
Look at a cost of somewhere around 350 for just the kit..
Batteries are gonna cost ya somewhere around 480 and that's just if you use SLAs, which will last no more than a year.
Now figure Lithium Ion batteries instead of SLAs that will get you that kind of distance and speed are gonna cost ya at least $1000 and would last about 3 years if you're lucky.

 

[deacon]

I agree pretty much with the last post but sla are a little less expensive here but the weight is a killer and you need to live in a flat geographic area to get any kind of range on an ebike. I don't.

If you don't want much work, you are going to be looking hub motor. If you are looking hub motor kits, look at least 500 watts. check out ebay. I have no idea how they are, I have one sitting in the shop. I tried it, then decided against it. I might have to go back to it one day, but not right now.

I prefer DIY...

 

[zabac70]

For hub motors(or kits) - e bay and directly from China (internet). Batteries too and $1000 is overestimated (there are much cheaper Li chemistry batts , with BMS; shipping and taxes are other matter). However , 50 mile range is possible (at 20 mph average) , but not cheap , as someone before posted. If your friend don't want to get his hands dirtu he can stretch for $4500 - 6000 for performance bike (which can go 50 mph easily and still have required range - depending on a topography of the route).

 

[SANGESF]

For hub motors(or kits) - e bay and directly from China (internet). Batteries too and $1000 is overestimated (there are much cheaper Li chemistry batts , with BMS; shipping and taxes are other matter). However , 50 mile range is possible (at 20 mph average) , but not cheap , as someone before posted. If your friend don't want to get his hands dirtu he can stretch for $4500 - 6000 for performance bike (which can go 50 mph easily and still have required range - depending on a topography of the route).

There are NO "cheap" Li chemistry batts, ESPECIALLY, if you don't want a DIY kinda thing.
Any of the other Li chems are dangerous, except for LiFePO4. (especially for someone who is not good with those kinds of things - hence why he didn't want DIY)

I'm figuring that the OP would need at LEAST 36v 40ah to get the desired speed/range.
You're not gonna find anything under lets say 850 on Ebay, and that's only if you want to wait 2 months for your battery.

SLA's can be the way to go, but you would need 36v 66ah worth of batteries (re: VERY heavy) to get even clost to 50miles distance.
and would only last you a year at best.

I would say, Figure $700 for 36v 30ah battery, would get you about 44 miles distance at 20 mph.
if you wanted to pedal some as well, you might get away with something in the 25ah range.

Best bet, is to find a deal on buying TWO E-bike kits and run a dual motor setup.
I am doing that now.

I got the kits for 230 each with no batteries, and use two 36v LiFePO4 batteries purchased on ebay.
One is 15AH (Front) and the other is 10AH (Rear), I get 50 mile range and i can do more than 20 if i want to... If I do 22 mph, i get 50 miles, if I do 20 mph, i get about 55 miles, if i do 18, i get 60 miles, and if i do 16mph, i get 80 miles.
If I pedal with the 16 mph, i can get 100 miles.
Total cost was
Two motors (460) and 2 Lifepo4s for approx (580) {took 2 months to get the batts}
So for a little over a $1000 USD, i get awesome range, and power if i need it.

 

[deacon]

The two motor idea have been advanced here before but you are the first I have heard who actully did it. Got me wondering now what my fishy hub motor would do in conjunction with my rhino drive. I have both laying in the shop gathering dust. I could run the nkpk pack on the hub in front and the big slak on the rear rhino. That might be an interesting combination.

 

[jdcburg]

http://elitepowersolutions.com/index.html has 12.8v 20ah LiFePO4 for $120 and 40ah for $200. I just bought 2 12/20's, paid $20 shipping (for both) and got them in a week. I live in New England and they ship from AZ I think. The 20's weigh 6.6lbs and the 40's 13.2, about half what comparable SLAs weigh. With reasonable care they should last 5 to 10 times as long as SLAs. The ones I bought don't have the built-in BMS so I watch them carefully when charging but I can get each cell within 0.05 volt and each 4-cell pack within 0.1 volt of the other. So far I've been able to get each 12.8 v nominal to about 15.20 fully charged and after 7-8 hilly miles they come in at 13-13.2 volts, with no noticeable drop in power. I'm still collecting data and will report back but so far I am nothing but pleased with all aspects my move to Lithium - jd

 

[deacon]

good to hear what kind of motor are you running on your bike. Not brand as much at type and watts. Please.

 

[jdcburg]

Unite MY1016Z3. It's a 24V brushed 350 watt with 9.78:1 gear reduction. It's the motor sold for a Razor Dirt Quad kid's 4-wheeler, usually around $35 with a #25 chain sprocket. TNC has it for $55 with a 9 tooth bicycle sprocket. It powers my dual freewheel front sprocket mtb setup through an 8-speed derailleur. Top speed is about 25 mph but the lower gears give it the hill power I need around here - jd

 

[SANGESF]

http://elitepowersolutions.com/index.html has 12.8v 20ah LiFePO4 for $120 and 40ah for $200. I just bought 2 12/20's, paid $20 shipping (for both) and got them in a week. I live in New England and they ship from AZ I think. The 20's weigh 6.6lbs and the 40's 13.2, about half what comparable SLAs weigh. With reasonable care they should last 5 to 10 times as long as SLAs. The ones I bought don't have the built-in BMS so I watch them carefully when charging but I can get each cell within 0.05 volt and each 4-cell pack within 0.1 volt of the other. So far I've been able to get each 12.8 v nominal to about 15.20 fully charged and after 7-8 hilly miles they come in at 13-13.2 volts, with no noticeable drop in power. I'm still collecting data and will report back but so far I am nothing but pleased with all aspects my move to Lithium - jd

The only problem with those at elite solutions, is the fact you didn't get them with the BMSs attached...
Once they get out of balance it's gonna be hard to get that back. Each of those are filled with either 4 (20ah) or 8 (40ah) cells and without a BMS it's a little difficult.
Why didn't you get the BMSs with them?

Also 15.2 is a bit high, I would stop charger at no higher then 14.4.

 

[jdcburg]

I didn't want to spend the extra $36 per and I didn't want the complicated wiring harness. 350 watts is a relatively small load for the battery size. After use I find the individual cells even closer than when I started. Also I have a single cell lithium charger so I can balance individual cells if necessary. I don't mind keeping a closer eye on things than I might if I had a BMS - jd

 

[twowheeledfox]

Thanks for the replies... had a chat with my friend about the realistic situation on the build, he says he could deal with pedal assisting at lower speeds and a range of 20 miles but would not be able to pay more than $250. This is quite a bit for a pedal-assisted electric bicycle, can it be done?

 

[SANGESF]

Thanks for the replies... had a chat with my friend about the realistic situation on the build, he says he could deal with pedal assisting at lower speeds and a range of 20 miles but would not be able to pay more than $250. This is quite a bit for a pedal-assisted electric bicycle, can it be done?

so le me get this straight, he wants a bike that will do 20mph AND 20miles and only pedal assist at lower speeds and wants all of this for about $250...
(not in THIS reality)
heh
sorry, not gonna happen

 

[twowheeledfox]

No, I mean pedal assist the whole time but still, electrics in general must be effing expensive if 20mph/20 miles is that difficult. I know electric motors are very efficient, it must be poor battery technology holding us up in this area in general. I mean, a pre-built electric bicycle I researched was $749, did 20mph for 30 miles and weighed about 70lbs. I could make a gas-powered bicycle that would do almost twice that speed and with seven times the range for half the cost.

Apart from noise and pollution, and I suppose maintenance for the non-DIYers, there seems to be no advantage to these things.

 

[SANGESF]

No, I mean pedal assist the whole time but still, electrics in general must be effing expensive if 20mph/20 miles is that difficult. I know electric motors are very efficient, it must be poor battery technology holding us up in this area in general. I mean, a pre-built electric bicycle I researched was $749, did 20mph for 30 miles and weighed about 70lbs. I could make a gas-powered bicycle that would do almost twice that speed and with seven times the range for half the cost.

Apart from noise and pollution, and I suppose maintenance for the non-DIYers, there seems to be no advantage to these things.

Gas bikes rock... However most require DL.
20mph for 30miles usually means about 1/2 to 2/3rds of real world.
Most manuf specs are based on flat ground, 170lb person, no wind and pedaling kinda fast. NOT reality.

It's the cost of the batteries themselves that are usually cost preventative for most.
Gas bike kit on eBay is $200 and gets 80mpg, but then again most states require a DL to ride one.

Tell me what bike you saw for $750 and I'll give ya my thoughts on it.

 

[Happy Jack]

Gas bikes are mostly a better bang for the motorbike buck.

 

[jdcburg]

twf - it can be done but it would have to be a DIY and would take some creative thinking. I would most definitely not believe kit claims of mileage, distance or speed. On my first build, I put a 3-speed rear hub/wheel on the front of a bike and powered it with a 350W motor and 2 12V 12ah SLAs. The total cost with a charger (using a pair of donated bikes) was about $175. It would do around 18 mph. The furthest I went was about 15 miles. If I'd bumped it up to 36V I would have made your speed/distance requirements for maybe $210. That was with new batteries. After draining them and overcharging them a few times they got tired quick and wouldn't do it now. You can read about the build at Endless-sphere.com • View topic - 3 speed front wheel drive e-bike - jd

 

[zabac70]

Only solution is to check e bay often (or Craig list or local adverts...) and buy something used (e scooter or e bike) without batteries and just (for the rest of the budget) buy new batteries. When you buy a kit, it doesn't jump on the bike itself , somebody must put it on , which requires basic skills (and sometimes not so basic). If you go that way (or your buddy), you can just as well put components separately (that's DIY version) which can be scavenged or obtained for less money. It is not that hard - people use to build e bikes out of nothing and without previous experience or knowledge about it. New kit with batteries (doing 20 mph for 20 miles) for $250 doesn't exist (yet) - anyway , not in real world and any vendor that claims that is , well , "exaggerating".
Debate of gas bikes compared to e bikes is like apples and oranges. It's incomparable and it shouldn't be commented on this part of forum.

 

[wheelbender6]

For $250, a gas powered bike is his only option. Electric bikes have advantages, but they come at over twice the cost.

 

[SANGESF]

For $250, a gas powered bike is his only option. Electric bikes have advantages, but they come at over twice the cost.

Why did he want to motorize a Bike in the first place?

What state does he live in?

Does he have a Driver's license?

These are important questions, because MOST people that have never gotten into (gas) Motor biking, all of a sudden, look into it, because they lost ther DL to DUI.
About 75% of the States require a DL to ride a gas powered bike, as well as some of the towns within each state that allow it in the first place.

If he's in Texas, like you, here are the requirements in a nutshell....

Required: light (always lit), horn, directionals, tail light or reflector, stop light(s), r.v. mirror. Approved helmet required. No riders unless ped has 2 seats (sidecars excepted). Inspection sticker required for TX residents. 30mph limit, 50cc, 2 BHP. No muffler cutouts. Liability insurance required . Medical coverage required on rider. Class "M" Drivers Licence. Texas has reciprocity with all other states but Wisconsin & Michigan to allow passage of other state's peds and legal drivers IF THEY HAVE TAGS. Constant lights not required on pre-1975 models not so equipped.