Electric Bike, 40 mile range

So here my plan. Apologies in advance if i'm dreaming with this kit, i am no electrical engineer. I checked the lipos for noobs thread, but couldnt find the answers to my questions..
Buythe 48v 1000w bicycle hub kit, it comes with speed control and throttle and all that jazz. Here the link(http://www.saferwholesale.com/Rear-Wheel-Electric-Bike-Motor-p/48v%201000w%20rear%20motor%20kit.htm)
For batteries i'm planning to buy 13 Turnigy 5000mAh 1S 20C Lipoly individual cells, and wire them in series to achieve 48.1 volts, and a total of 65000mah.
However i am worried, will this be too many amps for the motor/speed control? If each battery puts out 20c, then i will have 260c total, at 48v. If Watts=VOltsxAmps, then according to my calculations my batteries would be putting out 12480 watts. I hope my math is horribly wrong, because thats a lot more than 1000w. My question is, will this configuration work? And if so, what kind of range can i expect?

Series cells add in voltage but not in amp hour capacity, so you'll have 48V 5AH or 240 watt hours.

The controller and motor will draw the current they need, no more.

Use two 6S 5AH packs in series instead. Much easier and fewer wires to deal with.

You'll get about 7-12 miles of range from this battery.

What Alan said.

Getting a few terms mixed up I think.

The C rating is the maximum current capability of the motor. If the cell is 5 Ah, then 20C is 20 times the capacity. In this case, 20C would be 100 amps.

You can't increase capacity of a cell by adding them in series, only in parallel. Your 13 cell pack would still have a capacity of 5 Ah. The total amount of energy is going to be 48 x 5 = 240 Wh. For most applications 5 Ah is too weak and you will be loading the cells pretty hard. If you were to wire two cells in parallel to increase the capacity to 10 Ah, and put 13 of these in series you would have a 480 Wh pack. Now you can draw twice as much current; 20C is 20 times 10, or 200 amps. Please don't try to draw 200 amps Most controller outputs wouldn't exceed 120 amps anyway, but they are out there.

Thanks for the prompt reply! i'm sure what you're saying would make perfect sense to someone with more electrical knowledge than me, but sorry i am a still a little bit fuzzy as to what you are saying.
I think i understand now that even though i wish to use 13 batteries, each with a discharge rate of 20c(what exactly does that mean anyway, 20 amps?), each 20c doesnt add up to 260 amps.
Here is the link of the batteries i want to use. http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html
Question: on the battery stats, it says 5000mah. Is that how much energy the battery holds?
I want to have as much battery capacity as possible, while staying within the 48v 1000w range as to not burn up my speed control/motor.
How should i go about doing this?

You need to learn the basics.... start with ohms law and the difference between parallel and series.

Series means you hook the batteries up b+ to b- to b+ to b-.... as you do this the voltage goes up, the amperage stays the same. So, lets say you want 48 volts... you got it right with 13 cells in series getting about that. The amp hours stays the same. Watts available goes up as you add batteries (volts x amps = watts) but the amperage you can safely draw is still the same per cell and with them in series it's still the same as each cell.

If instead you wired them all in parallel... all the B+ together and all the B- together you'd have a giant 3.7v battery with 13x the amp hours but exactly the same total watts available as the series battery pack. The way to get higher voltage AND higher amperage is by wiring series parallel... strings of batteries in series each being hooked together with the end batteries in parallel. That is where the terms you see on the websites are talking about with descriptions of packs like 3s2p... that would be two strings of 3 cells in series hooked to each other in parallel. A 13s1p would be a 48v pack consisting of one string of 13 cells in series... in your case with the Turnigy 1s cells about 48v and 5000mah. Add another string in parallel to that (13 more cells) and you'd have a 13s2p pack of 48v 10Ah (10000mah). Keep adding strings in parallel to get the total amp hours you need (or watts available). Your 48v/5000mah =240 watts total energy... add a string and it's 480 watts...

Look at the descriptions of the Turnigy packs... you will see that they get the higher voltages by doing exactly the same thing. Only problem with trying to use high power RC packs to build a 48v pack is that odd number you came up with... 13 cells. Go down to 12 cells and you can use a pair of 6s (or four 3s or three 4s) packs to get your required voltage. Jump up to 14 and it's a pair of 7s for 51.8volts (about 59 volts hot off the charger... need to be sure the controller can handle it).

40 miles range requires a whole lot of battery depending on speed and terrain. See your 1000 watt motor... if you were actually doing that as an average from full to empty, that 13s1p pack would be drained in under 15 minutes. I run a Headway pack 48v10ah (16s1p of LiFePo4) and with it new got about 20 miles out of it tapping on 30mph mostly flat terrain and pedalling along with it. I have gone over 50 miles on a charge, using it just as a boost on hills when riding with other cyclists... so most of the miles were just me pedalling, just using it to keep up with a group of faster riders. I'd say 20 amp hours is about right if you are not planning on doing it flat out which would drain the pack each time, killing it rather quickly.

Oh yeah... your 20c is how hard you can draw the power without damaging the cells... so 20c means 20 x the amp hours 5000mah (5ah). So you can draw 100 amps safely... but it ain't going to last long. Anyways, 1000 watts at 48v... flipping the equation around is actually only about 20.8 amps. 20 amps draw (climbing a hill) would in theory last you about 15 minutes.... slower/flatter further.

Reality differs a bit... others can give you a better idea depending on your actual controller/motor/weight/speed/terrain as to how far you can safely travel. You do not want to drain the pack to cutoff voltage.

Confused yet? Muddle through learning it... it's worth the effort.

If you want 40 mile range with that golden motor kit, you will need 12 series 25 AMP hours
so for that range you will need to buy the six series 5000 mah batteries - ten of them

http://www.hobbyking.com/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html

Then you will have to make connectors to hook them up correctly and buy a charger

redorblack said:

Confused yet? Muddle through learning it... it's worth the effort.

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Yes.. Thanks for the reply... I will be muddling for quite a while, hopefully i will have a grasp on all this soon.

BikeFanatic said:

If you want 40 mile range with that golden motor kit, you will need 12 series 25 AMP hours
so for that range you will need to buy the six series 5000 mah batteries - ten of them

http://www.hobbyking.com/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html

Then you will have to make connectors to hook them up correctly and buy a charger

Click to expand...

So what your saying is, to achieve my approximate 40 mile range i should buy 10 of those 6s batteries, and wire 5 up in parallel to(in series, achieving 44.4v) to 5 more in parallel? Or shall i just run 2 at a time and switch them out when they get dead?
And also, what charger do you recommend? (im on a tight budget)

1 thing about your kit.. an equivalent kit can be found for $175 + shipping on emissions free ( cell_man ).. $200 on eBay.. $250 shipped from yescomUSA etc..

Save that $200 markup on a basic commodity Chinese hub motor kit and put it into your batteries.

Just a quick headsup to the original poster, redorblack has a few terminology errors in his post (says watts when it should be watthours). These things can trick you up when you are learning.

Think about the units as you do these calculations. A current of 1 amp, for 1 hour passed 1 amp hour of charge. If this was done at 3.7 volts, and we know that power = volts x amps, then we have 3.7 V x 1 amp hour = 3.7 watt hours. A watt hour is a unit of energy. 1 watt hour is equal to 3.6 kilojoules.

garett0439 said:

So here my plan. Apologies in advance if i'm dreaming with this kit, i am no electrical engineer. I checked the lipos for noobs thread, but couldnt find the answers to my questions..
Buythe 48v 1000w bicycle hub kit, it comes with speed control and throttle and all that jazz. Here the link(http://www.saferwholesale.com/Rear-Wheel-Electric-Bike-Motor-p/48v%201000w%20rear%20motor%20kit.htm)
For batteries i'm planning to buy 13 Turnigy 5000mAh 1S 20C Lipoly individual cells, and wire them in series to achieve 48.1 volts, and a total of 65000mah.
However i am worried, will this be too many amps for the motor/speed control? If each battery puts out 20c, then i will have 260c total, at 48v. If Watts=VOltsxAmps, then according to my calculations my batteries would be putting out 12480 watts. I hope my math is horribly wrong, because thats a lot more than 1000w. My question is, will this configuration work? And if so, what kind of range can i expect?

Click to expand...

Assuming you live in the US, you can buy that same kit for $275.90 shipped to your door.
http://www.ebay.com/itm/48V1000W-26-Rear-Wheel-Electric-Bicycle-Motor-Kit-E-Bike-Cycling-Hub-Conversion-/370554729385?pt=LH_DefaultDomain_0&hash=item5646c873a9
Best deal going.
Now, you are really messed up on battery calculations. Your proposed pack is only 5000mah total, not 65000. And you don't want to buy single cells (1s) anyway. You can run anything from 12s to 15s on that motor with the controller that comes with it.Simplest thing would be 12s using 6s 5000mah packs. Lot's of reasons to go with 12s using 6s packs, but main reason is at 12s the controllers lvc will keep you from over discharging your pack and ruining it. Figure 10 miles on a 5000mah 12s pack at 20 mph. Max speed of a 12s pack will be close to 30mph. If you're looking for max speed, then a 15s pack is what you want That would get you about 35mph. Use 3 5s packs in series for that. And for every 10 miles in range you want, you need another identical pack to parallel in with the other(s). Here's some reading for you. read it.
http://www.rchelicopterfun.com/rc-lipo-batteries.html
http://scriptasylum.com/rc_speed/index.html

Thank you all very much for the knowledge. I will definitely check out those links.
P.s I posted that link instead of the cheaper deal on eBay so the link would take people to an expired page once the auction ends.

You might get some stufff you need to know from the review section of the forum. They are pretty buried by now, but I did some motor kit reveiws a few years back that gave basic information on their performance.

One of the things I came up with was a general rule of thumb, for using a bike hubmotor to travel 20-25 mph. About one mile per amp hour of 36v battery capacity, and about one mile per .75 ah of battery capacity if using 48v. This "Dogmans rule" includes a pretty good reserve, plus actual mileage, depending on speed actually traveled, weather, terrain, pedaling effort, can vary a lot. The reserve is for helping the battery last longer, by not discharging 100%, and to give you extra when riding in cold weather, or into a headwind.

My favorite battery for low performance commuting use has been a lifepo4 from pingbattery. A 48v 15 ah one will generally get you 20-25 miles at 20-25 mph. This is about 750 watthours of battery capacity. Slowing down can extend range a lot, but to reliably get 40 miles at full throttle you'd need 30 ah of a 48v battery. That gets to be a lot of battery to try to carry, so if you can charge at work, and are doing a 20 mile commute one way, then a 48v 20 ah battery could be enough for you.

You are not alone, it does not help that so many ebike vendors inflate the range of the bike so much. Sure, you can get unlimited range, but the price is you only use the motor for 10 of the 40 miles you need to ride. To me, the whole point of an ebike is to be able to ride full throttle the whole way, and get there fast with only the pedaling effort you wish to use. Not pedaling a heavy bike for miles, only to use the motor on a hill.

What kind of use is this for? Daily commute 40 miles roundtrip? Hilly or flat? And what kind of speed do you expect to be riding? Most motor kits fall between 25 and 30 mph at full throttle 48v.

I predict!

That's what happens when you charge Lipo to more than 4.2V per cell. Inside the minivan on that nice flammable upholstery.

dogman said:

You might get some stufff you need to know from the review section of the forum. They are pretty buried by now, but I did some motor kit reveiws a few years back that gave basic information on their performance.

I will check that out, thank you

dogman said:

What kind of use is this for? Daily commute 40 miles roundtrip? Hilly or flat? And what kind of speed do you expect to be riding? Most motor kits fall between 25 and 30 mph at full throttle 48v.

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Yes 40 mile roundtrip to college. The way there is about a 400 foot elevation decrease, with a few mild uphills.

I would like to at least going 25mph. Its not really that important of a factor to me, just cheap reliable commuting.

In your place I would definitively get deep in to battery and LiPo related info before considering LiPo. Anyway have your camera ready when riding.

HMM, Riding to school makes the halfway recharge difficult if not impossible. But it depends on the school, the dept where you study. Mabye a charge while in class is possible. A student job could lead to a place to put a battery to charge for example.

40 mile range is doable, but to get fantastic range on a small battery you have to ride too slow. My guess is you'd need to travel at least 20 mph. Even then, you'd be suprised how long it will take to do 20 miles, including traffic, stop signs etc. My 15 mile commute always takes at least 50 min. Figure on close to 3 hours in the saddle.

At 20 mph, you'd be likely to need 48v 20 ah to do it with a reliable reserve for that windy day. The way to stretch range without slowing down so much is to set a throttle position, then pedal up about 2 mph more speed. This way you lower the amps the motor draws by about 100w.

One good way to be sure you travel slower, would be to pick a motor that can't go so fast. I've liked this motor a lot, and have it on two of my ebikes. It will go 19-20 mph on a 48v pingbattery. Methods is a respected vendor here. http://endless-sphere.com/forums/viewtopic.php?f=31&t=31146&hilit=wife+kit Hell of a deal, since it includes the tool every hypermiler needs the most, a Cycleanalyst.

You might be better off starting with a lifepo4 battery. Like a Ping 48v20ah battery at 22amps on the controller. The amount the controller ask to drain the battery. It is important how much the controller is rated for in amps. this is what your bike will be demanding from your battery. Some kits sell 40 amp controller which is to much for a ping. The amount of drain.

garett0439 said:

Yes 40 mile roundtrip to college. The way there is about a 400 foot elevation decrease, with a few mild uphills.
I would like to at least going 25mph. Its not really that important of a factor to me, just cheap reliable commuting.

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30ah of 12s lipo should do 40+ miles @ 25mph easy.

garett0439 said:

dogman said:

You might get some stufff you need to know from the review section of the forum. They are pretty buried by now, but I did some motor kit reveiws a few years back that gave basic information on their performance.

I will check that out, thank you

dogman said:

What kind of use is this for? Daily commute 40 miles roundtrip? Hilly or flat? And what kind of speed do you expect to be riding? Most motor kits fall between 25 and 30 mph at full throttle 48v.

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Yes 40 mile roundtrip to college. The way there is about a 400 foot elevation decrease, with a few mild uphills.

I would like to at least going 25mph. Its not really that important of a factor to me, just cheap reliable commuting.

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Here are my numbers:
51.8V22Ah LiPo - I use for going to school. I am in a lab, so I charge there.

Going to school is an 8miles ride and I use 6-7Ah (40-46wh/mile). But then again I am going full throttle w/o assist which comes out to be 30-35mph.

I have some stops, but my average speed is 25mph on the CA. Unless you are doing full throttle w/o stop and go, I think it's really hard to get 25mph average.

I think what you should be shooting for is 20mph average and top speed around 25-30mph. This means around your power consumption should be around 30-35wh/miles assuming no headwind.

Being Optimistic, 30wh/mile * 40 = 1200Wh. If you are on 48V, you will need 25Ah or 14s5p using 5Ah Lipo Cells. Pedal a bit, and maybe you can get away with using only 48V20Ah LiFePo4 like other people here states. Otherwise, build your own Lipo battery and get 25Ah. Make sure you read on Lipo Saftey before venturing on this.

As for cheap, this is not cheap by any means. You can get it money back if you get rid of your car for a few years. Save money on gas/registration/insurance/maintenance/etc.

As for reliability, I recommend reading a couple of reviews on DIY bike on this forum to see what problems people are running into and maybe you can filter and decide for yourself what you need to build to avoid or anticipate for the problem(s).

Good luck with your build. If you run into problems, people here will be welcome to help.

VoKuS said:

I predict!

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Yeah... That's DEFINITELY gonna happen...

The OP NEEDS to stick with a MUCH SAFER battery tech then LiPo...

1.) 36v 25Ah with a 36v 20amp controller would do what the OP really wants...
That would give him the 40 mile range at 18-20mph on an average motor...

2.) 48v 20Ah on a 48v 15a controller would do it too...

IF he can charge at school, then he could get away with a smaller battery, but the price difference between 15-25Ah batteries is not so bad, so prolly best bet is number 1 above..

You have much to learn about batteries and lipo. I highly suggest you purchase a battery like this one instead of going with lipo, http://www.pingbattery.com/servlet/the-17/48V-30AH-V2.5-LiFePO4/Detail

Building an electric bicycle is not cheap, but it will save you money in the long run if you aren't paying for car insurance, or car maintenance.

A direct-drive hub has specific benefits, they are great for high-speed builds. A geared hub would get better battery range than a DD. A cell_man geared hub would be a good start for comparison. 44V-48V is great, higher volts means lower amps to accomplish the same work.

For extreme range, I agree with Dogman, keep the speeds around 20-MPH. A small front-fairing and/or tail-sock will actually help. A recumbent would be best, but that is a choice that doesn't work for most riders (high price, or oddity factor?)

Ok... So would 3 8400mAh 4S2P 30C LiFePo4 Packs be a 39.6v 16.8 ah battery?
If so, if i had 6 of those packs wired for 39.6v would i have 33.6ah?
And if i ran that pack from full to dead would i overheat my motor/speed control, or would it burn up right away from the amps?

(Heres th elink to the battery)
http://www.hobbyking.com/hobbyking/store/__14074__ZIPPY_Flightmax_8400mAh_4S2P_30C_LiFePo4_Pack.html

garett0439 said:

Ok... So would 3 8400mAh 4S2P 30C LiFePo4 Packs be a 39.6v 16.8 ah battery?
If so, if i had 6 of those packs wired for 39.6v would i have 33.6ah?
And if i ran that pack from full to dead would i overheat my motor/speed control, or would it burn up right away from the amps?

(Heres the link to the battery)
http://www.hobbyking.com/hobbyking/store/__14074__ZIPPY_Flightmax_8400mAh_4S2P_30C_LiFePo4_Pack.html

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3 (3s,1p) would be 39.6v 8.4Ah
6 (3s,2p) would be the 39.6v 16.8Ah