New ebiker/ebike: Battery help please! (update 10/18)

[Johnny_Z]

Hey all,

I have spent the last few days and have about 80 tabs open to various sites here and there all trying to figure out how to build an ebike, and still feel woefully uninformed. Really the problem is there is tons of info that I can't really process because I don't know very much to begin with here. Perhaps you guys can help me.

A little about me:

28 years old, 6' 1" and 175 lbs. I live in Southern California and currently have a 30 mile commute-one way. 60 miles round trip. Previously I worked 7.5 miles from work and was able to road bike it every day, so I'm not a total newb on the road. I know all the laws, I know the courtesies, and I know of the dangers of biking in general.

What I would like in an ebike:

*60 mile range. If this is not possible, 40 would be workable, I'll just have to speak with the boss about charging my bike which shouldn't be a problem. I would just like that extra range. I also am not too interested in pedaling at all, seeing as I work 10-12 hours a day as a warehouse picker. However I would like the ability to maintain my ability to pedal when the motor's not on! And pedal assist might be nice, but I'm not harping on that.

*As street legal as possible. I'm not too interested in going 50 mph. That would be exhilarating for my NEXT build though. Current CA law states 1000 watt motor, 20 mph max.

*Long lasting battery (charge cycles).

*Triangle battery pack mounted preferred

*Rear hub motor preferred

*Most importantly it has to be reliable. I am hoping to sell my truck if all goes well.

My questions:

Do I really need front suspension?
Do I really need disc brakes?
Do I really need a steel frame?

Being that I have ridden for years on my own leg power regularly going 18+ mph in my aluminum framed road bike, I'm pretty comfortable with going the same route with the ebike. I'm open to opinions however, especially since I'm figuring on starting with a completely new (to me) bike. Going forward with getting a used bike to convert to ebike, I'm wondering what might be some pitfalls to avoid, what should I be looking for (brands, components, etc.) Would something like this (http://orangecounty.craigslist.org/bik/4698566637.html) work out ok?

Now for the conversion.

I'm currently looking at http://em3ev.com/store/index.php?route=product/product&path=36&product_id=138 for the conversion kit and something like this http://www.pingbattery.com/servlet/the-12/48V-15AH-V2.5-LiFePO4/Detail for the battery. Any suggestions, pros/cons, or thoughts to consider here? I'm gravitating toward LiFePO4 due to the battery life being way higher than li ion packs. Also, this guy claims 2000 cycles on his packs (http://www.empoweredcycles.com/products/48-volt-15-amp-hour-lifepo4-battery-pack-with-35-amp-bms)-any thoughts or suggestions on the battery?

I am hoping to put something together that will be reasonably reliable and self contained. Being this will be my commute to work vehicle, I really don't want to fiddle around too much, so customization really isn't so important to me as reliability. Knowing that, in my reading I've found that while it's probably easier to find a bike off the shelf at some shop or site, but I've yet to find one that can meet much of my criteria without bankrupting me. I'm hoping to keep the costs to as close to $2000 as possible. Since I'm not going to sell my truck right away I've got the patience to sit down and figure it all out and work with the kinks. So far I love simply reading about the ebike revolution you guys have going on here, but I can't wait to ride one!

 

[dnmun]

the only person i know who had that much commute distance, 27 miles each way, used a recumbent with two motors, a big lipo pack, and had to charge at work. 30 mile range is not trivial. you will have to charge at work.

do not sell your truck, but you could buy a honda civic that gets almost 40mpg with $2k.

 

[Johnny_Z]

the only person i know who had that much commute distance, 27 miles each way, used a recumbent with two motors, a big lipo pack, and had to charge at work. 30 mile range is not trivial. you will have to charge at work.

do not sell your truck, but you could buy a honda civic that gets almost 40mpg with $2k.

i was fortunate and bot my ZENN car for less than $2k. 275mpg equivalent.

Thanks for the feedback. Some bikes I've seen online have ranges that seem too good to be true and I'm not sure if they include pedal assist in those numbers since some are stated and some are not.

275 mpg-impressive! I'd really like to sell my truck, the gas and insurance are bogging down my savings goals. If need be, I can use public transportation partways, though it's a gamble being able to catch a bus with an available spot on the bike rack.

 

[Modbikemax]

Move closer to work.

 

[Johnny_Z]

Move closer to work.

If I could I would. Beside, all the posters at the "move closer to work" forum told me to build an ebike, so here I am.

 

[Jonathan in Hiram]

The terrain of your commute is fairly important in your choices, if it's flat(ish) a direct drive 9 Continent style motor would be more than adequate to push you down the road and is probably going to get a bit more range than a geared motor all else being equal, if you have more than moderate slopes to negotiate you'd probably be better off with a geared motor that climbs better.

Other than that it's battery, battery, battery, the battery is the heart of your ebike build even more than the motor and that long a commute is going to take serious battery capacity, the faster you ride the more battery you are going to need, count on spending two or three times on the battery what you do on the motor.

I've found the simulator at ebikes dot ca to give results that are remarkably close to what I actually get, I'd recommend plugging your numbers into that and see what you can get.

http://www.ebikes.ca/tools/simulator.html

The bike you linked to on CL seems fine for a conversion to me.

 

[dnmun]

the guy i knew with a long commute had to go over several long hills which is why he had two motors so he could maintain speed in traffic on the streets he had to follow to get over the hill. but he had spent over $2k on his lipo pack alone and another $2k to build the bike. he still had to charge at work. your boss can get a tax credit for providing a place to park your bike and charge it.

 

[teslanv]

I would suggest you shoot for a 30-40 mile range, especially if you don't want to pedal.

For Non-pedaling efficiencies, A good rule of thumb is that you will need 30 watt-hours of battery per mile of range.

Speed will also greatly affect your range. As your speed increases linearly, the power required to propel you at higher speeds will increase exponentially. This is primarily due to wind resistance/aerodynamics. If you keep your average speed closer to 20 mph, you will have a much better efficiency than if you ride at 30 mph.

You could either choose a 36V system or 48V system.

The two primary types of electric motor designs are a Hub (either direct drive or geared) and a Mid-Drive. Depending on your terrain, one will likely suit you better than the other. I have quite a few hills where I live, so a Mid-Drive works better for me, since I can gear down on steep inclines and still stay in the good efficiency range of my motor. If your commute is mostly flat with <5% grades, a Direct Drive Hub may suit you just fine.

It is my opinion that all things being equal, the direct drive Hub motor is the most efficient motor design, and also the most durable design, as there are very few moving parts. (Mainly the axle bearings). A Mid Drive is much more complicated of a motor, with various reduction gears. It also puts more wear on your bike's drivetrain system.

Suspension is recommended. Front is good, Full Suspension is better, but complicated battery mounting. I have a hardtail with a large triangle space, that I find sufficient. Another popular option is to use a hardtail frame and add a seat-post suspension like the Thudbuster.

Aluminum frames are fine for Mid-drive systems, and OK for Hub Motors. However you will want to have at least one torque arm and possibly two for a hub motor. And I prefer the Rear Hub option as opposed to a front hub, for better traction, and less risk to bodily injury if the motor should break free of the drop-outs.

As far as batteries are concerned, LiFePO4 will have the longest lifespan and probably the cheapest cost per lifetime kWh. However, LiFePO4 batteries cannot deliver very high current (typically only about 1-2 "C") so they are best for lower-power systems (800W/20A and less) Pingbattery.com sells very good LiFePO4 batteries.

The next best battery would be based on the High-power 18650 Cells that are used in power tool batteries. em3ev.com is now selling batteries made with the Samsung 25R cells, which are very good.

If you have experience using RC Lithium Polymer batteries, they can provide a LOT of power, but are more prone to pyrotechnics, and not recommended for the newly initiated, or for those who will charge unattended or in apartment buildings.
Hobbyking is the place to get your RC LiPo.

Best advice I can give you is to read other forum member's build threads, including my own (see link in my signature) for inspiration and possibilities.

Good luck, Johnny_Z!

 

[Raged]

I have that kit you're looking at but run higher power (a bit over 2kw). I got the MAC 10T for hill climbing and acceleration and my speed tops out at a bit over 50km/h (about 30mph) no pedalling on a 29er MTB at 14S lipo (48-58V).

To do a 30mile commute one way with zero pedalling you're going to need between 15-20Ah of battery. Less if its flat road and you can pedal. More if it's hilly or a lot of stopping for traffic lights. Or you can go cheaper on the controller to reduce acceleration and save battery power(20A or 30A... I however run the 12 FET 40A controller). EM3EV's kit does come with a 3 speed switch to save power.... I just hard wired it on high (never know when you need the burst of speed and got rid of an extra cable). At over 30mph, even with the upgraded gearing (11 speed rear) I can't pedal as fast as the the motor is pushing me. I don't have a Cycle Analyst (really no where to mount it) and I don't need different programs or adjustability. The controller programming when it comes out of em3ev is pretty good for a commuter.

However...

If you're also a weekend dirt trail warrior, the weight balance is off for track work and changing from commuter tires/slicks to knobby tires is a pain in the ass. If I was to do it again, I'd get a BBS02 750w and fit it to a 29er with an adaptor to upgrade front chain ring to 52 or something stupid for higher top speed. Use the rear gearing for when you need anything slow. I also believe the BBS02 is more efficient as it can utilise gearing to cover all scenarios. The MAC10T like all hub motors is just brute force.

 

[wesnewell]

Do I really need front suspension?
Do I really need disc brakes?
Do I really need a steel frame?

1 No. Bigger tires will help.
2 Not at all.
3 No, but I highly recommend steel dropouts. Many aluminum frame bikes have steel swing arms and dropouts.
My suggestion for such a long commute would be a 250cc or higher motor scooter or motorcycle if you want to 2 wheel it. A 30 mile commute is jut too far imo for a street legal ebike. It will take about 3 hours a day both ways at legal ebike speeds.

 

[Johnny_Z]

You guys are awesome. Thanks for the motivation and tips, all the small details really help.

Time to go through some of the builds and pull what I need. TeslaNV and Raged and everyone thanks for the feedback. Off to sleep and dream of spinning electric wheels.

 

[Johnny_Z]

Do I really need front suspension?
Do I really need disc brakes?
Do I really need a steel frame?

1 No. Bigger tires will help.
2 Not at all.
3 No, but I highly recommend steel dropouts. Many aluminum frame bikes have steel swing arms and dropouts.
My suggestion for such a long commute would be a 250cc or higher motor scooter or motorcycle if you want to 2 wheel it. A 30 mile commute is jut too far imo for a street legal ebike. It will take about 3 hours a day both ways at legal ebike speeds.

I considered it, but still the cost of gas and the cost of insurance + random repairs breaks my early retirement piggy bank. I even have to pay for a parking space where I live. This is $5,000 down the sh##er I can be earning interest on every year. So far I have 6 months left on my lease, most definitely I'll be moving at least 10 miles closer to work then. Till then, got plenty of time to wrench a bike together. If my commute was anything like the place guy lives I'd move 10 miles FURTHER away from work though!
[youtube]
https://www.youtube.com/watch?v=MepI8cco9-c[/youtube]

 

[wesnewell]

If I just had to, I'd get a 7 spd beach cruiser for the big triangle space, and put a motor similar to one of these on it.
http://www.ebay.com/sch/i.html?_from=R40|R40&_sacat=0&_nkw=48v+1000w+rear&rt=nc&LH_PrefLoc=1
Total cost or everything needed would run about $1K. 15ah of 48V battery isn't going to be enough for 30 miles unless you ride at 20mph or less. And regardless of claims, you won't get anywhere close to 2000 cycles from most lifepo4 battery packs. Most end up under 1000. Some end up well under that.

 

[Eclectic]

Information about my commute:

I commute from the eastern San Gabriel Valley to north Orange County (similar to the 57 fwy)
It's ~16 miles each way. I have a 20Ah 44.4V battery and I charge at work. I am relatively efficient @ 21-22 Wh/m (kind of like MPG). I used ~350-375Wh (Watt hours kind of like gallons) each way. I have an 800W rear DD hub motor (slower windings because I have a lot of hills). My top speed on the flat is 21-22 mph (faster if I pedal). My average speed is ~16 mph. Clock time is ~50+ mins and time under power is ~46-47 mins. I have long stretches where I run WOT. I used a 25-30 y/o MTB that I got off CL.

Based on my commute stats, you would need about double what I use. I am very conservative with my battery because I feel that it will last longer and be safer that way. That means I would recommend 40Ah @ 44-48V. You might be able to get away with 30Ah and still not stress the battery and still leave some headroom for head winds and detours. If I remember correctly my current battery costs ~$80-100 and weighs ~5-6 lbs for every 5Ah.

This means that you would still have to charge at work. I have a 300W charger @work and @home. It takes me 2-3 hours to charge each way. You would need to somehow double that. More time or more charger.

What you are asking is tough. Probably 3.5-5 hours in the saddle a day. Another 3-8 hours charging. Your battery is going to be at least 30-40 lbs (or maybe a lot more) and somewhere north of $700 (could be a lot more). If I was young enough, it could be an interesting life style. It's doable but you would have to be real committed.

Edit: my average speed is 19+ mph not 16

 

[Modbikemax]

I used to commute those sort of distances on a motorbike when I was in my 20s. It gets old pretty quick. Especially when it's raining. I would have another talk to those move closer to work guys. ( yes I know you were joking).
Or maybe the catch a bus or train guys.
Save the cycling and ebiking for fun.

 

[Johnny_Z]

I used to commute those sort of distances on a motorbike when I was in my 20s. It gets old pretty quick. Especially when it's raining. I would have another talk to those move closer to work guys. ( yes I know you were joking).
Or maybe the catch a bus or train guys.
Save the cycling and ebiking for fun.

It's a good thing it rarely rains here in Southern California, though El Nino is looming, so something worth thinking about. Perhaps I'll consider taking the bus partways. It is quite a distance.

Based on my commute stats, you would need about double what I use. I am very conservative with my battery because I feel that it will last longer and be safer that way. That means I would recommend 40Ah @ 44-48V. You might be able to get away with 30Ah and still not stress the battery and still leave some headroom for head winds and detours. If I remember correctly my current battery costs ~$80-100 and weighs ~5-6 lbs for every 5Ah.

I would suggest you shoot for a 30-40 mile range, especially if you don't want to pedal.

For Non-pedaling efficiencies, A good rule of thumb is that you will need 30 watt-hours of battery per mile of range.

Speed will also greatly affect your range. As your speed increases linearly, the power required to propel you at higher speeds will increase exponentially. This is primarily due to wind resistance/aerodynamics. If you keep your average speed closer to 20 mph, you will have a much better efficiency than if you ride at 30 mph.

You could either choose a 36V system or 48V system.

It's a good thing I plan on only going 20-25 mph max, I see the efficiency takes a major dive after 20 mph in the wiki charts. Going by the rule of thumb of 30 watt hours per mile, I need about 900. If I have the formula correct of watt hours = volts * Ah, any combination of 48 volt/20 aH or 36 volt/30 Ah should work, correct? Is there any particular benefit of having more volts if I'm only planning on going 20-25 mph the whole way or less? I see they're selling 60 volt battery packs even. According to the ES wiki here, the higher the voltage, the higher the top speed, but since I'm only going 20 mph anyway could higher voltage translate into longer range?

As far as batteries are concerned, LiFePO4 will have the longest lifespan and probably the cheapest cost per lifetime kWh. However, LiFePO4 batteries cannot deliver very high current (typically only about 1-2 "C") so they are best for lower-power systems (800W/20A and less) Pingbattery.com sells very good LiFePO4 batteries.

I'm pretty fine with a lower power system. Perhaps I'll give Ping a ring and see what they have to say personally about my situation.

 

[Modbikemax]

It's funny how it rarely rains when you are in a car. But when you have to ride it never seems to stop.
If you are fit you can ride 60miles a day on a bicycle. I know guys who do. Even a basic hub motor on a well set up road bike will cut your times down considerably to maybe 1 1/2 to 2 hours each way but you are going to need a shower at work.
It will certainly get you in shape.
I regularly go the long way home, about 20 miles, takes me about an hour. But I don't have to go the long way which makes a difference.
I have a small hub motor set up for 20mph, 10s 8ah lipos on a light weight, 33 pounds, road bike set up, 700c x23 tyres with a single gear. You might want a few gears if it's hilly and maybe a bigger capacity battery.
I am reasonably fit at 52, so you should be able to romp it in.
I mention this option because it's cheaper than some of the other suggestions put forward but you will have to work for it.
If you are riding on the road you do not want suspension and fat tyres they just sap power which cost either sweat or money.

 

[Johnny_Z]

I suppose I could do the ride as I have ridden centuries in the past-might even do it for fun one day. Being that my job is extremely physical though, I honestly don't need the exercise. To get the idea-I've lost 35 lbs in 4.5 months, and I wasn't overweight before! Your setup has me intrigued however, I just might forgo the MTB route and outfit my roadbike, which seems perfect for the situation. Gives me one less thing to agonize over and shell out for anyway.

 

[Johnny_Z]

Checking out BMS's site, their prices seem relatively reasonable and they seem to be a one stop shop (to get started anyway).

Of interest to me:

Motor (Magic Pie $278): http://www.bmsbattery.com/hub-motor/429-magicpie3-third-generation-ebike-hub-motor.html
Battery (36 V 20 Ah $404): http://www.bmsbattery.com/packs/158-36v-20ah-38120-lifepo4-battery-24-cells-ebike-battery-pack.html

I must say, the simple appearance is what attracts me the most here, it doesn't look like a giant pain in the ass to put together. I'm hoping that's the case at least lol!

As for the charger, I notice this has what is called "Active PFC." Is this important enough to pick over any of the other chargers? I'd simply like for my charger to shut off on it's own, are these things "smart" enough to do that? If anything, I'm willing to just pick a charger that will allow me to charge in a certain time frame where I know I can unplug the thing at 90% charged (like 4 hours into my shift when I get lunch or something).

As it looks, the basic kit components come out to about $700 with charger. Is there anything else I should be considering here? Extras and such? Reading a fellow's thread on his wheel being stuck makes me want to get torque arms, I'm wondering what other pitfalls I might need to avoid.

Oh, and I forgot to mention-my bike! I've got a Giant OCR 2 ready to strap this rocket power on to-any opinions regarding the bike would be appreciated.

 

[Johnny_Z]

Shoot, reading this article has me rethinking the Magic Pie. Apparently the DD motors have drag when pedaling sans motor, and are inferior hill climbers to the geared brethren. With a 20-30 mile commute there are a fair number of bridges and overpasses with significant grade, perhaps a MAC build it is.

 

[wesnewell]

The trick to avoid DD drag is to set motor speed and then pedal past that speed up to the no load speed where the motor uses little to no energy. If you pedal hard enough, you can recharge the battery while doing this. If you use regen braking, it will also recharge battery , save your brake pads, and give you much better stopping power.

 

[Eclectic]

It's a good thing I plan on only going 20-25 mph max, I see the efficiency takes a major dive after 20 mph in the wiki charts. Going by the rule of thumb of 30 watt hours per mile, I need about 900. If I have the formula correct of watt hours = volts * Ah, any combination of 48 volt/20 aH or 36 volt/30 Ah should work, correct?

If you were going to use 100% of your battery but I like to use less than 50% because I think it will be more dependable and last longer.

 

[Johnny_Z]

It's a good thing I plan on only going 20-25 mph max, I see the efficiency takes a major dive after 20 mph in the wiki charts. Going by the rule of thumb of 30 watt hours per mile, I need about 900. If I have the formula correct of watt hours = volts * Ah, any combination of 48 volt/20 aH or 36 volt/30 Ah should work, correct?

If you were going to use 100% of your battery but I like to use less than 50% because I think it will be more dependable and last longer.

Would you recommend higher amp hours then, or is there another option? The highest Ah battery I'm seeing anywhere is 30 Ah at Ping, perhaps there's another source. Would a 48 V 30 Ah battery last longer? I know V is for power/speed and not range, but it is part of the formula and will raise my watt hours.

 

[teslanv]

Yes, in theory, a 48V battery will have 33% more total watt-hours and range than a 36V battery of the same capacity.

It will also allow you to go faster. However, faster speeds will usually minimize the gains by a higher volt battery, unless you limit the amperage (and thus speed) through programming of the controller or a Cycle Analyst.

The alternative is to buy (2) 36V-20Ah batteries and connect them in parallel for a total of 36V & 40Ah.

 

[wesnewell]

And you can do the same thing with that thing you call a brain between your ears. And if you want to go faster, you won't have to reprogram your controller or CA.