Ebike information overload

I sorta "accidentally" built what in my opinion may be the one of the simpler, economical yet practical ebike examples & I generally recommend something similar to those whom aren't looking for motorcycle preformance, but aren't interested in pedaling the Tour de France either... I really am quite surprisingly satisfied with a no more a fancy complexity then a 48v 1000w hub motor w/a 15Ah LiFePO4 battery pack, which I like to refer to as a 30/30 as it's good for about 30 miles @ just about 30 mph worst case - that is no attempt to conserve reserve or undue pedal assist.

Not to say I'm against pedaling, I jus' think it's a bit of a cheat when they include such in in an advertisement's "estimated range" lol, nor am I against geared drives generally speaking, it's jus' with these "low power" ebikes the difference is marginal at best when compared to the added complexity, maintenance & cost of a mid-drive with it's primary benefit being slightly better weight & balance, it's secondary being able to use both the original wheels. While I gear all my gasbikes, the ease & simplicity of an electric hub motor is jus' too attractive to bother mussin' it up with any added redrives, chains & sprockets for such marginal differences. If there's anythin' I'd "upgrade" it'd be a larger battery reserve, which defo gives more a return for the investment I figure.

To each their own though, we all like different stuff for different reasons ofc - but if you're looking for a basic build to get ya 'round reliably without breaking the bank it's kinda tough to beat the 48v hub & LiFePO4 combo, which should be no more then about a grand, less with some huntin' around. I've beaten mine mercilessly for years now with the only maintenance (other'n crash damage lol) being the normal wear items, the bike's tires, the chain & cable lube routine


http://motorbicycling.com/showthread.php?t=38908&page=19

tell me about it

With electrics I'd put the majority of the pennies into the batteries without a doubt. The motors simple & mostly inexpensive - the investment & satisfaction really does seem to be range/reserve, which is ofc all about getting the most amp hours that can be afforded in battery packs.

Look at Craigslist from time to time. Buying a complete and working used ebike is the cheapest way to own one.

I wanted a bike that could be used on hills as well as flats and pedal OK if the battery is exhausted. A mountain bike met this requirement. Low enough gearing is especially important on a direct drive hub bike, because of the drag of a hub motor. But, the gearing also has to be high enough for effective pedal power when using the electric motor. Because a gear drive hub can freewheel it is an attractive option, but is limited in power output.

Power: based on recharge times, I'm using 200 to 300 watts for most rides. Motor is an Aotema direct drive, front hub motor. Note...a direct drive will require some electrical power all the time, except descending, because it can't freewheel. A gear drive hub motor will require electrical power less of the time and so you will use less average watts. My ebike speed is in the 12 to 16 mph range, using a gas bike my speed is more in the 15 to 19 mph area.

The Aotema front hub weighs about 15 lb, the battery pack is SLA, 36V, 12ah, it weighs a bit over 25 lb. You definitely feel the mass of the front hub when riding, not so much the mass of the batteries that are mounted atop a rear rack.

Range, first ride was 13.2 miles, the battery indicator on the thumb throttle still showed green. Recharge time was 4.75 hrs, using a 1.6 amp charger. Average amps was 6.1, average watts was 221, 7.6 ah was used, about 63% of the battery capacity and calculated range using all 12ah is 20 miles. Because the batteries are new SLA and I want them to last, 13 miles is a good maximum range. So, the ability to pedal home easily is important.

Hobby King sells Lipo batteries, I use them for RC planes, helicopters, quad copters, cars and boats. For $145 I can get three batteries, each will be 3S, 11.4 v, 8.0 ah capacity. Weight for this battery pack will be only 5 lb, compared to 25 lb for the SLAs.

Because only about 8 ah is usable in a 12 ah SLA pack, and all 8 ah are usable with the Lipos, range should not be any worse for the Lipos.

Battery power output: SLA batteries are made for low power output, Lipos are made for high power output, there is less chance of harming Lipos than SLAs during an ebike ride. Both SLAs and Lipos are harmed if you discharge them to too low a voltage, Lipos are more sensitive to this than SLAs.

Hope this helps. Ask questions and look on Craigslist.

PS, my gas bike uses a Subaru/Robin on a Straton friction drive.

BarelyAWake said:

I sorta "accidentally" built what in my opinion may be the one of the simpler, economical yet practical ebike examples & I generally recommend something similar to those whom aren't looking for motorcycle preformance, but aren't interested in pedaling the Tour de France either... I really am quite surprisingly satisfied with a no more a fancy complexity then a 48v 1000w hub motor w/a 15Ah LiFePO4 battery pack, which I like to refer to as a 30/30 as it's good for about 30 miles @ just about 30 mph worst case - that is no attempt to conserve reserve or undue pedal assist.

Not to say I'm against pedaling, I jus' think it's a bit of a cheat when they include such in in an advertisement's "estimated range" lol, nor am I against geared drives generally speaking, it's jus' with these "low power" ebikes the difference is marginal at best when compared to the added complexity, maintenance & cost of a mid-drive with it's primary benefit being slightly better weight & balance, it's secondary being able to use both the original wheels. While I gear all my gasbikes, the ease & simplicity of an electric hub motor is jus' too attractive to bother mussin' it up with any added redrives, chains & sprockets for such marginal differences. If there's anythin' I'd "upgrade" it'd be a larger battery reserve, which defo gives more a return for the investment I figure.

To each their own though, we all like different stuff for different reasons ofc - but if you're looking for a basic build to get ya 'round reliably without breaking the bank it's kinda tough to beat the 48v hub & LiFePO4 combo, which should be no more then about a grand, less with some huntin' around. I've beaten mine mercilessly for years now with the only maintenance (other'n crash damage lol) being the normal wear items, the bike's tires, the chain & cable lube routine


http://motorbicycling.com/showthread.php?t=38908&page=19

Click to expand...

Edit: Seen the link to your build, awesome bike!

I have been researching electric bikes now for a few weeks since I had to get rid of my gas bike due to state laws.

I want something that will get me around town, no hills, just the occasional bridge. I like the 1000W rear wheel setup. I have SLA batteries, four 12v that I purchased for an ezip I got off craigslist, but the bike is too far gone to put any money into. I would like to get a system that will run the SLA batteries until I have saved enough for a LiFePO4 setup.

Im ready to pull the trigger on the right kit, just overwhelmed with all the ones that are available.

If you are familiar with or care to learn safe handling of Lipos, then they will make a good lightweight battery with excellent power density, that's fairly cheap. 3S packs would work very well and are about the cheapest for ebike use due to the fact that they are the most commonly used. If you doubled up on the 8ah packs it would still be a compact light weight battery with 16ah!

Jus' two lil things I thought I'd mention - first, the battery investment is by far the most important... I'd suggest getting the best battery pack that can be gotten as insofar as I've seen, insufficient and/or SLA batteries are the number one cause for electric vehicle disapointment.

The second is a touch more complicated, some are not aware that "lipos" & "LiFePO4" while both lithium based, are not the same. The typical "lipo" is a lower cost lithium with a higher energy density but less charge cycles that can be thermally unstable whereas LiFePO4 has slightly less energy density & costs more - it's also stable with twice the charge cycles.

"Lipos" can be a great deal... or they can go up in a puff of smoke & flame. As I wanted dependable longevity w/o any fuss n'muss, I went LiFePO4 & now years later, I'm so very glad I did

Li-Ion chemistries are also included, these are or were in just about every portable electronic device. You all have heard me go on about my experiences with Lipos in the R/C world, so I wont do it here again.

If these batteries were as volatile as every one makes out then there would be fires all over the country as this chemistry is in the of the proliferation of small R/C toys unleashed on the rather Lipo ignorant public. I have seen pics and vids of Lipo fires right down to the burned UPS jet that was carrying 300,000 batteries(that was a crazy move!).
I take seriously the handling of this type and have not had an incident in the 11yrs of use. So from my perspective the advantages of power to weight, and cost out weigh the hazards. I try to offer actual experiences on topics rather than opinions.
We each choose how we do things, and here on the forum its a great tool for learning. All of our collaborative thoughts come together here to create quite a base of knowledge. This is a blessing for the readers/members/builders as its much nicer/easier to build on the base of all this experience. I believe almost any question that arises in the hobby can be answered here and that's a very fine thing!

yarp - no argument here man, I was jus' makin' broad generalizations for the perhaps uninitiated is all

I know you were. I was basically posting my experiences were good, doesnt mean it would be the same for everyone. And you are right its probably best for most to go the route of safety with LiFePo4 rather than have to learn the Lipos quirks.