Ebike build - need advice/information

[jpullen88]

Hello,

A while back I looked briefly into building an ebike and now I am back at it again as I have a source of income =). I guess I should tell you so far what I have gathered through my own reading/research.

I am looking at the 2806 rear hub kit from ebikes.ca. I am not 100% as to what all I will need for that but here is what I think.

2806 rear hub
8 speed freewheel - can I get by with what the bike originally has? I was thinking no due to spacing problems
caliper alhonga - same as the freewheel?
203mm disk rotor - same as above and I have never had a disk brake bike. Is a larger rotor akin to better stopping?
cycle analyst large screen upgrade
40a controller upgrade - It seems I may as well since the CA can limit the amps to 20 or 25, for example.

That is right around $600 and sounds like I have everything (except for a bike/battery). Would I also want to get their wuxing ebrake levers? What benefit do those have over the standard levers?

Onto the bike itself, I have heard that I definitely want to get a steel framed bike with disc brakes. I think I would also like to go with a full suspension as the roads around town are quite old/cracked. I have looked at walmart and a few bike shops online (nashbar, REI, bikesdirect) and found mostly alu frames. Does anybody recommend a place or brand of bike?

The battery. Oh the batteries... This is what really turned me off about this last time just due to the fact as to how expensive they are up front or heavy if you go a cheaper route. I really would rather shell out the cash for some LiFePO4's than SLA. I know how to build battery packs but have never used this type of chemistry before. I have a 4s 4a balancing charger (CellPro Multi4) and I know how to attach their doo-hickey to the packs so it balances the cells during charging. I am quite confident that this is practical and feasible but I would like some input. I plan to run a 38.4v20ah system and will probably upgrade to a 48v/40ah system as I get another $600 for batteries =/.

First of all, is it bad to mix newer and less new batteries? I was thinking no until you get to the end of their life. Second, I read about how different batches can have different IR and this can cause some cells to charge/discharge unevenly - would I be ok without using a cell balancer for discharge since I will be balancing them with each charge? Or should I just go ahead and put a BMS on the cells to avoid over-discharge (I'm not concerned about over-charge as the Multi4 has been a great charger so far for me)? Lastly, my charger only does a 4s charge so I was thinking I could have the batteries hooked up with a switch so I could swap between 38.4v20ah (to motor) and 12.8v60ah (to charger). That way I could use my Multi4 to charge at 4a (15hr) super slow charge. Is that ok to do or is it perhaps charging too slowly? My gut tells me it would be fine, and might even be beneficial for the batteries than say charging at 2c or 5c. Again, as funds accumulate I am planning on upgrading to a cellpro 8s which can charge LiFePO4 at 8s up to 40a. Do the same thing with a switch like before and charge at a maximum of 1c. Again, how does that sound?

The forerunner for me currently is the 12.8v20ah TS pack for $120 without the BMS at Elite Power Solutions. These are about $0.47 per watt and are the cheapest I have seen. I also like the 1 year warranty and the fact that they are in the USA, which are the major benefits over a Ping. I saw a few posts about them which were somewhat mixed in terms of good/bad. If I only plan on discharging at a maximum of 1c; are these batteries going to work well and last a long time? Anybody know any better deals?

Lastly I think is what everyone really wonders yet nobody really knows until they build it. The guesstimates of top speed and range, so please bare with me. I would like to be able to ride the 55-60 miles to my parents house. It's mostly flat but has some hills. If I ran a 51.2v40ah I would have ~2000 watt-hours. I have searched and it seems to be that some people can get as good as 10 watts per mile to as low as 40, 50, or worse watts per mile. I just picked 25 watts per mile and that puts me at about 80 miles on a 51.2v40ah pack with straight math. Do you think that amount would get me there? I weigh ~150 lbs if that helps =P. I'll probably start out with a smaller pack (38.4v20ah) and how far could I go with that? I was thinking somewhere between 15 and 30 miles realistically.

Any and all comments are greatly appreciated. It is a lot to process and also a good deal of money to do it right.

 

[yopappamon]

My first build was a 9c dd hub with 36v 20ah thundersky batteries from EPS. My max range before the BMS cut me off was 35 miles with very little pedaling. That's plenty of weight to carry. Double that to 40ah would require some special planning and storage for that much battery. You might consider going lipo from hobby king. It would be a lot easier to carry and the swarm sale pricing from the US warehouse is decent.

Last I looked the 20 ah TS cells weren't available from EPS. They refer you to the GBS cells.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16207

$42.66 on swarm sale, free shipping in the US.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=25037

44.4v 20ah would be around $340. (8 x $42.66) a little cheaper than the thunderskys

 

[MadRhino]

A 60 miles ride needs alot of battery. You must not count their full capacity, you can't discharge them flat or you'd kill them. If you want that kind of range, think first of an efficient and low power setup, then buy enough Ah of battery for a range of 80 miles.

The faster and more powerfull will be your bike, the more power hungry it will be. Long range and power altogether makes for a heavy bike. The grade of the hills that you'll have to climb is important too, for they burn alot of energy.

 

[jpullen88]

Oh yes you are correct, what is the difference between the two?

 

[yopappamon]

Oh yes you are correct, what is the difference between the two?

Between the TS and GBS? I don't know, the specs look very similar

 

[dogman dan]

Wrong motor for that kind of range. Won't happen at the speed of a 2806 at full throttle since 30 mph is a lot more like 55 wh/mile. When I need hyperrange, the best motor for me is my 2810 (6x10). It's top speed is 20 mph on 48v, so then I can get about 35 miles from a 48v 15 ah pingbattery. You could make the range on a 2807 motor running 36v too. At 23 mph, you'd get about 27 miles out of a 36v 20 ah battery, and could ride slower for enough of the ride to squeese 60 miles out of 36v 40 ah.

In affordable bikes, look at wallmart online. Online you should be able to get a Mongoose Blackcomb. It has steel rear dropouts and FS. Other wallmart FS bikes that are even cheaper also will have steel in the rear of the frame.

Carryig that much battery on a FS bike is another whole can of worms. Bracing up a seatpost rack on a blackcomb is pretty easy to do to carry the first 15 pounds of battery. The second battery would have to be strapped to the frame, or carried in a backpack. Assuming most of your riding would be shorter distances, I suggest a 36v 15 ah ping on the rear rack. Then use lipo for the range extending second battery. 36v 10 ah packs could be rotated into the rear rack, and the rest carried in a backpack or even a handlebar bag.