9 miles, 320 lb guy, 20 mph, flat, winter

[keninct]

I have read quite a bit here, but I think I still need advice. A few years ago I rode my bike (aluminum hybrid mtn bike, 26", not disc) to work and back all winter here in Connecticut, USA and enjoyed it. I'd like to do it again this year, but without pedaling.

As mentioned I have about 9 miles round trip, am a big guy at 320 lbs., and the terrain is fairly flat. I could pedal about 12 mph, so I was thinking 20 mph would be plenty fast for an ebike for these roads. I tried a calculator and it appeared that 36V/500W/10Ah rear hub kit would just about get the job done.

The problem is I can't seem to get the cost down to a point I can justify to myself for what is, essentially, a lark. I think if I could get the whole deal below $400 I would definitely go for it. But the battery alone seems to be over $300, and I have read all of the warnings about going after cheap stuff.

So I just thought I'd ask you all...does anyone think he or she has the perfect idea for my situation? Unfortunately, I'm not much of an electrical DIY-er...I mean, I'm sure I can install whatever we come up with, but I'm not going to be spot welding nickel strips to weed wacker batteries, or whatever it is you mad geniuses get up to on the weekend.

Also, I'd very much welcome advice on how important it is to weather/slush/salt proof these setups. My main goal would just be to get through one winter, until it is time to put the motorcycle back on the road.

Thanks in advance for any help!

 

[999zip999]

Luna cycle has good batteries and is in Cali. I don't have much rain so hard to recommend a good waterproof kit to go with it. But there are many good kits out there. Battery is the Most important part.

 

[gogo]

No trips other than work? Can you charge at work?

 

[999zip999]

I like around 15ah of battery. Less stress on cells. Don't run battery to it's limits as you don't drive your car with the peddle on th floor. But a lot of people run that ebike wot.

 

[keninct]

No trips other than work? Can you charge at work?

Thanks for asking. No trips planned other than work. We aren't really supposed to plug stuff in, but I suppose I could charge at my desk if the power draw wasn't too great (like a couple hundred watts probably okay) and if there was pretty much zero risk of smoke/fire/anything else bad.

 

[wesnewell]

https://endless-sphere.com/forums/viewtopic.php?f=3&t=66302
Get this bike.
https://www.walmart.com/ip/26-Huffy-Men-s-Fortress-Mountain-Bike-Blue/49058108
One of these motor kits.
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=48v1000w%20rear&LH_PrefLoc=1&rt=nc&LH_FS=1
And 2 of these or something similar.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=59056
That'll get you ~10 miles at 20 mph and a top speed of ~28 mph, with less range.
You'll need a cheap 6s rc charger too. But that's within your $400 budget.

 

[keninct]

Get this

This is the kind of response I was especially hoping for, thanks! I already have the bike, so that's all set. I was a little afraid of the LiPo fire risks but I guess I could just charge it in a safe corner of the garage. Can one leave them overnight on the charger unattended (but away from flammables)?

A couple more questions: would I be using the two packs in series to make 48-ish volts? If so, doesn't that mean we still have just 5 A-h? Others are suggesting that even 10A-h might not be enough...

Thanks again

 

[2old]

+1 on motor choice. You'll need a torque arm (maybe two with the aluminum frame.

 

[gogo]

You might be able to utilize power tool batteries for a 4.5 mile ride/recharge, and they'd be easier to present to your employer as safe. If you'd use them with the power tools as well, I'd think its a no-brainer.

 

[keninct]

You might be able to utilize power tool batteries

Interesting idea, thanks. Since it appears to be affordable, I'm leaning toward the suggested LiPo idea, and getting enough for the full round trip.

@wesnewell recommended two "Turnigy 5000mAh 6S 20C Lipo Packs", which are listed at 22.2V. They are currently backordered and I'm trying to consider alternatives. Is it obvious to anyone whether he was proposing I use those in parallel or in series? He recommended a 48V motor, so I was guessing he meant in series, but I'm really not sure.

 

[wesnewell]

This is the kind of response I was especially hoping for, thanks! I already have the bike, so that's all set. I was a little afraid of the LiPo fire risks but I guess I could just charge it in a safe corner of the garage. Can one leave them overnight on the charger unattended (but away from flammables)?

A couple more questions: would I be using the two packs in series to make 48-ish volts? If so, doesn't that mean we still have just 5 A-h? Others are suggesting that even 10A-h might not be enough...

Thanks again

Yes, 2 6s packs in series or 3 4s packs in series or whatever to get to 12s. Yep, 5ah is plenty for a 9 mile RT if you keep the speed down to 20 mph on fairly flat surfaces. That's 222wh, and at 20 mph you will use no more than 22wh per mile under normal conditions. If you go into a strong headwind, just slow down a little. As for charging, i do it in my computer room on a wooden table, but am almost never asleep. In over 5 years I've never had a problem. But I've never left them charging overnight. To do that, I'd do it somewhere with a fireproof surface and nothing within 6' pf them just to be safe. Maybe charge them in something flame proof like the fireplace. Info on wiring;
https://endless-sphere.com/forums/viewtopic.php?f=14&t=39666

 

[gogo]

Series. The motor needs full voltage to achieve top speed. The controller can only reduce the voltage to the motor, and it has a LVC (low voltage cutout) function that protects the battery from over-discharge. For a 48V controller the LVC will be somewhere around 40V, so 22V of LiPo would prevent the controller from sending power to the motor.

 

[motomech]

I use Lipo. Search my posts w/ the search word "Lipo" for lot's of Lipo/info.
(Hey I'm a poet and don't know it

 

[keninct]

Thanks so much guys, this was really helpful. I'm pretty sure this project is now a go.

 

[dogman dan]

10 ah plenty for 9 miles round trip, hauling ass.

 

[keninct]

Don't charge LiPo within 5 feet of employer's dog. Got it.

Seriously, thank you for the warning.

So my question would be, if I were to leave unattended, outside, what radius of safety would I need. My garage has a concrete porch slab adjacent (open on 3 sides) with a roof and 120v plug. It extends about 6 feet away from the garage. If I charged overnight out there there do you think I'd put the garage or roof (10 feet above ground) at risk? How about if I got one of those fireproof bags they advertise?

 

[Jon NCal]

What some RC guys do is make a rectangle of cement blocks and then a cement board top. The charger is outside it and battery inside. Also a smoke alarm for it. One thing to keep in mind is that not good to charge the lithium battery at cold temps. The bags are only meant for small lipos.

https://www.youtube.com/watch?v=gobFcNzGG9I

 

[mailseth]

You're gonna have problems charging/using a battery in freezing weather. I don't think you'll have the unscheduled fire sort of problems, but you'll severely harm the life of the battery charging/using it while cold.

 

[Jon NCal]

How about a small heating pad?

 

[WoodlandHills]

You're also gonna need some warmer clothes, now that you arent pedaling and are going 20mph instead of 12......... A set of zip-up coveralls or a snowmobile suit would be convenient. A pair of plastic pull-over boots will keep your feet from freezing on those zero degree mornings and will keep your feet dry during the slush season!

 

[wesnewell]

Charge it in the bathtub or shower. Without water of course. Remove plastic shower curtain. Turn on vent fan. When you get tired of doing this in a few months, take the same precautions as you do charging your cellphone. That's what I'd do if I owned a cellphone. Unless you sleep on the job, I'd charge them on my desk. Have a metal trash can close that you can put a fireproof cover on quickly just in case. Personally I don't worry about any of this stuff when charging and lately all I've done is bulk charging of my lipo packs. I do check them every hour or so just to see if any or getting hot. None have in over 5 years.

 

[Jon NCal]

I charge mine outside in a metal ammo can. Not cold in California, though.

I do a 15 mi. commute with 2000 ft. elevation gain, 19-20mph avg speed and use about 6-7ah on a 44v lipos (2 6S 16,000mah multistars), about 20wh/mi.

 

[t_tberg]

No one seemed to address the salt/waterproofing portion of the question.. My 2 cents is to keep the controller oriented with the wires down (so any water that gets in can drip out) and make a drip loop on the wires entering the hub. If you ride through slush or a wet and salty road be sure to lightly spray down the bike with water and wipe it dry when you get home. If you do get one of those cheap ebay kits (I highly recommend for the price) then by the end of your first winter you'll probably see some corrosion on the nipples. After a winter of abuse I suggest relacing the hub into a quality wide-ish rim and quality spokes, that way you can fit a wider tire on it (wesnewell suggested a bike with 3inch tires). As far as putting it together for under 400 it *might* be possible to build assuming you have all the necessary tools. If you want a clean build youll probably have to do some soldering which involves buying heatshink tubing, solder, quality connectors, ect if you don't own these items. Spirally wire wraps are common, zip ties are almost necessary. You'll need tape for the rim, a new tire eventually, lube for the chain, brake pads... You can do without some of these things if you're okay with a wirey mess strapped to a bike. My point is that there are a lot of little costs associated with owning an e bike, and it adds up quick.

 

[keninct]

Thanks for all the further advice. Won't it be a surprise the first time I stumble into the shower half-asleep and forget there is 420 W-h waiting to jump through my toes!

you'll severely harm the life of the battery charging/using it while cold.

So, I feel like this renders the whole project moot. Im not going to bring the pack into the office, so it has to sit in the cold all day. I don't think I'm willing to eat the cost, but would LiFePO4 be pretty much 100 percent safe in the office?

 

[gogo]

Did I mention the warranty on portable tool batteries and their chargers?