Electric Bike Conversion Questions--Custome built Bike

[Walkingant]

Hi,
I have a hand built/welded three wheel fat tire bicycle. It was four wheels, but I cut the front two off, welded one onto the front center and made it a three wheeler to be legal in Nevada.
(A four wheel electric bike requires a license--a three wheel bike under 750watts does not). The Picture below is when it was a four-wheeler--now a three wheel bike.

I plan on purchasing front hub electric motor kit on ebay or similar. 36V (using three deep cycle car type batteries) The tires are 4 x 26

The single speed set up, did make it hard to start moving, but peddled ok on the flat--this year the wife wants to ride and not peddle so much!

*The bike is heavy, weight not known. but it will have to carry about 500lbs with the two of us and refreshments
* This bike will only have to move at 5-7 mph
* Maximum distance on battery charge wanted.

Questions:

Will a 36V 500W front hub electric motor pull the bike?
Only having to go 5-7 mph max, what is the best option for batteries? (cost being the major consideration--second is long lasting power)
We will be using batteries, possible the same that power the bike to light up LEDS on the bike for night.
From what you can see from our needs and picture of the bike, are they any other considerations/concerns?

If there are any specifics I did not include, please ask. Any pointers or advice would be greatly appreciated!

**Yes, I read the how to ask forum posting, but it really doesn't directly correspond to this project**
"IF this is in the wrong category, I do apologize in advance"

 

[wesnewell]

For those speeds, run a 4s 14.8V rc lipo pack. Top speed ~7-10 mph depending on the motor you get.

 

[dogman dan]

Just about any direct drive, rear hub motor kit will work. Since it's a fat tire bike, your front fork will be the same width as normal rear wheels. The rear motor then gets used on the single front wheel.

For battery, around here lead is dead, but on the playa, the weight of lead might not be so bad, vs the cost of lithium. I'd say 20 ah wheelchair cells would do, then get somebodies generator to charge them again overnight.

maybe next year, some solar panels could make shade, and power. Getting late to build that for this year though.

 

[Walkingant]

Yes a 500 watt motor would pull that bike 5-7 mph.

Several of options for batteries. You could go high quality made in USA AllCell like I use, or low quality/cheap battery from China. What are you looking to spend on a battery?

Would like battery with longest run time for our speeds--no more then $300.

Just about any direct drive, rear hub motor kit will work. Since it's a fat tire bike, your front fork will be the same width as normal rear wheels. The rear motor then gets used on the single front wheel.

For battery, around here lead is dead, but on the playa, the weight of lead might not be so bad, vs the cost of lithium. I'd say 20 ah wheelchair cells would do, then get somebodies generator to charge them again overnight.

maybe next year, some solar panels could make shade, and power. Getting late to build that for this year though.

How long would the 20 ah last as compared to a deep cycle lead battery? I understand the weight difference--but as you said it shouldn't be too much of a problem on the playa. We work with DMV so can plug it in to charge there or we do have our MH generator to recharge.

Thank You all for your replies--

 

[wesnewell]

Find some 4s rc lipo packs on sale and for $300 you can get 100ah. You'll get at least 50% more range than the same lead capacity. and 100ah will be no larger or heavier than 2 car size lead batteries. 100ah of lipo will weigh under 20 lbs.

 

[Walkingant]

Find some 4s rc lipo packs on sale and for $300 you can get 100ah. You'll get at least 50% more range than the same lead capacity. and 100ah will be no larger or heavier than 2 car size lead batteries. 100ah of lipo will weigh under 20 lbs.

So wiring 4s rc 14.8 volt rc lipo packs together in parallel to run a 36volt 500W motor at 14.8 volts will run the bike at 5-7 mph, and have a longer range (50%) then deep cycle lead batteries while weighing less? Correct me if I am off ...thanks

 

[wesnewell]

You can run a 500w motor with it, but not with a 36V controller unless you lower the LVC of the controller. I'd suggest an lvc of ~14V for 4s lipo. That will let you use about 95% of total capacity. You'll probably need to order the controller with the lvc set to your specs, as it's not a common ebike voltage.

 

[Walkingant]

this option of changing the controller to 'fit" the 14.8v seems complicated for a novice like me, where to order, exactly what is needed (specs) --and an increase in cost to order a custom controller.

how about using 3 (three) 12V 35AH Sealed Lead Acid (SLA) Batteries. no change of controller. Weight of 24 pounds each

At 6 mph, 36v 500w, will we get decent "mileage"?? Yes, this would be perhaps 3 times as heavy as the 4s 14.8V rc lipo pack(s).

options?

this is the kit I am considering ordering--

http://www.ebay.com/itm/36V-Front-F...hash=item542429541f:m:ma_Kkn-D6ljCLWKmH6udZzQ

I know its not high end, but it only needs to last few weeks on the playa--and only move us at 5-7 mph. Or a rear wheel conversion as recommended.


thanks for previous comments and any forthcoming.

 

[wesnewell]

Assuming you already have wide rims for your tires, i'd buy one of these. then lace the motor into one of your rims. The standard rear motor is 220mm wide and will fit nicely into a fat tire front fork. I'd then run it with 8s rc lipo, on the standard controller, which will have an lvc of 29-31V Or with the money you'll save just buy a 24V controller with custom lvc of 14V for about $30 and run it on 4s lipo, No way would I use 72 lbs of lead when 11 lbs of 4s lipo (60ah) would work better and give you more range taking up only 1/3 the space or less.
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=36v%20500w%20rear&rt=nc&LH_PrefLoc=1&_trksid=p2045573.m1684
Controllers with custom LVC can be bought here.
http://www.aliexpress.com/store/313864
For some reason this is getting redirected to fr.aliexpress.com/store/313864, but sill the same place.

 

[Drunkskunk]

Welcome to the forum. Strangely, I can't see your pictures. My home and work firewalls are both blocking them. Sounds awesome, though.

For what you want to do, some deep cycle lead acid batteries will work fine. normally, they are a bad choice for an ebike, but for this setup, the weight is the only real drawback.
That motor kit won't work out, however. It's set up for 35mph, which means it will be lugging at 6mph. That's going to cause it to heat up fast, and with the added weight of a passenger and some heavy batteries, it won't survive long.
A slower hub motor would work out much better. but you might also consider a chain driven motor system.

 

[wesnewell]

Would definitely be better off with a bigger slower motor, but on level ground and 1000 lbs, the simulator doesn't show it overheating on 15V or 30V. For use on flat desert shouldn't be a problem. Something like an H3525 or MXUS 6T would be a lot better though.

 

[Walkingant]

thanks for the advice!

now i am undecided how to move forward. just know the wife wants an electric powered bike,
and i am rapidly running out of time, leave here the 23rd of August...about 5 weeks.

the other motors would be a consideration, but they cost more.

(pondering)

 

[dogman dan]

You won't be doing long runs at the burn. Just order up a rear motor kit from ebay, or amazon as quick as you can.

Yes, it will not be running at max efficiency at 5 mph, but with no hills, the load will be tolerable. To go 5 mph, you won't be feeding it full throttle, and the motor will not heat up that much. You'll be stopping at camps for a visit constantly anyway, letting the motor cool.

The ideal ( lower rpm) rear motor kit for your bike is out of stock right now, where I work. So just order a direct drive motor anywhere. 36v all you need.

Times a wastin, so get that thing shipped now. In general, Amazon ships fastest. Look for a vendor geographically close to you.

Something like this. https://www.amazon.com/MegaBrand-Electric-Bicycle-Engine-Conversion/dp/B011PZ9OFK/ref=sr_1_4?ie=UTF8&qid=1468667338&sr=8-4&keywords=36v+bike+motor+kit

 

[Drunkskunk]

Agreed. for the short time you have to prepare, the short amount of time you'll be using it, and as flat as that area is, that motor will be fine-ish.
However, it's going to die in long term use. the answer to that problem is fairly easy, though.
Once you're done with the trip. remove the wheel and spokes from the motor, bolt a sprocket onto the disk brake mount, set up gearing for somewhere between 3:1 to 6:1, and power the back wheels by chain reduction from the motor.

 

[Walkingant]

..
I found a 36v front hub kit here:
http://www.ebay.com/itm/36V-Front-F...hash=item542429541f:m:ma_Kkn-D6ljCLWKmH6udZzQ

Could not readily find a 36v rear kit--that wasn't from china. (long delivery)

Is there significant difference from rear wheel and front wheel application? I am going to place batteries just behind the front wheel.

Thanks for all the responses!

Below is what the bike looks like with 3 wheels...work to do yet.

 

[SlowCo]

Maybe get 2 of these motors (one per rear wheel) and gear them down enough to the rear wheels to get the desired max speed:
http://www.aliexpress.com/item/24V3..._4&btsid=d90f8aca-3a15-485b-bc6d-3b42aef35954

 

[Walkingant]

ok,
ordered the 36v front hub motor, suppose to be here in a couple days

Would this battery work? 36V 20ah -- http://www.ebay.com/itm/36V-20AH-Li...ic-Bicycle-Rechargeable-Battery-/331918148768
only 6.5kg or 14.33lbs.

Or this: http://www.ebay.com/itm/Lifepo4-Lit...222217?hash=item4195825a49:g:BAMAAOSwPhdVQE~5
at 24lbs..

I found a SLA battery, at 35ah, but would weight 75lbs for 3 to make 36v

Thanks--

 

[Walkingant]

Hi,

Ok, installed the 36V fat tire front hub motor--

Functions
High power brushless front hub motor that allows up to 35 MPH top speed for 26" rim.
Full Completely conversion kit included:
o Brushless Front Hub Motor mounted rim(rim width is 3 1/4") for 26" fat tire. the Hub Motor power can reach up to 900W. the dropout width is 135mm.

o Prewired Speed Controller Unit with 26 Amp current limit. This Controller can be powered by any 36V voltage battery pack with a min. 30A peak discharging drain current.
o Prewired throttle with LED Light and Battery Energy Gauge.
o One pair of brake lever switch.
o One pedal assist sensor.

Easy to install within 30 minutes.Installation manual are available online or request by mail. What you see in the photos are what you would receive:
1x Hub motor wheel mounted rim for 26" fat tire
1x Speed controller
1x Throttle
1x Pedal assist sensor
2x brake lever switch

Net Weight: 23.00 lbs

Mounted the 36V LifePO4 battery pack--

* 36V 30Ah LiFePO4 Battery pack is made of 12 pcs of 30000mAh LiFePO4 Cells
* One Special 12 cells PCB with balance function is installed with battery pack to protect battery from over charging, over discharging and over drain
* Voltage : 36V
* Capacity: 30Ah
* Cut-off voltage: 25.2V
* Max. discharging current: 60Amp
* Max Continuous Discharging Amperage: 30 Amps
* Rated Discharging Amperage: 25 Amps
* Charging Current: <5 Amps
* Charging Voltage: 43.2 Volts
* Lifecycle: > 85% capacity after 1000 cycles.
* Lifecycle of single cell: >85% capacity after 1500 cycles, > 70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate)
* Dimension: 275X170X120mm
* Weight: about 10kg

Tried to drive up and down the driveway--Motor kicks out repeatedly, if I let go of the throttle, motor starts again for a second,
does continually, until rolling at 4-5 mph-

Is this because there is too much weight? Too high gear of a motor?

Is this caused by the LifePO4 built in BMS?

Unfortunately, almost out of time, only 12 days before I leave...

Any suggestions?

Thanks

 

[LI-ghtcycle]

I would guess it could be a combination of the controller and or BMS, one or the other is seeing too much load and that might mean just the motor being wound for speed when you want torque. (*** edit *** I see it's a high torque motor kit, battery BMS or weak connection might be more probable)

I know pedaling is to be optional, but perhaps just to get it started moving? That takes a lot of the load off the electrics.

The other is just buying from Ebay it can be a crap shoot, might have a faulty BMS on the battery or controller.

Good luck!

P . S . Nice bike! I like the use of re-purposed bike frames in it's construction, hope this DD hub motor works out for ya, if not, it might still be useful as a mid-drive for next year, DD hubs are excellent for mid-drives in your application, just have to find out what you need gearing wise, 3.5 to 1 or similar to keep the hub motor happy and keep a nice slow pace at the wheels.

 

[wesnewell]

Could be a combo of problems, but the biggest problem is the motor you bought. Any motor rated for 35 mph at 36V is a fast wind motor. Probably close to 10Kv. What you really want is a slow wind motor with a Kv as low as they make. Not sure what that is but a 6Kv motor would be a lot better. Did you charge the battery up for at least 12 hours? Most probably come with cells out of balance and it sometimes takes days on the charger to get them balanced. If you have a voltmeter, note what the voltage is when it cuts out. If it's dropping below 31V, then the controller LVC is what's cutting you off. If not, then it's likely an unbalanced battery. Also check all the power connections for good contact.

 

[Walkingant]

Hi,

I charged the battery form 3+ hours after it was fully charged, according to instructions that accompanied the battery,
it took that long to balance. I will charge again for longer period.

I will be seeking a different drive motor for sure...

Thanks for the suggestions/replies!

 

[Walkingant]

hi,

Any suggestions for a quick fix/conversion?

I can't find any high torque/low speed fat tire dd hub motors with quick shipping and most good ones are mega bucks.

how about a electric motor kit such as the one below:

http://www.ebay.com/itm/800-Watt-36...ntroller-keylock-Thumb-Throttle-/151945880754

i would mount it over the passenger rear wheel and connect via chain to that rear wheel. Not sure it would have the torque needed to move
from a standing start, but as said would only have to go 5-6 mph. Yes, I know I would have to change the # 25 sprocket.

Any suggestions would be appreciated! Only 11 days left to have a working electric bike or will be in trouble with wife! lol

Thanks

 

[wesnewell]

This 6Kv motor may be overkill for what you want, But it will damn sure get the job done. Probably the same diameter of the motor you have so all you'd need to do is swap the motor out.
http://kinaye-motorsports.myshopify.com/collections/direct-drive-hub-motors/products/mxus-xf40-45h-45mm-3000w-motor-6t-6kv-for-fat-bikes
Top speed on 36V will be about 16 mph with 1100 lb load. At top speed range will be ~ 30 miles with your 30ah battery. That's assuming a 28" wheel diameter. Cut speed in half and double the range.

 

[Walkingant]

Can I use my existing controller? This would be good if I can keep price at their $ 340...of course I have never laced a motor onto a rim before...
or can existing motor housing stay in place and just replace the motor?

My rim is 26" x 4 .

IF this will do the job and get us rolling from a dead stop...great!!
As stated only have to go 5-7 mph.

Thanks!

 

[wesnewell]

Yes, you can use your existing controller. You may have to swap phase wires around to get it right, or maybe not, just depends. No, you can not just put the motor into the existing housing. The housing is part of the motor. Assuming your current wheel is laced properly, just do the new one the same way. It isn't that hard. You will need to true it. Lots of videos on youtube.