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Dahon Mu SL + ebikes eZee kit + ping 48V 10Ah

Joined
Oct 4, 2010
Messages
50
This forum has been really helpful to me, as I was making my first e-bike -- a successful project thanks in part to info gleaned here! So I wanted to share what has worked for me, and review the components I put on my bike.

INITIAL REQUIREMENTS: A regular commute bike that I could fold to take on the metro rail, with substantial range for the 9-10 mile commute from the train station to my office (road and paved trail). On a very busy day I might need to ride 30+ miles but would have a chance to recharge at the office. My office is about to move to the top of a steep hill, and I am carrying a laptop, clothes/rain gear, etc - so I needed a good amount of power. But I also need it to be light enough for me to carry up stairs. Other important features to me included: a good display for measuring energy usage etc, a proportional throttle control (not just "pedal assist") and forward freewheel so the bike is still highly usable with no power.

THE BIKE: I went with a Dahon Mu SL, which was about the lightest 20" folding bike I could find. In retrospect, I ended up ditching so many of the bike's high-end components (sweet rear wheel, shifter, saddle, handgrips, one of the brake levers..) that I would have done well to buy a little bit heavier bike for several hundred dollars less! After all the modifications, the final weight difference would have been minimal. But, I am still happy with the Mu SL as a base. Added a Dahon Touring Rack (high enough and far enough back to use panniers, unlike the standard Dahon rack) and fenders. NOT that happy with the Dahon fenders on the Mu SL - they interfere with the short-caliper brakes even before I put the wider rim on! I didn't like the stock saddle either, and because it was an "I-Beam" style seat post I had to get an adapter in order to put on a nice comfy Brooks saddle.

MOTOR & CONTROLLER KIT: Ordered an eZee motor kit from ebikes.ca, including the 20" wheel and 20 Amp controller with CycleAnalyst on board computer. According to many accounts I have read, there is little problem running this motor up to 1000 Watts (if run over 1000W however the warranty is void). This would makes it a perfect fit for the 20A controller with a 48V battery: 20A*50V=1000W.
* EZEE WHEEL - the wheel is well-constructed with a good quality rim and I am not an expert but it seems to be completely true. However, they shipped me a Shwalbe Big Apple tire instead of the Schwalbe Marathon I was expecting to get.
* EBIKES CONTROLLER - the controller is a solid little box with all the connectors you need on a short tail. There is a little red light to show you when it's powered. The mass of rubber sealant (gooped around the cable exit to make it waterproof) cracked when the cables were bent a bit, but I can always add some more sealant to close it back up again after cables are situated. At first I had the controller in the bag with the battery, and it was getting very hot. Once I mounted it under the rack where the wind can cool it, it barely gets warm.
* EBIKES CYCLEANALYST - the CycleAnalyst is kind of a big clunky looking box compared to what I'm used to in a bike computer -- hopefully in the future they will make it small! But it does its job just fine. The two large buttons are easy to use. The 'default' display shows speed, voltage and watts, and alternates between miles traveled this pack and Amp-hours used this pack -- just the information I want to see, or there are other screens for other details and cumulative statistics. I got the version that includes a speedometer, just the kind you're used to with a little magnet attached to a front spoke. It's very "hackable" with a serial data output, ability to flash new firmware, and assorted other modifications can be made. Looking forward to messing with it some more!
* HALF-TWIST THROTTLE - Perfectly usable, easy to install. Matching grip for left side. Looks more like something I'd expect to see on a scooter than a bicycle, but it's okay. At first it seemed like it was really touchy and I was thinking a full-twist would be better, but after a little while I got used to it and I'm happy with it now.

BATTERY: I went with a Ping v2.5 LiFePO4 48V 10Ah battery and a 4A charger. This should be a perfect fit for the 20A controller, allowing me to use the full range of the controller without damaging the battery by discharging too fast. The battery seems solid and although there is a bit of a mess of wires for the integrated battery management system, the construction is still fine. Performance is excellent -- the voltage stays very close to 50V until the pack is nearly discharged and according to my CycleAnalyst it exceeded its 10Ah rating by just a little bit before cutting out. From some stuff I had read, I was concerned about the battery getting hot in the bag but so far it's barely gotten warm.
[EDIT: I found out later you shouldn't draw 2C constant from a Ping battery... My battery was losing capacity from pulling too hard and I had to upgrade to a 15Ah battery in order to keep up 20A current capacity]
* CHARGER: The 5A Ping charger works great but is too big to practically carry around with me, and also quite loud (fan noise) and I am on the lookout for a better and maybe even portable charger.
[EDIT: I ended up getting a couple of extra smaller 2A chargers, one for work and one for spare/travel, works great]

BATTERY/TRUNK BAG: I strapped the battery into an Arkel TailRider trunk bag where its weight is essentially centered over the rear wheel. There is still plenty of room in the bag for tools, wiring, etc. There is a little padding even for some small protection from vibration. And it has an integrated rain cover that I can just flip over the whole bag. This is really a very nice bag. It is quite secure, although I feel the need to add some more reinforcement as I am concerned the nylon/Velcro straps that attach it to the rack could fail.

EBIKE ACCESSORIES (all from ebikes.ca):
* LED TAIL LIGHT, wide voltage range input - nice and bright. Remembers last setting (on/off/blink) when power disconnected. There is no bracket to install it, just holes drilled in the tough plastic casing that allow you to attach it with zipties etc. Worked perfectly for attaching to my rack. (Bare cable, had to attach connector.)
* 12V CONVERTER AND 12V HALOGEN HEADLIGHT - also very bright. Converter came pre-wired with Anderson connector on one end and 2.5mm barrel jack for the light on the other end. Two little problems - the connector tends to vibrate itself loose quite easily, and, I'm not sure how well it'll do in the rain (both problems can be solved at once with a little epoxy, I think). The converter itself is well made and sealed.
* BRAKE LEVER WITH MOTOR CUTOFF. Fine quality brake lever, just wish it was smaller instead of as wide as your whole hand. The cutoff is nice to have, because sometimes you need to stop quick while you're under power, but worrying about the throttle while you're grabbing the brakes might delay you for a dangerous fraction of a second! (I think this wouldn't be important if you had a thumb-lever throttle.)

PROBLEMS ENCOUNTERED:
* 9-speed freewheel wouldn't fit -- the eZee motor itself is only one or two mm too wide for the 130mm rear dropouts on the Dahon. It would squeeze in just fine without much force on the frame. But unfortunately, with a 9-speed freewheel in place, spacers were needed, and although I was willing to do some grinding/filing, there was still no "reasonable" way to get the wheel to fit. So I had to switch to a 7-speed freewheel, which also required changing the shifter to a 7-speed indexed shifter (found a SRAM X.3 shifter that is compatible with the bike's existing SRAM X.9 ESP derailleur). After that, no problem.
* Tire fit - I was slightly annoyed that ebikes shipped me a Shwalbe Big Apple tire instead of the advertised Schwalbe Marathon. Yet another size problem -- the Big Apple wouldn't fit well under the fenders and I had to buy a smaller Marathon. (Also took that opportunity to replace the tube and get a Presta valve so I have the same valves front and back.)
* Brake calipers too short/narrow. I think I might have to switch to different calipers on the rear wheel. The calipers are so short and narrow that with the new wide rear rim, they are splayed far out and the cable rides on the fender. Brakes still work okay, but this will not do. (Might have been a good reason to go with a Mu P8 as the base bike instead of the SL model that uses extremely narrow rims.) [EDIT: got the calipers adjusted fine but ended up going with longer ones to clear the fenders anyhow. Also since this project I've decided that the perfect Dahon bike to convert would be the Speed D7.]

PERFORMANCE AND RANGE: I get an effective range of 20 miles, with no pedaling and moderate hills. I can start from a dead stop and get up to speed quickly with no pedaling, if I'm feeling lazy. It climbs hills quite well. In a word - impressive! I might buy another charger for the office unless I can find a very small portable one to keep on the bike, but today I can make it to and from the train station & the office on a single charge, so it's not crucial.

FUTURE PLANS AND IDEAS:
* Custom wiring harness -- with all these separate cables for throttle + CycleAnalyst + headlight + brake cutoff (etc), I have a big honkin' mess of wire going to my handlebars. So the next thing I need to do is rewire everything to use ONE good quality multi-conductor cable that splits off to hook up all the handlebar stuff, and protect all the connections from water. [EDIT: did it, this was totally worthwhile, looks much nicer]
* Carrying strap -- With battery & motor this thing is heavy. Add a pannier carrying my work stuff, clothes, etc (don't want to wear a backpack...) and it's starting to get hard to carry it up stairs! So I need a padded shoulder strap that tucks away in/under the battery bag, and quickly snaps in place to carry the bike easily. For now, I have the Dahon CarryOn cover which has an integral strap, but it takes too long to put on, and the Velcro used to attach the strap is not secure enough for me.
* Geared crank for higher pedaling speed -- I'm considering installing a Schlumpf High-Speed Drive so that I can pedal along at a more leisurely rate when cruising under power at higher speeds.
* USB (5v) connections in the battery bag, to recharge my smartphone and headset -- I often listen to music or audiobooks (in one ear) over Bluetooth while I ride, also sometimes I want to use the GPS or other power-draining features on my phone and keep it charged. I bought a 5V converter from ebikes.ca that I will use for this purpose.
* Alternate battery -- I'm thinking of getting a smaller (somewhere around 7Ah 36V) battery to save a few pounds. On the other hand, my available power would be reduced from 1000W down to 500W-700W (depending on how hard I wanted to discharge the pack), but I this might still be ok for my normal commute - and easier to carry up the stairs! [EDIT: I'm just building another bike and leaving this one with its heavy battery...]

CONCLUSION:
After about 110 miles riding [EDIT: 3500 miles], so far I am very happy [EDIT: VERY VERY happy] with my ebike. It's practical and fun and I don't need any gas to get to work! I'm glad I went with a good sized 48V battery for the "fun factor" of having stronger acceleration, and the impressive 20+ mile range. It did not disappoint! However I may also try out a 36V system for weight.

I will post some pictures another time.
 
Ditto on the nice review!

Also ditto on the pictures. Let's see how this beauty looks.

Ambrose
 
Thank you for great review!

LiPO may work good as an auxilary baterry pack, less cycle life than LiFePO4 but better capacity/weight/C ratio.
 
Here are some pictures. Thanks for the advice ebikes-sf, I will look into LiPO for a lighter weight 1-way commute battery!

So far I get 20-23 Watt-hours per mile with no pedaling and moderate hills, a little more if I go easy on the throttle. At maximum power I am not sure if it could not do 28 mph, however that wouldn't be legal where I am, and besides it might involve peak power consumption of over 1000W, voiding the warranty and possibly damaging the motor. So, I would say that it is designed to go less than 20mph...

Already I am starting to think about building a full-suspension mtb ebike... Gotta get this one "just right" first though! :)

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handlebar.JPG
 
Very nice setup. I was leaning towards an Ezee kit for my first bike but in the end decided to go with smaller motors. I think you have a pretty reliable combo there.

For a travel charger I would recommend the Ping 2 amp unit. Mine has been going back and forth to work in my backpack for a few months and so far no problems. They are pretty quiet too. If you put it in the pannier I would wrap it in a layer of bubble wrap for a bit of extra shock protection.

Gary
 
nice complete project,wish i was your age,and had resources to do a D.I.Y. build.adding up your total cost,canyou compair it to a PRODECO STRIDE R 500 R with upgrede 12 AH battery @ $1300.00,with 2 year warrenty?ed
 
Hello, nice build.

You should also have some cables cover to hide all these cables everywhere!

Why did you choose Ezee motor over other cheaper geared motors such as bafang or mac?
 
I chose the eZee for my first kit because of the reputation for reliability and for support from ebikes.ca ... I put 3000 miles on that motor before selling it and never had a single problem, so I was happy with that choice. Nothing against the cheaper motors tho.

I agree about the cables! Soon after those pics were taken, I made a custom wiring harness which replaced all of the cables to the handlebar with a single 10 conductor gray cable. On my current commute bike, a very similar Dahon Speed D7 w/ BMC motor, there are almost no cables visible and people are often surprised to find that it is electric.
 
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