Giant TranSend LX

This was my first round of electric bikes. 

Top Speed ?: 38mph and still climbing (too fast)

Limited Speed: 31-33mph (controller low speed jumper wire)

Average Speed: 20-25mph (~1000w) 

Power Consumption: 30-37wh/mi


BMC V3 1000w Black Lightning Hub Motor (Brushless Motor Corporation)

BMC 50A 48V Controller

BMC Half Twist (no markings to identify)

2 LiFePO4 48V 15Ah Batteries (48V 30Ah or 1440Whrs)


It is a rough ride! With 100% pedal powering a bike you don't notice roughness as much. The suspension seat, post and neck all help smooth things out. The thing to note here is that while the commuter style seemed ideal for pedaling (before powered), I now know I should have stuck to my original plan of a full suspension platform. The characteristics that made FS bikes less desirable for street commuting under pedal power become benefits when powered and speeds increase.

I started this bike thinking that the 700c wheels and tires would be good for rolling resistance etc... What I discovered is that wider tires are better for a number of reasons and that resistance is really not an important factor in the scheme of things. The skinny tires sort of dance in the debris of the bike lane and is greatly amplified at higher speeds. Dancing over surface imperfections lowers surface contact.

My single battery in the frame is vastly better than dual batteries or just one battery on the rack. Rear weight and over-all weight take away from the "bike" like experience. Having weight balanced makes a big difference when negotiating obstacles!

The BMC motor and controller work great but 50A is simply too much for the motor and takes continuous attention to keep power delivery in a safe zone for the motor wires. I wouldn't let somebody ride the bike because they would likely melt the wires in a short ride as it really is soooooo much fun to twist full throttle!

I found this bike on sale (late fall).

Used pre-load resistance to overcome the BSM shutdown at power up.

I started with 470 ohm 10W (big) and then put 2 in parallel to get things to start right. The charge time was long so I put 3 in parallel and that was great but was way overkill for power requirement not to mention a large wad of resistors.

So, I now use a single 120 ohm 5W resistor and it charges the controller fast without much switch pop (very little spark).

BMC V3 1000w (V3-S or Black Lightning)

Light weight - freewheel but you certainly know you're turning it if you run out of juice and have to peddle!

Plenty of power and speed.

Phase wires get hot if run above 1300w

I went through a few controllers before this one came out

BMC 50A 36 or 48v Controller IRFB 4110 Mosfets

I use controller jumper settings

- soft start (still pulls out nice)

- power limit (about 31mph)

Too much current for the motor but makes the motor work better than others to date. A 35-40A limit would make this an ideal match IMO.

BMC Half Twist w/48v (don't care for the power indicator). But it works... unlike the previous Crystalyte Half Twist X-T200 that was bad. I like the half twist for holding precise control.

No markings to identify ... looks the same as the previous throttle but with lights.

Polymer  LiFePO4 48V 15Ah LFP-CY4815 3C (45A) max with LiFePO4 48V 2A LFP-BC4802 charger

in theory, 720 watt hrs (100 watt bulb for 7.2hrs) it is 15 pounds and 11x7.2x3.3


Kit battery from Betterbikes had 2 bad cells and they wouldn't replace/fix it! This was the last straw with them.

Same/Similar battery here works fine.

Juiced Riders LiFePO4 48V 15Ah 048015LIF002 (45A BMS limited) with LiFePO4 48V 3A WL-089-02 charger

Cut-off Voltage: 42V

Max. Charge current: 15A 1C Max. Constant Discharge Current 75A 5C

Impedance: (Max, at 1000Hz.) ≤ 30 mΩ    

Cycle Life: 0.2C to 85% of Original 2000 Cycles

Length: 310mm Width: 150mm Height: 110mm Weight: 7.5kg (16.5lb)

Picked this because it would fit the back rack nicely and was a similar spec to the other battery. Using them in parallel would allow riding farther and not be at single battery max so much.

First pack hit BMS cut-out at about 6mi and only got 232whrs when tested with 80w load! The replacement pack works much closer to specification. Communication and replacement was quick. Finally a good ebike vendor experience!

Two packs in parallel actually more than double usable distance!

Cycle Analyst (Stand Alone) - This is a must have little device!

MARWIusa Nightpro Bullite 6W Flood - works ok but light beam is too wide IMO

That's about it for eParts

The following connection uses 4 Ideal Diodes (ID80V2) for the dual battery wiring.

Previous blocking diodes worked but these drop considerably less voltage.

I hope this is the last time to rewire the bike (10th time I think).

Trying to decide on diodes for each pack in a parallel connection.

75A 600V stud blocking diode 

Works, but drops each pack voltage by .7-.8v.

I tried soldering to the threaded ends together but it just didn't work! So, I used ring ends.

Next I tried 4 of these Ideal Diodes - ID80V2 

(Specs/info as purchased from

90V 30A (75A peak) @ 15A no heatsink so 2 stacked for each battery should be plenty even if the bike must be run on just one battery.

I put these together in a similar way to my last harness connector. It worked pretty good and I like my new 10awg noodle wire (much easier to work with). This is a GREAT diode! Very low voltage drop! It's a keeper.

The controller recomended by Brian but never quite worked right and it was specifically for the V3 motor