Sur-Ron BAC4000 upgrade kit · Light Bee X and L1e · Segway X260
Three times the power of the stock controller, tuned to the battery you actually ride with.
The Sur-Ron BAC4000 upgrade kit replaces the stock Light Bee controller with an ASI BAC4000 on a loom that plugs straight into the bike. On the original 60V battery it is set to 5 kW. Bypass the pack and it runs 7.2 kW. Feed it a 60V or 72V battery that can deliver the current and it reaches 12 kW or 15 kW.
Nothing is soldered and nothing is cut. You unplug the old controller, plug in the new loom, and an ElectricGen engineer tunes the BAC4000 to your setup in a remote session that comes with the kit.
What the Sur-Ron BAC4000 upgrade kit changes on the bike
A Light Bee is limited by its controller long before it is limited by its motor. The BAC4000 removes that limit and then gives you the tools to decide how much of it to use.
Torque
Instant pull off the line
The BAC4000 delivers far more phase current than the stock unit, so the rear wheel answers the throttle in the first metre. On loose ground you will feel the difference before the first corner.
Speed
A higher ceiling in every gearing
More power raises top speed with any sprocket. How far depends on your rear sprocket and tyre, so the same kit can be geared for tight trails or for long straights.
Settings
Yours to change
Power, assist levels in percent, wheel size for accurate speed, km/h or mph. With FabiRide Dash Pro you change them from the bars. With any other display, our engineer sets them with you.
Heat
Motor temperature protection
The controller watches motor temperature and trims power before heat becomes damage. An optional radiator keeps the BAC4000 itself cooler on long climbs and hot days.
Battery
Protection for a tired pack
When pack voltage sags, the controller pulls power back on its own. As a result, an old battery is not pushed into a cut-out in the middle of a ride.
Loom
Made for the Light Bee plugs
Our harness carries the stock throttle, brake sensors, motor phases and battery plug to the ASI. Everything clicks together with the connectors already on the bike.
Power by battery: 5, 7.2, 12 or 15 kW
The controller is the same in every Sur-Ron BAC4000 upgrade kit. What changes is how hard we let it pull, and that depends on what your battery can give.
| Battery | Controller setting | Notes |
|---|---|---|
| 60V original Sur-Ron battery | 5 kW | The stock BMS limits current. This is the safe ceiling for an untouched pack. |
| 60V bypassed battery | 7.2 kW | The bypass kit routes power around the stock BMS. More power, but also more wear on an ageing pack. |
| 60V high current battery | 12 kW | Needs a pack built to deliver the current, for example our 60V 70Ah High Power Sur-Ron battery. |
| 72V high current battery | 15 kW | The full BAC4000 figure, on a 72V 50Ah or 72V 55Ah Sur-Ron battery. |
How you answer Select your battery depends on the display. With FabiRide Dash Pro choose the range, 60V to 72V, because you set the controller’s battery voltage yourself and change it when you change packs. With Eggrider V2 pick the exact battery you ride, because the controller is tuned for that pack and only a re-tune by us changes it later.
One honest note on the bypass option. Bypassing the stock BMS raises power because it removes the current limit that protects the cells. Therefore a healthy pack handles it well, while an older or poorly maintained pack will age faster. If you want 12 kW or more, a battery built for the current is the better road.
Choose your display: FabiRide Dash Pro, Eggrider V2 or your own
The Display option decides what you see on the bars and how much of the ASI you can change yourself. Every Sur-Ron BAC4000 upgrade kit ships tuned and ready to ride whichever display you pick, but only one of them talks back to the controller.
FabiRide Dash Pro
A colour touchscreen that reads the ASI and writes settings back to it, from the bars or from the free FabiRide app. It also carries your phone: calls, messages and music appear on the display. See the full Dash Pro feature list.
Eggrider V2
A compact display with a button that switches the controller on and off and a phone app for the basic readings. A good fit if you want the power and not the screen. Eggrider V2 details.
Already running an Eggrider V2? Contact us before you order and we will set the kit up for it. The APT 750C is not offered with this kit at the moment.
What Dash Pro adds to the Sur-Ron BAC4000 upgrade kit
Most displays only show numbers. Dash Pro changes them. On an ASI BAC controller every one of these works, because the display talks to the controller in both directions.
Tune from the bars
Power, speed and assist levels
- Edit the assist levels in percent and the power and speed behind them
- Up to ten riding maps, each with its own speed, power and regen
- Pin one map so the bike always starts there
Battery voltage
Run a 60V or a 72V pack, your choice
- The battery voltage setting is yours to change in Dash Pro, so one kit runs a 60V pack today and a 72V pack next season
- Swap batteries without sending the controller back for reprogramming
- Choose 60V to 72V in the battery selector; that option exists for Dash Pro only
Limiter
A cap you lift with one press
- Set a speed and power ceiling for the road, the kids or a new rider
- Lift it again from the handlebar remote
- Per rider ceilings stay on the bike
Reverse
Reverse gear from the bars
- Select reverse from the handlebar buttons, the ASI does the rest
- Walk the bike backwards out of a rut or off a trailer
- A live indicator on the dashboard shows when reverse is engaged
Phone on the bars
Calls, messages, music
- Answer or reject calls from the handlebar remote
- Read incoming messages on the display
- Skip tracks and change volume without touching the phone
Safety and trips
Crash detection and ride history
- Crash detection sends an SOS with your location to your emergency contacts
- Every ride is recorded with its route on a map
- Full statistics per trip in the app
Reverse gear is one more thing Dash Pro adds on the Light Bee. Select it from the bars and the bike walks backwards out of a rut, a trailer or a tight garage instead of you dragging it.
The FabiRide app is free on iPhone and Android, and the same account opens in any browser. Settings and ride history live in the account, so a new phone loses nothing.
01
Set up
A short wizard connects the display to the ASI and asks only about things your bike has.
02
Tune
Riding maps, battery voltage, assist levels, throttle and brake feel, all written to the controller.
03
Share
Add riders with their own ceilings. The bike remembers who is on it.
What is in the box
Pick the options you need in the selector above and the Sur-Ron BAC4000 upgrade kit arrives complete. Nothing else is required to ride.
Controller
ASI BAC4000
Tuned for your battery before it ships, then fine tuned with you in the remote session.
Harness
Plug and play Sur-Ron loom
Phase leads, battery lead, throttle, brakes and display on the connectors the Light Bee already uses.
Display
Your choice
FabiRide Dash Pro or Eggrider V2, plugged into the loom and ready.
Mounting
Controller bracket
Holders that put the BAC4000 where the stock controller sat.
Optional
Controller radiator
A finned heatsink for the controller. Worth it for long climbs, heavy riders and hot summers.
Optional
Regen thumb throttle
A second thumb lever for regenerative braking, so you slow the bike and put charge back without touching the brakes.
Optional
Bypass kit
For the 7.2 kW setting on the stock 60V battery. Read the battery note above before you tick it.
Fitting the Sur-Ron BAC4000 upgrade kit
01
Remove the stock controller
Lift the battery, disconnect the plugs on the stock controller and take it off its mount. No connector is cut.
02
Plug in the loom
Every lead on our loom ends in the plug the Light Bee already has: throttle, brake sensors, motor phases, battery and display. Match colour to colour and click.
03
Mount and route
Sit the BAC4000 in its bracket where the old controller was, add the radiator if you chose it, and route the display lead to the bars.
04
Remote tuning session
Book the session that comes with every kit. An ElectricGen engineer connects to the controller, checks your installation, and tunes the settings to your battery, your riding and your terrain.
Keep it dry. The controller and its white signal connector must be protected from dirt and water during and after the installation. Water inside that connector is the one failure the kit cannot protect itself against.
Sur-Ron BAC4000 upgrade kit specifications
| Item | Detail |
|---|---|
| Controller | ASI BAC4000 (manufacturer page) |
| Motor control | Direct field oriented control, sensorless, auto tuning |
| Input voltage, manufacturer rating | 24 to 72 VDC |
| Peak phase current, manufacturer rating | 430 A |
| Kit power settings | 5 kW, 7.2 kW, 12 kW or 15 kW depending on battery |
| Battery | 60V or 72V pack; with FabiRide Dash Pro any pack from 60V to 72V |
| Communication | CAN bus and TTL to the display; Dash Pro reads and writes settings |
| Fits | Sur-Ron Light Bee X, Light Bee L1e, Segway X260 |
| Displays | FabiRide Dash Pro or Eggrider V2 |
| Installation | Plug and play, no soldering, no cutting |
| Tuning | Remote session with an ElectricGen engineer, included |
Questions before you order
Does the Sur-Ron BAC4000 upgrade kit work with my stock 60V battery?
Yes. On the original pack the controller is set to 5 kW, which already feels like a different bike. For 7.2 kW add the bypass kit. For 12 kW or 15 kW you need a 60V or 72V battery that can deliver the current, such as the ElectricGen packs linked above.
Do I have to solder, cut or reflash anything?
No. The Sur-Ron BAC4000 upgrade kit uses the connectors already on the Light Bee, the controller arrives tuned, and the display plugs into the loom. Fitting is a matter of unplugging the old controller and plugging in the new one.
Which display should I choose?
Choose FabiRide Dash Pro if you want to change power, speed, battery voltage and assist levels yourself and see live data on a colour screen. Choose Eggrider V2 for a compact display with the essentials. If you already own an Eggrider V2, contact us before you order.
Can I move from a 60V to a 72V battery later?
Yes. With Dash Pro you change the battery voltage setting on the display or in the app and the controller follows, which is why Dash Pro orders use the 60V to 72V option. With an Eggrider V2 the kit is tuned for the battery you pick at checkout; contact us and we re-tune the controller remotely when you change packs.
Does the kit fit the Segway X260 and the Light Bee L1e?
Yes. The Light Bee X, the Light Bee L1e and the Segway-branded X260 share the same controller and the same plugs, so the Sur-Ron BAC4000 upgrade kit fits all three. Send us a photo of your controller plugs if your bike has been modified before.
Will the motor overheat at 15 kW?
The controller monitors motor temperature and reduces power before the motor reaches a harmful level. The optional radiator takes care of the controller itself. For sustained high power, a motor upgrade is the next step, and we can advise on that during the tuning session.
How does the BAC4000 compare with the BAC8000 kit?
The Sur-Ron BAC8000 upgrade kit reaches 18.5 kW on the stock motor and up to 32 kW with a motor swap. The BAC4000 is the lighter, more affordable route to 15 kW and is the right choice for most riders who keep the stock motor.
Related to the Sur-Ron BAC4000 upgrade kit: Sur-Ron BAC8000 upgrade kit · FabiRide Dash Pro display · BAC4000 and BAC8000 radiator · ASI BAC harness for Sur-Ron · Sur-Ron batteries · all Sur-Ron controllers and electronics
will –
I purchased this upgrade kit not too long ago and I am enjoying every minute of it.
Kasparas –
Amazing kit, improved acceleration and range with the stock battery