Fifty at Fifty Amps

12 x 4110 MOSFET Extreme Modder Controller – LYEN Edition

Part 2 – On the road

The LYEN Edition controller in its new home on my Ego Scoota

Now that the resistor mod was in place that would give me my regen braking at 72V, and my lvc and regen settings were set up accordingly, it was finally time to take the bike for a test-drive. But there was one more thing to consider – how high I should set the rated and phase amperage in the controller settings. Everyone I knew was using the customary formula of setting the phase amperage to 2.5 times the rated amperage, but the question remained about what basic, rated amperage I should start off with. According to Lyen,  the controller was capable of taking a sustained current of around 60-65A in its unmodified form, but I knew from the experiences of others that anything above 40A might be pushing it simply because of the fairly thin phase wires running to the hub motors on these bikes.

The motor on the Ego Scoota was nominally rated “1400W”, and was assembled with a mind to its original 48V SLA bank and 35A controller. Consequently little was spent on the wires required to handle this, and they have a tendency to get quite hot if the motor is pushed too hard.

The rather feeble phase-wire cable serving the Ego’s 1400W motor, with a dime and a five pence piece for scale

The name of the game in souping up these bikes, then, is to pay close attention to the temperature of the phase wires while gradually upping the current level on the controller. Others who have upgraded to better controllers have therefore been quite diligent in monitoring these temperatures, usually by nothing more complicated than feeling how hot the phase wires (and the motor hub) are to the touch. Another rider on the Electric Motoring Forum, with the same bike, with the same wiring upgrades (wires on the battery bank are 170A welding cable) and a similar 4110 12-FET controller reports that he’s running his at 40A.

So with this in mind, I decided to start out at a slightly more adventurous 50/125A – that is – a rated current of 50A and the phase current set to a 2.5 multiple of this – 125A. This was, I felt, pretty much at the limits of my bike’s capabilities given the feeble phase wires. I resolved, though, to be gentle on the throttle at first and check my phase wires very regularly to see if they got uncomfortably hot. If things looked in danger of overheating, then I would just ramp things down a little.

The rated and phase current settings, here with 50/125A selected

The Maiden Voyage

The budget 72V ‘McControllers’ that I have been using (and now sell)  – though fine to get you up and running with more power and speed  – are not built with the same quality components or range of features that are offered by controllers with these superior “infineon”-style boards. The LYEN Edition controller, though, with its premium grade IRFB4110 MOSFETs and good, solid tracks, can pack a good deal more punch.

One consequence of this is that the cheaper controllers have to have a built in ‘soft-start’. To haul a scooter, a rider and a 48 kilo bank of batteries  from a full stop and into motion demands a quite phenomenal amount of current to be drawn, so these budget controllers have to be a bit more leisurely in pulling a bike into motion. The ‘soft-start’ on a ‘McController’ restricts the current at the initial take-off, with the effect that it doesn’t seem to enter the power band until it’s up past 10 mph or so. As I tentatively squeezed the throttle and pulled out into the road, it was obvious straight away that the LYEN Editon controller was having none of that nonsense! Gone was the soggy soft-start, and in its place a solid belt of power that yanked me swiftly into motion and catapulted me off down the road…

Setting off along a nearby dual carriageway I was taken by how much better the acceleration was, and how swiftly I topped the 40 mark on my clock compared to before. The vastly superior pull-away was an absolute boon in traffic, as I could sneak through to the front of the line waiting at traffic lights and dash away and ahead as soon as they turned green, without fear of some obnoxious driver trying to out-accelerate me and cut me off just out of malice. Any lingering resentment about my unit arriving without regen working – and having to perform the necessary resistor mod myself – was gone within about 30 seconds. ‘All is forgiven, Lyen!’ I thought.

The bike could now eat up even the steepest inclines, swiftly barrelling up hills at 30 plus if needs be. And for the first time since I’d owned a petrol bike I could actually overtake now! My motor packed more than enough punch to pass the occasional slow-coach dawdling along a country lane, and for the first time I really felt that I had something that was every bit as good as a petrol bike. The little mopeds that – just a few months ago – I had struggled to keep up with as I pootled along at 48V and 28 mph were now eating my dust as I blasted past them at whatever speed I pleased. This was as it should be, I felt…

The Regeneration Game

This inaugural run was also exciting for another reason, though: I would finally get to experience the regenerative braking that I’d heard so much about. I did wonder if it might be too harsh, as some people have complained, but fortunately the resistor value Mike recommended seemed to be spot on!

As soon as I eased of the throttle, a subtle but distinctive braking effect kicked in, much like the ‘engine braking’ that you get with ordinary petrol engines. And like with ‘engine braking’ it was a little harsher at high speeds and gentler as you slowed down. An added feature that I absolutely loved was that at around 10-15 mph, the regen would ‘let go’ and allow you to coast gently to a halt with the help of just a gentle squeeze of the brakes.

I was delighted with this as it proved that the resistor modification that I’d nervously done on the board had done its job. The 90V regen gave me the ability to extend my range a little by ‘using’ hills to claw back some of the energy I’d spent climbing them. Even better, with judicious use, I could greatly improve the life of my brake pads by allowing the regen to do the lion’s share of the braking for me, turning all that forward momentum back into useable energy again, – a true delight for any environmentalist!

The Speed Test

This preamble done with, it was time for the speed-test I’d been so looking forward to. After giving it a nice full charge, I decided to  put it properly through its paces with a good long run. This second test run covered a total of 14 miles total over various types of terrain, and I took my satnav with me, mounting it onto the instrument display, and also plugging it into the accessory socket I’d fitted into the little glove compartment. This was more as a safety net for if the satnav’s sucker cup came loose, than to provide power, as the connector was more than strong enough to keep the unit tethered to the bike if it fell off the dash!

The  satnav confirmed, as before, that the speedo reads about 12-15% over actual satnav (more accurate than the factory version, due to my slightly bigger K-62 tyres). With it’s topbox on, it wasn’t in the best condition for a speed-test, as this acts as a massive airbrake at higher speeds, but three miles into a fresh charge, I topped out at about 41-42 mph ( as measured by satnav) on the straight, 43 mph with the help of a downhill gradient.  The clock was nearly off the scale at this point, reading just a squeak short of 50 mph! This was a 4-5 mph improvement on the bike’s performance with my budget 72V controller.

The Scoota with its airbrake of a topbox

I later took off the topbox and redid the speed-test. This time I was getting 43-46 mph (satnav), topping out at a new personal record of 48 mph with the help of a hill. That would be 50 mph+ on most speedos!

As I put the bike through its paces, I was very mindful of the issue of the skinny phase wires, and regularly pulled over to check the temperature, especially after I’d done full throttle for a few minutes. They were warm, but not worryingly so, even further up the wire towards the junction box (where it seemed to get hotter for some reason).

As they say, though, the light that shine twice as brightly shines for only half as long. Dashing around full throttle at this setting consumes a great deal more power and quickly drains the batteries, and I only had about 12 miles of high-powered fun before performance started to tail off and hill climbing lost its lustre. A voltage measurement after my full 14 mile run revealed that I was down to 73.8V, which would leave probably another four to six miles or so before it started to conk out. If I had been easier on the throttle. I would no doubt have got plenty more range, but at the end of the day its a trade-off between power and range.

One weird thing I did notice a couple of times though, was something that cropped up after I’d been running it hard for a while. If I yanked open the throttle from a full stop or very low speed, the motor would cut-out. It wouldn’t have it unless I opened up more gradually, and then fully once I’d got moving. I’m pretty sure I’ve got this figured out though.

After some experimentation – including a brief foray into running the controller at 55A, I decided that what was happening was most probably down to overtaxing the limited delivery capacity of the SLA batteries I’m using. Whenever you draw power, the voltage sags, sometimes quite considerably, and I can see this on my LED power monitor which fluctuates quite a bit, dipping as I accelerate and then returning to a nominal level as I ease off the throttle. With the added current that I’m pulling from the batteruies, the voltage may drop low enough to trigger the LVC (low voltage cut-off). This is consistent with the fact that it seems more prone to occur after a prolonged period of flat out driving, when the batteries are struggling to keep up with the demands.

I can fix this by lowering the LVC setting, but then that won’t offer the protection that it affords when the batteries are genuinely low. Alternatively I can upgrade to a Lithium bank, as I’ve been meaning to for some time now. The superior battery technology will keep up with the demands of my controller, and losing 32Kg of weight will add even more performance and speed. Hello 50 mph club! 🙂

Ratings & Summary

The LYEN Edition 4110 12-FET controller

4.5/ 5




Delivery time

Customer service


All in all, I was more than happy about the LYEN Edition controller.  In addition to delivering excellent power, and the programming features that allow the user to tinker with all manner of settings via his extended version of the Keywin interface, there is also an upgrade path for more adventurous users who want to push the controller to its limits. Reinforcing tracks on the board, adding thicker wires and  modifying shunt values can make the controller capable of pulling up to 100A and 100V, it is claimed. The unit I felt was great value for money and was shipped and delivered incredibly fast.

My main gripe was the fact that the controller had not been set up so that regen braking functioned out of the box on my 72V system. I was also puzzled about the lack of a 12V ‘high’, brake cut-off wire of the type that comes with any bog-standard controller. The lack of this was not especially important if you used regenerative braking, but the e-brake connector he included could not easily be incorporated into my bike’s systems, as it required a switch like the one on a brake lever that was already in use by my bike’s 12V system.

Apparently the lack of this feature is due to the absence of a BC-107 transistor on the EB-212 board, which will need to be added to get this feature working. With so many other excellent features on this controller, such as the USB and cycle analyst interfaces – both of which are far more complex – I couldn’t understand why Lyen would neglect to also include the type of brake cut-off that even the cheapest controller has included as a matter of course. Perhaps he felt that his existing e-brake and regen features just made it unnecessary, but a 12V high cut-off of this type isn’t just for the brakes, it’s also an essential feature of many BMS systems for Lithium battery banks.

Though Lyen was very attentive generally and gave excellent feedback and help, he sometimes took a day or so to respond, which left me chomping at the bit and impatient to get to work on things while I had the time available. The issue with the regen braking, I felt, was a lapse in his otherwise excellent communication. He knew I was running off a 72V system, and that I wanted regen, so the resistor mod, I think, should already have been in place. This isn’t a problem for a reasonably competent DIYer such as myself, but a more timid customer might have been left with no option but to return it to be fixed, incurring quite expensive mail fees. The lesson here, then is to expressly ask Lyen for the resistor mod to be included if you are using a 72V system or above. If you want the 12V ‘high’ brake wire included, then likewise this should be expressly requested.

This aside, the LYEN Edition controller gets a big thumbs up from this happy user. If you want to get the most out e-bikes like the Ego Scoota and their ilk, and be secure in the knowledge that you will have reliable, quality after-sales support to help get you up and running or deal with any snags you might encounter, then I don’t think you’ll find a better choice! 😀

2 Responses to Fifty at Fifty Amps

  1. I have the Lyen Edition 18 fet 4110 controller mated to a leaf motor 1500w nominal powered rear hub motor, laced to a 26″ by 2.3 rim and fed by a 24s1p lifepo4 30ah a123 prismatic pack (60-120a bms) All monitored by my CA V3 that I purchased from Lyen with the controller and USB>TTL cable etc (+ some other stuff too, like a DC to DC line.)… Although the bike styling is very different on our two bikes as mine is a Vector type custom build not an electric moped (Plus ur SLA batt pack is heavier than my 19k pack) they nevertheless share many features too, I was wondering then, how consistent your experiences have been in the couple years since since this review using the 50a setting? (or have you upgraded to lithium to battle the peukert effect you described as vexing you?) or perhaps further tweaked the settings on the controller some more?

    • Zenid says:

      Hi Chaim,
      Sorry about the delay getting back to you. It sounds like you’re behind on my blog story. I replaced they SLAs with a LiFePO4 system. I built a Lithium pack and Goodrum-Fechter charge system, then upgraded the controller with the 18-FET one – same as yours. Link below, for chronological list of articles.
      As for my experiences, with the 12-FET controller, I eventually concluded that an 18-FET one would probably be better for me given my desire for more power and speed. Both perform great, but it’s like they say – you get what you pay for – and the 18-FETer, though pricier, was definitely worth the money.

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