Adding a Car Accessory Socket

August 19, 2010

A nice feature for any vehicle to have is a power socket. The classic ‘cigarette lighter socket’ is practically ubiquitous in cars, and accessories based on this fitting are widespread. Anything from phones to sat navs are equipped to use it as a source of power. It’s also handy for running a small compressor to put air in your tyres.

The Car Accessory SocketIncreasingly useful in our Gadget-cluttered World



  • A drill with a 25mm bit
  • A pair of wire snippers
  • A crimper or needle-nose pliers

This is very easy to do. The only issues are with the practicalities of mounting the socket in a suitable position, and running cable to a suitable source of power.

1. Choosing a Site

I decided to mount mine in the lockable ‘glove compartment’ box, as obviously it should be weatherproof and reasonably secure. The clear choice here was either the left or right recess.

A quick look under the front-wheel recess shows that the horn is directly in front of the left recess, and may risk getting hit by the drill-bit. The space behind the right recess is a little more roomy and easier to reach and work around.

2. Drilling the Hole

The first thing to do is to drill a hole. The hole actually needs to be 28mm if you’re using the connector I list, but a 25mm drill can suffice, as the plastic is soft and the hole can be easily ground larger with the bit.

3. Connecting the Cable and Mounting the Socket

Next, you need to prepare your connecting cable. Crimp the spade connectors to one end of the figure eight cable, then thread the connectors through the hole and plug them onto the terminal heads at the back of the socket. Once this is done, thread the big plastic nut that comes with it up the wire and into position behind the compartment. It’s easier to reach this area if you turn the wheel hard right so the forks are out of the way.

The socket can then be pushed through the hole and secured from the back of the compartment casing by the nut. It’s a good idea to use a large rubber gromit or some silicone sealant here to prevent water seeping through the join during bad weather.

It’s also a good idea to tape the cable to the inside of the bodywork to keep it clear of the forks.

4. Connecting the Cable to a 12V Source

Next, the cable needs attaching to a 12V source. It might seem logical to simply attach it to a live 12V wire in the nearby instrument panel loom, but the problem with that is that this will only be life while the ‘ignition’ is on. I suspect that most people, like myself, will want to be able to charge or power things without the keys sitting in the ignition.

So I have opted to thread the cable to the last battery in my (currently 60V) bank, where it will be available as ‘always-on’. This may raise battery charge-balancing issues with frequent use, so you should occasionally balance your batteries as a matter of course to keep them at peak performance.

I’ve run my cable alongside the existing main wiring conduit along the left side of the bike, so that it emerges into the battery bank under the seat. You can remove the side panel by unscrewing the bolt and screw securing it at either end and releasing it from its retaining clips.

Cut off the wire at a suitable length, attach the ring connectors, and secure the end of the finished cable to the terminals of the battery of your choice. In my case I’ve opted for Battery No.5 of my 60V system, as I charge this battery separately anyway and use of the socket won’t throw it out of balance so easily.

Remember – the positive terminal of the socket (marked on the plastic) goes to the positive terminal on the battery.

And there you have it: A ready power socket for all your rechargeable doodads and other accessories!

Can’t Stand It…

August 16, 2010

The precarious side-stand finally got the better of me today. With it being mounted so as to prop the bike at approximately 1 degree from the vertical, I’ve already had a few near-misses with this badly designed mechanism. Just a waft of air, an insect landing on the right wing-mirror or anything else to even fractionally upset the bike’s precarious center of balance can send the bike keeling over to crash ignomoniously into whatever unforgiving surface it happened to be teetering over.

On this occasion it was removing my helmet – for the first time – from the top-box that was sufficient to sending it crashing into the tarmac, scratching up the pristine paintwork on the right-hand side. Mercifully the ‘Street Scoota’ logo that is seemingly laminated onto the bike’s side panel took the brunt of the fall, and the scrapes aren’t to noticeable.

Still, it has left me seriously contemplating removing it altogether, or at least – as I did on my TZR 125 that has a similar problem – having the stand blowtorched and bent so it stands at a more respectable angle to the ground. Others have also complained that the stand whacks against the ground if you lean the bike over too far, but as yet I’ve not pushed it far enough on bends to have this happen.

65V Max

It’s been about a week since I tweaked it up to 60V, and I’ve seen the same controller issues that were reported by Nig in his own blog: Fully charged, the voltage is just a fraction over the limit that the 48V controller will tolerate, and Nig’s workaround for this was to simply take it for a quick spin round the block in 48V mode to take enough edge of the voltage to bring the five-battery configuration within the controller’s operating range.

Witnessing this for the first time with all my batteries fully charged, I decided to experiment to try and establish where the cut-off point lay. Not having easy access to the full battery bank below the underseat area (with it all being set up and primed with the extra battery), I settled for just taking voltage measurements from the easily accessible extra battery.

The first measurement I took put the battery at 13.1V. So I turned the headlights onto main beam and waited a minute or so, occasionally checking the throttle, with the bike on its stand, to see when the thing would whirr to life. A couple of minutes later it did just that, and so I switched off the lights and rechecked the voltage: It was now registering about 12.9V.  A reasonable approximation of the critical value, then, is about 13V per battery, or 65V total. Just using the main beam, though, rather than taking it for a ride in 48V mode seems sufficient to deplete them enough for the controller to kick in. It did, however, take a little longer to get there after a fresh charge this morning. After five minutes of this it still hadn’t come to life, but switching off and then re-engaging the breaker switch seemed to nudge it to life for whatever reason.

72V on the horizon…

I don’t expect to be fudging things with this configuration for too long, though, as I almost have all the bits I’ll require for the full 72V upgrade. The 72V charger that I initially thought might be faulty turned out to be OK. An adaptor I was using had a mysterious condition whereby it would run my electric shaver, but fail to operate the controller. The next day it wouldn’t even start the shaver either, and it turned out that its 1amp fuse had blown, but – oddly enough – only partially (is that possible?), as it still briefly operated the shaver even after I’d tried to run the recharger off of it a couple of times.

It’s been nearly a couple of weeks since I ordered a 72V controller, again from a Chinese vendor. The price looked good, but shipping times look pretty uncertain, and I’ve been unable to get the vendor to tell me when they shipped it or how long they expect it to take beyond the stock answer they have on their web-page. The poor English, and apparent complete lack of comprehension of anything I say in my emails leads me to believe that they’re using one of those on-line translators which renders anything but the simplest sentences into barely comprehensible gibberish. Presumably this is then fed back to them in the form of Cantonese pictograms, from which they pick out key concepts like “when” and reply with stock, menu-driven statements in the hope that it will suffice.

Well it won’t, so in desperation I’ve ordered one from the first affordable vendor who could respond to an email in coherent English within 24 hours. So I’ll either have to send back the surplus unit, or – more likely – hang onto it as a spare or sell it on to somebody in the EV blogosphere (or ‘forumasphere’). I should at least be able to claw back what I paid for it, as I can see offering next-day delivery on something that usually takes weeks to acquire being a very appealing selling point.

Until then, it’s onto my next little project, – an upgrade for the dodgy battery meter that comes as standard. Apart from the fact that it won’t work on 60/72V configurations without bodging, in my opinion it’s not very good anyway, and is worth replacing with something better. But more about that later…


August 10, 2010

I spent the morning lovingly putting together some thicker cables to replace the existing smaller guage wiring that supports the formerly-48V circuit. I encountered a problem though with installing them. There was some trouble with the bolt securing the removable crossbar that goes across the top of the battery enclosure and secures them into their casing.

The makers hadn’t done a very good job of this part. The crossbar was slightly bent, aparrently to compensate for the joint at the end which would not properly align with the hole in the case to the rear, where it was bolted at a very strange angle. My attempts to remove it failed, as even though the nut on the other side would come loose, the bolt seemed to be jammed, and turning it made it just – well – turn.

The bar though, is fairly flexible, so in the end I decided to just pull it to one side to unscrew the terminal screws.

Unfortunately, in my eagerness to get the leads changed, I’d not thought about the consequences of the shaft of my screw driver touching this bar as it was connected to the terminal head (doh!). One almighty flash and puff of smoke later, I was looking at the charred remains of the ring connector I was trying to remove. Mercifully – despite being partially arc-welded to the bolt – It all came free and I was in a position able to be able to put in my new cables.

Eager to learn from this, though, I got some thick insulation tape and wound several layers of it along the six inches of crossbar immediately above the four terminals in the middle. I also stuck a good amount of it on the walls near the terminals by the side of the case. I’d have to do something about that seized bolt at some point, as I wouldn’t be able to remove the batteries at all. But that could wait for another day.

I also did a quick check of the master terminals of the battery system with my multimeter. It seems that nothing catastrophic has happened to them as a result of this mishap, and the bike still goes.

Input: AC110V – errm…

Along with the length of black cabling that I’d received in the mail this morning, I’d also finally got my 72V power supply unit from e-crazyman, which had taken the best part of two weeks getting here from China. I thought I’d plug it in and check it out with my multimeter to make sure that it was working. The connector that came with it was an American style two pin connector, but I had a few adaptors, including one that was already in use by my shaver.

So I plugged it in and… nothing. 😦 Neither of the two lights lit up to indicate something was happening.  Disappointed by this, I went and got another adaptor – this time one with a step-down converter that delivered 110V ac. Low and behold the unit came to life and both lights blinked a couple of times as it came to life.

I was none too happy about this, as the unit clearly stated “Input: AC100-240V  50/60Hz”, as is standard with most adapters nowadays.

I’ve emailed e-crazyman to ask what is going on here. I don’t know whether this unit is just defective in a way that only upsets its 240V operation, or whether his specs were telling fibs. Alternatively he has separate, cheaper units that only support one or the other. I’ll find out in due course I dare say… Until then it’s “sayonara” to this unit (or whatever the Chinese equivalent is).

‘Voltage Curve’ Experiment – 9 August 10

August 9, 2010

This was an experiment I did to chart the range of voltages my batteries ran through as they went through a cycle. It isn’t a true test of range or longevity, in that I had already used the bike for a run of about five miles the day before. But what I wanted was an idea of the bikes operational voltage ‘window’. The bike was also run at night, with the lights on. But this was OK because a quicker discharge was desirable for my purposes.

For the purposes of this test, my bike was returned to its 48V configuration so that I could also chart the behaviour of the existing battery meter in relation to the decline in voltage. I stopped every few miles and took a reading of the total voltage, and divided by four to get voltage per cell.

There were only five readings over the course of 14 miles, but it did serve to give me an idea of the operating characteristics of the bike in realtionship to the voltage.

Voltage Total Voltage/Cell Miles
51 12.75 0
49.6 12.4 4.2
48.8 12.2 7.6
47.3 11.825 12.3
46.4 11.6 14

The results was the following chart:

I ran the vehicle until it was clearly struggling and I felt that it would be harmful to discharge them any more deeply. The starting voltage was 12.75V, and the final ‘terminal’ reading was 11.6V.

Upgrading the System to 60 Volts

August 8, 2010


  • A battery of the same type that comes with the bike
  • A short length of 4mm wire the same grade as the existing battery connectors
  • 2 x 6mm “battery” ring connector, 30 amp grade


  • A screwdriver with socket and phillips head attachments
  • A Stanley knife or other sharp blade
  • A pair of crimpers
  • A ruler and marker pen

1) The Battery System

The Ego Scoota is powered by four 12V batteries connected in series to deliver a total of 48V operating voltage. The master terminals of the bank therefore consist of the negative terminal of Battery 1 and the positive terminal of Battery 4.

Reading the voltage across the master terminals gives a reading of about 48V, the total of all four batteries in the bank (slightly higher reading here, due to the full charge)

2. Upgrading to 60V

To add more power and range to the bike it is possible to simply add an extra battery in series with the existing ones to raise the operating voltage to 60V. The existing controller, power converter and other electrical components can tolerate this rise in voltage with few ill effects. There are, however some drawbacks to this system:

  • The 48V battery charger can only charge the original four batteries. When the bike is recharged, the extra battery must be isolated from the loop and charged separately with a 12V charger. The original 48V circuit must be temporarily restored for the duration of the charge by connecting together the leads from the new battery, thereby bypassing it.
  • When all five batteries of the new configuration are fully charged, the bike will not aways function straight away in this state, as the slightly higher voltage level of a fully charged system falls above the threshold required for the controller to function. It can therefore be necessary to give the bike a short ’round the block’ run in 48V mode before the charge has subsided slightly and it will once again function with the extra battery reattached. I have found, though, that immediately after a charge, leaving the headlights on main beam for a couple of minutes is sufficient to bring it life.

However, many people find the improved performance, power and handling of the bike well worth the added inconvenience, and unlike a ‘proper’, complete 72V upgrade – which requires a new controller and power converter – it is very inexpensive to do, requiring nothing more than a battery, a lead, and a couple of connectors. Much of the actual work involves cutting a cavity in the underseat recess to house the new battery so that it sits on top of the existing bank.

If the 60V configuration is no longer required, it is just a matter of removing the extra battery and closing the circuit again to return it to its original condition (with the exception of the hole in the underseat compartment). This upgrade can also be used as a ‘halfway’ house to a full 72V system, where only one half of the hole required for a new two-battery bank is added.

3. Removing the Seat and Enclosure

The seat is attached by two flanged, hex-head bolts front and rear, and one phillips head screw. Remove these and put them somewhere safe.

Front under-seat compartment (one bolt already removed)


The seat lid is held onto the enclosure by one bolt which comprises its hinge. It is best to remove this while you are cutting the hole, as it makes the work much easier.

4. Cutting the Hole

Put your battery on a piece of paper and use it to trace an outline. Then cut out the square you marked out. This can be used as a template to mark the area of the seat enclosure that needs to be cut out.

The underseat enclosure already has a groove cut into it as a guide for cutting a hole for two batteries (for a 72V upgrade). I’m making one side of my hole run along this groove, as it makes cutting easier. I’m not using the whole length they suggested though, as I want my battery to be a very snug fit so it doesn’t rattle around.

Mark it with a ruler and pen, or just score lines along with the blade of your knife as a guide to where you need to cut. Then carefully cut through the base with a fresh, sharp blade. The plastic is tough, so be patient.

Test out the hole you’ve cut with the battery. Trim to size where necessary. Here is my finished hole with a nice snug fit.

5. Assemble a Battery Lead

Next you’ll need to assemble a lead. Just measure up and cut off enough wire to reach the negative terminal of your battery in situ from the positive terminal of battery 4, then crimp the 30 amp ring connectors to the ends of your piece. Make sure you have some suitable screws to secure the cable to the battery heads.

6. Modify the Battery-Meter Setup

The problem with upgrading to 60V, is that the power-level readout on the instrument display expects to receive only 48V. If it is run at 60V, then it does not function properly; it permanently displays a ‘full’ battery level even when the bike finally grinds to a halt completely out of power, as I found out the hard way!

My solution to this was to simply upgrade the battery meter. If you’d rather not go to this trouble, and simply want to continue using the existing meter with the higher voltage, there are a couple of workarounds available in Mike’s Upgrade Guide. One involves running a line from the battery meter to the positive terminal of the fifth battery to get the desired 60V and wiring a relay so it is initiated by the ignition system. The other involves using a zener diode to modify the incoming voltage. Check the Electric Motoring Forum for further discussion of these options.

7. Wire up the Extra Battery

Remove the existing terminal connector from the positive terminal of Battery 4. This terminal connector will need to connect to the positive terminal of your extra battery, which will become the new master positive terminal of the 60V system. In its place (on Battery 4), attach one end of the battery cable you made earlier.

Re-attach the seat and compartment to the bike, and run the two loose wires (your own cable and the battery cable) through what remains of the access hatch so that the hole is free to slide your battery into.

Slide the battery into position and attach the leads to the terminal. The existing cable with the red hood goes on the positive terminal remember! The free end of your own lead goes on the other, negative, terminal

All done! Now turn the circuit breaker back to the ‘on’ position. If it snaps back off again, you’ve done something wrong and will need to check your wiring.

Otherwise, the chances are that eveything is fine. Turn the ignition key to make sure the instrument display comes to life as it should.

Then hop on and take it for a spin round the block, and see the difference!

REMEMBER: You cannot recharge all the batteries in the 60V configuration with your 48V charger. It will not work. Whenever you need to recharge, you must take the leads off the extra battery and couple them together with a suitable nut and bolt, so that you bypass the new battery and return the configuration back to 48V for the duration of the charge. The extra battery must be recharged separately with a 12V charger, but you can do it in situ if you wish.

The Joy of Sixty Volts

August 6, 2010

60 Volts are Go! 🙂

Battery Woes

I was just one 6mm ring connector short of my home-made battery lead that I’d need to hook up the extra battery and reach the milestone 60v upgrade. So I made the short trip to the local Halfords to try and find a connector more substantial than the flimsy items they had in stock for 12v wiring. One overpriced purchase later, I was heading back home with a pair of 30 amp connectors pretty much identical to the one I already had in place, when I heard an odd rattling noise. All was not well.

I stopped to have a look around and quickly saw the problem, the nut and bolt securing the rear mudguard to the left side of the frame were conspiciously missing, frustrating as I’d only done 70 miles on the bike from new. It was double annoying because yesterday the throttle practically came off in my hand in the middle of a journey because of a small, poorly tightened alan bolt securing the throttle housing to the bike. Quality control has something to be desired when they’re not properly tightening the nuts and bolts that hold the thing together.

The previous day the bike batteries had had a full charge, and I left the extra, brand new battery on charge with my Optimate 3 12v charger hoping that I would be all ready to connect up to the bike in the morning. However eight hours later a “weak” warning light came on, indicating that it thought there was a problem it. I took the clips of the battery, fiddled about a bit, and switched the unit off then on again, and the light promptly disappeared, going back again to the orange ‘charge’ light.

It seemed unlikely that a brand new battery would fail, and it occurred to me that, though practically unused, the charger had been just lying around for some years, and might have just succumbed to some kind of electronic senility. The voltage across the terminals was about 14v, which I was told is about what I should expect.

There was only one way to settle it. I’d hook it up to one of the bike batteries, isolating it first, and see if I got the same results. If the near-full battery it was still on orange “charge” after a couple of hours, then it would be some issue with the charger, and not the battery.

The Big Day

Lo and behold, two hours and a couple of forum posts later, the light was still steadfastly orange. I’d finished off my battery lead and was all set to hook it up, and decided that enough was enough. The suspense was killing me and I was dying to see what difference the extra cell would make. I knew that a full charge of all the batteries can result in the controller shutting down until a little of the oomph has been taken out of the batteries, but between picking up my final parts and finding a replacement for the vanishing nut and bolt, I’d done three or four miles this morning and figured that this should be more than enough.

Nig described how a quick run round the block in 48v mode was sufficient to take the edge off the charge enough for the voltage to drop that tiny bit below the threshold permitted by the bike’s controller.

This kind of messing around, plus the fact that the extra battery has to be taken out and charged separately did initially put me off bothering with the 60v fix; I figured I’d just skip straight to the full 72v upgrade, complete with new controller and homemade converter. But as things progressed, I realised that some of the components – such as 72v controllers and chargers – are only readily available in China, and that my orders may take weeks to arrive. 😦

Since I’d have to eventually cut a hole in the underseat compartment anyway, I might as well do this in half-stages, and see if the new battery really did make that much difference. After all, all I had to do was build a suitable cable, make a hole to accommodate the extra battery, and wire it in.

I have to admit I was more than a little nervous though. So many things could go wrong. Changes have been introduced unannounced between runs of this model (such as the new 63 amp circuit breaker), and I was concerned that some change might have been introduced that would give me nothing but a fried controller for my trouble.

So it was with a certain amount of trepidation that I switched the circuit breaker back on, and gingerly turned on the ‘ignition’, wincing slightly in anticipation of some noise that would signal a serious failure of some component. But I needen’t have worried. All the lights on the display sprang to life in their usual fashion. But the proof of the pudding would be in the throttle, I thought, and so hopped on and gently opened up the throttle.

The Test Ride

The difference was quite obvious right away, the response was much sharper, pulling away and accelerating up through to 25 mph with pleasantly surprising swiftness.  Whereas before, the acceleration felt progressively soggier as you got into the twenties, now it cheerfully pulled my 92 kg mass (+ 4.5kg chain) past thirty before starting to flag, and maxing out at about 34 mph (clock speed) on a dead level straight, as opposed to the 28 mph I was getting before. It felt like it had finally found its legs.

In heavy traffic I didn’t feel quite as apologetic about the ubiquitous car hovering behind, waiting impatiently for a chance to get past me, and the slow pace now seemed more in keeping with the appearance of what I was driving – a low-power moped capable of a (real) 30mph or so. Hill climbing was also less of a struggle, with speeds staying above 20 mph on all but the steepest of inclines.

Though there were still long periods of holding the throttle full on and really wishing there was more juice to draw on, I fully expected this, and look forward to the next rung of the ladder when I have all the parts for the full 72v conversion. It feels much more like a real bike now, and less like an egged-up mobility carriage.

So all in all, I’m delighted with the improvements that such a minor change has brought, and think it is well worth the inconvenience of removing the battery every couple of days or so. I plan to just short the cables with a nut and bolt so I can charge the on-board batteries in the usual way. All I need now is a charger that actually tells me when I’m done charging…

The Big Speedo Debate

This brings me to another point that has been muched discussed amongst Ego riders, – that is the extent to which the speedometer over-rates the actual speed. It’s well known that most speedometers do over-rate speed to the tune of 10% or so, but the Scoota makers – desperate to make the factory Ego look less pathetically slow – have taken the piss a little with their display.

I was fortunate enough pass one of those read-your-speed signs as I was struggling up an incline on a main road. As it flashed “19 mph – Thank You” at me, I noticed the speedo needle, which was wavering somewhere between 22.5 and 23.5  mph. Based on this observation I’d put my clock at +17% of the actual speed. So I think a fair assessment – based on individual variation – is that the speedo on the Ego Scoota over-estimates to the tune of 15-20%.

Based on that, this conversion chart might be useful as a guide:

Actual — Car Speedo — Ego Speedo

10 mph —- 11 —————- 11.5 – 12

20 mph —- 22 —————- 23 – 24

30 mph —- 33 —————- 34.5 – 36

40 mph —- 44 —————- 46 – 48

Wire we waiting…

August 6, 2010

What a day! What does a person have to do to find a piece of red wire? I tried a B&Q the size of a small airport, Halfords, then Maplin, then Screwfix, and none of these people could offer me a simple length of wire in red.

A stickler for detail, I was determined to get hold of the short lengths of red and black wire of a suitable grade for the 72v DC converter part of my upgrade project, and after 15 miles of hilly terrain I really was starting to sweat that I wouldn’t make it home, as one by one the green lights on my power meter dropped off, leaving me descending into the dreaded orange-zone. Fortunately I made it back home with juice to spare and gratefully plugged it back in for a long recharge session.

Finally, in desperation, I did the one thing I really would have preferred not to. I cannibalised my older, more unattractive 12v charger for the small length of red and black wire that I would need. I tried to unsolder the clips so I could resolder them further down on the ends of the newly shortened wires, but my soldering iron couldn’t penetrate whatever they’d done it with. In the end I spliced the wires back together, and wrapped them in black and red insulation tape, so it still works and the scars of the operation are barely visible.

But all in all it was a pretty productive day. I completed, photod and documented the 72v DC converter build, and started the upgrade path to 60v. I was going to go straight to 72v, but it looks like the 72v controller could be some time in making its way from China. I bidded on one in ebay, but got gazzumped in the last 45 seconds – aargh!

My neighbour, a retired electrician, kindly found me some suitable wiring to extend my existing battery circuit to the extra cell, and found a terminal ring of the right size (but alas only the one), something that B&Q did not seem to stock (they only have assorted bags of little flimsy ones).

I also cut a one-battery hole in the seat enclosure, and managed to make it a beautifully snug fit. Once I have one more of those terminal rings for the end of my lead, I’ll be in business. The bike’s fully charged and the extra battery I got is on the optimate charger. Hopefully tomorrow I’ll find someone who stocks a decent range of terminal rings to tide me over to when I switch to the welding cable-grade setup that Ian and Mike already have in place. The big chunky rings for that arrived today, but the cable itself is still on its way.

At least I found some bolts that would fit my battery, they’re too long, but I can bodge the connection with extra nuts and washers until Northwest bikes can send me some of the proper ones with the unsmashed topbox they’re shipping me.

So Building a 72v DC Converter is now in place, and I’m a good way into the 60V upgrade. Hopefully tomorrow I’ll be in a position to try it out with the extra battery.

Building a 72V DC Converter

August 5, 2010

NOTE: This section was written before I found a supplier for a quality 72-12V converter. The unit has exactly the same 3-way mini-connector as the 48V converter that comes with the bike, and can therefore be mounted ‘plug and play’ in the same position as the old one. I would recommend this above building your own out of a PSU, as it’s built for this specific purpose, is more efficient and works out cheaper too.

Once batteries are added to the electrical system to raise the system to 72V, it is no longer possible to use the existing 48V factory converter which drives the 12V electrical sub-system. 72V converters are available to buy, but they are usually aimed at the marine market, and prohibitively expensive.

By modifying a more common, and relatively affordable LCD TV power supply unit, a perfectly adequate converter be fashioned to replace the existing redundant unit.

Mike of the Electric Motoring Forum has already documented this in his guide “Making the new DC converter”, but I’m also doing this as part of my ongoing upgrade activity. Much of this has therefore already been covered in his guide, but I have tried to improve upon the existing documentation by adding  more detailed explanations of the procedure along with a simplified explanation of the reasoning behind the rewiring schema. There are also quite a few more illustrations for clarity, and details of how to deal with the wiring in PSUs that don’t follow the circuit board layout for this particular model.

The modification to the unit is fairly straightforward. No extra parts need to be added. There is just a small amount of wiring and some soldering to do, and can be accomplished in a couple of hours or so by any reasonably capable DIY hobbyist with basic soldering skills.



  • A phillips head screwdriver
  • A soldering iron and solder wire
  • A multimeter
  • A pair of wire snippers
  • A crimper or needle-nose pliers
  • A Stanley knife or other sharp blade

1) The LCD TV power supply unit

The power-supply unit as it comes consists of a box which is powered from the mains via a lead (not shown) plugged into a butterfly socket on the front end of the unit. The circuit board converts this into a 12V DC/1.5 amp power supply to serve an LCD display or TV via a 3.5mm plug at the end of a lead leaving the back end of the unit.

The circuitry, however, is capable of making a similar conversion on the 72V DC signal supported by the upgraded battery system.

2) Check the Unit

The first thing to do is plug the power supply unit (PSU) into the mains to make sure that it actually works. Once it has been tampered with, obviously it cannot be returned for a refund or replacement.

Plug in the unit and use a multimeter to confirm that the unit is giving out around 12V DC. Hold one contact against the side of the 3.5mm jack, and insert the other into the hole in its end, like so:

When you’re satisfied that the unit is functioning, then remove the mains lead and leave it for a few minutes to make sure that the capacitors have discharged.

3) Open the Case and remove the Circuit Block

On the back of the case, four screws are located underneath rubber grommets at the corners, that are used as the PSU’s ‘feet’. Peel off the grommets and undo the screws.

Remove the circuit block from its case by gently sliding it upwards to allow the socket to slide from its runners. It may be secured in place by a blob of glue on the base, in which case you may need to gently prise it free with a screwdriver.

4) Remove the metal casing from around the Circuit Block

The circuit block inside is encased in a metal wrapper held in place by two small rivets. To release the metal casing, just make a small cut with the snippers and fold back the metal to free it from the studs.

Underneath the metal casing, is a plastic insulating layer. Remove that too and set it aside.

We are changing the layout so that both the input and the output of the unit are on the same end, and served by a single plug that is compatible with the motorbike’s electrics. The existing socket will therefore have to be removed so that we can wire our own in its place.

If your PSU circuit board is identical to this one, then the illustrations will be an accurate guide as to where you need to solder the three connections we have to make. However, if the unit is different, you will need to clearly identify where the connections from the socket meet with the PCB and make a note of them, substituting the locations on your own board for the ones here.

Either way, you won’t have to worry about the earth connection beyond removing the lead used by the existing socket. Only the live and neutral terminals on the circuit board are used in our new schema.

The first step is to de-solder the existing plug and remove it.

Next, we need to prepare the output lead. Cut the plug off the output wire to leave about 12 inches of the cord remaining. Then feed the lead back through the case to the other end, where the socket for the mains was originally located. Strip back the insulation to where it passes the end of the circuit board, revealing the 12V out, live wire (blue) and the neutral (bare copper strand) wire. (The insulation tape over the black wire is just there to cover a split I found on the wire).

Thread this through the hole next to the one you just removed from the neutral solder-point. It shares the same terminal and will be cross-connected with our input neutral so that they are shared.

Solder it and clip off any extraneous length.

Next take your red and black wires and solder them to where you just removed the two black wires. The Red will be your 72V input, and it will go to the live terminal on the board, and the black will go to the neutral terminal alongside where you just soldered the copper strand, neutral output wire.

N.B: The blue wire (12V output) runs back through the circuit block to the other end where it originally emerged. The ‘black’ I used has a red stripe running down its underside that is visible from this angle.

Next, you need to cut a small piece of plastic to fill the hole left by the original mains input socket. You can get this from some household item like the side of a shampoo carton or a plastic lid (I used a piece cut from a Lynx shower gel bottle).

A square 22mm x 19mm forms a near exact fit. If you make the fit a little tighter, it can be held in place by the case itself once it is screwed shut, without the need for glue. Check the size of your cut-out by closing the plastic case around it.

Next, drill a 6mm hole through your plastic to feed the wires through which are to be joined to the 3-way motorbike connector.

Crimp the wires into the pin connectors for the 3-way socket, then push them through the back of the female end of the socket. The Black goes to pin 1, the blue goes to pin 2, and the red goes to pin 3, as they are viewed from the back (where the wires go in) with the latch facing down.

Refit the plastic and metal shielding, re-engaging the metal sheet with the rivets and securing with a drop of solder if required.

Finally slide the assembly back into its plastic case and screw it shut. If the plastic square does not stay firmly in place then a dab of glue, like epoxy resin can be put along the edges of the recess.

You should now have a fully functioning, plug-and-play converter that is compatible with 72V electrics!

Ego Scooter System Schematics

August 4, 2010

5.1. 48/60/72V Simplified System Schematic (above)


5.2. 48V System Schematic (Thanks to Ian, Electric Motoring Forum)


5.3. 12V System – Right Handle Control Unit Schematic

5.4. 12V System – Left Handle Control Unit Schematic

5.5. 12V System – Instrument Panel

5.6. 12V System – Front Lights Schematic

5.7. 12V System – Rear Lights Schematic

12V System Schematics by Zenid

At last I can see my Turn-Signals!

August 3, 2010

Today was like Christmas!

As well as getting a new (well, second-hand) gas oven picked up and fitted, I also got loads of electronic bits and pieces in the mail, some for the LED bulb upgrade I wanted to get done ASAP, and the rest for the 72V upgrade. I’m meticulously documenting everything I do, so hopefully future upgraders will have an easier time of things. The LED indicator warning light upgrade is now fully documented, complete with photos, expanding on Ian’s original instructions.

Amongst my haul that arrived this morning was the LCD PSU to convert into a 72V adaptor, and the three-ways connectors to build it. I just need to figure out how to supply power to it in its original condition so I can test that it works before I start tearing it apart, which should be tomorrow! I also got the 12 volt 1 amp relay and the 1N4148 diode, which are needed for the power meter to work properly with the upgrade. I’ve also excavated most of my electrical tools, crimpers, and wiring bits and pieces, as well as a couple of decent 12V battery chargers.

The downside of purchasing small components is that it is now virtually impossible to buy single resistors, or even packs of ten or so, so I ended up buying Maplin’s pack of 480, which wasn’t particularly pricey, but now means that I will probably never get to use a fraction of them even if I live until a million. If anyone wants resistors, they can PM me and I’ll give them a c/o address where they can send an SAE to me. Payment can be in the form of a first class (unused) stamp or two – I can always use those…

Thanks, again, to Ian for his continuing support and help with identifying and locating the bits I’ll need, and to Mike for his existing documentation on the PSU modification and battery & controller system upgrade. I’ve decided I’m going to build bigger and beefier battery cables while I’m re-building. The welding-grade cables that Ian and Mike are using look like an excellent idea.