Upgrading the System to 60 Volts

Parts

  • 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

Tools

  • 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)

Rear

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.

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6 Responses to Upgrading the System to 60 Volts

  1. Nils Moller says:

    I did my 60V upgrade similar to this but modified my original 48V controller by putting a 47k resistor in series with the voltage sensor wire. This way the cut off voltage is raised and the fully charged bank does not make it cut off because of too high voltage. My original cut off was about 43V low and 64V high. Now it’s about 49V low and 70V high which is just perfect for 5 fully charged batteries in series. When bypassing the resistor with a switch it allows to run on 4 batteries again or use it as a reserve setting with 5 batteries which is good when using old batteries with higher inner resistance.

  2. time for a gueuze says:

    Hi there, can you define which wire is the voltage sensing wire, would it by any chance be the red wire from the ign switch into the controller

  3. time for a gueuze says:

    Hello thanks for replying, above Nils Moller says” put a 47k resistor in series with the voltage sensor wire* to raise the cut off window of the controller, I assume he means the wire from the ign switch to the controller but he was not specific and also the wattage of the resistor? can you calrify this?
    I was also thinking of putting the 5th battery on a relay to only use as a boost when required for hills and a sort of reserve tank when the batteries are getting low, also switching in/out the 47k resistor and the battery meter zener with the same relay, can you see any problem with this?

    Thanks from Time for a gueuze.
    (a retired electronics engineer with nothing better to do)

  4. Roger says:

    Do u no the easiest way to remove the batteries from the bike? And where to buy replacement from?

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