Upgrading the Power Cables

August 30, 2010




If you want to upgrade your system to 60V or 72V by adding the extra battery or batteries, it is a good idea to also upgrade the power-cables connecting the batteries to one another and the rest of the system. This is a good way to spend your time while you’re pulling together the other parts you need, or waiting for for your 72V controller or battery charger to make its way from China.

The simplified schematic below shows the battery arrangement regarding the addition of batteries for the 60V/72V arrangement.

For your upgrade, you will therefore need to replace the existing cables, and also add a couple more to wire in the extra batteries (or battery) you will be adding as follows:

  • Battery 1-2, 2-3, 3-4 & 5-6:  5 x 120mm (5″) BLACK
  • Battery 4-5:  1 x 300mm (12″) BLACK
  • Battery 6 to breaker switch input terminal:  1 x 450mm (16″) RED

When it comes time to wire in your new controller, you will need two more lengths of cable to run from the master positive (battery 6+) and negative (battery 1-) terminals. These following lengths will be connected to one side of an Anderson connector:

  • Battery 1 to Anderson Connector:  1 x 600mm (24″) BLACK
  • Breaker switch output terminal to Anderson connector:  1 x 120mm(5″) RED (though you may want to make this longer depending on where you wish to locate your Anderson connector for the final configuration)

Don’t take these measurements as gospel, they are for guidance only. They will depend on how you want to route your cabling around your system, or how much free play you like to have. The short lengths can be even shorter as they have so little distance to span and their length is taken up by a bend anyway.

Building the Cables

Most important of all, you’ll need one of these. It’s the only way you’ll get a good, solid connection. Use the orange section of the ‘jaw’ for these types of crimps.

Cut off the lengths you need (in this case about 120mm) for the four short lengths of battery-to-battery connector.

Take 10mm of the ends with a stanley knife or sharp blade. This should give you exactly the length of wire to fit it snuggly in the crimp-end of the 6mm lugs.

Crimp them with that honking great crimp tool. It requires a good amount of force even with the ratchet mechanism. If your hands aren’t so strong you might need to brace them against the floor and push down with your weight. Or else get Daddy to do it.

Next cut off a length of 10mm heat shrink and see to both ends of the cable (I just use a lighter to ‘set’ the heat-shrink). Neglecting this will leave you with hazardous lengths of exposed, live high-voltage cable

Beautiful. Just the bare minimum of exposed cable we need to secure our connections.

The final couple of lengths of cable that meet with the Anderson connector will not be needed until you are ready to install your new controller, these will need to be crimped at one end to the crimps used by your Anderson connector, so that they form a cable like this to be used in the final installation.

For the ends of the red cable running from Battery 6 to the breaker, and from the breaker to the Anderson connector, it is a good idea to tin them (that is, coat them in a layer of solder) so that they form a solid block that connects firmly with the breaker contacts.

And there you have it! The new wiring is now capable of carrying a whopping 170 amps, more than the ego’s motor will ever need, or can even withstand. Take a look and see how it compares to the flimsy wiring that it originally came with…

Thanks to Ian and Mike of the Electric Motoring Forum for pioneering this upgrade, and providing the details of the cables, connectors and tools required.

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