We’ve got the power: Part 3.

When you are producing power 24/7 you don’t need much in the way of storage, unlike in a solar system. The sun only shines for half the day so to make use of that energy at night, you need to be able to store it in deep cycle batteries. Our waterwheel produces power constantly and used to charge 2 massive truck batteries. When we used power, it came from the batteries and usually what went in from the waterwheel was more than we used so they held their charge. The electric car uses much more than the batteries could hold and sucked them dry pretty quickly so to be able to charge the car, we needed to upgrade the power system. It was something we should have done a long time ago.

The Man of the House working on the old power system. The batteries are at the back, inverter is obscured by the power controller (white box on the wall)

We were never too concerned about security of supply but we rely on power as much as anyone else these days to run our fridge and freezers. So power cuts that last days are not as easy to shrug off as they used to be. We bought our car from Steve Greenwood at Drive EV in Taupo (https://www.driveev.co.nz). He referred us to Carl Barlev, founder of Blue Cars in Auckland (https://bluecars.nz) to upgrade our power system. Carl had been using the batteries out of the electric Nissan Leafs for alternative power systems for houses.

It can be expensive to set up an off grid power system, lead acid batteries usually account for the bulk of the cost. It would cost us about $20,000 for lead acid batteries for the size system we needed. You should get at least 10 years out of those batteries. Carl supplied our batteries for about a quarter of that. We don’t know how long they will last but we can replace them 3 times for the cost of the lead acid equivalent if we have to. So far they are performing brilliantly.

New power shed going up.

Our old system was messy, would get very hot in summer and only the Man of the House had any idea how it worked. We needed to up our game, for safety’s sake if nothing else and now have a purpose built shed to house our system. Switches are labelled and even I know what to do in an emergency.

49 battery modules arrived in 7 wine boxes.


Our new inverter/controller took a bit of setting up. It’s the latest technology and proved much smarter than we are and didn’t come with much in the way of instructions. And being so new, local support hadn’t caught up yet.  The controller protects the batteries from over charging and from too much discharge. It will disengage the waterwheel when the batteries are fully charged or turn the power off if they get too low.

The new power system. The blue box is the inverter/controller. Dc power from the waterwheel charges the batteries, is converted into ac power by the inverter/controller for use in the house.

Being winter, the stream is full and the unthinkable has happened. We have too much power. So when the car is fully charged and the house is humming, there is power left that has to be used. Just when most people are trying to save as much power as possible, we’re trying to think of ways to waste it. In summer we use the excess to heat our water but the fire does that in winter. The MotH bought a spa pool off Trademe, cheap as chips because none of the electrics work and has turned it into a hot tub, heated with our excess power. But even the hot tub can only be so hot before turning into a giant soup pot so we tried a heater. The house has never been so warm and the waterwheel won’t freewheel and flog itself and the power system to death. All is well in the world again, for now.

Some useful websites:

Drive EV – For amazing electric car sales – https://www.driveev.co.nz/

Blue Cars – For electric vehicle information & rentals & alternative energy –  https://bluecars.nz/

Power Spout – for DIY alternative energy systems – http://www.powerspout.com/



  1. OMG that was so funny!! I just had Martin complain to me because our power bill was $250 for two month which I thought was fairly good considering how much we have used the reverse cycle this year….. oh & forgot to say the money comes out of my account to pay the bills anyway lol!! Ross is definitely very talented & has done a fab job…… maybe it’s time to get a second EV?

    Liked by 2 people

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