The regulator or charge controller is an essential bit of kit in any renewable energy system - without it deep cycle batteries can become damaged through over-charging. However just as dangerous is choosing the wrong charge controller. Here's why.

It can be very tempting to use the PV controller to regulate both the wind and solar energy systems. What's right for solar isn't necessarily right for wind though. When batteries become full PV controllers work by electronically disconnecting the PV panels from the batteries or 'shorting out' the panels so that the batteries are not in danger of becoming over-charged.

This is bad news for wind turbines. Electronically disconnecting the turbine from the batteries or shorting out the turbine (stopping it in what is called 'dynamic braking') can damage small wind turbines. Under high wind conditions when the batteries are more likely to be fully charged dynamic braking can be overcome by the force of high winds. This leaves the turbine sending the generated current through the short circuit and back into itself. This is bad for the turbine and will often result in a burnt out stator.

Furthermore this frequent stopping and starting of the turbine can be bad for the batteries themselves as it will cycle the state of charge more quickly. This can reduce the length and quality of service that the deep cycle batteries can offer.

Off loading excess power is best

The approach here at Leading Edge Turbines is to off load excess power to a dump load and the charge controller's job is to facilitate this. Some other micro turbine manufacturers use a charge control system that switches the turbine off when the batteries are full. This is no doubt why we've had quite a few calls this winter from people complaining that their turbine has burnt out and can we help them!

The charge controllers we recommend are our own DL-300 Diversion Charge Controller the Morningstar TS-45 and TS-60 Diversion Charge Controllers and the Xantrex C40 and C60 controllers. The Morningstar and Xantrex controllers must be set to 'diversion mode' and the controller and its dump load wired straight into the battery just as you wire the wind turbine straight into the battery. The dump load then acts like an 'overflow' for your batteries - excess power that the batteries cannot absorb is sent straight into the dump load and converted to heat.