Chrispydoc
Prominent Member
worth knowing.....
Interesting one.Sorry, what I meant was, are there more or less losses (e.g. through heat etc.) on one or the other, in other words (being a tight Yorkshireman) would there be a difference in the cost to charge a fixed amount at a fixed electricity rate.
It isn't a charger. It's basically a relay, with some electronics to control the relay and generate a PWM signal. The actual charging is done inside the car, with the On Board Charger. The granny brick is properly called an EVSE (Electric Vehicle Service Equipment), but it's a losing battle trying to correct people on this.The granny charger is quite small for a 3kW charger but I suppose it is possible.
Slow AC charging will spend a slightly larger proportion of the overall energy (and hence cost) running pumps and other overheads. So medium charging (at a wild guess, something like 7 kW) would be the most efficient way to charge, charging the battery with the fewest pennies.are there more or less losses (e.g. through heat etc.) on one or the other, in other words (being a tight Yorkshireman) would there be a difference in the cost to charge a fixed amount at a fixed electricity rate.
I think the Zoe system you refer to actually uses the motor windings as a filter to stop any noise spikes getting into the rectification/charging system. It’s a good idea in some ways, but is presenting the resistance of those same windings in series & this wasting energy. I saw a video about this on YouTube recently.Slow AC charging will spend a slightly larger proportion of the overall energy (and hence cost) running pumps and other overheads. So medium charging (at a wild guess, something like 7 kW) would be the most efficient way to charge, charging the battery with the fewest pennies.
Edit: Some Renault Zoes, for example, have an unusual charging system with large overheads; they don't recommend very slow AC charging for that reason (you might get up to 80-90% of the power from the AC in swallowed up in overheads).
My understanding is that the Zoe uses the motor controller as a big part of the AC on-board charger, and the inductance of the motor is a necessary part of the power converter. This seems like a clever idea, making use of high-power electronics that is already present in the vehicle, and reduces weight and cost. A colleague and I considered this design when converting an mx-5 to electric; the first design used an off the shelf VFD as the motor controller. But it turned out to be be physically too big for the compact convertible.the Zoe system you refer to actually uses the motor windings as a filter to stop any noise spikes getting into the rectification/charging system.
Indeed yes. 5.5p with Octopus go, or “free” using solar or stored solar. It isn’t actually free of course as I had to buy the solar and storage systems in the first place……I take the point about lower efficiency when using low power charging systems.
However, if using a granny charger on a home electricity supply you will probably be on a pretty low £/kW rate and thus still get a low cost recharge.
Chargers are wrongly named.Well the charge time (from empty) of 18 hours corresponds to 3kW constant charge. The granny charger is quite small for a 3kW charger but I suppose it is possible.
This is adding to my education. Before I got my EV the only thing that I knew about electricity was how to wire a plug.Chargers are wrongly named.
The AC "chargers" - Granny and fast are not actually chargers.
They are charge controllers which switch on and off the mains electricity and signal to the real charger inside the car how much it is allowed to take from the supply.
The size only has to be big enough to contain a power relay, protection devices and a circuit board, so Granny and a 7kW are similar sizes.
I think they make them bigger so it looks like you are getting something substantial for your £500 rather than a box and £20 worth of components.
The charger in the car takes the mains power and converts it to DC at a voltage high enough to charge the battery.
(The mains 10 amps probably results around 5-6 amps going into the battery).
Rapid chargers are effectively a much bigger version of the charger that is inside the car.
They convert AC to DC and supply DC direct to the battery.