Educator

While not quite a renovation (unless one renovates the lawn every week when one uses the lawn mower ) I was curious if anyone has any experience with a solar charged brushless electric lawn mower?

I don't understand solar stuff or electrical stuff but lots of y'all seem to by the posts in this ara of the forum.

We recently purchased the new solar charged lawn mower which is being sold at a few retail outlets in the Boston & Seattle areas as well as throughout Canada that uses a solar charging station so the mower is completely off grid.

We chose the 19 inch model (also comes in a 21 inch model), is self propelled, etc., etc., (i.e. does all the stuff a mower can or should). The solar charging station was easier to install than I thought and once the batteries become fully charged in the next day or two we'll have our first test run. We have started to write some articles in our blog with some pictures,etc. which you can view here using this link to the first article.

But, have I gotten myself into a mess? Is this brushless motor technology for real and if so, which is better, brushless or a brush type of motor for an electric lawn mower?

As well, what about the solar charging station? How long do those panels actually last? If I lay it horizontal (which I have done) could it be damaged by a hail storm or a strong rain storm?

Thanks for your experinces,
Dan

micromind

It'll be interesting to see how this pans out, but I'd bet it works ok.

Brushless DC motors come in two types that I know of. The first is a true DC motor that uses electronic commutation. In a brush-type DC motor, current is transferred (commutated) to the rotor (the part that turns) through brushes that ride on segmented bars (the commutator). In the brushless type, this is done electronically.

The second type uses a DC source to power an AC motor through an inverter. One example of this is the variable frequency drive. The speed of most AC induction (brushless) motors depends on frequency, not voltage. (There are exceptions, like variable speed ceiling fans, etc.). If the frequency of an AC motor is varied, with an appropriate voltage change, its speed will change accordingly, but it can maintain its full rated HP or torque. VFDs can be applied to motors of less than 1HP or more than 1000HP.

A VFD works like this; first the incoming AC power is converted to DC, then is re-inverted back to AC at whatever frequency is selected. This is necessary because the frequency of the incoming AC power cannot be changed.

If the VFD is fed with a DC source on the DC bus, it'll work just fine. The inverter part doesn't care what the source of the DC is. It only cares that it is DC power of appropriate voltage and current.

I suspect this mower uses this type of technology.

When VFDs first came out, they were notoriously unreliable. In my experience, about 8 out of 10 failed in the first 6 months. They're much better now, I doubt that 1 out of 100 will fail these days.

I think the biggest problem you'll have is batteries. They're temperature sensitive, don't like to be left uncharged for any length of time, and don't like to be overcharged. Hopefully, there's some sort of charge controller between the solar cells and the batteries.

Rob

Educator

Hi Rob,
Thanks very much for this. I certainly appreciate the time you took.

Yes, the solar charging station has a 'controller' which is supposed to prevent the batteries from over charging. And, yes, the manufacturer's instructions state to leave the batteries in the charger when not being used in the mower. As well, per the manufacturer's information, we won't be leaving the batteries out in the winter as they are not supposed to freeze otherwise some type of damage can occur.

Dan