Solar Powered Lawn Mower

The message I posted, re: Final Yr Project, is in relation to this.

I want persons to comment on the choice of photovoltaic cells and suitable battery for the solar lawn mower I am going to build for my project.

Thanx

Reply to
Adrian Jamaica
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You're not going to be able to get enough power from the solar cells themselves, unless you have at least 4 m^2 of solar cells. You'll have to charge the battery first, and then use the mower. Better yet, just have an electric mower you can charge up at a fixed solar cell during the week, and disconnect the solar cells and use the mower by itself.

You'll probably want NiCD batteries (since they're usually the winner as far as discharge magnitude goes), and lots of them. Li-ion or NiMH usually can't provide as much power per kg as NiCD can, although they have a higher energy density.

Assuming you use your mower for t minutes and your mower uses an average of p kilowatts, you'll need:

p*t*(1000w/kw)/(60min/hr)=x watt-hours of energy

So if you put some numbers to that (say 30 minutes of mowing and 2 kw average power), you'll need about 1000 watt-hours. Knowing that NiCD can store about 40 watt-hrs per kg, you'll need about 25kg of batteries. Not exactly a small battery.

Hope that helps, Dave

Reply to
David Harper

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