The Mad Professor

The circuit is a little old but the principle is sound enough.

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It may seem like a good idea at the time , but never stir your cold coffee with a soldering iron.

Paul Obrien

Sounds like a very slow way to charge a battery 9V@30mA from 0.4V @1A.
The small panels ie solar garden lights, produce around 40mA.

The Mad Professor

I did say it was an older circuit , construction of solar cells has come a long way in the past few years and conversion efficiency has been improved. Yet they still remain an expensive item to purchase.

£1 (one english pound) gets you a single solar cell with the characteristics..
[lifted straight from the Maplin website]

Ouput voltage: 0.45V
Output current: 100mA (in bright light)
Dimensions: 47 X 27 X 7mm
Weight: 10g

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It may seem like a good idea at the time , but never stir your cold coffee with a soldering iron.

Paul Obrien

And with the circuit that would supply 3mA to a 9v battery, in bright light.
So in 1 day of bright light, no clouds, that would supply 30mA to the battery and as the battery would save only around 80% of the charging current it really makes for a slow charger. If you were to buy 16 of the solar panels you could charge a 7.2 PP3? in 1 hour

Hero999

It doesn't stop it from being a clever little circuit though.

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oldtimer

Solar panels cost about $5 a Watt. I bought a 110 W about 18 months ago at around $550, hurricane Wilma stole it though.

bryan1

Ouch I've got 14 kaneka 65 watt thin film panels on the house and 8-65 watt poly crystaline panels along with an 80 watt panel on my shed roof. I'm glad we don't get hurricanes around here or I'd be stuck running gensets just to turn a light on if the winds not blowing.

Cheers Bryan

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