Hi, this is my first time on the forum and am hoping someone could give me some guidance.
I am looking into a project concerning charging 2V to 6V cells (charging at nominal + 17.5%) using solar and/or wind.
I reckon that the solar source would have to supply eight hours (daylight) at 1A and the wind source a lesser current over a longer time in a 24 hour period.
My searching has revealed that there are bucket-loads of people who would supply me with something that would do the job with plenty to spare, but the wasted energy would have to removed (probably through some sort of resistive network) which would then produce unwanted and potentially wire insulation damaging heat in a small protective cabinet. Also, the costs have to be at the bare minimum therefore there is no desire to pay for unusable energy.
The sources would, in many cases be remote with no way to put any excess energy back into the network - not that it would be worth a great deal anyway.
Has anyone got any experience of such a product or advice to where to look?
Regards
Malcolm

Hi Malcolm,

If heat dissipation is a limiting factor, then I'd suggest you go for a solar system. Either select a "self regulating" type of panel or a standard panel with a regulator which switches off the charge current when the battery is charged (rather than introducing a shunt load).

Most small wind turbines I've come across are not suitable for running open circuit as very high voltages can result.

In any event, I'd recommend you speak to a reputable supplier for detailed advice and help in sizing your equipment (eg, it would be overoptomistic to expect rated output from a PV panel for 8 hours/day).

Hope this helps

Jonathan

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Jonno

G'day Mal

If you are interested in a DIY approach, try using stepper motors as a wind generator. A real beaut is obtained by recycling a Fischer and Paykel washing machine motor. These are a 200W 3 phase machine with (as I recall,) 42 poles (14 per phase). The poles of each phase are wound in series for operation at 240v but you can rearrange the pole connections so that you place them in parallel and with enough prop you can generate all the current you will ever want at roughly 15V. Of course a machine this size is going to requre some outdoor dump resistors made from radiator or jug elements. On the micro scale you can use motors from old floppy drives powered by props bought ready made from the local model aero hobby shop. Have fun.

If warm dissipation is a restricting aspect, then I'd recommend you go for a solar system. Either pick a "self regulating" type of section or a conventional section with a regulator which changes off the charge current when power supply is energized (rather than presenting a shunt load).

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