ixb(at)videotron.ca Guest
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Posted: Tue May 05, 2009 6:56 am Post subject: Solar chargers (was System Off Current Requirements...) |
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I'd suggest you read the specs on the solar panel. My local store sells
a variety of them and they seem to come with over-voltage and
under-voltage protection, even for the cheapest.
The Powersports 1W (80mA) charger is sometimes on sale here for as
little as $15, and it includes protection against both over charging,
and draining the battery.
You don't really need a lot of Power if you're just trying to top up the
battery during extended periods of inactivity. The alternator would do
a much better job if you're flying often.
Ian Brown
On Mon, 2009-05-04 at 13:08 -0700, David LLoyd wrote:
[quote] Carlos,
If you are using a solar panel for example that puts out 1/4 amp. max
current, then I would use a zener diode that is rated for 1/2 amp or
more. I don't know the cost of zeners these days. The higher current
types maybe nearly as cheap as the lower current models. Also, you
need to buy one that the breakdown step, Vz, occurs at or near 13.2 v.
If you can't find one at 13.2 then, get the next larger voltage.
If the next available is too high but is the only available type,
then, buy it, and some cheap 1 amp plain diodes as they can be used to
bring the zener break voltage back down to the desired 13.2. Each
diode connected in series with the zener, will drop the voltage
approx. 0.5 to 0.6 volt. Thus, if you have a 14.2 v. zener and put 2
diodes in series with it, the final result will be a zener looking
like it is regulating to about 13 to 13.2 v. which is what you are
looking for.
You also need a series resister to limit the shunted current in case a
short occurs somewhere, At this point, you need to find a buddy that
knows electronics and mention the idea to him and he will know how to
wire it up or even find a one piece device that is better than a zener
that is still cheap. You might wait until Bob returns and ask him the
same question as he is super current on all the devices available
today. I am a bit of a dinosaur being a retired EE engineer.
Dave
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