Date:         Tue, 18 Sep 2007 09:43:28 -0700
Reply-To:     David Kao <dtkao0205@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Kao <dtkao0205@YAHOO.COM>
Subject:      Re: LVC adding LED interior lighting
Comments: To: Larry Alofs <lalofs@GMAIL.COM>
In-Reply-To:  <96c89c360709171428v6a3e01d8r7348322f9e508e0a@mail.gmail.com>
Content-Type: text/plain; charset=iso-8859-1

--- Larry Alofs <lalofs@GMAIL.COM> wrote:

> If you have two identical 6V devices, you could probably just connect the
> two in series and run them both from 12V with no problem.
>
> Larry A.

Unless the two LED devices are really exactly identical and remain identical
throughout the entire service life it is really not a good idea to connect
them in serial. It can be done but if they are not exactly identical the
voltage drop on each one of them may not be 6V equally.

If one has lower internal resistance than the other, it will receive less than
6V and the other will get more than 6V. Even each has its own current limiting
resistor one will bear more voltage than the other and will be brighter too.
One will die earlier than the other as well.

If connecting them in serial is really desired then you can pair those that
will equally divide the 12V supply and emit equal brightness.

I have a LED flash light with a single 3 watt LED in it. It is incredibly
bright. You won't need more than a few of them to light up the entire interior
of the westy like day light. It seems ideal for a single 12.8V (car battery)
to power 3 of them in serial. But need to make sure each one gets 1/3 of the
supply voltage. The flash light takes 3 AAA cells to power the 3 watt LED.

David



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