[RE-wrenches] unique battery bank design question

[Exeltech]

At the risk of sounding sarcastic (and I assure this is not my intent) .. to allow a DC appliance to wait and simply turn on when when necessary and not waste power when it is off would take a battery ..  internal or external to the appliance.

Something has to keep the appliance powered.  The best we can do is minimize the idle power consumption.

"Super capacitors" can provide some degree of backup for very low-power needs (micro-watts), but they too will go dead over time if not used, or when given a long-term power draw without being recharged (sounds like a battery again .. no?).

Dan


--- On Thu, 9/1/11, Darryl Thayer <daryl_solar at yahoo.com> wrote:

From: Darryl Thayer <daryl_solar at yahoo.com>
Subject: Re: [RE-wrenches] unique battery bank design question
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Thursday, September 1, 2011, 5:01 PM

I am both interested in the idle power, and the operating efficiency

This often comes up, but what does it require to allow a DC appliance to wait and simply turn on when when necessary and not waste power when it is off?  
Darryl



From: Exeltech <exeltech at yahoo.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Thursday, September 1, 2011 3:30 PM
Subject: Re: [RE-wrenches] unique battery bank design question
 




Hi Jason,

Well designed off-the-shelf converters can achieve 90% efficiency, and as you mention, this will vary a bit depending on the rated output current of the converter vs. the actual load current.

I've designed and built  24V @ 25A to 12V @ 50A converters for my own use that are in the 95% realm.

Your mileage may vary.

Dan


--- On Thu, 9/1/11, Jason Szumlanski <Jason at fafcosolar.com> wrote:


From: Jason Szumlanski <Jason at fafcosolar.com>
Subject: Re: [RE-wrenches] unique battery bank design question
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Thursday, September 1, 2011, 3:07 PM






Dan,
 
What kind of efficiency level (%) can you get out of a DC-DC supply on a small load, say <5A @ 12V with a 48V->12V converter? Is the efficiency level highly variable depending on load as a percentage of the converter’s maximum capacity, or is it pretty constant?
 
I run into this once in a while, so this piece of information would help me make some better decisions.
 
Thanks,
 
Jason Szumlanski
Fafco Solar 


 
 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches at lists.re-wrenches.org Options & settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
-----Inline Attachment Follows-----

_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110901/596f5ccb/attachment-0003.html>