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Thread: Solar Systems

  1. #1
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    Default Solar Systems

    Stuck in this predicament. We have multiple 24v solar systems with metros running 4 cm9. However they just don't do do much past 30mbit and we needed that faster yesterday. Figuring 24v was a sate bet we have some 24v specific hardware on one of these sites. Swapping out to multiple boards ruins the power budget (requires a switch), alix only does up to 20v. And one site has a 18-32v cisco 2955. Just all around not good!

  2. #2
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    Default 24 vdc to 18vdc Regulator ?

    Maybe a 3 legged adjustable regulator that pulls the 24Vdc down to a safe 18vdc. for the Alix.
    There are all kinds of little kits out there.
    You need at least 2.5 volts over the voltage you want to adjust the unit to.
    24 down to 18 or 20vdc is just about right.

    Something like this ought to work.

    http://www.eidusa.com/Electronics_Ki...Supply_Reg.htm
    Last edited by David L. Vrablic; 03-10-2011 at 06:42 PM.
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    I wonder what the efficiency of that is? I think two Alix use more than a metro. I wouldn't mind buying something that is over engineered. Just hate to trade another day of runtime for a voltage converter.

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    I just replace the clamp diode on 2 different alix 6d3 (new dual eth single wpci) boards and am running 24V into it. pcengines supplies the schematics for their boards. If there is a LM7805 voltage regulator coming off the voltage input of the board, you can go as high as 37V with the right clamp diode. I got the diodes at digi-key for 75 cents ea.
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    A word of caution. The Alix internal power regulators will die above 28V. One of the internals can take up to 35V but the main regulator has an absolute max rating of 27V. I have tested to 28V but after reading the specs I will not do that again. 24V is a great voltage, but you have to treat this as the maximum so you have some headroom for surges, etc.
    ..a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match..

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    Default Alix power consumption

    Quote Originally Posted by amp View Post
    I wonder what the efficiency of that is? I think two Alix use more than a metro. I wouldn't mind buying something that is over engineered. Just hate to trade another day of runtime for a voltage converter.
    I measured a Metro w/o any radio cards at 5.5 watts, and two Alix w/o any radio cards at 6 watts total.

    I agree you want to look closely at the efficiency of whatever step-down converter you use. Efficiency varies with load, so ideally you can find its graph of efficiency versus load. The worst thing to do is buy a high-efficiency converter that handles more current than you need, and whose efficiency is actually poor when run at the load you actually have.

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    I have been using some little constant voltage converters from solarconverters for any voltage matching I have needed. Something like a CV24-12-4A (18-36V input, 12V output at 4 amps continuous, 8 Amps surge). The standby current on these is about 15mA. and they are small enough to put near the board you want to run to reduce any power loss on the lower voltage. The WRAP and ALIX systems run fine with a 12V regulated source within a few inches of the power plug on the board.

    They also make converters to get 24 or 48V from 12V, or 12 or 48V from 24V, and 12 or 24 from 48V amongst others.


    Quote Originally Posted by amp View Post
    Stuck in this predicament. We have multiple 24v solar systems with metros running 4 cm9. However they just don't do do much past 30mbit and we needed that faster yesterday. Figuring 24v was a sate bet we have some 24v specific hardware on one of these sites. Swapping out to multiple boards ruins the power budget (requires a switch), alix only does up to 20v. And one site has a 18-32v cisco 2955. Just all around not good!

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    Default

    Quote Originally Posted by Stratolinks View Post
    I have been using some little constant voltage converters from solarconverters... ...They also make converters to get 24 or 48V from 12V, or 12 or 48V from 24V, and 12 or 24 from 48V amongst others.
    We tried these a few years ago after Stratolinks recommended them, and they've worked VERY well for us. We have all our solar/battery side on 12v, and convert up to 24 (Canopy) or 48 (METROS) and it works very well, with very high efficiency.

    That allows us to scale the solar/battery side one battery or panel here and there as needed, and also allows the battery/solar side to vary from 11 volts to 14.5 volts as it does throught some days, while the output is a constant regulated 24 or 48 all the time.

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    Thanks for the replies.

    I could not find the CV24-12-4A but some searching found this. I think its the most efficient one ive seen, while not being overkill.
    http://www.meanwelldirect.co.uk/prod...15/default.htm

    Is there any noticeable difference on alix boards when giving them 12v or 15-20v?

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