[MLB-WIRELESS] New Node to be

[Ratbaggy]

Hi David,

The Sparklan radios that we have in the hop between Templestowe Lower and 
Kangaroo Ground draw 200 mA at 12.5V (2.5 Watts).  A WRT54G draws 250 mA at 
12.5V (3.1 Watts).  The R100 draws 800 mA at 5V (4 Watts) but also seems to 
run OK at 4 volts for the same current consumption and a 20% reduction in 
power to 3.2 Watts.

The power consumption does go up a bit when you load them up with traffic.

The Sparklans are basically a WRT54G minus the 5 port switch with half the 
flash memory but happily run the Freifunk flavour of OpenWRT.  We have these 
sorted out pretty well now and they run 1.2 Megabytes/Second real throughput 
on our 10 km link.

I feel fairly confident that we can take our pick of the above units.  We 
may get away with another radio and that would be a bonus.

For example, with a Sparklan and a WRT54G we are at 0.45 Amp for a total of 
10.8 A/H per day, definitely worth a try.   ...and with a fully charged 
battery, 18 days of backup from the 200 A/H batteries!

With a Maximum Power Point switchmode regulator (expensive) you can get 
almost all of the available energy from a solar panel because it matches the 
impedance of the panel to that of the battery in effect converting the 18 V 
at 4.4 A to 13 V at 6 A although on a small installation for the cost of one 
of these babies it is probably cheaper to buy a second panel.

Dave.

----- Original Message ----- 
From: "David Ashburner" <d_ashburner at hotmail.com>
To: <melbwireless at wireless.org.au>
Sent: Thursday, May 18, 2006 12:52 PM
Subject: Re: [MLB-WIRELESS] New Node to be


> >
>> * Mark (IKD ILW etc.) has offered to purchase an 80 watt solar panel and 
>> construct the power system.
>> We'll monitor the performance over the first weeks to see exactly how 
>> much more solar capacity is required.
>> * A pair of 12V 100A/H battery have been purchased.
>>
>
> how much power is an interesting issue.  I look forward to see how much 
> you can get out of the panel.
>
> I'm assuming you are going to run the routers/radios from the batteries, 
> they will be up 24 x 7
> they probably draw less then the 1 amp the plug pack is rated at but it 
> makes a good first pass estimating figure.
>
> 2 units x 1 amp x 24 hours = 48 Ah per day so your batteries could run the 
> system for 4 days without sun. But it's the problem of not recovering full 
> charge over a period of time that is going to be the hard one.
>
> 80 watt panel at say 18 volts gives you  4.4 amps for something like a max 
> of 6 hours in VIC so you have a max of 2.4 amps charging for 6 hours = 14 
> Ah
> The battery will have to provide  48 - 12 = 36 Ah
> I'm thinking you are going to go into deficit . Of course the AP's will 
> probably draw a lot less than 1 amp each so it might do it.
>
> One other thought is if the site is only for relaying data ( no AP 
> access ) you could run one radio in WDS mode and configure a WDS link at 
> either end. It would halve the available throughput but use half the 
> power.
>
>
>
> _______________________________________________
> Melbwireless mailing list
> Melbwireless at wireless.org.au
> http://wireless.org.au/mailman/listinfo/melbwireless
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.392 / Virus Database: 268.6.0/342 - Release Date: 5/17/2006
>
>