From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x22c.google.com (mail-qt0-x22c.google.com [IPv6:2607:f8b0:400d:c0d::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 229C43B2A4 for ; Mon, 5 Jun 2017 12:01:33 -0400 (EDT) Received: by mail-qt0-x22c.google.com with SMTP id c10so37298428qtd.1 for ; Mon, 05 Jun 2017 09:01:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=xKVgxpsDKKk/u5zFHxyDgEo87umy0QVH59lEAFVhMfg=; b=ST45QxR4z+if34ofkPbr9I0I98ZVCmqeO5XB27H+csfhI7gz0W7YtfPmsDIZF7xa5t xk9jgg9sCpvge1Go9cSCX7wldFOXq4MzVi+aDvepmbgphqi1IvddsItjZCrenHbCRIJn k1QgJWpB9EjvLsWXpAUesMfgImyoDz9c2NtDEu9lCfy3WdakSTDyB9lrPn8aLWMEB1i0 9BjbqqKEn/bvQZPUccywrFK/PjcTCxOKNeddSjM3bskcGykAUoYsZloHlmkeGROF9fY7 Jt6dkOuYmFgGio9fcLYEBWHQRghc9gl051RNF7zIUFbzSflaqfmD8cFgTpMTs3ZdVhNf T9Ug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=xKVgxpsDKKk/u5zFHxyDgEo87umy0QVH59lEAFVhMfg=; b=YFoXpYY07Pj1CBK4QuBZWkE/aZsSWz+S0gR6Bp/Dkmoy5lRt7VlQRpvXLYcqIBKaDW ePDhdOAYLRDuSi0euzAgzJazc8ua6zwmtB4cTCpep6qC6eRaVWvbN9d2FhoAOMUBwEtf 7tMpO+rPtzXsFH9KStBehA5b9oxgtWAowwRY3aGZ9wA5foMXy7XB0GO5K0S3IjCQfncl Xk8QBNgdO2WnlWhsV5LH3PHv/98Ii9Qs+105oQzllP44lXt8YdVncOkMjbFBR1o/cXdh roamud+VAtc1SoL11rhV/uD9u03ZGMSsihY5K72dv1bu7tqqMCQJ2bzmiNx0WzkuKP4h mtIg== X-Gm-Message-State: AODbwcBVwJc/ruVHU4aTKfqCst10PG5chvj/hpq292noCgywHYO0CP0d J8zWlgCG/Ccxrt/r X-Received: by 10.55.12.129 with SMTP id 123mr23660000qkm.180.1496678491209; Mon, 05 Jun 2017 09:01:31 -0700 (PDT) Received: from [10.100.1.55] ([144.121.2.62]) by smtp.googlemail.com with ESMTPSA id l184sm21275321qkc.33.2017.06.05.09.01.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Jun 2017 09:01:29 -0700 (PDT) To: Dave Taht , "cerowrt-devel@lists.bufferbloat.net" References: From: Richard Smith Message-ID: <2d60e776-2a4f-de66-0d2f-a36568562f96@gmail.com> Date: Mon, 5 Jun 2017 12:01:28 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Cerowrt-devel] solar wifi ap designs? X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Jun 2017 16:01:33 -0000 On 06/04/2017 08:49 PM, Dave Taht wrote: > I keep finding nicely integrated solar/battery/camera/wifi designs > > https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Delectronics&field-keywords=solar+wifi&rh=n%3A172282%2Ck%3Asolar+wifi > > But what I want is merely an solar/battery/AP design well supported by > lede... and either the ath9k or ath10k chipset - or mt72 - that I can > hang off a couple trees. I've not worked with solar much in the past > years, and picking the right inverter/panel/etc seems like a pita, but > perhaps there are ideas out there? This is something I was up against constantly when I worked for OLPC. There's a big gap for products that use more power than a cell phone but less than an RV or a off-grid cabin. For the XO itself we worked around it by designing the front end of the XO to be able to handle the range of output voltages from "12V" panels (open circuit voltages up to 20V) and to implement an MPPT algorithim in the EC firmware. You can plug up any solar panel with a Voc of 20V or less to an XO-1.5 to XO-4 and it will DTRT. Figuring out what to do with the deployment's APs though was always a struggle. Solutions exist but you need to get a good estimate of what sort of power budget you need. It makes a big difference in what equipment you need. Unless its a really low power device the numbers can get large fast. My WNDR 3700v2 power supply is rated at 12V 2.5A which is a peak of 30W. Lets assume your average is 30% of peak. That's 9W. Your 24h energy requirement is 216Wh. A reasonable input to usable efficiency for a PV system is 70%. Given average 5 hour window of full sun you need a PV output of at least 62W. It only goes up from there. Realistically you need to survive a 2-3 day period of terrible solar output. So your storage requirements should be at least 2-3x that. When you do get sun again you need excess PV capacity to be able to recharge your batteries. You would probably need a PV output in the 100W-150W range to make a system you could count on to have 100% availability 24/7. That's going to be a pretty big chunk of hardware up in a tree. If the average power draw is more in the 3W or 1W range then things look a lot better. That starts to get down into the 40 and 20W range. > so am I the only one left that likes edison batteries? you don't need > a charge controller... they last for a hundred years.... > _______________________________________________ I've never used this battery type but it looks like the resistant to overcharge assumes you replace the electrolyte. All the cells I've looked at on a few sites seem to be flooded which means maintenance. Are there sealed maintenance free versions? For discharge nominal is 1.2V but charging is listed as ~1.6V/cell so you are going to need 16V to charge. I don't really see how you can build a workable system with out some sort of setup that can isolate your 12V loads from a 16V charge. Perhaps undercharge them at a lower voltage and live with the capacity loss? -- Richard A. Smith