Posts Tagged ‘batteries’
Marine Solar Power
Wednesday, October 28th, 2009
Want to power this with Solar panels?
I want to build a standalone wifi repeater — powered by the sun. The problem is how much solar power and how big of a battery?
net draw 4.5v @ 0.66A with load
net draw 4.5v @ 0.60A no load
I’m assuming the best choice would be a 6v battery with a a couple diodes in series to induce ~1.5v drop. Then, I need something to charge it — I found 12v 6w solar chargers in the automotive section of Sears and 16v 2w solar chargers in the marine section of Dick’s Sporting Goods.
How many solar panels and what capacity batteries should I use? Is this the best method or should I use a voltage regulator and go with 12v batteries?
I need this to be as cheap and simple as possible…
I never said anything about using an inverter, changing DC into AC back to DC is just stupid…I’m saying to use a REGULATOR which takes a range of higher voltage, unregulated DC and outputs lower voltage, regulated DC. This is how most car-cellphone chagers work (cellphones use 4-6v to chage)
You will find a much larger selection of system components to make a 12V solar system rather than a 6V solar system. So you might consider finding a switching regulator to drop 12VDC down to 5VDC, then use a diode to further drop it to about 4.4V. A switching regulator can be had with efficiencies in the 85% range. Avoid a linear regulator; its efficiency will be less than 5/12 = 42%.
Assume the following design criteria (adjust to your liking):
1. battery to be a deep-cycle (a.k.a marine battery)
2. battery discharging stops at 20% capacity
3. battery nominal voltage 12Vdc
4. run-time on battery 3 days between charging (due to cloudy days)
5. effective charge time 6hours/day at full output (this depends on your lattitude and season).
6. 12Vdc/5Vdc switching power supply with 85% efficiency
7. Load is a continuous 0.66A at 4.5V
8. Battery charging is 78% efficient
9. Solar panel operates at 17.1V output (maximum power point)
Calculations:
The needed battery capacity (to 20% charge) in ampere-hours is:
0.66A x 24h/day x 3 day x 5V/12V / .85 / .80 = 29.1AH
The number of kWh needed per charge cycle (6 hours) is:
29.1AH x 17.1V / .78 = 638 VAh ==> 0.638kWh
The average current required during the 6-hour charge cycle is:
29.1AH / 6H / .78 = 6.22A
The nominal Solar Panel size required is:
6.22A x 17.1V = 106W
Most solar panels today are constructed of strings of 36 individual cells. These panels require that a solar charger be used to regulate the charge current (to preclude overcharging the battery). A simpler system is to obtain a solar panel with 33 cells per string. This is considered to be a self-regulating panel that can be connected via a diode to the battery, without a charge controller. It is a less expensive system, but it won’t charge as well as a 36 cell panel will on an overcast day.
As cheap and simple as possible…
Consider relaxing your design criteria. E.g., allow outages after 1 day. Power down the access point at night or during periods that it isn’t used.
Good luck! Sounds fun.
Solar Panel – Frameless, Unbreakable – Non Glass Construction. 12V Battery Charger 30 Watts
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Sunforce 50022 5-Watt Solar Battery Trickle Charger $47.91 Solar Power Chargers for your 12V batteries and accessories. Power-up anywhere, affordably! These Solar Power devices grab free “juice” from the sun! They extend the life of your 12V batteries, maintain the charge and allow you to run various electronics (deer feeders, landscaping pumps, etc.) from your batteries. Clean, silent operation… with both cigarette lighter adapter and battery clamps. T… |
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Cobra CPI 880 800 Watt 12 Volt DC to 120 Volt AC Power Inverter with 5 Volt USB output $32.87 Cobra 800W DC-to-AC Power Inverter CPI 880 416… |
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Cobra CPI 1575 1500 Watt 12 Volt DC to 120 Volt AC Power Inverter $189.95 This inverter provides household power on the go. It converts battery power to 120 V AC household power, allowing you to power up office equipment and household appliances from your vehicle. This unit is ideal for such appliances as microwave ovens (1000 watts or less), coffeemakers, laptops, TVs, video game consoles, CD and DVD players, cell phone chargers, and more. Power equipment and applia… |
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Xantrex C60 Charge Controller for Wind and Solar Generators $147.00 The C60 is a rugged 60 Amp controller that is the perfect controller for handling any DC charging source. Xantrex charge controllers are versatile and reliable. The C60 is a 100% solid state, microprocessor-driven controller which is UL and cUL listed. Like all Xantrex charge controllers, the C60 controller is flexible and can be configured for a variety of applications. The C60 is excellent fo… |
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Stellar Labs Power Rapid Charger With Lcd Display Built In Micro-Controller For 4 Aa Aaa $27.50 Back-up safety timer. Thermal overheat detection/protection. Foldable AC plug…. |
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New-BATTERY CHARGER FOR MARINE / TRICKLE – SOL1002 $52.51 Features and Benefits: Automatic operation On board charging Battery attachment kit included Weather resistant plastic case 1 year limited warranty With on-board charing and automatic operation, the Solar 1002 combines supreme convenience and reliable charging power in a lightweight, compact design. Perfect for keeping seasonal use batteries in top condition…. |
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Schumacher SE-1-12S Fully Automatic Onboard Battery Charger – 1.5 Amps $22.05 The Schumacher SE-1-12S Fully Automatic 1.5-amp Onboard Battery Charger is an AC powered automatic trickle charger / maintainer for use with 12 volt lead-acid batteries. The unit features an automatic charge cycling process that allows charging to turn on and off automatically as is necessary, and its “onboard” design and included hardware makes for easy, convenient mounting adjacent to batterie… |
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Midland XT511 22-Channel FRS/GMRS Two-Way Emergency Crank Radio $56.00 Midland’s XT511 is a durable GMRS emergency crank radio with a wealth of features to keep you informed, charged up, and in contact no matter the situation around you. Stay in touch no matter your environment. Dynamo crank allows recharging of batteries without access to electricity. Built-in flashlight and USB port for charging your cell phone or other device… |
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Clore Automotive JNC660 1700 Peak amp 12-Volt Jump Starter $118.00 Rugged, durable and reliable 12 Volt jump starting for professional applications Delivers 1700 Peak Amps of jump starting power Long, 46″ #4 gauge heavy duty cables allow the unit to be positioned in the ideal location during jump starting Volt gauge provides an accurate, detailed state of charge for the onboard battery Built in charger will never get lost and works with any US extension cordTrus… |
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Battery Tender Snap Cord Ext. Super Smart Replacement Parts Motorcycle Battery Charger $14.95 25 ft. Extension Lead for use to extend the length of the charger’s reach from input to battery.Use the 25 foot long lead extension with the Battery Tender Junior, Plus, 4, 5, or 10 Bank units. (Not for use with the 6 Volt Battery Tender Plus or any other Battery Tender product with white disconnect plugs.)… |
