Batteries

I feel that car batteries are the most readily available power sources. For some people, a used car battery (say from a wrecked car) may supply enough of a reservoir to maintain a bedside light and four hot mugs per day, as long as there is enough wind to charge it daily.

What do I know about batteries? Linked in parallel for stable voltage and maximise load, sort of. In Series we increase the voltage.

I think of car batteries as easy to obtain, but consider the Rolls S-480-spec-sheet described by Rolls as a "flooded deep-cycle" device.

Its 20 HOUR RATE is 375 amp-hours at 18.75 amps.

That means that I can draw a current of 18.75 amps for 20 hours.

The Rolls S330-spec-sheet.pdf says its 20-hour rate is 12.50 hours.

A table of Rolls batteries shows me:-

I believe that I will need two of the 6-volt jobs to give me 12vDC, three of the 4-volt, and six of the 2V.

What does it mean to get 18.75 amps over a 20-hour period?

I learned yesterday: Heating Cup Coffee Cup $30, 450ml, 50W, 10 minutes, "Can make tea, boil eggs, heat liquid food.

The system consists of:-

(1) A wind turbine that supplies electrical energy to

(2) A Battery bank which supplies electrical energy to

(3) An application (in this example, an electric jug)

For each application I need to know the Power (watts per hour) of the application, the watt-hours available in the battery bank, and the watt-hours that can be supplied by the wind turbine.

If an electric mug uses one hundred watts per hour then if it takes 20 minutes to boil a mug, I need 11/3 hours at one hundred watts, or 133 watt-hours each day from my battery bank for water-boiling. If I burn a 40-watt bulb for two hours each night, then I need 80 watt hours each day from my battery bank for bedtime reading.

That means I will drain 213 watt-hours per day from my battery bank, and I will need, on average, 213 watt-hours per day from my wind turbine.

If the wind blows every day to a total of 213 watt-hours then I am breaking even, but perhaps the wind does not blow at all for two days! Then I will need a battery bank that can store 426 watt-hours.

What does a device consume?

My kitchen mixer (two rotating blades) has a plate that reads 60Hz, 120v, 2.15a. Power P=i*V "Power (in watts) is current (in amps) multiplied by voltage, so my mixer is a 2.15*120 device, or a 258 watt device. If I ran it for a solid hour it would consume .258KW Hrs which, at about $0.12 per KwH would cost me about thirty cents.

Wednesday, December 30, 2020

Normal charge rate is 10 % of capacity

NiMH batteries do not like to be overcharged, and there is no easily discernible indication of full charge, so you really need to measure how much energy is removed, and then put about 125% back in

The capacity of your batteries is usually stated in Ah (or mAh). If a battery has a capacity of xxx Ah, charge current should be 0.1 × xxxA. In your case: 2.800 mAh --> 280 mA charge current .

Saturday, September 17, 2022

https://www.abc.net.au/news/2022-09-17/couple-uses-laptop-batteries-to-reduce-carbon-emissions/101414610 "They installed solar panels at their property and now essentially live "off the grid" with help from an unusual source: recycled laptop batteries."

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