How to power things using batteries and alt power, part 2 of 2

Part 2 of 2

Power draw from the battery

If all 4 amps is being used on the Amazon inverter, how many amp hours are actually being drawn from your battery? 4 amps / 0.8 (efficiency rate), or about 5 amps per hour. Worst case scenario for an inverter that provides 4 amps: If your battery holds 20 amp hours, it will last for 20 amp hours / 5 amps per hour, or 4 hours if there is no power being added to the battery. If your battery holds 80 amp hours, it will last for 80 / 5 amps per hour, or 16 hours of continuous use with no power being added to the battery.

Examples of batteries

Below is a variety of batteries. I don't know about their quality, but let's compare the cost per amp hour of capacity. Do not use "cold cranking amps" for capacity, find the amp hours rating.

- Optima Marine battery, $200 for 55 amp hours. Cost per amp hour: $3.64usd
- 12v battery, $100 for 35 amp hours: $2.86usd

How to power things using batteries and alt power, part 1 of 2

I've been looking into using solar power and batteries to power things. My first kit is used to charge a battery using a small panel, about 12" x 8", and the battery powers an LED light. The battery box also has a 5vdc USB port for charging USB things. Or simply for powering a USB device like a USB fan.

Terms

Here are some terms to get you started.

• Amps: how much current a device draws, per hour. A 1 amp device uses 1 amp per hour. 
• Amp hours: the capacity of a battery. A 2 amp hour (Ah) battery provides 2 amps for 1 hour, or 1 amp for 2 hours, or 0.5 amps for 4 hours.
• Volts: volts is another measurement of a battery. Devices have a minimum voltage they need to run. A radio powered by 2 AA batteries needs about 3.0 volts to run (2 * 1.5 for each AA). An LED can work on a range of voltages. If the ideal voltage for maximum brightness of an LED is 3.3vdc, then as the battery is used up, the voltage drops, and the LED gets dimmer. The LED might go out at about 2.9vdc.
• Watts: A general unit of measure which is volts * amps used. A 12vdc device that uses 0.5 amps per hour uses 12 * 0.5, or 6 watts per hour. Electricity in the US is charged by 1000 watts per hour, or 1 kw per hour.

My next step was looking into using a solar and battery system to power my flat screen TV.

Alternative power usually uses an energy producing device to charge up a battery. If you use solar power (photovoltaics) you are using a solar panel to charge up a battery, and the battery stores energy for later use. You won't need lights during the daytime when the sun is out, so the battery provides power for nighttime use.

In the case of wind power or hydro power, in both cases they turn a generator to produce power, which then charges a battery for energy storage.

But how do you size the system to meet your needs? A battery provides DC power but your TV needs AC power. So you will need an inverter to change from DC to AC power. Buying an inverter based on watts it supports is not helpful. You need to look at relevant energy units, volts and amps. While watts = volts * amps, watts is just a very general way of looking at things. The inverter must provide both the volts and amps our TV needs.

My TV is rated at 12vac and 50 watts (labeled "50w" on the back of the TV). This does not tell us the amps that it draws/uses so we must calculate that. 50/120vac = 0.417 amps, or 417 milliamps (called "mA" with a big A). Amps is how much power it uses per hour. "Amp hours" is for battery capacity, and is how many hours a battery will provide 1 amp. A 1 amp hour (Ah) battery provides 1 amp for 1 hour before the voltage gets too low to be useful.

Solid electrolytes can lead the way to safer batteries!

Researchers at a Japanese institute (KEK, no that's not a Reddit joke, that's the letters of the institute) have come up with a substance to act as a solid electrolyte in lithium batteries. But researchers at Tufts University are doing something similar. A solid electrolyte greatly reduces the chance of a "runaway reaction", or spontaneously exploding batteries like Samsung had. But many problems have to be overcome with a battery technology:

1. Self-discharge is bad. It should be low or zero.
2. Should not explode.
3. Should work from -30C to 100C. 
4. If they are rechargeable they should have fairly good recharge time, and the power they can save should not degrade as fast as current technology.
5. They should be cheap enough for consumers. 
6. Ability to scale up production for consumer use.

Source
Phys.org. 2016-03.

Research continues on non-exploding lithium batteries

Researchers at Tufts University continue to develop their lithium battery that does not explode or catch fire or even heat up when punctured or cut. Prof. Zimmerman does not use an electrolyte and instead uses a plastic barrier between the anode and cathode. This could be a great leap in safety, and storage capacity, for lithium batteries. But can they scale up production?

There was even a Nova show (Search for the Super Battery) with Prof. Zimmerman.

Source
Slashdot.
Prof Mike Zimmerman's page at Tufts. Zimmerman founded a company Ionic Materials to develop the battery.