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| batt:batteries [2025/12/03 18:08] – [Lead-acid batteries] Simon Grant | batt:batteries [2026/04/04 12:43] (current) – external edit 127.0.0.1 | ||
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| - | # Batteries | + | This topic is part of [[gt: |
| + | ====== | ||
| - | . | Batteries are units containing various combinations of metals and chemicals, between which occur reversible chemical reactions to store and then provide electrical power on demand. Some of the metals and chemicals can be quite nasty and toxic (e.g. cadmium). | ||
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| . | + | _A single 2-volt, lead-acid traction cell, as used in forklifts (a 24-volt forklift would use 12 of these, and a 48-volt forklift, 24)._ |
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| - | ### Lead-acid batteries | + | ==== Lead-acid batteries |
| Lead-acid cells are built to many differing formats, are commonly used in industry and form the heart of many off-grid, or hybrid renewable energy systems. The lead-acid battery is still popular, because of its affordability, | Lead-acid cells are built to many differing formats, are commonly used in industry and form the heart of many off-grid, or hybrid renewable energy systems. The lead-acid battery is still popular, because of its affordability, | ||
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| , that can be added to a home power system. Power is stored during the daytime, and then used in conjunction with a power-sharing inverter to provide electricity to the home in the evening (lead-acid batteries can be used in the same way, but you’d have to set up a separate charger and inverter yourself. In a power wall, it’s all there already). | Lithium-ion batteries are more expensive, but are becoming more popular, as they are used in electric vehicles, and in ‘power walls’ (units, about the size of large storage heaters, comprising a lithium battery pack, a charger, an inverter and some software to control it), that can be added to a home power system. Power is stored during the daytime, and then used in conjunction with a power-sharing inverter to provide electricity to the home in the evening (lead-acid batteries can be used in the same way, but you’d have to set up a separate charger and inverter yourself. In a power wall, it’s all there already). | ||
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|  won’t be shining all the time, and the [wind](/wind/wind_generators) won’t be blowing all the time (although if you’ve got [micro-hydro](/ |
| If you’re not on the grid, you’re going to need batteries. There’s a strong environmental case for saying that if you’re in an area where you can have a grid connection, then you should have one, and use the grid like an enormous battery, as the infrastructure is already there. Also, batteries contain lots of noxious metals and chemicals – so the fewer of them the better. | If you’re not on the grid, you’re going to need batteries. There’s a strong environmental case for saying that if you’re in an area where you can have a grid connection, then you should have one, and use the grid like an enormous battery, as the infrastructure is already there. Also, batteries contain lots of noxious metals and chemicals – so the fewer of them the better. | ||
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| ; 600 x 48 = 29kWh, and so the available power is 50% of this (you should never discharge a battery to less than 50% of its capacity), or 14.5kWh. Voltage is the electrical pressure and amps is a measure of flow. Amp-hours is flow over time and so can be used to give the capacity of a battery. | + | _A collection of 600 amp-hour, 2-volt cells wired in series (a 48-volt battery pack); 600 x 48 = 29kWh, and so the available power is 50% of this (you should never discharge a battery to less than 50% of its capacity), or 14.5kWh. Voltage is the electrical pressure and amps is a measure of flow. Amp-hours is flow over time and so can be used to give the capacity of a battery._ |
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|  make this a bit clearer: a 12-volt bulb drawing 1 amp from a 12-volt battery will draw 1 amp-hour per hour. So if you have a 50 amp-hour battery, then theoretically you should be able to run the bulb for 50 hours before the battery is completely flat. But – you should not discharge a battery below 50% of its capacity, or you will create serious imbalances within the battery over a relatively short period of time. So, in this case – a 12-volt bulb drawing 1 amp – you can safely run for 25 hours with a fully-charged battery. | First, do your sums – work out how much storage you need. Battery capacity is based on amp-hours and volts. Here’s an example that will (hopefully) make this a bit clearer: a 12-volt bulb drawing 1 amp from a 12-volt battery will draw 1 amp-hour per hour. So if you have a 50 amp-hour battery, then theoretically you should be able to run the bulb for 50 hours before the battery is completely flat. But – you should not discharge a battery below 50% of its capacity, or you will create serious imbalances within the battery over a relatively short period of time. So, in this case – a 12-volt bulb drawing 1 amp – you can safely run for 25 hours with a fully-charged battery. | ||
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|  | + | ===== Further resources ===== |
| - | **Thanks to Andy Reynolds of [the Ecolodge](http://www.ecolodge.me.uk/) for information.** | + | - [Off-grid solar battery sizing calculator](https://www.altestore.com/ |
| + | - [Battery University](https:// | ||
| + | - [Energy Storage Europe Association](https:// | ||
| + | - [The 12-volt side of life](http:// | ||
| + | ===== Related topics ===== | ||
| - |  |
| + | - [Narrowboats](nrbo: | ||
| + | - [Solar electricity](soel: | ||
| + | - [Wind generators](wind: | ||
| + | - [Pedal-powered machines](pedp:pedal-powered) | ||
| + | - [Micro-hydro](mhdr: | ||
| + | ===== Specialist curators of this topic ===== | ||
| + | {{tag> | ||
| - | _Date on Lowimpact: | ||