Differences

This shows you the differences between two versions of the page.

--- batt:batteries [2025/12/05 11:18] – [Specialist(s)] Dave Darby
+++ batt:batteries [2026/04/04 12:43] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-# Batteries
+This topic is part of [[gt:power|Power & heating]].
+====== Batteries ======
-![](https://www.lowimpact.org/wp-content/uploads/2013/08/batteries.jpg)
+![](batt:batteries.jpg)
 ---
@@ Line 10: / Line 11: @@
-## What are batteries?
+===== What are batteries? =====
 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).
@@ Line 20: / Line 21: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-single.jpg)
 <caption>
- 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).
+ _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)._
 </caption>
 </figure>
 </WRAP>
-### 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, availability, and the fact that it is so robust if looked after properly.
@@ Line 34: / Line 35: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-meter.jpg)
 <caption>
- Testing the voltage of batteries with a voltmeter.
+ _Testing the voltage of batteries with a voltmeter._
 </caption>
 </figure>
@@ Line 61: / Line 62: @@
-### Lithium-ion batteries
+==== Lithium-ion batteries ====
 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).
@@ Line 71: / Line 72: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-lithium.png)
 <caption>
- Lithium-ion battery.
+ _Lithium-ion battery._
 </caption>
 </figure>
@@ Line 94: / Line 95: @@
-## What are the benefits of batteries?
+===== What are the benefits of batteries? =====
 The main benefit of batteries is for people who wish to generate and use their own electrical power whether on or off grid. If you’re building a renewable electricity system, you’re not looking to use electricity as it’s generated – the [sun](/soel/solar_electricity) 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](/mhdr/micro-hydro), your stream is probably going to be flowing all the time), and you’re going to want more electricity at some times than others. So you’ll need to store your electricity.
@@ Line 104: / Line 105: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-pack.jpg)
 <caption>
- 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.
+ _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._
 </caption>
 </figure>
@@ Line 117: / Line 118: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-elements.jpg)
 <caption>
- Exposing the elements of a lead-acid battery.
+ _Exposing the elements of a lead-acid battery._
 </caption>
 </figure>
@@ Line 123: / Line 124: @@
+===== What can I do? =====
-## What can I do?
 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.
@@ Line 145: / Line 145: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-cupboard.jpg)
 <caption>
- leisure batteries and an inverter on a vehicle with 12 x 80-watt PV panels on the roof, plus a 350-watt wind turbine.
+ _4 leisure batteries and an inverter on a vehicle with 12 x 80-watt PV panels on the roof, plus a 350-watt wind turbine._
 </caption>
 </figure>
@@ Line 156: / Line 156: @@
 ![](https://lowimpactorg.onyx-sites.io/wp-content/uploads/batteries-hydrometer.jpg)
 <caption>
- Testing the specific gravity of the electrolyte in a cell with a hydrometer.
+ _Testing the specific gravity of the electrolyte in a cell with a hydrometer._
 </caption>
 </figure>
@@ Line 163: / Line 163: @@
 You’ll need a charge controller in your system to make sure you don’t overcharge and damage your batteries, and to run standard 240-volt appliances from a 12-, 24- or 48-volt battery bank, you’ll need an inverter. It is possible to buy 12-volt appliances, but they are a lot more expensive, plus mainstream 240-volt appliances are being made much more efficient all the time – so it may be as well to focus on getting a really good inverter.
-So, looking after batteries is a bit of a dark art, and can be quite complicated. Our publication [_Wind & Solar Electricity_](/soel/solar_electricity) is a good place to start. Batteries are the recalcitrant teenager of your renewables system. Keep an eye on them and they’ll be just grand, but ignore them and they’ll cause problems.
+So, looking after batteries is a bit of a dark art, and can be quite complicated. Batteries are the recalcitrant teenager of your renewables system. Keep an eye on them and they’ll be just grand, but ignore them and they’ll cause problems.
+===== Forum =====
+This topic belongs to the section [[gt:power|Power & heating]]. You can ask questions or add information on the corresponding [Forum section](https://forum.growingthecommons.org/t/power).
+===== Further resources =====
+- [Off-grid solar battery sizing calculator](https://www.altestore.com/pages/off-grid-solar-system-sizing-calculator)
+- [Battery University](https://www.batteryuniversity.com/) - learn about batteries
+- [Energy Storage Europe Association](https://energystorageeurope.eu/)
+- [The 12-volt side of life](http://marxrv.com/12volt/12volt.htm) - lots of info on 12-volt batteries and charging
+===== Related topics =====
+- [Sail boats](sail:sail_boats)
+- [Narrowboats](nrbo:narrowboats)
+- [Solar electricity](soel:solar_electricity)
+- [Wind generators](wind:wind_generators)
+- [Pedal-powered machines](pedp:pedal-powered)
+- [Micro-hydro](mhdr:micro-hydro)
-## Further resources
+===== Specialist curators of this topic =====
-## Specialists
+{{tag>[energy]}}