24V 12V DC DC Converter

Find out how you can use a 24V battery (bank) to power 12V devices

There are many advantages to using a 24V or 48V battery bank (1) rather than the more commonly found 12 Volt. Primarily, the cable used to connect the alternator/generator (2) to the battery bank, and from the battery bank to the load appliances can be thinner since line losses (3) (energy lost as electricity passes through cable) are less the higher the voltage transmitted.

While affordable power inverters (4) are available for use with 24V batteries and battery banks, other useful items are much more expensive if rated for use with 24VDC rather than 12VDC - for example, Sat-Nav chargers, LED lighting (5), and the huge array of items designed to be used in-car or with caravans and powered by 12 VDC.

24V to 12V DC-DC Converter

If you have a 24V lorry battery or a 24V battery bank, but you still want to be able to power 12VDC rated appliances, you need a DC-DC Converter. These are designed to give a regulated 12VDC output from an input voltage of around 24V-30VDC. These can be quite cheap to purchase as there is a large market of lorry drivers who want to be able to use 12V rated kettles and televisions etc in their 24V wired cabs.

The key things to look for are the maximum load current rating (measured in Amps). This tells you how much current the connected 12V rated appliance can safely draw. The second is the efficiency. Ideally you do not want to be wasting stored battery charge as heat, so try to purchase the most efficient DC-DC converter you can afford.

Pictured above is an 8 Amp rated 24V-12V DC-DC Converter. This has been designed to be plugged straight into the 24V cigar lighter socket in a lorry cab, but the plug can easily be cut off and the bare wires connected to a 24V battery bank. The two output sockets are for devices which can be powered directly from standard car 12V cigar lighter sockets. One device can be powered at up to 8 Amps (100 Watts), or two at up to 4 Amps each. The built in on/off switch is very useful for saving battery charge when no loads are present.
This basic 8 Amp unit was found on eBay UK (6) in July 2008 priced at Ł15.75 plus Ł2.45 postage.

Pictured above is a higher quality, higher current rated 24-12V converter. Rated at 16 Amps (200 Watts), this can be used to power large laptop computers and 12V rated kettles with ease. It can accept inputs from 22-29 VDC, and uses just 30mA of current when switched off.
Added features include low voltage protection (prevents battery being excessively drained), and over voltage protection (stops converter being damaged if connected to voltage source exceeding 29V.
Connections to this converter can be made by 12V sockets, pillar terminals, or the supplied cables.
Again this converter was found on eBay UK (7) in July 2008, but a bit more pricey at Ł44.99 plus Ł3.50 postage.

Buy a 24-12V DC-DC Converter

If searching eBay for a 24V-12V converter we have found the best search to be 24V Converter (8), with around 30-50 items being available for sale at any one time. The latest listings are displayed below:

Web Link References

(1) http://www.reuk.co.uk/Interconnecting-Batteries-for-Battery-Bank.htm
(2) http://www.reuk.co.uk/Permanent-Magnet-Generator.htm
(3) http://www.reuk.co.uk/Minimising-Line-Losses-in-RE-Systems.htm
(4) http://www.reuk.co.uk/Power-Inverters.htm
(5) http://www.reuk.co.uk/buy-12V-LED-SPOTLIGHT-BULB
(6) http://rover.ebay.com/rover/1/710-53481-19255-0/1?type=3&campid=5336034809&toolid=10001&customid=&ext=converter+24v&satitle=converter+24v
(7) http://rover.ebay.com/rover/1/710-53481-19255-0/1?type=3&campid=5336034809&toolid=10001&customid=&ext=converter+24v&satitle=converter+24v
(8) http://rover.ebay.com/rover/1/710-53481-19255-0/1?type=3&campid=5336034809&toolid=10001&customid=&ext=converter+24v&satitle=converter+24v

Article from REUK.co.uk:
http://www.reuk.co.uk/24V-12V-DC-DC-Converter.htm
Published: 24th July 2008
Š REUK 2009