Spinelli 0 Posted April 6, 2016 Hi, i'm hoping someone can help me out. I have a 12V, 41Ah car battery, which I want to use to power a CCTV system. I'd like to know how long I can run it for without risking battery failure. The system comprises: 2 cameras - 350mA, DC12V; a digital timer - 16A (8)A, 250VAC a DVR unit - 3A, 12V, power supply AC110, 230V. One of the cameras has 28 m of cable between it and the power supple & monitor, so I don't know if this would effect the power draw much. All units are as described on the labels, so I may have given pointless information in there too! Many thanks if anyone can help. Share this post Link to post Share on other sites
Daryl733 0 Posted April 6, 2016 Hi, i'm hoping someone can help me out. I have a 12V, 41Ah car battery, which I want to use to power a CCTV system. I'd like to know how long I can run it for without risking battery failure. The system comprises: 2 cameras - 350mA, DC12V; a digital timer - 16A (8)A, 250VAC a DVR unit - 3A, 12V, power supply AC110, 230V. One of the cameras has 28 m of cable between it and the power supple & monitor, so I don't know if this would effect the power draw much. All units are as described on the labels, so I may have given pointless information in there too! Many thanks if anyone can help. Best way, charge the battery up full, and let it run down. Your DVR would have recorded the period of time when the system is working. The type of battery, the temperate it is operating at, how old the battery, etc all will play a part. Looking at purely these information are pretty useless to gauge actual power consumption. If you are using unbranded or even some branded equipment, the way some manufacturer labelled all these specs is by copying similar products specs and not actually running tests. They are also supposed to be the max power consumption rather than the usual power consumption if they are correct. The timer you have doesn't give the power consumption. It indicate what's the maximum load that can pass through the timer safely. Also, you are using a AC Timer, so you'll have to put in a invertor as well. Last but not least, from experience, it is not advisable to connect electronics especially the DVR to the battery. You might want to consider putting in a safety cutoff in your design that cut off voltage from the battery when voltage drops below certain voltage, e.g. 11.5V. This will alley your concern about overdrawing the battery, and also protect the equipment from exhibiting funny symptoms. e.g. When insufficient power, the DVR might still be on, but the harddisk connected to it might not operate, etc. If you still want to calculate, here's some tools. https://www.batterystuff.com/kb/tools/calculator-for-load-specific-run-time.html Share this post Link to post Share on other sites
Spinelli 0 Posted April 8, 2016 Thanks very much for the detailed reply, it was very useful. Share this post Link to post Share on other sites
