RV FEATURE
Late last year , we held our Offroad Challenge as part of the filming for our upcoming TV show . Trouble was , it was blistering hot and shade was hard to come by . Inside our gazebo , we had drinks , chairs , snacks … and four Sirocco II fans .
Yes , we realise that these fans are designed for permanent installation inside a caravan or motorhome . But I smelled an opportunity . Energy efficiency is , nowadays , a major selling point for any electronic appliance , and this topic is particularly important in an RV context . After all , when off-grid and completely reliant on your battery for power , it ’ s essential to ease the load on the battery wherever possible .
The Sirocco II fans have a reputation for energy efficiency . It ’ s one of the factors that sets them apart . With the summer sun expected to be brutal , we sourced four Sirocco II fans along with four 6.5Ah batteries . The idea : run each fan off one battery and note how long they ran before its battery gave up the ghost . We even had four brackets specially 3D-printed which would allow us to secure each fan to each post of the gazebo .
The Sirocco II draws 0.12A on its lowest setting while operating on 12V , and 0.35A while operating on its highest setting on 12V .
Each fan was connected to a 6.5Ah battery .
But rather than simply observing how long the fans ran on each battery , we could calculate in advance the expected run time , and the good news is , this formula works for all 12V appliances and batteries .
THE FORMULA
In order to calculate how long a 12V appliance , in ideal conditions , would run off a battery , we simply divide the battery ’ s capacity in amp hours by the current draw of the appliance .
In our case , it looks like this :
Fan on low setting : 6.5Ah / 0.12A = 54 hours of run time .
Fan on high setting : 6.5Ah / 0.35A = 18.5 hours of run time .
It must be said , however , that this is theoretical . Depending on factors such as the condition of the battery and its chemistry , it ’ s likely that in the real world , these run times would probably be reduced by about 10 per cent .
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