@Allegiance: Hi. selecting the fuse for the dash-cam is really about the quantity of power you will allow to be dissipated into the device in a fault - specifically, fuse selection for car situations (it's called "grading") isn't about current limiting for overload protection. Certainly, knowledge of the maximum normal operating current is important because the fuse must be able to not-melt when the device is not experiencing a fault!
So - the specification for the DR750S-2CH is that it draws an average of 4.2W at 12V, when GPS and Wi-Fi are ON. This is 350 mAmp. Conservatively, you could assume reasonably that under peak conditions, the maximum electrical current for normal operation could be as high as 1 Amp (for a short time) - maybe. The general rule-of-thumb for vehicle applications is that the current rating of a fuse is typically de-rated 25% for operation at 25 ̊C to avoid nuisance blowing. So for a 1 Amp device, a appropriate fuse of 1.33 Amps is sufficient (nominally, let's say 1.5 Amps).
Of course, you can opt for larger amperage fuses if you want - but be aware that the "cost" of increasing the fuse size is that the power dissipation when a fault occurs becomes greater by the square of the increased rating. So - for example, installing a 3 Amp fuse (i.e. doubling the fuse size) will quadruple the power that is dissipated into the fault (all other electrical conditions remaining unaltered).
So, increasing fuse size beyond the "optimal grading" value means greater damage inside the device when a fault occurs - it's all about balance
Don
Last edited by DV52; 29-11-2020 at 08:57 PM.
Please don't PM to ask questions about coding, or vehicle repairs. The better place to deal with these matters is on-line, in the forum proper. That way you get the benefit of the expertise of the wider forum! Thank you.
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