Monday, Jan 16, 2017 at 21:53
Don't skimp on your wire size for the charging circuits, best to buy 8 or 6 B&S depending on the length of the run. I can send you the formula to measure the voltage drop across any wire if you like but anything more that .2 of a volt is too much. As suggested by others spend the money on the wire on the charge side as it is
well worth it.
Depending on your vehicle type, some newer vehicles with smart alternators require you to use the vehicle body for earth return and not direct wired (running earth from each accessory back direct to the battery). The reason for this is that the smart alternator will only produce what it needs, this saves the alternator producing power that is not needed, hence saves fuel. (How much is debatable or even worth while) How the alternator finds out what it needs to produce to replace what is used, is by measuring the current in the earth strap from the body to the earth terminal of the battery (actually at the battery).
Not all vehicles use this method but if it is, you must ground each accessory to the vehicles body for this to occur, because if you run a direct earth cable it by passes the earth return current detection. Therefore doesn't produce what you are actually using which can flatten your main battery. This could be from radios,
driving lights etc, not just BCDC charges.
Older vehicles, I have always run a return earth direct to the battery as it much more reliable circuit to guarantee a good circuit but some newer cars are just getting to clever (problematic I would say). You just need to be careful which way you wire by the type of alternator you have.
Hope this helps and doesn't confuse the issue.
Dave
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