Ask PYS: Power

Ken – Fuses for Battery Charger, on Mar 04, 2015 asked:

Upon installation of our new 20A battery charger, I noticed the PYS Tech put in new 15A fuses at the new un-switched 12V terminal (for each line, from the old 10A charger), which seems OK. For the new 20A charger should these be 20A, 25A, or maybe 30A? I am not sure whether I need a margin beyond the 20A max rating on either side, or how much that margin should be?

Hi Ken,

When fusing a charger (aka converter), you should use 1.25 times the maximum rated capacity of the charger as your fuse. That way you will not get any nuisance tripping.

Also make sure the DC wiring can handle the 12VDC 20A load versus the 10 amp load from previous charger.