Don't know, but likely not induction. Is your bilge pump
connected directly to battery
like many of us do? Might be 'leakage' of 12v from failing bilge
I'll try disconnecting EVERYTHING from the + battery
terminal and re measuring to see if you still see 5.5v. Hopefully not. If not try reconnecting whatever was connected to the + terminal one at a time/ remeasure each time.
If you still don't see source/ try flipping each circuit breaker off one at a time/ remeasure after each.
If you have a dual power AC/DC refrig... or any dual power AC/DC device that auto-switches between AC and DC depending on which is available... with AC still to the boat and 12v main switch off... the AC/ DC dual power device may have switched to AC, which in some designs powers an internal power supply that still powers the device... maybe that's where your remaining voltage is coming from. Easy test to see if your backing up right tree is to also switch off the AC power to boat as well and remeasure.
5.5v DC is an unusual voltage in marine
world... but not to modern electronics
. All recent iPhones/ Pads/ Samsung/... and most modern 'wall wart' and USB chargers for modern electronics
are all on the new 5.5v standard. Seems interesting that your phantom voltage is the same as this increasingly common gadget voltage. Might you have any 12v cigarette socket-to-USB charger
and iPhone/ some device still connected to your now off/ floating 12v line that one of these devices might be improperly back feeding 5.5v back into your switched off 12v circuit? Wish I was there... like interesting troubleshooting/ brain teasers like this. There is always a logical explanation.
When you find cause, please post it so we can all learn from your interesting electrical
Sent from my iPhone
using Cruisers Sailing Forum