Battery Charger seems to drain the battery?

Apr 21, 2020
13
Hunter 30T Marina Del Rey
Hi all,
Recently doing some boat work, I disconnected and removed both 12v house batteries, and left them sitting out for about a week. I put them back in the other day and wired them back like normal, and plugged in the shore power. Today i noticed on the Victron Battery Monitor that my % was down to 59%, down from 100% two days ago, even though voltage still read as 13.94. AC shore power was working fine, but the 20 amp Professional Mariner Battery charger, which had always worked, wasn't showing any amperage... but it was "buzzing" and very hot to touch. The "buzz" turned off when i switched the charger off/unplugged shore power.

The Victron showed that there was a negative drain on the battery's amps/watts when the battery charger was "on". When i turn off the battery charger switch, the amp/watt drain goes back to zero, and there is no drain.

Anyone know what's going on here?

thanks!
 
Sep 25, 2008
7,075
Alden 50 Sarasota, Florida
I hate guessing games without some clues like resting voltage or fluid density measurements of the electrolyte but....

If your charger was pumping “13.94” volts into fully charged batteries, that’s a pretty good clue who committed the murder.