Something odd happened to me last Friday. Was on the boat and I got a low battery warning @ 11.9V. Hmmm, I have been plugged into shore power for a good 5 days and assume my 2 year old charger is working fine. The 2 other battery banks for the engines are registering around 14V on a float charge which is pretty much normal. Went out fro a ride and nothing changed in voltage on the house bank so I assume that both alternators are not malfunctioning. Though I must have a defective isolater output going to the house bank since all juice needs to go through this to get to the battery. As luck would have it I had installed a 4 bank charger for use when on the dry for 120v only which is connected directly to each bank so I flipped off the main charger breaker and plugged in the 120v charger however the battery did not increase much at all after a good 14 hrs to only 12.3V. It has been charging since Friday evening and I just checked remotely, shows 12.98v but this is after almost 3 days of charging. It should be on a float charge by this time at around 13.5v++. Can only assume the battery has gone bad even if it is only 2 years old. Unfortunately this is dual L16 6v battery setup which is worth around $1000.

A little info. Dual 435AH 6V L16 batteries, secondary charger is only 10a per bank and seems to charge but at a ridiculously slow rate. This charger is hooked up directly to the battery so no acr or isolator to go through. Water levels on both batteries are fine and a visual inspection shows plates clean as a whistle.

Bottom line is the bank just seems like it does not want to take a charge at a normal pace.

Anyone have any advice/suggestions for me before I dish out a bunch of boat dollars and lug 125lb batteries around?