To start this post off, This is my first major electrical problem on the boat since buying it 4 years ago. I know the basics and in the past few days have read as many of the posts on alternators and batteries I could.
Background...
Last week, after 1 hour of motoring then a 5 hour sail with radio and depth finder on the engine started up but blower was weak. Upon picking up a mooring ball, and shutting the engine down, both our batteries were dead. We have a battery selector and had it set to both all day. That's how we've used them for 4 years based on the PO's suggestion. One battery was 5+ years old and one was 2 years old.
The next day we got a jump, motored into a slip, charged the batteries and started troubleshooting. The oldest battery wouldn't take much of a charge and would die below 8 volts as soon as any load was pulled from it. This measuring was taken with a multi meter at the battery posts. We just considered that battery to be dead so we removed it from the boat. The newer battery would read around 12.5 volts after 12 hours of charging then I started the engine once, shut the engine off let the battery sit for a few minutes and it would be reading around 11.7. The next start up was very weak. We figured the oldest battery had weakened the newer battery. We also noticed the alternator was only outputting 12 volts at half throttle. That measurement was taken with a multi meter at the alternator. We needed to get home and wanted to be confident in our batteries so we replaced them with 2 new batteries (group 24 lead acid, one is a starter the other is starter/deep cell). I charged them up for a few hours with my 2 year old ProMariner ProSport 2 bank battery charger. We were going to get the alternator rebuilt when we got home. But we're still seeing a problem, we haven't fixed the alternator yet but I think this is a bigger problem than the alternator.
We took 2 sails since, different days, after full charges. Around 5-30 minutes of motoring and 2-3 hours of sailing with just the depth finder on. We're keeping the batter selector on 1 battery at a time now. Both times, the selected battery died after an hour or so of sailing, different batteries each time. I'm assuming based on our previous experience that you can sail with the depth finder on for a long time without draining the battery, we've done 6 hour sails with radio and depth on with no noticeable loss.
So I charged the batteries up and tried to do some more trouble shooting. The only odd thing I have noticed is that when the batteries are at rest, fully charged they read 12.6-12.7. When you turn the battery selector on to either battery they immediately drop down to 12.1 even though the ignition isn't on and no electronics are on.
Here is the only piece of out of the normal info that I think could be of help. The PO installed a macerating toilet that doesn't run through a circuit breaker. Right when I turn the battery selector on the toilet can operate. So technically, it's the only thing getting power when I switch the battery on.
So what should I be looking for? Should the batteries drop to 12.1 when I turn the battery switch to on even though no electronics are on? Could voltage just be leaking out somewhere? I've used 2 different multi meters to do my testing so I don't think I have a problem there.
I just need some guidance as to how to start troubleshooting this one.
Sorry for the long winded start but there are a lot of pieces this the puzzle.
Background...
Last week, after 1 hour of motoring then a 5 hour sail with radio and depth finder on the engine started up but blower was weak. Upon picking up a mooring ball, and shutting the engine down, both our batteries were dead. We have a battery selector and had it set to both all day. That's how we've used them for 4 years based on the PO's suggestion. One battery was 5+ years old and one was 2 years old.
The next day we got a jump, motored into a slip, charged the batteries and started troubleshooting. The oldest battery wouldn't take much of a charge and would die below 8 volts as soon as any load was pulled from it. This measuring was taken with a multi meter at the battery posts. We just considered that battery to be dead so we removed it from the boat. The newer battery would read around 12.5 volts after 12 hours of charging then I started the engine once, shut the engine off let the battery sit for a few minutes and it would be reading around 11.7. The next start up was very weak. We figured the oldest battery had weakened the newer battery. We also noticed the alternator was only outputting 12 volts at half throttle. That measurement was taken with a multi meter at the alternator. We needed to get home and wanted to be confident in our batteries so we replaced them with 2 new batteries (group 24 lead acid, one is a starter the other is starter/deep cell). I charged them up for a few hours with my 2 year old ProMariner ProSport 2 bank battery charger. We were going to get the alternator rebuilt when we got home. But we're still seeing a problem, we haven't fixed the alternator yet but I think this is a bigger problem than the alternator.
We took 2 sails since, different days, after full charges. Around 5-30 minutes of motoring and 2-3 hours of sailing with just the depth finder on. We're keeping the batter selector on 1 battery at a time now. Both times, the selected battery died after an hour or so of sailing, different batteries each time. I'm assuming based on our previous experience that you can sail with the depth finder on for a long time without draining the battery, we've done 6 hour sails with radio and depth on with no noticeable loss.
So I charged the batteries up and tried to do some more trouble shooting. The only odd thing I have noticed is that when the batteries are at rest, fully charged they read 12.6-12.7. When you turn the battery selector on to either battery they immediately drop down to 12.1 even though the ignition isn't on and no electronics are on.
Here is the only piece of out of the normal info that I think could be of help. The PO installed a macerating toilet that doesn't run through a circuit breaker. Right when I turn the battery selector on the toilet can operate. So technically, it's the only thing getting power when I switch the battery on.
So what should I be looking for? Should the batteries drop to 12.1 when I turn the battery switch to on even though no electronics are on? Could voltage just be leaking out somewhere? I've used 2 different multi meters to do my testing so I don't think I have a problem there.
I just need some guidance as to how to start troubleshooting this one.
Sorry for the long winded start but there are a lot of pieces this the puzzle.
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