r21EC electrical system - general question

[bjp447]

When I bought my 2012 R21 w/AC I was told the system charges the
the batteries in a particular order - Starting than house than AC (3),
I don;t know what the components are that makes this work or what it is called.
Here is why I am trying to find out how all this is connected/works
I had not used the boat in a few weeks, when I went on it and started it up my
battery meters showed Starting Bat 12.5vdc House was 12, something AC batteries
showed 5, something VDC Even charging bat 1 &2 go to 13+ VDC while the AC show a slow
build but still under 8VDC, When I metered the AC batteries they are fine - good voltage
so I need to figure out how the system works.
I just need to know what to look up to figure it out
Thanks
Bruce
R21 marietta GA

 

[harry ames]

super simply stated. There are voltage controlled realays that keep the 2 and 3 batteries off the charging circuit from the motor until the starting battery is at full charge. Then voltage sensitive relay says, okay, now I can move on and add the number two battery to the charge circuit. I think you will find that the starter battery will always be "on line" for continuous charge even when the VCR relay adds the number two battery. After start and number two are at full charge, then another VCR will kick in and start charging the number three battery.

In any case after running a few hours, the engine should have brought all three batteries up to charge. The concept of having an AC unit running on a battery at all is a little mystifying. Even small AC units such a huge amount of power from a battery not hooked to a charge source.

You may be expecting too much to be running AC from it's battery for more than a few minutes.

I predict that without constant charging that your AC battery will always run low and very quickly. I don't have specific experience with your EC, but in general, the systems for a three battery circuit are as simple as I've described.

You can do a quick search on the internet for marine battery management systems, and you will find lots of info including basic circuit diagrams and component labels.

 

[McMark]

I would think that the third battery would benefit from a low voltage cutoff to keep the battery from going that low. 12.6 is usually considered fully charged and 12.0 is near depletion. In general, going to 5VDC can cause damage.

 

[bjp447]

I appreciate the feedback - what exactly am I looking for with those relays? I need to know what they look like, and do they have a specific name for that circuit? I am not an electrical whiz but I can stumble thru it if I know what I am looking for..
As for the Ac I used it once last year for about an hour (engine running) otherwise I have had no use for it. Which is one reason why I am trying to figure out the wiring so I can pull those 3 (heavy) batteries , yep the ac has 3 by itself. When I finally sell the boat if someone wants the AC they can hook them back up.

By the way - an FYI= When I bought the boat I had a starting issue sometimes it would start and sometimes it wouldn't (wouldn't turn or click or anything). But I could start it but using a remote switch from the starter to the battery bypassing everything else. We tried replacing the start switch, disabled the neutral switch, cleaned/reseated connections and contacts metered wires it would work for awhile than - same problem, Finally I decided lets change the starter. for no other reason than desperation - problem fixed. The boat is a 2012 the issue was in 2015 when I bought it and may have been there longer,
Thanks

 

[McMark]

Some are called VSR (voltage sensitive relay). Sometimes they are called low voltage cutoffs. There are plenty available ready to wire right in line. It will save your battery.

 

[SGIDAVE]

I appreciate the feedback - what exactly am I looking for with those relays? I need to know what they look like, and do they have a specific name for that circuit? I am not an electrical whiz but I can stumble thru it if I know what I am looking for..

You are looking for a Blue Sea product called an Automatic Charging Relay (ACR). They look like this:

As Harry explained, they simply sense voltage...when ABOVE a approx 13 VDC, they 'close' or COMBINE and thus pass the charging current on to the next battery in the circuitry. Whether the batteries are actually 'charged' is immaterial...when voltage is below approx 12.5 VDC they 'open' or ISOLATE the batteries (so you don't run down your 'start' battery for instance).

Your set up will have at least two ACRs.

Now the clincher...when the ACR senses LOW voltage, like 9.5 VDC, it will 'lock' open...won't combine even when it's senses 13.5 on one terminal...if the other terminal is 9.5 it won't combine because it thinks it COULD be a 6V battery. SO, be aware that if any of your batteries or banks get really low, the ACR will not allow charging. If you have a battery switch with a 'combine' function, that will allow the alternator to charge the low battery and maybe bring it's voltage high enough that the ACR will 'combine' and allow charging.

Good luck figuring out your boats electrical system.

dave

 

[glthomas]

Out of the four batteries you have,
In the engine compartment a Start battery, and a House battery for lights and accessories and I think the bow thruster.
In the port rear storage you have two batteries for the Air conditioner and water cooling pump.
If your setup is different then someone changed it from factory set up.

 

[bjp447]

Water cooling pump is for the AC???

 

[bjp447]

New question
Have not started tug for a few weeks, Batteries show full. Can't start with key - nada - nothing but lights on panel for starting on. Go to pigtail I have on starter - attach one end of remote starter switch to pigtail other end to starter battery hit the remote switch and she cranks right up. Take her out ( or just run in neutral at 2200rpm. Shut it down and it starts right up.
Someone suggested that it might not be voltage to the starter but amps to the starter, they suggest that the voltage might be staying up the the kicker (amps) may be dropping when the boat is not used. I keep a small solar trickle charger connected to the starter battery I am officially out of my depth - any thoughts.
Still working on wire layout diagram.

 

[Capt’nKarl]

Good morning. Before you go looking for any major issues when your engine doesn’t crank but you have lights on the panel do this. Move the shift/throttle lever back and forth a hair or two. I’ve had the same issue and it was just a matter of not having that lever in the right spot. See if that helps.
Cheers

 

[Det503]

I second Capt'n Karl. Just jiggle the shifter/throttle lever. Apparently a very common problem. Works every time on my 2011 21EC.

 

[bjp447]

Thank
from the last time I had this issue, turned out to be the starter, we removed the neutal switch and replaced it with a button. To start the vessel you hold the button in and turn the key. This time I just have the switch jumpered so it isn't part of the problem. Again the issue is if I don't start it for a few weeks, nothing happens with the key so I clamp one end of a remote starter to the starter, touch the hot battery terminal with the other end, hit the remote switch and it is running. Shut it down and it start with the key for a week or two. Never a problem in the summer because I use the boat once or twice a week. I would say it is the battery except that it starts with no problem with the remote starter.