CO detectors sounding alarm

[Low Flyer]

After fighting some kind of bug for a week I was finally able to make it to the boat and disconnect the two batteries from everything and hook the charger directly to them. I refilled them with distilled water (they were low AGAIN) and left them for four days.
I contacted NOCO about their Genius 4 bank 40 amp sealed Marine charger and was told it should not be "boiling" the water out of the batteries. The automatic portion should (as we know) charge the batteries and then go into a maintenance state to keep them charged. I was told to check for approximately 14.7 volts (+/- .02 volts) while connected with a solid green LED status lights. NOCO stated the I should check the batteries monthly to ensure that they have the right amount of fluid level. I told them that the batteries are constantly boiling and need fluid every week.
When I returned to the boat both batteries were showing Green with 14.6 volts and both batteries needed fluid and were bubbling. There was nothing connected to the batteries except the charger. I disconnected the charger and both batteries indicated approximately 13 volts so I used my load tester and verified they were still good. All tested well.
I disconnected and removed the Genius 4 charger and it is boxed up and ready for shipment back to NOCO for them to verify the condition and if it is working correctly. The charger is still under warranty so I should know a status in a week to 10 days.
I was going to replace the CO detectors like 405driver but they have been replaced and are only 4 years old. I have a stand alone Kiddie CO detector, as a back up to the three onboard detectors, and it sounds the alarm during battery charging also. That would lead me to believe the onboard detectors are functional.
When the charger is returned or replaced I will install two new exchanged batteries with only the charger hooked up for a couple of days to check the status and have a baseline. Then I will connect it to boat DC system and see what happens next.

I'm sorry this is so long guys but I wanted to try and detail my steps so maybe with your help I/we can reach a solution that helps me and anyone else that may encounter this or a similar problem.

As a side comment... has anyone had any experience with the NOCO Genius chargers? Any suggestions on a different replacement charger since I removed the old Charles charger? Thanks in advance.

[bud37]

IMHO, you are on the right path here, cutting out all the interferences.......they can now verify their chargers operation for you. Did you happen to check how many amps your charger was trying to put in there??, that might be telling....anyway keep us posted ,learning experience for all,..... good info......

[Midnight Sun]

Sounds like you spoke to the receptionist! A float charge (maintenance) should be around 13.5-13.6v yet you measured 14.6v? This is not a float voltage and definitely the reason you need to add water and have gassing issues causing alarms. Either you have a bad cell(s) in a battery causing the charger to charge incorrectly or the charger is defective.

Here is a good read on battery charging. http://batteryuniversity.com/learn/arti ... id_battery

[Viper]

I've seen those types of chargers in smaller applications and bass boats but never in a motor yacht. I trust it is hard wired to an AC line and not plugged into an outlet? and that alligator clips are not being used? I couldn't find any info on how the output is distributed to each bank. That's important to know.

Personally I wouldn't go with this type of charger but that's just my own opinion. I'd go with something like a ProMariner ProNautic P charger. They have a proven track record in larger boats. I've installed many.

http://www.promariner.com/en/63140

I agree it's either a faulty charger or you have a bad battery/bad cell that is causing the charger to stay in a full charge mode rather than floating when done. As mentioned before, it's also important to ensure ALL your connections are clean and tight. Not doing so will also cause overcharging. One bad battery in a bank will cause all the batteries in the bank to overcharge/boil. If a bank consists of vastly different (specs) type and sized batteries, this could also cause overcharging.

[405driver]

Thanks.. it is the pronautic... seems to be working great. I went to "Inverter" a subsidiary of Marysville Marine and the helped me with the charger.... they were great.

[Viper]

Source of the post Thanks.. it is the pronautic... seems to be working great. I went to "Inverter" a subsidiary of Marysville Marine and the helped me with the charger.... they were great.

Sorry 405driver, I was responding to Low Flyer.

Low Flyer, perhaps it's best that you start a thread of your own for this, it's getting a little confusing.

[km1125]

Just wanted to weigh in here for a moment to clarify/correct an earlier assumption that might occur to a reader of this thread.

It is that a load on the system (like lights, a fridge or something else) might prevent the battery charger from changing modes and overcharge the battery. While this might happen on some charger somewhere (which would indicate a problem with the charger - thus the suggestions to isolate and identify), it should not happen in a properly operating system.

Unless there is a problem with the battery charger, this should never happen. The battery charger should start out in a constant-current mode, providing whatever current it can, until it hits a threshold voltage. Some of this current is used up by the existing loads (lights, fridge, etc) and the remaining goes into the battery. If you have a lot of other loads, it will take much longer for the battery to get through this charging stage. However, unless the loads exceed the capability of the charger, then the charger will indeed finish this stage. When the charger gets to stage two (the "topping" charge) the voltage is held constant, so the current to the battery will decrease as the battery charges. There will still be current flowing to those other loads, which again will make the battery charge take longer. At this point, the charger either 'times out' or senses a lack of change in the current, and switches to float mode.

[405driver]

Thanks....
When I took my 1997 Charles (50A) to "Inverter" for testing, they explained exactly what you said above. The charger tested ok but I decided to replace it with a Promarine because I liked some of the features on the charger. Specifically that after a given period of time and completely charged batteries, it shuts off.

[Happy Ours]

I had this problem and would get a call or arrive to my boat and find that my mid cabin CO alarm would be going off. I am not discounting your battery trouble shooting but would like to ask, how old are your CO alarms? They are actually only good for 5 years and then should be replaced.
I replaced all of mine as they were well beyond 5 years old. Problem solved.

[405driver]

Thanks....they are brand new.

Haven't had the issue since I replaced the batteries and the charger. My fingers are crossed...we'll see.