CO detectors sounding alarm

[Viper]

Ya I get what ABYC says but NO amount of CO is acceptable in my books. Without a monitor, there is no way to measure accumulated amounts in a stagnant cabin under the right conditions that CAN be harmful even from low emission engines. One must also consider worst case scenarios when it involves life and death, like improperly tuned engines, and as mentioned, neighbouring vessel CO production. There is no way I trust emissions from ANY fossil fuel burning device. The day we achieve a 100% burn will change that but it'll never happen and because there are so many variables affecting the burn, I still wouldn't risk my family's safety.

[405driver]

Thanks for all the responses.

Tomorrow all three batteries come out and will be checked out. A few days ago I was replacing a few hoses and a vented loop in the engine compartment (yuch) and I kept my eye on the charger (Charles 50A). It never got below about 10 amps (DC system off). I checked a battery with a volt meter and it read 15 volts plus a little. Looks like the charger isn't shifting to the maintenance voltage. I would guess that could be caused by a bad charger or a bad battery. However, I disconnected all of the battery wiring and checked each battery and they all checked slightly more that 12 volts with no load, and it had just come off the charger.

So here's my theory. It's bad battery and the charger can't get it to the maintenance level so it's charging the batteries on high voltage continually. This would cause the batteries to out gas eventually reaching a concentration of H that sets off the CO detectors. Ok...it could be the charger but I called Charles and talked with a tech about it and he said if it's charging, it's not very likely that the circuit is bad. It's like it either does or it doesn't.

One other thing to support the battery theory. The front and rear cabins are at the forward and aft end of the bilge channel (obviously). The batteries are in the lowest point in the center bilge just behind the engines. My theory is that the H is filling the engine compartment then traveling through the bilge channel to the forward and aft compartments where the CO detectors are.

I think I'm over thinking all of this......just check the $%#@ batteries and go from there.

[405driver]

Thanks to everyone......batteries come out tomorrow to be checked. In a discussion with a tech at Charles (Charger manufacturer) he said that it was not likely to be the charger...usually it either does or it doesn't. I did note that it's not shifting to the maintenance trickle charge even with the DC system off. All three batteries have normal voltage but that's with no load and all had just come off the charger. It's either the charger or the batteries and since I don't know the battery history...I'm betting on a weak battery.
More when they are checked.

[bud37]

Good move.....a bad battery or two can really lead you astray, got to start somewhere,just make sure all your connections positive and negative are clean and made good....... I think you are covering the bases, let us know what happens.......

[Viper]

Did you check the electrolyte levels in the batteries? Also, as mentioned, poor connections will cause high resistance resulting in overcharging and boil your batteries. A bad cell in one battery will take down all the batteries in that bank and prevent the bank from maintaining a decent charge.

This brings up the topic again of the need to ensure you don't leave a battery selector switch (if applicable) on "ALL" or "BOTH"

[405driver]

Viper...I checked the electrolyte level in all three batteries, one was a bit low, the other two were normal. Added distilled water to the low one. The battery select switch is in the #2 position. I cleaned the connectors yesterday and this morning when I returned to the boat, the forward CO detector was announcing an alarm loud and clear. The rear didn't go off because a window was open in the aft cabin........has to be either the charger or the batteries.

Thanks for your reply, I appreciate all of the suggestions folks on this forum have shared.

[Viper]

I concur with the tech at Charles. Given what the charger is putting out, chances are it's okay and simply responding to an external problem/influence.

[mjk1040]

Well you never stated the age of the batteries. Please if your going to replace a battery, replace them all. Or at least make sure the two engine house batteries are the same (New), the third I believe is for the jenny only. I would never run a aged battery against a new battery. Replacing batteries is the least expensive maintenance issue I can think of in the long run. Mike

[405driver]

I agree 100%.....when they come out three new ones are going in. I am going to have the old checked to try and pin down this CO issue.

Thanks,

Lynn

[405driver]

Took all the batteries out and had them tested. Two were bad, one was marginal. There were two Interstates and one Deka. One interstate and the Deka were bad. The deka was dated 2013, have no idea about the other two. I bought three new Dekas and installed them. I turned the DC system off and watched the battery charger amp meter. It started out off scale high then decreased fairly rapidly to near 0 (which would be expected with new batteries). At the low amperage reading, the voltage across each battery was 13.4, 14.1, 13.4. It appears that the charger has successfully switched to the maintenance mode.
Interestingly, two of the batteries were wet on top with battery acid in the plastic case when they were removed.
Surely this is the answer to the CO issue. The charger is charging in series, so seems to me that two bad batteries would cause the charger to continuously run in the high mode, boiling the batteries and releasing H2S.

Does anybody turn the DC system off when leaving the boat? That way there would be no draw on the batteries so the charger would stay in maintenance mode?