View Full Version : Carbon Monoxide Detectors and Batteries

Ken Lake Powell
08-24-2017, 12:54 PM

Our CO detectors alarm, usually early in the morning (around 2 - 3 AM) but we do not think it is due to CO but rather the batteries associated with the inverter system. We have been working this problem for several months without success and are hoping someone else has had a similar issue and developed a solution. Here are the background facts:

- The boat is a 75' Skipperliner - 10 years old
- Engines and generator are relatively new diesels
- The hot water and cooking is propane
- We have 24 Trojan T-105 6 volt batteries on two inverters
- The CO detectors are Kidde KN-COB-B-LPM

I bought a Sensorcon CO meter and checked the engine compartment with the engines running, and, once beached, with the generator running and found no CO. I also checked the air around the hot water heaters and got 0 reading. The CO levels in the boat ran from 0 to 30 - 40. But the CO level in the bow compartment where the batteries are installed (which is sealed from the main boat living areas and compartments) reads up to 1,700. We know the meter responds to hydrogen, which is produced when the batteries are charging.

Based on the meter readings, and the fact that diesel generators produce very low levels of CO, we believe the cause of the CO detectors alarming is hydrogen gas from the batteries. How it gets into the boat is a bit of a mystery, as there is a bulkhead between the bow compartment and the rest of the boat, and we have sealed every possible opening where wires or cables come through the bulkhead into the main cabin area.

Has anyone had this issue? What did you do about it?



08-25-2017, 02:46 AM
How old are the CO detectors? They have a maximum lifespan of 10 years.

Ken Lake Powell
08-31-2017, 06:43 PM
Thx. They are a year old. The CO meter is new.

09-01-2017, 07:57 AM
Do you have a forced air vent in the battery compartment? Maybe a small fan to force fresh air in and Gas out? Just a suggestion.....

Miller Tyme
09-02-2017, 07:17 AM
Fumes from the batteries (sulfiric acid) will indeed set off a CO detector. About 10 years ago my dad's boat CO detector went off at 7am so he called me, he was at the slip and there was nothing around him running to set it off. Being a couple of slips down I went to check it out and found the battery charger for the engine batteries had gone bad and "cooked" the batteries dry.

09-08-2017, 04:42 PM
Hydrogen dissipates vary rapidly if there is the slightest opening at the top of the compartment. It rises and dissipates even through a pin hole. So you need to make sure the battery compartment is properly vented. This is not only common sense. it is the law. I can't emphasize that enough. Battery compartments are required to be ventilated. This prevents explosions. However, if the hydrogen gas has nowhere to go it will migrate from a high pressure area to a low pressure area. So you need to devise some means of venting the bow compartment. There are all kinds of devices on the market for this but probably the simplest and oldest is a Dorade vent. What's important is not the cowl but the box (dorade box) under the cowl. This lets air pass but keeps water out. They have been around for probably hundreds of years. Old sailing ships used them. Anyway this will also prevent mold in the bow compartment and keep it dry. But as I said there are other gadgets that do this too.

Ken Lake Powell
09-18-2017, 11:32 AM
Thanks for the inputs. Appreciate it. Ken