They replaced the charger that was overcharging, making the dual lead-acid batteries release hydrogen. So far, the CO sensor is not registering any H2 with the new charger.
Here's the problem: The guy who installed the new charger said that as long as there is no H2 registering, keep the charger plugged-in, even after the green light is lit (full charge). However, the manufacturer's instructions say: "At green light, keep charging for a couple of hours for complete charging. When charging finished (Green LED), disconnect from mains and remove clips from battery. Charging can continue in 'float stage' without harming the battery."
It means follow the advice of the guy who installed it. Otherwise you will need to remember to hook it back up from time to time and I am sure you will forget the three months prior to needing it. The "Charging can continue in 'float stage' without harming the battery." Means you can leave it on without damage. It will use a little power on standby however.
What the hell good is a sump pump battery charger that you have to plug in and unplug? It's not as if there's never been an automatic charger invented, either.
Though I don't see the point of a backup battery; it won't have enough lasting power if you need it (there's a very narrow range of flood sizes that it will help you with, most being either too small - so you don't need the pump - or too large - so the pump buys you five minutes and then the basement floods anyway. It's conceivable that there's a perfect-sized flood on the way, not too small and not too large, and you will look like a genius, but I doubt it).
While I tend to agree, they do make sense for anyone with an unreliable power source and who also needs the pump on a regular bases, especially if they are on a well, that would not be able to power a jet pump. Power outages and extra water often go together.
The thought of a battery fire or hydrogen saturation is terrifying. Would it harm the system if I just "topped it off" a couple of hours per day, every day or every other day, and kept the plug pulled the rest of the time?
It certainly says it is okay to leave it plugged in, but I would check with the manufacturer to be sure. They have contridicted themselves, and either could be correct.
I would think about 30 minutes a week would keep them topped off. It depends on several factors.
Anytime you charge lead acid you are going to get some hydrogen. Normally it is not enough to worry about.
A special charger designed to stay on all the time, and just keep the battery charged, not really charge it, sounds like what you should really be using. Something in the under 1 amp area.
Dont fret about the hydrogen saturation problem. The buoyancy and atomic size of hydrogen make it very, very unlikely to cause a dangerous hydrogen content in your basement. During excessive charging you will have a small excess of hydrogen gas very near the terminals on your battery, so be careful about hooking up the charging leads, but other than there is no worry about the furnace or hot water heater lighting off hydrogen in the basement. Most trickle chargers operate at 13.2volts / 1.5amps. The mere milliliters per minute of generated hydrogen are not a cause to plug and unplug your charger, although if you are really concerned just put the charger on a timer and forget about it. Just check your water level from time to time and add a bit of distilled water if neccessary. AS long as you keep your battery topped off with water you will not damage it with trickle charging.
The old charger resulted in a 256 on the CO sensor in the room with the batteries and 75 on a sensor two rooms away. Someone said you can estimate H2 by multiplying the CO reading by 2.5. This would be far below the 40,000 ppm (4% saturation) danger level. Problem is that the alarm sounds at these low levels and if I disconnect the sensors, there's no way to know how high the H2 reaches. They're lead-acid maintenance-free batteries, by the way. Someone suggested they be replace with gel batteries.
The gelcells are designed to recombine nearly 99% of the hydrogen & water which may be a good choice in your situation. I am quite surprised that you are seeing such high CO readings, as I would not expect that much hydrogen to be evolving. Where again in the CO detector. I charge a sump pump battery in my basement 24/7 with a CO detector (digital ppm readout) about 7 feet away around 4 feet off the ground and never have been above 1 on the readout. You might consider putting in a different detector to verify the data you are seeing. Typically the standard home detector is a metal oxide type, which as far I know is only sensitive to 10 - 15% actual hydrogen content. The different types of CO detectors are listed below for your reference. Also I came across a reference that indicated that the maximum rate of hydrogen evolution of a standard lead acid battery is 0.42 liters per amp per hour of overcharge. (0.21 liters of oxygen per amp per hour).
Also, contrary to typical representation in MSDS sheets for safety purposes, the lower flammability limit of hydrogen in air is approx.
4%, while the actual lower explosion limit of hydrogen in air is approx. 17%. These limits are empirical though and depend greatly on the the ignition source and other variable. It is always best to be on the safe side, but this may ease your mind a bit.
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Biomimetic (mimics body response) - usually battery operated, but sensitive temperature and humidity, lasts approximately 6 years. The technology uses gel-coated discs that darken in the presence of CO, tripping the alarm. Oxide Semi-conductor (most common) - usually plugged into wall, uses Metal more power, sensitive to moisture, lasts approximately 5-7 years. With this type, heated tin dioxide reacts with carbon monoxide to determine levels of toxic gas. Electrochemical (least common, more accurate) - expensive, battery operated, short sensor life. With this type of sensor, three platinum electrodes in an electrolyte solution generate energy when they react with CO.
Original Charger: The CO sensor was 25 ft. away and plugged into an outlet one ft. off the ground. The reading was 75 when the alarm sounded. It is a Kidde Nighthawk CO sensor, direct plug-in. That same day, the fire dept. got a 256 reading in the battery room, using a hand-held sensor.
I bought a second Nighthawk, direct plug-in, and placed it 3 ft. from the batteries, and 5 ft, high.
Second Charger: When the light is orange (charging) the highest reading in the battery room has been 48. When the light turns green (charged) the reading drops to zero, which means it could be anywhere from 0-30 as it doesn't register below 30. The old sensor in the room
25 ft. away is more sensitive, it will show readings 0-30, but they have so far been zero with the new charger.
I disconnect the charger at night for peace-of-mind purposes and reconnect the next morning. It takes anywhere from 15 minutes to an hour for the light to go from orange to green. If I skip a day, it takes two hours to turn green.
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