S. Heisley wrote:[Tom, at 10.5, the battery is considered dead and needs replacing. But you probably know that. A battery should be checked before the start of charging and not allowed to get below 11.6. If that check reads 10.6 or below, it does little to even try to charge it. However, out of curiosity, I tried it and there was no out-gassing, even after a couple hours, and the battery did not get too hot.
Well, two points here: 1. It may not have done it that time, but it might another, 2. How do you know there was no out-gassing? Without a hydrogen detector, I don't think one could tell. Its not clear to me that hydrogen molecules, being as small as they are and at a relatively low but positive pressure, would even make some sort of out-gassing noise like air. If in a ventilated area (which I hope you were in when you tried it), the hydrogen molecules would likely have diffused so quickly even a good detector wouldn't find any. (Exactly why the AGM battery manufacturers say they should be in vented battery compartments, or out in the air.)
Oh, and suppose a cell fails
while the battery is charging?
S. Heisley wrote:It would make sense that there's a safety mechanism built in to the controller since the charger seems to "know" when the battery is fully charged and changes its charging to a maintenance routine or whatever, but my knowledge in that area is slim.
I don't know either. Neither the charger in my PD 4045 nor the one in my solar controller mention anything like a low voltage check. I did read something on the inter-webs about AGM batteries being able to drop below 10.5 volts (all cells down an equal amount, rather than one bad one) and still being good enough to "revive", whatever that may mean, so these chargers may, in fact, not look at low voltages. The PD 4045 still powers the DC systems in the teardrop when there is no battery (0 volts), so I suspect it may have voltage to offer anything across the battery terminals. (I'll put a meter on it in the next week or so when I have the system back together.)
S. Heisley wrote:Also, From my experience, the battery only seems to discharge fumes when I first begin the charging.
Sharon, that is really concerning. Hydrogen has no odor, and you certainly won't see it. Are you smelling/seeing hydrogen-sulfide, or something else that is poisonous? I don't know. It shouldn't be discharging
any fumes.
My basic point is that it probably isn't a good idea to assume an AGM battery or smart charger is always going to work as specified. There is a reason all of the AGM battery manufacturers say they must be in vented battery compartments, and I don't think it's just to appease the lawyers. We're talking about rare events, but ones with potentially life threatening consequences. I do know that when they build systems that do similar things in manned aircraft, spacecraft, or submersibles, a lot more money goes into ensuring a design safe for that environment.
But as the announcer at Woodstock said "hey, it's your trip." (Of course, it may also be your family's trip.)
Tom