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Power Inverters
Thanks guys. I am going to try the 24-hour trickle charge. This site really has knowledgeable members. This morning I lost a neighbor of 40 years in a house fire but I will read in more detail the post to my question. He was near the point of death from ephemera but the entire attic was involved before they knew the house was on fire. His wife lost some hair but made it out. She and a nearby son just could not get him out of a window but the fire department arrived and kept the fire from his body. If you are planning to build and like me have (or may have) mobility issues look at having an outside exit from your bedroom. Batteries are still on my mind but my day would have been better if my neighbor had had an exit door in his bedroom.
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Oh man, too bad about your neighbour and it's not an easy time for you either. The exterior bedroom door idea is a good think to think about. We have a fire safety video in our Library that shows a frame house going from start to completely engulfed in about 10 minutes. The messages is that even with smoke detectors--if hear it there's no time to do anything but get out immediately. Standard houses really aren't good for many seniors and people with limited mobility.
Very good info from AC and I learned something about batteries. Maybe we'll get back to the subject.
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Battery charging update. I tried the trickle charging idea and it worked. As a reminder from my post above I had 4 deep cycle identical batteries that would stop taking a charge at 2, 2, 3, and 4 amps on the charger meter.
First working with the battery that would stop taking addition charge at 4 amps I would knock off the surface voltage by using about a 500 watt load for 1-2 minutes (700 watt inverter running some lights and fan) and then trickle charge for about a day. Repeat knocking of surface voltage and to regular charge, then repeat the trickle/full charge cycles.
The first time it would still drop down to only 4 amps when fully charged. It went to 3 amps after the second set of cycles and went all the way to 2 amps after the third cycle. I will try this a few more cycles to see if it will approach Zero but first I am working to see if I can now get the two batteries that were only dropping to 3 amps down to 2 amps so I have 4 batteries stopping at the 2 amps point.
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Good that the trickle charge thing helped. Somebody who knows batteries such as AC proably will weigh in on this. As far as I know you get the full effect pretty quickly and you can't expect to get all batteries to very similar charge states. Even if you do you they likely wouldn't stay there after some use. There may be further room to tinker by doing hydrometer checks on individual cells and adding a bit more acid here and there. I'm being vague here since I don't know if that'd work or be a good idea even if it did.
I would keep in mind that AC said that the application would be unlikely to damage the batteries anyway--no guarantees though. For me it'd be fun to keep experimenting with things but I would keep in mind that it might end up crafting a solution that then needed to search for a problem.
I seem to remember that this is for a computer network. My individual PC backup has a USB connection to the computer. It's supposed to backup open files and then execute a Windows shutdown when the battery supply starts getting low. Something like that also should prevent the battery mismatch problems described.
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I believe battery chargers used for large battery banks in solar and diesel generator applications are 'smart' and have a conditioning phase where they slightly overcharge the batteries to ensure they are all as similar as possible.
I don't know if the trickle charging of individual batteries in the bank can achieve the same results, but I don't think it will hurt anything. I wonder after a number of discharge/charge cycles if the 'off' batteries revert to their original condition.
Just my 2-cents,
bliz
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As a follow-up I have not yet connected the second set of batteries for my office 5.3kVA UPS but I have been able to get all 4 conditioned by trickle charging as mentioned above to stop charging at the 2 AMP reading on the scale now when doing a full rate charge by working with them individually using a 12 volt charger. Soon I will use them to build another 48-volt pack that will be connected in parallel with the other 48-volt pack. Below is what a tech from another forum had to say about adding the second 48-volt pack in parallel. Remember all 8 batteries are new, the same brand and same specs and from Wal-Mart. 
Other forum reply:
No, the battery charger will not exceed it limits. The added 48 v pack will not cause undue hardship, but will require slightly more than twice the time to charge. "Slightly" due to the added internal resistance of the added batteries. Run time will basically be doubled
Before you add an another set, check the batteries are not excessively "gassing", produced by excessive charging voltage. This should not be an issue due to the circuitry was designed for sealed batteries. Simple remove the cell covers, you should not see gas bubbles, maybe occasional small bubbles are OK, large and numerous bubbles, are not good, in a fully charged battery set. The room these batteries are in should have a small amount of air exchange, all open cell batteries do produce a small amount of hydrogen gas, (from first hand experience, it is explosive). As long as they are not contained in an airtight room they are safe.
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Sounds like a good outcome and there's been decent comments all around. Maybe we've all learned something. For myself I might have guessed that hooking a charger across several batteries in parallel would increase the charge time but not the load on the charger if I though about it. It didn't occur to me at the time and now I know. It makes a lot of sense that chargers would be designed to limit current at low load resistance.
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