Well, there they are, our nice new bank of Dynasty DCS-100L AGM batteries. They are sold under the Iterstate Battery label but are manufactured by C&D Technologies Dynasty Division. If you're wondering what got us to finally spend money for new batteries, after getting free ones for the last 3 years...read on!
About early July we began to have problems with our bank of recycled Dynasty High Rate Series batteries. They'd work fine for a day of heavy loads and not sun but without a full recharge they would crash very quickly on the third day, regardless of how careful we were. Now this is the sort of thing that happens with free recycled batteries, they have a limited life span and I'm always on the lookout for weak or underperforming batteries. But this particular incident somehow spurred us to thinking that maybe it was time to finally plunk down the cash for new batteries.
I'll be gone from home more over the next couple of years and while I'm here I don't mind babysitting the batteries (I like getting them for free, what can I say...) but it is a bit much to expect Maggie to do that. She isn't as well-versed in battery babysitting as I am and she is not inclined to want to deal with rewiring a battery bank or unwiring a series pair or two. Besides, if batteries had to be moved from the bank they weigh 100 pounds each and have no handles, and she definitely doesn't want to mess with that.
Plus there will be times when we are both gone and leaving that sort of maintenance item to a housesitter is not a good idea. So, after three years of living on free batteries I decided to get new ones. I talked to the folks at C&D (very nice, very helpful) and the engineer I talked to said that the High Rate Series I had been using was probably not the ideal (certainly not new) for the kind of system I run. Basically it boiled down to the fact that the High Rate AGMs were not designed for lots of cycles and so would not last as long in my system, even with shallow cycling.
That is good because I really wasn't going to pay the price for new High Rate batteries, they are really pricey, so I asked him what he would recommend in terms of an AGM battery for my kind of installation. He suggested their DCS-100L series, a 100 amphour 12-volt battery most commonly used in wheelchairs. They are rated for 1000 deep cycles (80% DOD) and would, in his estimation, be good for at least 3000-4000 cycles at 20-30% DOD, which is my average usage. That works out to well over 10 years. The trouble was he could only quote me the manufacturer's list price, which is always high (I won't repeat it here) and suggest that I call their outlets in Colorado for specific pricing.
I was almost turned off by his price but decided to call Interstate Battery in the Springs anyway, and I'm glad I did. I managed to get a bank of 24 DCS-100L AGM batteries from them for $100.95 each. This is more than a comparable flooded cell battery but less than a comparable Concorde AGM battery (one you commonly see on Solar websites for sale). So for around $2500 I got myself years of peace of mind.
Do I mind having used the recycled batteries? Not at all. It was more work but less money and gave us 3 years of service before we made the upgrade, so it was a worthwhile effort. But now we are in good shape for the future, I can travel knowing Maggie won't have power problems she can't deal with and we have a battery bank with excellent capacity (1200 amphours) and excellent health. Oh, they're also under warranty and they weigh in at 69 pounds with handles, so they are far easier to move around, if need be, and I'm sure not getting any younger!
Here is a closeup of the buss bar arrangement and a shot (below) of the battery box all closed up and ready to go. Notice that the wiring is even neater than before, for some reason it was far easier to route the wired from the existing system than to install them initially (I have no idea why), plus the batteries are shorter (same footprint) than the others so there is more wiring room above the batteries on each shelf.