During an unusually long and unusually cold spell, my main batteries "failed" - after ~ 18 years in service. That doesn't mean "dead", what it meant to me is that they dropped below 24v under a 100 amp load early one morning (microwaving that cup most of us have in the AM) having been fully charged the night before (the sun wasn't up yet either).
This is kind of analogous to a car battery failing in the cold of February - darn,if we just made to March, we'd make it to November, as all these work better in the warm. Oh well - I'll maybe put the best of the old ones into another system I don't use much - but which can back up the main one in a pinch (buried wire with 120V can push power either way and run a battery charger).
At any rate, I kinda panicked and ordered a new batch of lead-acids (newer tech is mostly a pipe dream so far, you can't buy it for a reasonable price per WH, if at all). Not cheap...$7800.
I'd ordered 1300 ah cells, but they shipped 1800 ah ones at no extra charge and they paid shipping - no complaints here. (Wholesale Solar) You can tell them I sent you. I also bought some nice panels to replace a few of my older ones and gain around 1kw of output (more on that when I'm putting them up) and like the batteries, the old ones can go on the backup system (for a storage trailer I have). Or who knows. I could divvy them up between the east and west sides of the shop and pick up a few more sun hours on lots of days - just postponing the time things start to discharge can be a real big deal especially in winter.
The new ones look real nice:
I spent this morning making those really nice and beefy copper terminal blocks for the new guys, all nice and tapped holes and so on. You want this to be easy to do and mistake resistant...
I also did some improving on the box, as it should be more insulating and it's pretty old now - OSB lasting > 20 years outdoors isn't too bad but...
The old one was pretty beat -
So, all these nice puppies gotta move (ugh) to make room for the new guys. These were nominally 1080 aH total.
This wasn't all I had in the box. In the next compartment over was a bank of L16'S and a couple of deep cycle trolling batteries contributed by Bill to the cause to keep me going till now.
Those are all new enough that they should match well enough to stay and be in parallel with the new ones, but of course I'll check...
This is kind of the dirty underwear of that box. 2 inverters and a small charger (modified from one for a forklift - ferroresonant) as well as a raspberry pi and arduino that take data and make plots for my LAN, as well as control the water pump and fan on that big Lister diesel.
After a glitch on that upper inverter (a square wave one) involving mouse pee and such, I just left the cover off. Now they don't have place to rest and pee without getting hammered with the HV.
The lower inverter is a sine wave one - Trace SW 4024 - that's run 99% of this place for many years, and is heating me a shower right now. Those things will easily make huge peaks - short it with 20' of #16 for a huge ball of plasma. Dead short it and it shuts off in mid half cycle without a spark. Pretty cool.
I now have a larger 240v one inside with the charge controllers for the big machines and fusor power as well - same brand (now Schneider electronics). This is a case where these are just better than what even a really good engineer would do for himself.
While I was at it, I put a new back wall on there too - the old one was getting weak, and I just slapped this on top of it - as well as adding some thermal insulation. The little Wen gennie runs the forklift charger, or my chainsaw etc. Those little inverter generators are nice - and worth the extra bucks in reduced hassle alone - they are FAR easier to start, use tons less fuel...clean output...if you use a gennie any amount - this is what you want. The old 3600 rpm hardware store ones make good boat anchors and doorstops, I hear.