Beware those Yuasa NPs. I had one and it only lasted 23 years.
LOL! It was an NP12-4 (4AH) in my family home's alarm which I installed in the 1980s and it's still going strong. We tested the battery yearly to check its 24-hour reserve and on the 23rd year it failed (I can't recall if it was hours or minutes).
Upon replacement I realised how old the beast was. Yes - Yuasa were definitely a QUALITY battery (something I learned from the 1970s when replacing motorbike batteries).
FYI - I replaced it with the 7AH NP12-7. It was the same price and merely required the cut out of one panel, and vertical mounting instead of horizontal.
Sure, that was standby use where a battery is normally not used and merely sits on float for most of its life - and in theory (ignoring chemical aging) it should last forever - but still, IMO 23 years is ridiculous. Even HUGE telco 2V wet cells with 20-year design lives which are maintained (with 3 monthly checks etc) don't last that long, and they are likewise "standby" batteries which traditionally were wet cells thereby enabling equalisation and other life enduring practices.
Anyhow, that was something I was going to mention. Sucking & seeing a battery like the NP might yield surprises. They are quite a battery, not only suited for standby with low current loads (as in an alarm with 24-hour reserve), but also cyclic crankers (they are used in motorbikes etc).
And 23 years - that really exceeds the spec. I think they are a 10 year battery tho maybe only 5. But IMO those specs usually mean ideal conditions on float and probably unused - you then subtract for the number of discharges, their discharge rate & depth, time to recharge, temperatures, etc.
BTW - my NP12-4 testing was very scientific - I'd disconnect the AC and the battery was deemed flat when the PIRs stopped detecting movement and did not light up. Now everyone knows you should not test a battery by "flattening" it - it should be done with a known load to a predetermined set point (ie, never less than 10.5V or 1.75V/cell for most batteries). But despite that abuse she still lasted 22+ years. (AFAIK the alarm does NOT have any LVCO - Low Voltage Cut Out or "battery protector", and I'm reasonably certain it did not have any sophisticated charging algorithm. Though it was a brilliant alarm - a locally made IEI unit. IEI also made the VESDA - Very Early Smoke Detection Alarm - which became popular in many critical environments internationally.
I guess now I will have to read the rest of this thread. (Rats!) I'll bookmark it for now (into my round tuit folder for which I'll need a 23" x 16 mile screen to read) and pray I don't find anything that rings alarms (is that a pun or post-segway?).
Alas I rarely read or re-read earlier pages of threads (that's something that can partially backfire as in AutoWiz's My Accord build carputer communicating with ecu REAL TIME TUNING) but I happened to spy your request due to fate (aka your PM).
But you have researched etc, and have probably gone nuts over the application of battery specs and balancing all the different factors involved. I go nuts too except where the application is fairly clear cut - eg, regular car crankers or long-slow solar systems etc. Even then, IMO nothing would top the experience of someone that has had that precise application, and hence why I heed the advice given by certain battery suppliers etc. [ I love my supplier. His customers come back - albeit usually after 8-10 years LOL - and he experiences his typical car & 4WD applications and hears of solar and other customer applications including golf carts & bikes etc. He confirmed early on what I knew (that Apollo batteries were crap) and later similar for Optima and even my "theoretically beloved" Odyssey (where I accepted his comments tho unexperienced myself). And where he contradicts me, I'll follow his wisdom - tho that has never happened on the theory side, but I'm still out on batteries flattening on concrete (I have yet to confirm if his were thermally equalised - long gone are the days of batteries flattening on concrete, at least according to all "documented experts" I know of. ]
One grace is that battery specs are usually conservative - they should cover 95% or 99% etc of their released batteries. And given the spread of manufacturing possibilities, that could mean exceedingly under-spec'd in some cases. But any non-spec abuse could kill the battery quickly (over discharge, high temperatures, excess charge voltage or current).
Again, my usual ramble. But that's the art of batteries.
PS - Ped: Battery ESR is not the same as battery internal resistance. That's somewhat pedantic but I suspect some think ESR is internal resistance and use them interchangeably - but the 2 should be similar anyhow. Technically ESR is what "we" want for short circuit (current) & voltage drop calcs - even though a battery's resistive voltage drop is (or should be!) insignificant at the currents we use - and I'd expect most do give the ESR which is easy to determine.