The battery is obviously of an age where you'd expect the side effect of loss of plate material to accumulate in the clearance space at the bottom of each cell to become a source of high self discharge leakage, if not to the point of shorting the cell when you've lost more than 75% of capacity.
Initially the worst effected cell loses charge from self leakage which exacerbates sulphation, further reducing capacity such that you get a runaway effect, perhaps mitigated by applying a gassing charge that ensures *all* the cells start gassing on each charging session, necessitating a top up of water where the best cell needs the most with the worst needing the least amount of topping up. However, once you've reached this stage, the situation rapidly deteriorates to the point where no amount of gassing charge and gallons of distilled water can mitigate the final demise of the battery.
A sure fire sign of a 'shorted out cell' is the resting voltage, hours to days after receiving a full charge, settling to a mere 10.6 volts instead of the more typical 12.7 volts. I'm guessing those 12vdc CFLs use an electronic ballast that can compensate for the reduced voltage, so, unlike an incandescent filament lamp, can hide this symptom of low battery voltage by the other, not quite so obvious one of shortened autonomy which might well be hidden by a regular recharging schedule that prevents the remaining "good" cells from becoming totally discharged.
I can see some benefit in making use of a worn out high capacity car battery for light duty where the fractional capacity is enough for a month or so's worth of autonomy when it's not kept in a secure location wherein the sheer weight (of a boat anchor) becomes a nice deterrent against theft but, IIRC, I believe you keep it locked away in a secure shed where you might be better off using a much lighter 25AH SLA instead.
I knocked mine down one click in the PROG mode to 54.05V according to multimeter, and the internal data log agrees with that, however this is constant regardless of temperature.
Most APC UPSes arrive from the factory with CSB (now Hitachi) batteries, the datasheet for NP17-12 specifies all their characteristics at 25°C, with a nominal charge voltage of 2.25 to 2.35V per cell, mine sits in a cupboard where the UPS has an external temperature probe and measures the temperature outside the case as 19°C and inside the case as 31°C.
Technically, I think the voltage ought to be dropped by 3mV per degree above 25°C, and given that mine seems to sit between 31 and 34°C maybe I'll knock it down another couple of clicks.
Did you see my photo? Quite a hump, though not from my own UPS I hasten to add, currently using Tayna/Powerline batteries which seem to be doing fine after 2 years.
Yes, they are on the inefficient side ... but I've had a couple of power cuts in recent months and the smug feeling when you see that every other WiFi signal in the street has gone off is worth it :-)
My little one doesn't come with a fan. I hi-jacked the SNMP(?) card slot space and fitted a PC slot exhaust fan along with a speed controller.
Complain to your DNO. Ours (Electricity North West) takes complaints about the supply quite seriously, especially if you have data to back up the complaint. A regulator shouldn't spike as it changes and "around midnight" (*) strikes me as a bit odd as well. I wouldn't expect load variation to be that consistent, weekday/weekend being different at the very least.
I understand that you should be ok with broadband staying up with ADSL but do you know if those of us on cable would be ok? Eg, are the green cabinets (assuming they aren't passive) remotely powered or have a UPS of their own etc?
27.6 sounds familiar, I have a feeling I took it lower than 27, to something in the upper 26's. OK it now takes nearer 15 to 20 mins (instead of about 10) to get to the 15% recharge level before it switches the load back on after switching off due to low battery but I can live with that.
That was a bad set, other sets have just swollen. Had to junk a rack mount APC PS as to remove the batteries would have required major metal work surgery. The batteries had expanded into the framework gaps.
I have a small (4 x 12") solar panel permenantly connected to the gensets starter battery. That keeps it nicely fettled, but is another thing that I ought to test soon. ie wheel it out, check oil etc, start up, load with 1 kW fan heater and let it run for an hour or two. Ocassionally switching the heater off or up to 2 kW for several minutes.
Cover a switching dropout or auto recloser trip/reset? Cover 10 mins whilst DNO engineer drives between manual switches to restore supply via a different route?
36 hours whilst they replace snapped poles and switch gear bought down by an ice storm?
As well as overcharging *for* their batteries. :-(
In my limited experience of other, admittedly old brands of UPSes, the use of 13.8v per 12v battery pack was a universal practice. Today, I would hope a more intelligent charging scheme other than utilising the dumb constant 13.8 volt charging of SLAs is being used with the current crop of UPSes.
Although the likes of SmartUPS2000s and SmartUPS700s have extremely complex circuitry with microprocessor control of the sinewave inverter and its mains conditioning for over/undervolt events as well as dropouts, the battery charging circuits are about as basic as you can get (essentially a constant voltage supply).
It seems there's ample opportunity to improve on the basic battery charging management system of old with today's modern UPS kit. Whether an extra percent or two of the total manufacturing cost has been diverted to battery management with modern commodity UPSes to improve battery life or not, is something I'm not aware of since I've not shopped for new UPS kit ever.
It might pay me to check out the adverts for new UPSes to see whether any models are boasting of such improved battery care. I might get a hint as to whether reducing the classic 13.8v setting to a mere 13.5v would be the best way to go with my existing UPSes.
My experience with charging a 2nd hand 12AH SLA just once a year to maintain it in good condition by leaving to sit at its 12.7 volt resting voltage for over 11 months of the year, rather implies that a setting of
13.5v per 12v SLA would provide an improvement with just a small reduction in autonomy compared to a brand new, not yet shagged, battery that's slowly dying a death from being relentlessly subjected to the full
13.8 volts typically used by APC and others to maximise their advertised autonomy times on a brand new set of not yet shagged out batteries. It pays to keep in mind that advertising is the art of lying by omission.
Yes, there is that factor too but, in my case, that can't explain the short life of SLAs and the even briefer life of two sets of cheap 36AH SLI batteries with the APC SmartUPS2000 acquired 2nd hand without a battery module (it's a split design and I only got hold of the inverter half sans battery case). The unit was set up in my basement shack, wired up to a set of four 12v SLAs in parallel with a set of four car batteries on the shelving below the UPS itself. The basement temperature rarely got above
18 deg C in summer and no lower than 8 to 10 deg C in winter.
Excessive temperatures are a proven deleterious stress on batteries of every type, primary and secondary cell types alike but is even more so with LA batteries subjected to an unremitting constant voltage float charging regimen. However, in my case it seems an unremitting 13.8v per
12v SLA and/or car battery alone was sufficient of itself to shorten battery service life. Excess temperature simply didn't apply in this case.
Thanks for thoughtful comments. Didn't get to check the voltage yet (mad day today) but I will do ASAP. I agree, I think these "caravan/boat" CFLs cope very well with low voltage (which is probably part of the design spec). One of the huge advantages from moving to "12V" lights run directly from battery instead of what I used to do, using a cheap inverter with mains CFLs. Great suggestion from someone on this NG which had not occurred to me.
As I said before, this isn't a smart charger, just an old fashioned transformer/rectifier.
One of the reasons I am persisting with "old, knackered" batteries from diesel cars is that I have now had two specially purchased sealed proper "leisure" batteries fail after something like two or three years in this location. They don't get particularly well looked after, they are mainly needed in the winter so don't necessarily get checked regularly in the summer. They are connected to a couple of PIR floods but in the summer, you never see these trigger so the batteries can get flattened by the cats and foxes without it being obvious. I suppose I ought to add a "battery low" circuit with a warning light, but that would steal current and in any case ICBA. In the winter, the PIRs normally trigger when you arrive in the evening, also you are using the non PIR lights so you know if the batteries need charging.
It's a relatively sheltered location, otherwise I would be tempted to put up a small windmill charger, which would probably sort everything out with leisure batteries.
We've only suffered one major outage of supply back in the mid 80s just after I'd acquired my very first UPS (a 2nd hand Emerson 30 - 450VA 300W quasi-sinewave jobby using a pair of NP7 SLAs).
The power went off about 7pm on a Wednesday (Radioham club night) just as I was about to set off. Luckily, the UPS was plugged into the mains and backing up my desktop PC so I was able to shut down the PC (or it may already have been shut down, I forget which) and relocate both the UPS and a lamp stand (with a 13W CFL fitted) onto the half landing to illuminate the hallway and first floor landing.
I daren't shut that UPS off since it couldn't do a 'black start'. I later found out, when I returned from the club meeting about 3 hours later, that the children had sat on the loo seat lid in the half landing toilet to finish their school homework by electric light.
The power was back on by the time I got home. Apparently it had only lasted about 3 hours or so before the supply was restored - apparently, an underground joint that had been damaged by roadworks which allowed water ingress over the preceding days which had caused a few random glitches before it finally tripped the supply off at the local substation.
Since that one and only memorable outage event, we've only experienced the odd half second or so dropout maybe only once or twice a year. The last one happened about 6 months back and was just long enough to reset unprotected computers, including those that were cunningly disguised as domestic TV sets, little more than a full second or so's worth.
The almost total absence of power outages by the time I needed a new set of batteries for my basement SmartUPS2000 (feeding protected sockets around the house) made me pause to reconsider a less costly UPS solution than using an expensively large capacity battery to give me hours and hours of run timen means I'm now looking to getting an inverter type of genset in the 2 to 3KVA range so I can make do with a cheaper bunch of NP7s in place of the originally specified 18AH battery pack or a set of
50AH car batteries all of which are likely to be in need of replacing in less than 5 years of service (maybe 10 if the voltage reduction to 54v float charging proves an effective solution to the problem of short battery life).
I've already discovered the hard way that the classic emergency genset just won't cut it due to the the capacitive loading of the SmartUPS2000 mains input network which totally screws up the AVR of such generators causing them to drastically overvolt whilst the UPS is in pass-through mode[1]. As soon as the UPS switches to battery power the genset voltage drops from some 275v or so back to its set voltage of 230 and the UPS senses this and goes back into pass through to trigger yet another overvolting cycle and a flip back to battery power ad infinitum.
The only type of emergency gensets that are immune to this problem are the inverter types which are considerably more expensive to buy although a little cheaper to run if an eco-throttle feature is incorporated (the cheapest ones don't). The consequence of which has lead me to procrastinate over the decision to recommission the basement UPS.
Needless to say, the NAS box was undisturbed by that recent 1 second dropout, being as it was, the only item of IT kit that was still protected by an APC BackUPS500 UPS which is now recovering from a
27minutes and 40 seconds autonomy test on the 50W NAS box load (booted into a Knoppix Live CD session to get the power management operational without risking the integrity of the file system). ISTR that the last such test was over three years ago when I fitted the current 7AH SLA and got something like 33 minutes or so runtime before the UPS quit.
This time, I restored the power shortly after hearing the mournful beeps change to a continuous beeeep, indicating critically low battery voltage and imminent loss of power in anywhere from seconds to minutes, depending on the loading. It's possible I may have had another 3 or 4 minutes left but I was happy to cut the test short after seeing over 27 minutes runtime, about twice as long as I was hoping for considering how long the battery had been installed in an APC UPS. I suspect what contributes to a longer than typical APC battery life in this case is the fact that the maintenance power consumption is a mere 2.7W once the battery pack is fully charged up.
I've had to repair both these UPSes (failed 7812 regulator chip in the BackUPS500's battery charging circuit and a broken mains voltage switching relay coil connection pin in the SmartUPS2000). Rather fortuitously, I'd discovered a Russian website with downloadable circuit diagrams and service manuals for most of the older APC UPSes just a few years earlier (over a decade ago now) and I ransacked the lot (several dozen afaicr, including several variants of the SmartUPS2000 and BackUPS500 models).
[1] The problem with augmenting a UPS with a cheap 'n' cheerful emergency generator set isn't due to "The Dirtiness" of such mains voltage sources, it's all to do with the overvolting effect from even modest amounts of capacitive reactance across the generator's output terminals.
The UPS isn't bothered by harmonic distortions of the genset's waveform measured in tens of percent or even of a modest 2 or 3 percent departure from the nominal 50 or 60 Hz frequency of supply. The issue is solely to do with a defect of all such rotary magnetic machinery when connected to a modest value of capacitance, a defect that's been put to good use when people have used large HP rated single phase squirrel cage induction motors as genset heads in their DIY genset projects where several dozen microfarads' worth of capacitive loading is used to magnify the effect of residual magnetism into full blown excitation to saturation of the rotor core to create a genset that needs to run at slightly higher rpms than the 1500 required to generate a 50Hz ac voltage output with a conventional generator head(the reverse of what happens when used as a motor).
What I discovered when experimenting with trying to filter the 5KHz or so slot ripple frequency on a 2.8KVA genset in the mistaken belief that this was possibly one source of "Dirtiness" that was upsetting the UPS, was that a mere 4.7uF (a 20W fluorescent light fitting PF correction capacitor) was all it took to send the voltage north of the 270v mark.
The SmartUPS2000 has a pair of this size of cap effectively in parallel across its mains input only when in pass-through mode, disconnecting them when running on battery, hence the endless switching between genset supply and the battery powered inverter supply. It's not the "Dirtiness" of the emergency genset supply, it's the overvolting effect of even modest amounts of capacitive loading that does all the harm.
Hell! As sine-waves go, the mains waveform as displayed on an oscilloscope is a far from pretty sight. As I've already mentioned, the inverter gensets are free of this overvolting effect so are the only practical solution to this specific problem. Mind you, since most house lighting is now comprised of LED lamps which mostly utilise a wattless volt dropper in the form of a mains voltage capacitor, the demand for inverter gensets just to provide emergency lighting power alone must be going up, hence those 1.2KVA inverter gensets now being sold by the likes of Aldi and Liddle.
The demand for an emergency genset that *won't* instantly fry all the house lights will lead to a decline in production of the classic cheap 'n' cheerful genset and hence to cost savings in mass production runs of the ever more popular inverter based emergency genset reflected in the more competitive pricing already appearing in the small suitcase sized end of the market.
The last time I saw the Parkside gensets on sale in Lidl a few months ago, they were priced at a mere 150 quid each. I'd have bought one just to test but they'd either sold out or else didn't get delivered to any of my local stores, possibly on account of a last minute recall for which I couldn't track down any stories to corroborate what one Lidl shop assistant had intimated to me. Hopefully, I'll get my chance to sample one of these suitcase sized inverter gensets in the not too distant future to try out for myself. I might yet invest in another battery pack for my basement UPS after all (a small 7AH one - I'm not made of money!).
Which is all fine and dandy for car batteries and wet cell deep discharge leisure/marine batteries but deadly when used to charge SLAs unmonitored.
SLAs, particularly the Gel type (AGM types are a little more tolerant) don't take kindly to receiving a gassing charge, hence the precisely defined constant 13.8v charging voltage specified for 12v SLAs to preclude such gassing charges which will create fixated bubbles of hydrogen and oxygen in the Gelled electrolyte or within the Absorbant Glass Matting used to fix the liquid electrolyte in AGM cells. These gasses are known to behave like insulators just like every other gas at NTP so such trapped bubbles increase cell resistance and reduce the effective active area of the plates.
If you're going to use SLAs, it's essential that you use a proper battery charger or a purpose designed solar panel charging controller to protect them from overvoltage charging.
One of the things to avoid with SLI batteries is a regime of deep discharge between each recharging cycle, especially if the battery is likely to spend a lot of its time in a partially charged state since this aggravates the sulphation problem on the lowest capacity cell which accelerates the normal reduction of capacity with each discharge/recharge cycle. you need to limit the DoD to no more than 50%, preferably 30% if you want to avoid premature failure under such a regime.
Relying on the brightness of your 12v CFLs won't alert you to the lowest capacity cell becoming fully discharged in time for you to remedy the situation with a complete recharge to get all the cells gassing to make sure that all are brought up to their maximum state of charge to overcome any imbalances due to variations in the self discharge characteristics of each individual cell.
Even if all 6 cells in a car battery start off with identical capacities and self discharge characteristics, it doesn't take too many charge/ discharge cycles for differences to build up which continue to accelerate, even when given a balancing gassing charge to eliminate one of the causes for the acceleration of the weakest cell's deterioration rate. There's a lot to be said for designing equipment so it can be powered from a single cell "battery" rather than an actual battery of series connected cells to make up a higher voltage.
If you're planning on a monthly routine recharging cycle, then choose a capacity that represents at least three month's worth of autonomy to ensure you don't burn through the limited number of charge/discharge cycles prematurely. AFAICR, the SLA and deep discharge leisure/marine batteries can tolerate a 70% DoD without harm provided they're not left in this state for more than a few days at a time.
This can work if you use a suitable charge controller designed to accept windmill driven PM alternator and/or solar panel inputs which can handle the 'wild voltages' of a windmill driven PM alternator and match the varying impedance of a solar panel source to maximise the power transfer to the battery (as well as limiting the maximum charging voltage to avoid cooking the battery when you have a surplus of either source of 'Free Power').
All rechargeable batteries need babying to get the best life out of them, even the more robust NiFe cells can benefit from a sophisticated battery charger and are essentially immune to being left discharged for extended periods of time without harm.
So do ordinary, nominally 230 V, CFLs. Confused the heck out of me having been woken up in the wee small hours when the ice storm had done it's thing and left our supply at around 120V. Things with lumps of iron power supplies were off, things with SMPSU's were quite happy, CFLs worked but were probably a bit dim, tungsten just emitted a dull brown glow...
Once I'd sussed out the low supply voltage just operated all the main switches to "off" and went back to bed.
When I was a datacomms guy we had some X.25 kit in a remote site that seemed to be regularly 'locking up', roughly the same time each Friday.
Long short, we put a mains voltage monitor on it and found a large spike on the cabinet PSU and that coincided to when the cleaners came in and plugged 'Henry' into the cabinet power strip. ;-(
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