I don't believe any of them are particularly 'special' however they perform an IR task that is nigh on impossible to accomplish otherwise.
When testing SLA batteries and various deep cycle batteries, it is not appropriate to heavily load the battery. The batteries are not designed for the types of loads as per the normal 'car' / automotive battery. The thin plate / high current automotive batteries are only designed to give intense bursts of power for very short periods. They are not designed for sustained light / medium loading and will in fact be damaged more rapidly by such usage.
SG was and still is a gold standard in battery testing however, it is time consuming, can be messy, often has difficult access and indeed, not a lot of modern batteries even
have access or indeed wet cells. Various 'maintenance free' (read disposable) and absorbent mat units are around. Many 'dealers' and garages use the BBB meters (Bulshit baffles brains) that give a nice little printout to the owner. These mostly rely on 5 thing only. Voltage at start of test, voltage on load engine off, voltage at engine cranking, voltage with engine running (usually above 2k rpm) and internal resistance approximation. All the voltage checks can be completed in seconds by a spanner monkey but the internal resistance check is not available to the 'normal' SM. From the very approximate IR check they estimate CCA
cough..... - widely inaccurately . Temperature is noted to apply fudges to calcs, ambient and DUT however DUT is hardly ever probed for temps due to CBA factor. which is a shame - as it can get fairly toasty in a car engine bay - or indeed the other way where it may be warm in the garage and the battery is still around zero c from the overnight stand before testing.
These units do not offer much - if anything - more than the simple tests that we were carrying out 30 or 40 years ago. Same voltage tests and also (if alternator is ok) disable ignition and crank for 15 seconds with lights on. If it is still ok after that, it is a good battery.
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Any battery (LA) that has been taken to below 12V resting voltage will almost certainly be captain cooked and awaiting a nice UK morning in winter to let you REALLY know.
(AGM automotive thin plate design units are really good for being able to recover quite effectively from deep discharge / low voltage where a thin plate LA unit would be almost certainly permanently damaged.
Specialist units for 'stationary battery systems' only offer 1 thing of real use imho - that being approximation of internal resistance. !. That is the only thing of 'use' that cannot be readily checked with a multimeter - it can be used along with the voltage readings as an approximation of ability to discharge. Even the good old flukey expects a steady load timed discharge test - and heavens above, it can tell you the approximate capacity from this
..... so could the monkey holding it...
The rest of the functions- take the fluke 500 as an example - can be carried out by any monkey with a multimeter to be honest. It looks good to the client though
.. always worth a lot more dosh. Every flashing LED used to be worth 25 quid on top of the hourly rate... now it is a bit of simple data logging PC software that is nothing more than could be accomplished with a spreadsheet with the most basic of calcs in. Plotting a baseline - for anything really - should be automatic for anyone in the business. You then have something to refer to.
I really see nothing of any great value apart from internal resistance approximation. But hey
.. it looks flash and the BBB meters and boxes definitely add an extra zero to the invoice.
- KerCHING ....
like most things 'techy' these days it is mostly a case of an expensive solution looking for a problem.
Actually, to be serious, It does certainly have a place in checking safety backup and stationary units. It can be delegated to a junior monkey (within reason) and the pc / laptop whatever makes the notes and reading. So there is a use I suppose.
. It also offers an IWM feature for the bosses in the event of the excrement hitting the rotary oscillator . An IWM unit is where, because of the expensive device you got the DIrector / manager / company to pay for, you can blame the device and not yourself ..... "IT WASNT ME" ...................