On Mon, 20 Nov 2017 10:04:41 +0000, Huge wrote:

On 2017-11-19, Dave Liquorice wrote:
On Sun, 19 Nov 2017 12:31:09 +0000, Fredxxx wrote:

Voltage is everything in charging a Lead Acid battery. Also, the
higher the temperature the lower the ideal float charge voltage.

Some ought to tell APC.

APC are well-known for overcharging their batteries.

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.

--
Johnny B Good