SIELCO srl
- Via Toscana, 57/59 - 20090 BUCCINASCO (Mi) - ITALY - tel. 02 - 45713300 - www.sielco.org
EXC/RTX19 - USER & MAINTENANCE MANUAL - rev.1.5 - 05/16
Page 15
Battery life
A discussion of correct installation and maintenance of the battery system goes beyond the
purpose of this manual: we suggest not to underestimating the problem and to refer to specialised
literature and to the suggestions of qualified battery manufacturers.
Our advises may be summarised in the followings:
- Use batteries whose capacity is at least 2.5 ÷ 10 times higher than the maximum expected
power absorption, on prolonged mains loss.
- Never permit batteries to undergo below minimum safe voltage, on prolonged discharges.
Following these rules, battery life expectation may range from 2 to 5 years, depending on
duty factor and temperature (low temperature decreases the capability but increases the life).
Back-up and recharge time
An estimate of the backup time, i.e. the capability of the batteries to power up the equipment
in case of mains failure, may be done by considering that:
- The manufacturers usually specify the nominal capability of a battery, discharged in a
period of 10 or 20 hour.
- For discharge faster than 10 hour, the capability will be reduced. For slower discharges,
it may be increased. Typical values are 70 % for discharge in 2 hours and 110 %, for
discharges in 50 hours.
- The capability will diminish with time and usage: typical derating may be 10÷30 % /
year.
- Taking in count all previously said, with a real capability which is derived from the
nominal one with the suggested corrections, the backup time is given by the capacity in
A/hour divided the absorption of the equipment which makes up the load, in A.
- The supplied recharge current delivered by the equipment is nearly 0.5-1.0 A by the
EXC19 and 1.5-2.0A by the RTX19, when the batteries are almost discharged.
- While the charge voltage is roughly constant, the charge current is not. The charge time
may be rather long, even some day, especially in case of deep discharge and heavy load
on the equipment.