Having read the reviews here, I have three things to say: (a) it is possible that some of you have got a ’lemon’ from Su-Kam, where the QC was caught with their pants down at assembly, (b) there could be a house-wiring related problems where battery power is being diverted to unwanted areas or the earthing is at fault, and (c) poor quality of power storage (battery) units.
I live in Chennai and 39 months ago I installed a Smiley-i (1400VA/24V sine-wave) inverter along with a pair of Exide EL series 6EL+ (100Ah/12V) deep cycle lead-acid tubular batteries connected in series to give me 24V output. I did not care much for Su-Kam’s batteries. The Exide EL6+ are probably the best batteries available in India and comes with a warranty of 5 years. During a quick chat with the technical in-charge of Exide at Kolkatta, he confirmed a fact that the electrodes for the EL6+ were of the highest standards and with regular top-ups, you can expect a life term of 7 to 8 years at least. Yes, these batteries are heavy (50 kg/each), large and will not fit into any ’off-the-shelf’ battery trolleys. So, I had one made locally of steel fabrication and caster wheels.
https://exideindustrialbatteries.com/standbybatteries-tubular.php
In three odd years, I have topped-up the cells of these batteries three times with distilled water (around 1 to 1.2 liter per battery). Few days ago, Exide service personal who came to service (top-up) the units, tested them and found all the cells in prime condition and overall, with almost no loss in their rated output. This goes to show that the Su-Kam unit is doing it’s job well, trickle charging the batteries as it should.
There is an audible fan noise when the Su-Kam unit takes over power duties or when it is recharging the batteries. But at idle or neutral mode, there is no noise or sound of any kind. The record, to date, stands at 7-odd hours of back-up, running two TVs (CRT), a PC, three ceiling fans, six CFLs.
This home UPS system has never given me any problem so far - zilch. Folks in the house are mostly unaware of mains power going off and UPS taking over, or the the other way around. It plain words, the take-overs and cut-offs are seamless. To have something working correctly, I think one would benefit from hiring an qualified and experience house electrician privately (which is what I did, as I am not an expert in these matters) who can understand your house-wiring and direct the Su-Kam appointed agents’ (half-baked, if you’re lucky) installers on how to go about the job. I have never had the need for any post-sales service from Su-Kam, so I can’t comment on that.
Added on 4th Jan 2012: It has been 6 months since I wrote this review, and 45 months since the unit was purchased. Chennai, where I live, for the past 6 to 8 months power cuts has become a regular affair, that is in addition to the govt’s "scheduled" power cuts of one hour every day. The Su-Kam unit performs flawlessly, and it still has not had the need for any kind of repair or even service. Only the battery gets topped up every six to eight months..!!
Added on 2nd June 2012: The Su-Kam Smiley-i and the pair of Exide 6EL+ (100ah tubular) continues to work flawlessly. Chennai is going through a spate of electricity cuts and low voltage levels. Apart from the daily ’schedule’ outage of 2 hours and a once-a-month maintenance outage of 9 hours, there are non-scheduled cuts that could last up to 3 to 4 hours. The previous record of 7-odd hours was recently broken by this UPS/battery pair, 9 hours and 45 minutes, just a few days ago. I am thankful that I have not had the need to call up the Su-Kam service people yet!