According to your peak load of 400w, a 1000w UPS will give you about 7 minutes of battery backup time. This is on basis that the batteries can still hold its 100% capacity.
1. Which protection are you more concerned on?Irregular voltage (spike/dips) and/or inconvenience of power supply interruption
Line interactive UPS for the former.
Online UPS for the later.
Overload protection is a plus, else the UPS will just shutdown instantly. A word though, even with overload protection, its just a temporary measure and will still auto shutdown after X period for Y% overload.
2. Malaysia standard warranty for UPS is 3 years for electronics failure, 2 years for batteries.Koss, Neuropower, Powerlogic, Power Solutions, Right Power to name a few known local UPS resellers. Don't be surprised if some of them look similar to one another as these are just OEM and rebranded locally. The price you are paying for is the after sales service.
If you are confident and know how to replace these batteries, then just look for the cheapest bargain.
Batteries will need to be replaced every 2-3 years at worst case. You're lucky if it goes to 4-5 years and more. Anything lesser indicates a problem with the batteries itself or environment.
Online UPS tend to be hotter due to the Inverter and Charging circuit running constantly. You will definitely feel an increase of temperature if the online UPS is in the same room as the PC (without aircond).
12 VDC 7.2Ah Sealed Lead Acid battery is the common type. Some will use 12 VDC 9Ah which is not sold by every battery manufacturer due to limited demand.
3. 3KVA and below UPS will use the common BS1363 3-pin plug. Anything above 3KVA will need to be connected to an Isolator.4. Check if the UPS outlet are using BS1363 or IEC C13 socket. If its the later, do get the supplier to bundle in a few cables or be prepared to buy them separately. Thanks for the detailed explanation. Online seems like a better choice but my budget of rm400 definitely don't allow it😅