Originally Posted by pulverizor
k thx for the info I didn't know that batteries dont like to "rest" at full (I always thought the opposite)
a few more questions then ^^
1) wouldn't a simple solution be for the line-in UPS to stop the charging when the battery's at 80% or something? the effective capacity & autonomy would be lower in case of power outage but the battery would last longer
2) for the online this means the battery's being charged & discharged at the same time? I didn't know that was possible for a battery (so this means online UPS batteries are special & can't be used in a line-in UPS or vice-versa?)
3) what about brown-outs don't line-in UPS protect the PC better then offline UPS against brown-outs?
4) also battery output ain't it (usually) better quality in line-in UPS? at least higher end ones (high end line-in UPS => true sine wave but any offline UPS only spits out stepped sine wave which iirc can be dangerous for some PSU's)
and finally...5) if a UPS is of the online type does it by definition automatically imply that it outputs sinewave? or can there be such a thing as an online UPS with only stepped sine wave (eg. iif the manufacturer wanna save costs)
1. That is not quite the same as constantly working within that upper 25%, as you said it would just be worse for its main use case and still wouldn't change the battery life.
2. This is true, you will see most of the offline and line-interactive use the same battery packs. Their systems for attaching to the line are basically the same between those two. Online ups's have different batteries that are quite a bit more expensive, and work on a different line attachment system.
3. The line interactive will hold the voltage up to a steady 120V the whole time. In reality though, most of our stuff will function perfectly fine down to about 92V. This is what makes me not bother with line interactive and go straight for the offline or online ups's. In a situation where the voltage drops out of range, the line interactive and the offline are equal. Let the AC supply line run down to out of range voltage before even bothering with my offline ups (i set mine ~98v switchover), the line interactive will be draining itself before that point already.
4. I'll say the quality of battery is directly linked to mfg specifications. A good offline will use the same batteries as the line interactive, it will also generate a sinewave that is perfectly usable (over-hyped issue). If your PSU blows or has a problem with either of these issues (sinewave within range, or voltage sensitivity within spec range) then chances are the PSU deserved it and was well below specification ranges. The only thing that could be sensitive to this is some older analog equipment... which is why we required Online UPS systems back in the day in older data, switching, signal, and audio centers. In this case, the line-interactive MAY buy you some extra use, but that's already a use case where if you are looking at anything other than Online you are wasting your time anyways.
5. By nature of their design, most online type try their hardest to emulate a purer sinewave as their main job is to make everything see literally no difference between line power. That isn't to say that buying a cheap no name "Online" UPS might possibly net you a line-interactive masquerading as "Online". Rule of thumb, stick with companies that are dedicated to power backup systems.