[lug] building a server room

[John Karns]

On Mon, 8 Jul 2002, Sean Reifschneider said:

> On Mon, Jul 08, 2002 at 08:50:48AM -0600, Nate Duehr wrote:
> >Also, if you can afford it, buy UPS's that run the inverters
> >continuously to feed the machines and therefore have zero switchover
> >time.  (Hint: Most of APC's product line does not do this.)
>
> I guess...  I've never had any problems with using standby UPSs, and
> they're quite a lot cheaper than online UPSs (the ones that always run the
> inverter).

Also, one might compromise by using a hybrid such as the Best ferrups
where the field is maintained durin switch over to the inverter.


> >Well, at least that's my opinion anyway... plus you learn quicker about
> >batteries that are having problems with that style of UPS -- because who
> >remembers to change their UPS batteries out on a regular basis?
>
> Most of the standby UPSs will periodically fire up the inverter and will
> regularly test the batteries.  That's how the "replace battery" light on
> the front panel is controlled.

Do the APC models do this?  Then there is the little rocker switch on the
front panel that allows a manual test.


> As far as replacement, the interval for replacing the cells depends greatly
> on use.  Lead Acid batteries lose an amazing percentage of capacity by just
> being drained once -- I think something like 50%.  We keep a labeler in our

I wonder how NiCad and Lion cells compare with that.  I know that the cell
life is dependant on the number of charging cycles, but how about 1/2
charges etc?  My 3 yr old Compaq cell still carries a 2 - 3 hr charge, and
I've rarely discharged it more than about 50%.

----------------------------------------------------------------
John Karns                                        jkarns at csd.net