RE: External APC Batteries?

["Jim" <jim@xxxxxxxxxxxxxxxxx>]

"Standard" automotive batteries (Flooded Lead Acid) don't
like deep
discharge of <50% capacity, neither do they like standing for long
periods
as they are really designed to be shaken around, otherwise they tend to
sulphate particularly if being float-charged.

Absorbed Glass Mat (AGM) type are better for standby use, IIRC this is the
technology used in Yuasa-type sealed lead acid batteries - the sort used in
UPS's.

Squadron batteries have a good guide to the different types, life and depth
of discharge.

http://www.energy-batteries.com/downloads/marine_rec_broch.pdf

Their website also has info on chargers.


As you have identified, the key is not to let the batteries discharge too
far and that could be managed through the UPS shutdown parameters (i.e.
shu=
t
off at 40% instead of runtime limit etc.)


My opinion (and I'm sure Andy will confirm or rebuff this), is that the
replacement batteries sold by APC are exactly the same as the Yuasa NP or
NPL range, just with the relevant connectors etc. (which can be removed
fro=
m
the existing cells) and an extortionate =A3lots price tag.




Jim


-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Guy Clark
Sent: 20 December 2007 18:13
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] External APC Batteries?


HI, Jim!
=20
My biggest concern is the charging circuit...will it be up to charging a
pair of automotive-sized batteries instead of a pair of motorcycle-sized
batteries.   My guess is that if I don't let the batteries discharge too
far, there shouldn't be a problem.  If the charging circuit is designed
properly, I would expect it should charge any sized battery (of the same
chemistry and voltage (number of cells) ) but take longer for a 100AH
battery than a 10AH battery (for example).
=20
I may just have to bite the bullet and get a pair of marine batteries and
hook them up in place of the original (dead) batteries and see what
happens=
!
=20
Thanx!!!
Guy> To: ukha_d@xxxxxxx> From: jim@xxxxxxx> Date: Thu,=20
Guy> 20 Dec 2007 18:02:32 +0000> Subject: RE: [ukha_d] External
APC=20
Guy> Batteries?> > Never done it (but considered it a few time),
can't=20
Guy> see there being a> problem in principle.> > A few
considerations.>=20
Guy> > Make sure the cables, and particularly connectors, are up to
the=20
Guy> job as> there are a lot of amps flying around!> > You will
need=20
Guy> something to stop the batteries discharging into each other ->
Big=20
Guy> diodes are harder to find and not cheap.> > The UPS charger
is=20
Guy> unlikely to be rated for more batteries (unless it's an>
expandable=20
Guy> unit), so an external off-line system with a big changeover
relay>=20
Guy> to connect the extra capacity might be an option.> > >
Jim>

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