Re: External APC Batteries?

["Andy Whitfield" <andywhitfield2002@xxxxxxxxxxx>]

Hi Guy,

24" cable is a little on the long side.  Though as your load is low
it should be ok.

What VA is your UPS rated at?

You won't/can't overload your UPS charging circuit.  But it is
designed to charge AGM type batteries.   See what it says on the
side of the battery for charging voltages.

Remove your watch, rings, lucky Saint Christopher chain.  I know a
guy who was working on a piece of live equipment and his Saint
Christopher chain dangled in to the equipment.  Shocking
experience!   ;-)

Andy

--- In ukha_d@xxxxxxx, Guy Clark <guyclark@...> wrote:
>
> HI, Andy!
>
> Thanx for the detailed reply!
> My plan is not to use actual automotive batteries, but the "deep-
discharge" type of battery, like those used (I believe) for marine
use.  They are roughly the size of an automotive battery, but are
different inside.  These have a lower peak current output, but
maintain their voltage level longer than automotive batteries which
are designed for high current short duration use, starting engines.
> I plan on using heavy wire as short a possible between the
batteries and the UPS, probably no more than 24" at most, and of
gauge as large or larger than that already in the UPS (my
recollection is that the wires currently in the unit are 10 or
12Ga.   Since the load placed upon the UPS will be light (remember,
it's only to power the controller and ignitor of the on-demand
propane water heater, so it shouldn't be more than an amp max, but
I'll double check to be sure).
>
> Once a power failure event is passed, I might just turn off the
UPS and individually charge the batteries from an external battery
charger to avoid overloading the internal UPS charger.
>
> Since the garage is unheated, the temperature during the rainy
season (Dec-March or so) is relatively low, 10-15C so the UPS should
be pretty happy ;-).
>
> Of course, polarity is important!  ;-).
>
> I guess that if I do it, I'll report back to the group how it
went, and if I don't report back.... lift a pint in my memory!
>
> ;-)
>
> Guy> To: ukha_d@xxxxxxx> From: andywhitfield2002@...>
Date: Thu, 20 Dec 2007 21:04:24 +0000> Subject: [ukha_d] Re:
External APC Batteries?> > Hi Guy,> > There are a few problems
with
this idea.> > You must use very heavy duty cables and keep the
cables very short > otherwise you'll have significant voltage drop
over the cables. > This can cause the cables to get very hot and
even melt the > insulation. Plus the UPS will switch off early as it
will think the > battery voltage is lower than it actually is.> >
It's possible the UPS onboard microcontroller will have a problem >
with the long runtime and switch off early. Though generally they >
keep running.> > The charge time can be very long.> > Make sure
the
UPS has a fan that comes on for charging and > discharging otherwise
it may overheat with the longer > charge/discharge times.> > Car
batteries are a little different from UPS AGM batteries. The > car
batteries may gas a bit. I remember a case where a guy left a > car
battery on an old car charger in his shed. Unfortunately his >
charger overcharged the battery and when he opened the shed door and
> turned the light on, the spark from the light switch ignited the
gas > and blew his shed up! ;-)> Make sure the batteries are well
ventilated.> Also periodically discharge and charge the car
batteries on a good > car battery charger.> > There are proper
long
runtime UPSs that are designed for extra > battery packs. I do have
some in stock.> > BTW make SURE you connect the batteries the
correct way around. I > heard the other day of someone who connected
them the wrong way > around on a 3kva UPS and the was a massive bang
and huge arcing to > the case. It's rather like a box of fireworks
blowing up in your > face! ;-)> > Regards> Andy the UPS Man
>