Re: Re: External APC Batteries?

["Rob Iles" <rob.iles@xxxxxxxxx>]

Andy,

Are you by any chance a pyromaniac / sadist?

It's the smileys after the guys shed blowing up and again after the 3kva
box
blowing up like a box of fireworks in someones face! :O

(I'm joking - hope you take it in the spirit it's meant :-) )

Rob


On 20/12/2007, Andy Whitfield <andywhitfield2002@xxxxxxx> wrote:
>
>   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
>
> --- In ukha_d@xxxxxxx <ukha_d%40yahoogroups.com>, Guy Clark
> <guyclark@...> wrote:
> >
> > HI, Jim!
> >
> > 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).
> >
> > 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!
> >
> > Thanx!!!
> > Guy> To: ukha_d@xxxxxxx <ukha_d%40yahoogroups.com>>
From:
> jim@...> Date: Thu, 20 Dec
> 2007 18:02:32 +0000> Subject: RE: [ukha_d] External APC
Batteries?>
> > Never done it (but considered it a few time), can't see there
> being a> problem in principle.> > A few considerations.>
> Make sure
> the cables, and particularly connectors, are up to the job as>
there
> are a lot of amps flying around!> > You will need something to
stop
> the batteries discharging into each other -> Big diodes are harder
> to find and not cheap.> > The UPS charger is unlikely to be
rated
> for more batteries (unless it's an> expandable unit), so an
external
> off-line system with a big changeover relay> to connect the extra
> capacity might be an option.> > > Jim>
> >
>
>
>


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