On Fri, 09 Nov 2007 14:09:22 -0800, tim_s_moore@yahoo.com
wrote:

>Hi,
>
>Has anyone tried plugging external lead-acid batteries to the APC
>RS1500 UPS (model number BR1500)?
>
>This unit has an external connector to connect the BR24BP external
>battery back. However, the battery pack is expensive, and I was
>wondering whether it is possible to connect a set of the batteries
>that are found inside the BR1500 to this connection instead.
>Compatible non-APC-branded batteries are available for around $40,
>which is a lot better than the $150 that Amazon.com is charging for
>the BR24BP.
>
>Does anyone have a copy of the service manual for either of these
>units? Can anyone verify if there is any electronics in the BR24BP,
>or whether it contains only a set of batteries?
>
>Thanks for any help!


I've not seen this model in person but will put a few
thoughts out there...

The primary battery appears to use only 3 pin connection
which would be positive, negative, and current sensing. The
external battery is the same, does not appear to have
electronics in the external battery pack but whatever you
use would need to have the same connector or you'd have to
add the connector yourself.

It appears to use a pair of 12V cells in series for 24V, you
could use whichever you find more economical except if the
total capacity is not the same it might throw off the
software which IIRC, estimates runtime and battery health.
For example if you set the UPS to run until there was only 5
minutes of battery life remaining and that calculation the
UPS makes is based on a different cell capacity, the result
probably won't be an accurate calculation. Likewise with
charging, if you were to use a significantly larger pair of
batteries, for example a couple of deep cycle marine
batteries, the UPS might be programmed to conclude there is
a problem in that the battery pack did not fully charge
within the expected interval, or it might have a timer
shutoff from normal to float charging so it took quite a
long time until the battery pack was up to full charge
again.

If the compatible non-APC pack is $40 I don't understand
what you're asking, since by definition "compatible" should
mean they'll work... but are they compatible replacements or
compatible as-in identical? If only a replacement that is
just the batteries themselves and you are expected to reuse
the APC connector from the original pack, then you still
won't have the 2nd connector you need for the external pack.