How to hook up a second battery to my APC Back-UPS 650?

[Anonymous user]

Hi guys!
I know this UPs was not designed for that, but where I live, there are not many possibilities (Africa). So I have 2 batteries (on is a regular apc battery 8,5A and the other a 7A battery - I know it's not perfect, but it is what I have)
I have 2 batteries I hooked up, works fine but... it seems that the time alloted by the ups does not change (in powerchute).
What I'm looking for is to have more time (not more power) with this ups. Here a shorcut can last usually 1 hour.
Thanks so much for help ; answers like "it is not designed to do what you're looking for", or "Buy another another one for that" would not help here.
I'll tell you more about the results of my experience if you could give suggestions. Thanks again! LAU.

[Anonymous user · Accepted solution]

Since nobody has replied until now,

As a co newbie consumer, just interested in being self supportive:
Assumptions:
- You need a DIY solution for your existing UPS, not an upgrade to a more powerful UPS, or even to a diesel / gasoline generator.
- You do not need more power, just more time (I guess more power might overheat or shutdown of the UPS).
- Power outage occurs once a week or less, not every day (otherwise there will be not enough time to recharge the heavier battery).
- You do not mind losing support / warranty.
- You are aware of the risks using a car battery for in house use, and the risks of using a budget consumer UPS for a longer time than designed for.
Then you might consider connecting a car battery (or better: a deep cycle marine battery) instead of the standard battery. The smallest type, something like 40Ah, will do for your needs?.
Google for something like 'ups apc car battery'. Read the pros and cons.
(Will it work? I don't know, did not try any of this, just my thoughts)