UPS Battery Upgrade - 1.5 Hours Backup Time!!!

Replaced two 12V, 9AH batteries in my APC Back-UPS XS 1500, Model BX1500LCD, with two 33AH, AGM Deep Cycle batteries for more than triple the backup time.

Step 1 Purchase Needed Items

I purchased two Werker, 33 AH, deep cycle, AGM batteries from a local Batteries Plus store for about $80 each. At the hardware store, I purchased 5 feet each of red and black, stranded, 10 gauge wire; a 1 foot piece of stranded 6 gauge wire; 2 copper terminal lug connectors; crimp (butt splice) connectors; and spade terminal connectors.

Comments

[somoney]

Nice work. I like the idea of using AGM type batteries found at any automotive store. I'm curious to know if this system is still in use and functioning for him 2 years later.

[zebibyte]

You didn't say whether or not you charged the two batteries first.  I'm guessing that the batteries were only partially charged when you purchased them.  If you didn't charge them first then that would account for the 10 minute run time at first.  Perhaps you can avoid the discharge step and just let the unit charge itself for a day. 

Since I have an automotive battery charger, I would charge the batteries first and then connect them to the unit.

Nice job.  Thanks for sharing this.  I'm going to try it on my APC unit. 

[zebibyte]

Perhaps there is a large capacitor as part of the power supply.

Always a good idea to be cautious when working on items with an internal power supply that is creating DC voltage.  You can always discharge it through a large resistor.