UPS question

[davemchine]

I have an APC J10 that I purchased "refurb" about four years ago. As I mentioned in a recent post the batteries lasted about half as long as I expected during a recent power outage. So I purchased a new "battery pack" which is basically two batteries in a plastic box with the wires already connected. When I received it the plug for the UPS was incorrect though. So I simply swapped the batteries from the new pack to the old one and voila I'm good to go.

Now comes my question. After opening the pack it is obvious that four batteries could fit inside as half of the space is taken up by a foam insert. Could I add two additional batteries and wire it to still output 25V? Would this work?

Oops, forgot the pic..

[Racer X]

sure. You will get twice the run time, but it will take twice as long to recharge when the power comes back on.

[Filliam H. Muffman]

Maybe clay will sell you some...

The only problem I see is that twice as many batteries is double the load on the charging circuit after a power outage. The J15 is about the same size, and is likely very similar inside.

[davemchine]

Racer, can you describe how I would wire it? You think this would be safe? Thanks for any info.

[Racer X]

In parallel 2x2. I assume it now has 6 volt batteries in series, or 2 12 volt batteries in parallel.

If the + are all wired together, and the - wired together, they are in parallel. If they are + to -, then 2 6 volt batteries are wired to make a 12 volt battery in 2 boxes, and that would be in series. Each cell is @2.1 volts. So a 6 cell battery is 12.6 volts fully charged, at rest (when new) Assuming we are talking about a typical lead-acid battery, like a SLA battery used in a UPS.

In our old military surplus Sea Scout boat, it had a 24V electrical system, and we had 4 6V batteries wired end to end to make a 24V "battery bank" Way easier to move a medium sized 6 volt battery than a massive 12 volt 8D monster.

All your batteries should be the same make/model and age, or darn close in age. Otherwise the new ones will drain into the older weaker ones to try and equalize the whole system.

http://www.batterystuff.com/kb/articles/...orial.html

[Bill in NC]

those are probably 12v batteries - larger ups use 2-12v wired in series.

i would not add batteries in parallel

get some anderson power poles and wire the ups up to 2 external 12v batteries if you want longer life.

[mrlynn]

If you got the wrong battery pack, are you sure you got the right batteries?

/Mr Lynn

[davemchine]

The UPS has 2x12v right now. The batteries inside the old pack and the ones in the new pack had the same specifications so I'm good there.

[OWC Jamie]

That ups may even have sockets on the board for another set of batteries
may have a separate circuit for the second set of batteries with separate protections, sensing and charging

the charging circuit may not work well with the extra load - just like adding a second battery in a car trunk for a amp can tax a small alternator - sometimes you get away with it until one battery gets discharged more than normal then you've got problems
it may work fine as kind too


APC may have a schematic and instructions on how to increase the battery capacity the 'best way'.

[Speedy]

davemchine wrote:
The UPS has 2x12v right now. The batteries inside the old pack and the ones in the new pack had the same specifications so I'm good there.

Hook up a 12v automotive battery. Or a 12v lawn mower battery.