Hello!

I've seen a few YouTube videos that explain how to turn a regular cheap computer UPS into a UPS with a huge runtime by swapping the 12V 7ah battery for a large deep cycle marine battery.

This seems pretty straightforward as long as you have basic electric knowledge, and i'm seriously looking into this. Things to keep in mind :

-The built-in charger in the UPS (mine is an APC ES 550) has very low amps (1A or so) so it might take WEEKS to top off the deep cycle battery once it's partially depleted.

So yeah, i'm thinking about drilling holes on the UPS battery panel, pull the battery out and use 14AWG cables to extend the leads so I can connect them to the deep cycle battery.

I was wondering...

1) Will the APC Powerchute software report correct runtime once it runs off the deep cycle battery? (i.e. 623 minutes of runtime rather than 8 minutes).

2) Would it be safe to permanently attach a trickle charger to the battery, to top it off, even through there already is a "tiny" charger on the UPS?

Your thoughts are welcome! Try everything you try at your own risk, always.

Thanks!

Not sure I would do that. I have limited faith in the safety of mods such as that. Where I used to work we made satellites and of course they have rechargeable batteries. Our battery testing lab caught fire one weekend when there was no one but security on site, the alarm worked and the FD came but the lab and all the computers monitoring the testing were toast, along with a lot of building damage. YMMV

Curious, why rewire a UPS to do this? If its a matter of the UPS being available 24x7 in order to power down you PC, you should have that already - switching out the UPS battery for a marine battery voids the warranty and makes the UPS begin to operate in an unwarranted and possibly dangerous configuration. I would rather take the deep cycle marine battery and apply your wiring skills to create a hot back up power supply: so you should plan to power down your PC like any other UPS user, and then maybe power it back up with your separate but more rational marine battery power backup. I'm sure there are videos out there to get you started. I do appreciate the impulse to tinker. I am electrically deficient myself, but I suspect I could match up the right inverter and connections to power a few necessaries - like my ham radio if I had a hankerin to do that.

Trying things at your own risk is just that, at your risk - god bless you and your local responding fire dept if you get this retrofit wrong.

PowerChute works on the reported battery model and measured voltage, so I doubt you could get it to report the correct runtime.

It's easy to wire things wrong and get hurt. I would recommend against this course of action.

I have thought of this too.

Here are some toys to consider:

http://www.mini-box.com/DC-DC

Cut out the PC Power supply and go right from battery to motherboard.

This certainly wouldn't be as efficient, but it would be much safer (I'm assuming you're not an electrical engineer to do the UPS mod correctly):

Buy a deep cycle marine battery, a car battery charger, and a power inverter. This would work fine if you're willing to let your computer go down with a power failure, then boot it up later on your backup setup. But if you want your computer to stay UP during the whole ordeal, yeah, you need a UPS. Buy one, don't try to make one. Heck, I *am* an electical engineer and would be considered technically competant to do what you're proposing. But I'd definitely buy rather than make myself, even though I *could* make if I really wanted to.

With a good quality charger and/or inverter that can be more efficient. What you described is an online ups, lots of ham radio guys do it. And you don't need to be an electrical or electronic engineer to do it, you can buy basic off the shelf components.

Most of your inexpensive made for home use ups's are the offline type and when you try using a larger battery you have the issue of longer charge time and you could even run into an issue where the inverter is not designed to run longer then the original run time so it cold overheat.

Thanks for your advice, everyone. Guess i'm going to keep reading before I actually begin experimenting, maybe it's not worth the hassle in the end.

Thanks again!

I did this many years ago. An APC BackUPS 500 connected to two Yuasa 38Ah batteries in parallel. Big cables to the batteries and quality connections on everything. Works like a dream. It powers all of my computer setup for hours and I use the 12V directly for my ham station.

The 500 cannot run Powerchute unfortunately so I can't help there.

Why not just get a bigger UPS and avoid the liability of making your own? The risk is real.

I use a high-end Dell laptop which has as internal battery so all I needed was something to continue powering the battery to extend on-time. For that purpose I have a Xantrex 400 Plus. It's available in bigger sizes such as the Xantrex XPower Powerpack 600HD. The Xantrex 802-1500 XPower 1,500 Watt Portable Powerpack is probably a little bigger than necessary. All of these units can output 120VAC or 12VDC.

Duracell markets similar units such as the Duracell DPP-300EP Powerpack 300.