Reuse Old(er) UPS w/Solar+Battery?

System

1st: Very new to the whole solar arena. Been researching it for a while and would like to start with something small (few outlets) to test and get some good feelings that this works/etc/etc

I have some older UPS (APC) that have batteries that are almost shot. I was thinking instead of throwing these away that I might be able to use a solar panel to provide the ~12v to *trick* the UPS into thinking the battery was fully charged. I know there are tons of issues with this (Would love to know them)

Big (electrical?) question I have is how can I charge a battery and be using it at the same time? I know that we need a diode to prevent anything from backfeeding but how do I get the solar panel (cut down to a clean 12v) to charge the battery which in turn is connected to the APC/UPS unit (unplugged) with a few devices on it.

My first guess was to put a solar controller/charger in there to feed the battery.... thoughts??

Big goal is to have different sources charging the batteries like solar/wind/pedal but I haven't found anything that really describes how to do this.

TIA!

mike95490

Re: Reuse Old(er) UPS w/Solar+Battery?

dsun1 wrote:

My first guess was to put a solar controller/charger in there to feed the battery.... thoughts??

The controller will do all the "cleaning up" needed, to not BBQ the battery. Does the UPS have a charger that is charging at the same time?

System2

Re: Reuse Old(er) UPS w/Solar+Battery?

mike90045 wrote:

The controller will do all the "cleaning up" needed, to not BBQ the battery. Does the UPS have a charger that is charging at the same time?

I can only assume the UPS would charge the battery if plugged in. The worry I have is I don't know the logic behind it's charging/etc but I do know what it wants...clean 12v :-D

It would be very very ideal if I could charge from PV BUT if the battery dipped below XX% pull from the wall/line to charge the batteries (I know it's getting complicated!)

Brock

Re: Reuse Old(er) UPS w/Solar+Battery?

With a typical UPS plugged in it just passes the power from the wall to the load and trickle charges the battery. Typically you have to unplug the UPS from the wall to get it to use the battery. Also the batteries are pretty small so you would need a solar panel at least the size of the load. Say your running a 25w light bulb, you would need about 50w panel to keep the battery from running dead and keep up with the losses fro the panel, wiring and the inverter in the UPS and the battery itself.

Also most UPS's are not meant to run for extended lengths of time. They are made to run 30 minutes or so and then the battery dies. So if you attach them to a larger battery make sure you have good cooling for the unit or you are running them at a light load, say 100w for a 400w UPS.