battery considerations for a whole room UPS system.

[Suprasoup]

Solar sexy gurus!
So my fish room contains 4 APC SmartUPS units that back up various pumps and power heads in my saltwater system. A recent failure of one of the units, bulging batteries due to overcharging, got me thinking of a better way to back up the whole system. Rather than replace all the APC batteries I am contemplating moving the fish rooms circuit into its own sub panel and hooking up a spare trace sw4024 I have lying around as the UPS.

We rarely get blackouts where Im at but do experience a few brownouts every year which wreaks havoc on some of the powerheads and controllers.

So which type of lead acid battery would be preferable in my situation? For reference the APC batteries last roughly 2-3years before failing due either to overcharging or testing below 80% of rated capacity.

Thanks for taking the time and appreciations in advance.

[Sunking]

So which type of lead acid battery would be preferable in my situation? For reference the APC batteries last roughly 2-3years before failing due either to overcharging or testing below 80% of rated capacity.

That is not going to change when using inexpensive AGM Batteries. The answer lies in how long you want the UPS to keep you powered up during outages. UPS are designed to only last anywhere from 15 minutes to 1-hour. Example Data Center UPS are deigned to only run 30 minutes to 1 hour, and rarely if ever used. Their job is to run the equipment long enough to get the generators up and running on-line. AGM batteries made for UPS are not designed to be cycled or used. Just for emergency power for short periods. They are made like car starter batteries. Deliver a large amount of current for a very short period of time.

How do you get around that, don't use batteries made for UPS, use batteries made to be cycled and used daily. But there is a catch, the time will have to be much longer measured in days, not hours. That means much larger batteries. Now you can use AGM's made for commercial UPS for even a 15 minute run time. Those kind of batteries will last 5 to 7 years on Float Service, but you are going to pay way up for them.

So it alk depends on how much pain your wallet can take and how much time you require to run on batteries. If it were me in your shoes I would make a McGuiver UPS. Select a battery that will last at least 2-days as that gives you one day run time. You size a Battery Charger that can charge the battery in 10 hours and supply the load at the same time, and then use an Inverter to power the aquarium. Charger > Batteries > Inverter. If you run into an outage greater than 24 hours, you plug the charger into a generator to recharge. Same concept all critical systems use in telecom, data, and military.

[Mike90250]

What sort of power do your critical loads consume in the fish room ? 2Kw, 4kw ? 473w ? How long do you want it to run, 1 hr, 5 hours ?

Brownouts, usually only a UPS manages those well, sometimes the switching speeds on inverter transfer relays can't keep up with fluctuating brownout conditions.