Battery for 12v UPS

[KillerWatt]

Was thinking a 4s and possibly a 3s for a UPS ES 550. Anyone tried making a pack for one of these with lithium-ion?

Specs Page: https://www.apc.com/us/en/product/BE550G/apc-backups-es-550va-120v-8-nema-outlets-4-surge/

 

[robbob2112]

They have batteries on the market pre-made to fit most UPS - inside includes the BMS and multiple cells...

I have read mixed reviews for how well they work and how long they last ....

In the end I opted to scrap my APC units and build LFP battery+inverter+charger+timer ... so the timer leaves the charger off until when you aren't using the setup.... and when you are using the computer or whatever you run off the battery -- size the battery right so it can be recharged in 2~4 hours and you can run from it the rest of the time and not go below around 20~40% so you have backup power if the power actually goes out.

It is basically a double conversion UPS without the price....

IMO lead acid based UPS are dead and until the MFG redesign with LFP batteries in mind I won't buy any more batteries or UPS....

 

[KillerWatt]

Thanks for the reply. Trying to make use of some old lithium-ion cells I have laying around. I only need an UPS to prevent the wifi router from losing internet during the day. Family is getting irritated with the ongoing solar upgrades/reboots, so I shouldn't need one for too long.

 

[pollenface]

My UPS runs constant 27.6v to charge batteries. I replaced with lead-acid, I thought that was more suitable for that constant voltage while batteries are kept at 100% SOC and only cycled a few times a year.

 

[Supervstech]

Thanks for the reply. Trying to make use of some old lithium-ion cells I have laying around. I only need an UPS to prevent the wifi router from losing internet during the day. Family is getting irritated with the ongoing solar upgrades/reboots, so I shouldn't need one for too long.

I have successfully used LFP drop in batteries for ups, but the issue is not runtime, the issue is output wattage.

Lead acid will feed much higher output amps for their small footpring ups.

Usually they have a 7 to 10Ah battery in them.
Lead acid 10Ah batteries will output 30 to 90A which allows 350 to 750W output
However a LFP 10Ah footprint battery only outputs 10A, limiting your output to 120W
Keep that in mind.

If you only have an LED light and a few wall warts, you will be fine with them...

Any larger loads, and nope, the battery bms will drop out and you lose power.

 

[BigGun]

Thanks for the reply. Trying to make use of some old lithium-ion cells I have laying around. I only need an UPS to prevent the wifi router from losing internet during the day. Family is getting irritated with the ongoing solar upgrades/reboots, so I shouldn't need one for too long.

Li-ion doesn't line up well with a 12v battery ( 3S too low / 4S too high ) If you're just trying to backup a Modem / Router that's 12v input. There's a bunch of videos on youtube on how to build battery backups.
I personally just use a APC with lead acid, I don't like the idea of Li-ion being auto charged in my house.

 

[RCinFLA]

Lead-acid Gel cells in UPS's are often floated on the voltage high side.

If UPS has a float voltage above 13.6v it will be degrading to 12v LFP, four cell battery.

You will need a BMS with at least 50 amp continuous current capability for 12v 500w UPS. At 500w, UPS inverter efficiency and wiring voltage loss to inverter DC input will result in about 80% input to output power efficiency.

 

[Supervstech]

Li-ion doesn't line up well with a 12v battery ( 3S too low / 4S too high ) If you're just trying to backup a Modem / Router that's 12v input. There's a bunch of videos on youtube on how to build battery backups.
I personally just use a APC with lead acid, I don't like the idea of Li-ion being auto charged in my house.

LFP is a lithium ion that lines up correctly wirh lead acid charging profiles.

You are thinking about LiNMC style cells.

 

[BigGun]

I never associated LifePo4 with li-ion before. I took it as the OP had some laptop pulls or some sort of 3.7v Li-ion cells laying around the house.

 

[bolhuijo]

Like BigGun said, for just a wifi router buy or build something small with DC output, like this:

https://www.amazon.com/Shanqiu-Battery-Backup-Uninterruptible-Security/dp/B0CDP7WFJ8