larger battery replacement for rackmount ups

[MorganCS]

Hello
Thanks for a great forum
I have an APC SMT1500RM2UC 1500va rackmount UPS that is powering around 200-300w of servers at 120v. I would like to expand the batteries for longer runtime. I've been unable to find out what the combined voltage of the 4 12v sla batteries, but if it is 24 or 48v, could i replace it with a lifepo4 batter with the same output voltage?

I know I have seen some people do this with car batteries.

Optimally, I'd love to get one of the 24v or 48v MPP mk series with a battery to make a UPS of unlimited size. I could run it off of Grid Power, and suppliment it with Solar when we own a house I could put panels up in. The only 2 things stopping me is I do not know how loud those MPP units are, and I don't know how much parasitic draw they have.


Any help would be greatly appreciated
Morgan

 

[PeSCaLo]

Hello
Thanks for a great forum
I have an APC SMT1500RM2UC 1500va rackmount UPS that is powering around 200-300w of servers at 120v. I would like to expand the batteries for longer runtime. I've been unable to find out what the combined voltage of the 4 12v sla batteries, but if it is 24 or 48v, could i replace it with a lifepo4 batter with the same output voltage?

I know I have seen some people do this with car batteries.

Optimally, I'd love to get one of the 24v or 48v MPP mk series with a battery to make a UPS of unlimited size. I could run it off of Grid Power, and suppliment it with Solar when we own a house I could put panels up in. The only 2 things stopping me is I do not know how loud those MPP units are, and I don't know how much parasitic draw they have.


Any help would be greatly appreciated
Morgan

Hi Morgan,

The answer to the first question is yes. LifePo4 with the same voltage is a drop in replacement for Lead acid, any type.

 

[MorganCS]

Hi Morgan,

The answer to the first question is yes. LifePo4 with the same voltage is a drop in replacement for Lead acid, any type.

Thank you very much!

 

[Mithril]

Hi Morgan,

The answer to the first question is yes. LifePo4 with the same voltage is a drop in replacement for Lead acid, any type.

I thought LifePo4 has slightly different charge profile for optimal life? I actually have the same rackmount UPS and have been thinking of switching it to LifePo4 myself

 

[PeSCaLo]

I thought LifePo4 has slightly different charge profile for optimal life? I actually have the same rackmount UPS and have been thinking of switching it to LifePo4 myself

Yes it has "slightly different charge profile for optimal life".
The question was, Can I. Answer is yes. Will still last longer than AGM.

 

[Rednecktek]

Will still last longer than AGM.

Yes as you can use 100% of the battery capacity rather than the 50% that lead acids use. As I understand it the stock common profiles for AGM will get you to 98% of a LFP's capacity.

 

[Mithril]

Yes as you can use 100% of the battery capacity rather than the 50% that lead acids use. As I understand it the stock common profiles for AGM will get you to 98% of a LFP's capacity.

One of the things that has come up when I've been searching is that keeping LFP at a high state of charge (SOC) damages their lifespan significantly, this is reduced by cycling the battery apparently.
How much of an impact does that have when kept at "reasonable" temperature ranges (say a simi insulated garage). My understanding is any good BMS will prevent both under and over charge so there shouldn't be any worry on going over voltage, just potential damage from sitting at a high SOC in standby.
How often does the battery need to cycle to prevent/reduce that? And how far down does it need to discharge to? If I'm going to spend over a grand on a rackmount LFP I'd prefer not to kill it in a few years

 

[PeSCaLo]

Battleborn guidance is:
3.4 v per cel is recommended for Float charge. They say that it will balance the voltage and will not move current. They will honor their 10 yr warranty with the float charge.

 

[PeSCaLo]

One of the things that has come up when I've been searching is that keeping LFP at a high state of charge (SOC) damages their lifespan significantly, this is reduced by cycling the battery apparently.
How much of an impact does that have when kept at "reasonable" temperature ranges (say a simi insulated garage). My understanding is any good BMS will prevent both under and over charge so there shouldn't be any worry on going over voltage, just potential damage from sitting at a high SOC in standby.
How often does the battery need to cycle to prevent/reduce that? And how far down does it need to discharge to? If I'm going to spend over a grand on a rackmount LFP I'd prefer not to kill it in a few years

Well, Its all about return on investment.
Compare LFP to SLA.

At this point, LFP is too new to know for sure when calendar life will kill it.
What we can asume is that LFP will last more than 3 X SLA in same condition.
That alone should make payback good enough to prevent the hassle of replacement every year.