UPS on lithium batteries

[jsfitz54]

LiFePO4 seems safer than other lithium chemistries

Lithium iron phosphate battery - Wikipedia

en.wikipedia.org

It's time for you to buy the LiFePO4 and report back to us on the outcome.

 

[Deleted member 191766]

My problem is that I would need over $400 worth of batteries for the UPS I would use, so it seemed sage for me to first find out if it was going to work.

 

[Caring1]

My problem is that I would need over $400 worth of batteries for the UPS I would use, so it seemed sage for me to first find out if it was going to work.

Cost is a major factor.
As for use scenarios I feel using them in a UPS where they are trickle charged is much safer than the example of a Motor Cycle battery, where they are fed 14V and can be deeply discharged by the CCA required, Lithium batteries are not capable of handling deep cycle environments over a long term.

 

[lexluthermiester]

Replacing with a larger (externally connected) lead acid battery worked, though.

I have one that runs on a pair of deep-cell marine batteries. Can run my systems(3) on that setup for nearly 4 hours.

 

[Deleted member 191766]

How often do you need to replace them?

 

[lexluthermiester]

How often do you need to replace them?

Don't know. The batteries themselves are rated for 10 years of operation but this is not a standard use-case-scenario. Haven't needed to yet. Got them on clearence right before Sears closed and that's been a few years.

 

[Deleted member 191766]

10 years is impressive, are they sealed or flooded?

 

[Deleted member 191766]

These guys

High Discharge Rate Lithium Iron Phosphate (LiFePO4) Battery

The 12 Volt, 7.2 Amp Hour LiFePO4 (Lithium Iron Phosphate) battery is designed to be a drop in replacement for standard sealed lead acid batteries.

www.backupbatterypower.com

make high discharge rate lithium batteries
"designed to be a drop in replacement for standard sealed lead acid batteries in UPS"

 

[lexluthermiester]

10 years is impressive, are they sealed or flooded?

Mine are sealed.

These guys

High Discharge Rate Lithium Iron Phosphate (LiFePO4) Battery

The 12 Volt, 7.2 Amp Hour LiFePO4 (Lithium Iron Phosphate) battery is designed to be a drop in replacement for standard sealed lead acid batteries.

www.backupbatterypower.com

make high discharge rate lithium batteries
"designed to be a drop in replacement for standard sealed lead acid batteries in UPS"

Those are not designed for a UPS. High discharge rate batteries are designed to release their charge in short big bursts for starting combustion motors and the like. You want lead-acid batteries design for slow release of charge over a long time period. That is why I chose marine batteries for my setup, they are literally designed to provide standard power for boats with living quarters when the motor is not running. A set of 10 of them(because 10x12v=120v) can run for a few days depending on how you use the power. Using fewer than 10 requires the use of a step-up voltage transformer.

 

[Deleted member 191766]

Interesting, I imagine you can run a normal computer on 120V DC

However

makes me worried about using high voltage DC


I beg to differ on the 'not designed for a UPS'; they are good to 540W continuous, which I would say was a good match for a UPS using that size battery.

 

[lexluthermiester]

I beg to differ on the 'not designed for a UPS'; they are good to 540W continuous, which I would say was a good match for a UPS using that size battery.

The wattage is not the main consideration. Voltage x Amperage=Wattage. High-discharge batteries are design to deliver very high amps at 12v for short periods of time. They do not work very well delivering low amps for a long period of time. 540w may seem like a high number but it's actually very low when compared to the cold-cranking wattage needed to start a combustion motor.

 

[Deleted member 191766]

How are your switches holding up on your 120V DC?

 

[lexluthermiester]

How are your switches holding up on your 120V DC?

What? Think I lost you there...

 

[IntelliSys]

I would recommend APC RBC not refurb personally - despite higher price point it provides some peace of mind at least.

Echo the point about disposal of batteries - if you don't know how to make sure to get a professional to dispose of it properly!

 

[Deleted member 191766]

What? Think I lost you there...

 

[1freedude]

Thought you might get a kick out of this....that isn't 1% of the batteries we used at my recently resigned job.

 

[Shrek]

Was surprised to find small lithium UPS batteries now at 18 Ah capacity

 

[OneMoar]

Was surprised to find small lithium UPS batteries now at 18 Ah capacity

You can get a lot more then then Tracker Marine makes a 80 AH
and these are up to 170 AH

Lithium Iron Phosphate (LiFePO4) Batteries

The safest Lithium chemistry, our LiFePO4 battery packs is available in 12V and 24V including battery packs, modules and carry case kits.

www.tracerpower.com

 

[ThaiTaffy]

It's pretty easy to convert a DIY lithium battery to use on a ups with a simple bms charging circuit designed for the voltage, but alot harder to do with the batteries shown here.
The issue is the cells, the charging circuits might take 12v but they spread out the voltage into manageable chunks for the cells meaning their output might be serial but the charging is done on per cell basis see a small circuit below.

Ripping apart a contained battery to split the cells for charging makes these sealed lithium batteries need a more specific charging circuit.

 

[OneMoar]

the battery's I listed already have integrated bms no need for a external one
a cheap DIY BMS is not going to handle the current shunt-ing of a line interactive AVR/UPS

 

[ThaiTaffy]

the battery's I listed already have integrated bms no need for a external one
a cheap DIY BMS is not going to handle the current shunt-ing of a line interactive AVR/UPS

Some cheap DIY BMS's can handle it and alot more the above photo just has a nice picture to explain heres a cheap DIY bms for your home solar battery.

That's besides the point as One Moar pointed out unless your battery has a built in bms you have very little use options

The issue then is that lithium can charge at 50% of output current where as a gel battery is generally 10%

 

[OneMoar]

a primer on AVR's
a Good UPS is whats called a line-interactive Meaning the Battery and Inverter are always in Sync with mains power
in the event of a brownout the extra power is taken from the battery and the inverter is brought on line to supplement the low mains voltage
the problem happens in the event of surge event
in most Units I have seen any SURGE Current, is Shunted in the batteries as the protect relay is grounded to the battery cells this lets the battery soak up the energy of the event
if the BMS can not handle the sudden spike of current going into the cell the same way a SLA or GEL would then the result is a fried bms and potentially a fire
be aware of that when adapting existing units to li-po or LiFePO

 

[Shrek]

You can get a lot more then then Tracker Marine makes a 80 AH
and these are up to 170 AH

Lithium Iron Phosphate (LiFePO4) Batteries

The safest Lithium chemistry, our LiFePO4 battery packs is available in 12V and 24V including battery packs, modules and carry case kits.

www.tracerpower.com

I meant 18 Ah in that form factor (double the normal SLA capacity) 15.1 cm x 6.5 cm x 9.4 cm

That is why I wrote

"Was surprised to find small lithium UPS batteries now at 18 Ah capacity"
and included a picture

 

[trog100]

i run 10 100ah LiFePO4 batteries.. two in my rv trailer and eight in my shed...

the drop in replacement ones have battery management systems built in to them.. these switch off the charge when fully charged and switch of the battery when flattened.. its all automatic..

lead acid batteries need complicated charging profiles.. lthium ones dont as long as they have the bms..

they cost more up front but last for years..

the ones in my shed are solar charged but can be mains charged.. i power part of my house with them.. they have a 3000 watt inverter to give mains power and an automatic transfer switch.. when the switch detects a user set (low) battery voltage it seemlessly switches over to mains power..

the only downside with LiFePO4 batteries is the higher upfront cost.. apart from that they have everything going for them..

trog

​

 

[Shrek]

I meant 18 Ah in that form factor (double the normal SLA capacity) 15.1 cm x 6.5 cm x 9.4 cm

That is why I wrote

"Was surprised to find small lithium UPS batteries now at 18 Ah capacity"
and included a picture

I do believe that I mixed up the battery sizes... best ignore what I said.