Inverter usage

[kitkat+]

Hi Guys

I need some help to figure out how long a 1440W inverter lasts on a server with a 300W power supply.

2400VA Mecer Inverter + 2x 100AH Batteries Trolley (8 HOUR BATTERY LIFE) KIT - 1440W (150-200 cycles) - GeeWiz

2400VA Mecer Inverter + 2x 100AH Batteries Trolley (8 HOUR BATTERY LIFE) KIT - 1440W (150-200 cycles) for sale online at the Best Prices! Door to Door and Overnight Delivery

www.geewiz.co.za

Dell EMC PowerEdge T40 Technical Specifications Guide | Dell South Africa

www.dell.com

Thanks
Kitty

 

[JustinB]

Hi Guys

I need some help to figure out how long a 1440W inverter lasts on a server with a 300W power supply.

2400VA Mecer Inverter + 2x 100AH Batteries Trolley (8 HOUR BATTERY LIFE) KIT - 1440W (150-200 cycles) - GeeWiz

2400VA Mecer Inverter + 2x 100AH Batteries Trolley (8 HOUR BATTERY LIFE) KIT - 1440W (150-200 cycles) for sale online at the Best Prices! Door to Door and Overnight Delivery

www.geewiz.co.za

Dell EMC PowerEdge T40 Technical Specifications Guide | Dell South Africa

www.dell.com

Thanks
Kitty

It's not the inverter but the batteries.

If you convert to watt hours by multiplying the voltage and amp hours, you get 2400wh (24v x 100ah). So, in theory, that's 8 hours.

But... Discharging the batteries does hurt them, so you'll need to see what the ratings are for those specific batteries - depth of discharge and how many cycles they're rated for.

 

[RonSwanson]

It depends on how much power it consumes, which depends on it's configuration and how it is used. The 300w PSU is the maximum that it will draw, it is usually a whole lot less than that.

But using 300W as an assumption (the box is running flat out) the two batteries will last for about 3.5 to 4 hours. That means that they will be at 0% state of charge at the end. If you only want 150 cycles out of them, then that's cool. If you want them to last longer, you will only run them down to 50%, that may give you 450-500 cycles (and around 2 hours).

 

[JustinB]

I see they mention that their quoted 8 hours is based on 150w. Sounds like they're using a 50% depth of discharge.

That'd mean 4 hours at 300w.

 

[kitkat+]

It depends on how much power it consumes, which depends on it's configuration and how it is used. The 300w PSU is the maximum that it will draw, it is usually a whole lot less than that.

But using 300W as an assumption (the box is running flat out) the two batteries will last for about 3.5 to 4 hours. That means that they will be at 0% state of charge at the end. If you only want 150 cycles out of them, then that's cool. If you want them to last longer, you will only run them down to 50%, that may give you 450-500 cycles (and around 2 hours).

Any idea what sort of time it takes to bring them back to 100% ?

 

[RonSwanson]

Any idea what sort of time it takes to bring them back to 100% ?

Not sure, I don't own one @RedViking and his thread https://mybroadband.co.za/forum/threads/mecer-2400va-inverter-community-support.1015178/ could assist with specifics, but assuming that you have two 100Ah batteries and using the 20A charging option on the Mecer, it would probably take around 13 hours.

If the inverter is good for you (it's a modified sine wave inverter after all) then you may want to consider ditching the lead-acid batteries and opting for some decent Hubble lithium replacements. The S100 is a lithium battery, so it has its own BMS, which protects the battery from over-charge, over-discharge & over-temperature (no BMS on the lead acids). You can discharge far lower than the 50% for lead acids. and get around 2000 cycles at 1C (that's 100 amps discharge rate, far more is achievable at lower rates that the Mecer can deliver, possibly even 6000 and beyond). And because it's a 1C battery, it can take a 100 amp charge rate, many have modified FrankenMonstered their Mecers with a decent charge controller.

 

[Speedster]

Not sure, I don't own one @RedViking and his thread https://mybroadband.co.za/forum/threads/mecer-2400va-inverter-community-support.1015178/ could assist with specifics, but assuming that you have two 100Ah batteries and using the 20A charging option on the Mecer, it would probably take around 13 hours.

If the inverter is good for you (it's a modified sine wave inverter after all) then you may want to consider ditching the lead-acid batteries and opting for some decent Hubble lithium replacements. The S100 is a lithium battery, so it has its own BMS, which protects the battery from over-charge, over-discharge & over-temperature (no BMS on the lead acids). You can discharge far lower than the 50% for lead acids. and get around 2000 cycles at 1C (that's 100 amps discharge rate, far more is achievable at lower rates that the Mecer can deliver, possibly even 6000 and beyond). And because it's a 1C battery, it can take a 100 amp charge rate, many have modified FrankenMonstered their Mecers with a decent charge controller.

He should only use the lead acids to 50% SoC, or 50Ah. Recharging these 2 x 50Ah at 20A should take a bit more than 5 hours, depending on the inefficiencies involved.