battery discharge with 2amps with no loads

[abdelrahman mubarak]

hello everyone. please help
I'm using Sako 6.2 48v inverter with 48v 120ah lifepo4 battery from sako .. using it as ups charging from Utility only.
after charging to 100% , and charging stops, the battery start to discharge with 2.15 amps , while grid is on and no loads are connected.. the battery drops to about 90% and the inverter starts charging to 100% again .
the battery and the inverter same brand connected with communication cable.
battery type is set to LIB.
what the 2amps feed ?
how can I stop this ?
please help

 

[Cronix]

It is probably the inverter itself. They consume power when on because the circuits to convert AC to DC and then DC to AC are active, even if there isn't a load...so that when you connect a load the power is available immediately. The only time it won't do that is when it's off and not able to provide power.

 

[Lt.Dan]

Yup, I agree. Sounds like idle consumption to me. Could be the batteries internal BMS drawing power as well, dependent on the type.

 

[abdelrahman mubarak]

It is probably the inverter itself. They consume power when on because the circuits to convert AC to DC and then DC to AC are active, even if there isn't a load...so that when you connect a load the power is available immediately. The only time it won't do that is when it's off and not able to provide power.

that's correct when battery is powering the inverter.. but in my case utility is powering the inverter, i believe battery should stay in float voltage without any discharge, am I correct?

 

[abdelrahman mubarak]

Yup, I agree. Sounds like idle consumption to me. Could be the batteries internal BMS drawing power as well, dependent on the type.

when i turn off the inverter that 2amps discharge stop , inverter when on after charging the battery stays on grid power .. correct?

 

[Cronix]

that's correct when battery is powering the inverter.. but in my case utility is powering the inverter, i believe battery should stay in float voltage without any discharge, am I correct?

Typically in UPS mode, the battery is directly supplying the power to the load. That's what makes it Uninterruptible so that if main power goes out everything hooked to the UPS will be fine and not lose power. Then when battery gets low, BMS kicks in and charges from main power, if available. It's the behavior you're describing.

 

[abdelrahman mubarak]

correct, but I'm using it with a change over switch.. meaning inverter output is not supplied to loads unless I flip the switch, that's why I'm confused on where the 2 amps are going. because the inverter is powered by grid when available

Typically in UPS mode, the battery is directly supplying the power to the load. That's what makes it Uninterruptible so that if main power goes out everything hooked to the UPS will be fine. Then when battery gets low, BMS kicks in and charges from main power, if available. It's the behavior you're describing.

 

[Cronix]

meaning inverter output is not supplied to loads unless I flip the switch

I don't think that matters here. The inverter is powered on and consuming power (idle consumption) itself, whether a load is connected or not. A switch between the inverter and load won't change that unless the switch itself consumes power (such as an indicator light). I could be totally wrong in all of this. I don't know your system and not all systems behave the same.

Check the manual for the inverter. There should be some specs there that tell idle consumption, inverter efficiency, etc.

 

[Lt.Dan]

Some inverters will not allow you to draw the idle consumption from the grid, and will always draw it from the DC side when it is available. As stated above, this should be documented in the manual, if there is an option to change it.

 

[Cronix]

Some inverters will not allow you to draw the idle consumption from the grid, and will always draw it from the DC side

I did not know that. Great point.

 

[abdelrahman mubarak]

Some inverters will not allow you to draw the idle consumption from the grid, and will always draw it from the DC side when it is available. As stated above, this should be documented in the manual, if there is an option to change it.

it doesn't mention this in the manual, if that's the case it's very dumb to function like this

 

[Lt.Dan]

it doesn't mention this in the manual, if that's the case it's very dumb to function like this

Try reaching out to the manufacture. Maybe they can answer it better, and if that's the case, maybe they can send you a firmware update to change it.

 

[abdelrahman mubarak]

Try reaching out to the manufacture. Maybe they can answer it better, and if that's the case, maybe they can send you a firmware update to change it.

today i disconnected the communication cable from inverter, the 2 amps discharge dropped to 0.44 amps , battery type set to LIB ,
once i reconnected the CAN cable the discharge returned to 2.15 amps once again.
this is very confusing !
can i connect the battery bms to pc to see what's going on ?

 

[Crowz]

My tp6048 gets its idle consumption from the grid in solar/util/bat mode. There is no draw on the battery when set to that mode when the battery has reached the "float" point. If the battery voltage is greater than the float voltage it will draw the battery down to the float voltage via using it to handle idle consumption part.

 

[abdelrahman mubarak]

Can you tell why my battery bms after charging with bulk voltage with 57.6 v to 100% it changes the cv and float to 50v can you tell me why this happens?

My tp6048 gets its idle consumption from the grid in solar/util/bat mode. There is no draw on the battery when set to that mode when the battery has reached the "float" point. If the battery voltage is greater than the float voltage it will draw the battery down to the float voltage via using it to handle idle consumption part.

 

[Crowz]

Can you tell why my battery bms after charging with bulk voltage with 57.6 v to 100% it changes the cv and float to 50v can you tell me why this happens?

Your saying bms but that screen shot looks like a inverter/charger screen.

On mine when it gets done charging it drains the battery down the float level via using it as idle consumption. It stops when it reaches what I set it to for float.

 

[abdelrahman mubarak]

the screenshot is from the inverter but what i mean is i have no control over charging parameters because the battery is telling the inverter what it needs via communication cable
i believe the battery bms is determining the charging values .. because as we speak the battery is discharging and the values changed

 

[Crowz]

I don't run coms so I can't help with the best way to make changes on that. Sorry.

Whatever I set things to it just does since the battery and inverter don't talk to each other on my setup.

 

[abdelrahman mubarak]

coms are very important to me because i tried without it , the inverter started to detect wrong battery voltage and wrong state of charge

I don't run coms so I can't help with the best way to make changes on that. Sorry.

Whatever I set things to it just does since the battery and inverter don't talk to each other on my setup

 

[Crowz]

coms are very important to me because i tried without it , the inverter started to detect wrong battery voltage and wrong state of charge

I'm not knocking it. My battery doesn't do coms with my inverter so I don't have any choice in the matter.