Lifepo4 48v batt running down

[Seabhac]

I have a 48v bank of batteries with a Growatt Spf 500es charger/inverter. When I go away for a few days instead of charging up it runs down. If I turn off the switch on the inverter it charges but the next day it stops charging and theres a current draw eventually emptying the battery bank. Tjis is not a problem in summer. I also have a 12v battery bank (lead acid) and it has a wind mill solar charger powered by just one solar panel. It has no problem staying charged. Have I set up the Growatt wrong? I cant see why it should not stay charged when the inverter is off. Can anyone shine some light on this please? I'm pulling my hair out eventhough I'm already bald

 

[DougL]

If there is nothing connected to the battery pack and it goes to 0 SoC in one day then there's something wrong with your batteries.
You should monitor the individual cell voltages at 100% charge and at 50% charge to see if they are all within ~30mV. It could be you have a single bad cell.

 

[timselectric]

With the inverter switch turned off. It won't restart the MPPT's the next morning. Unless you reached floating charge on the previous day.

 

[Seabhac]

With the inverter switch turned off. It won't restart the MPPT's the next morning. Unless you reached floating charge on the previous day.

Thanks for the info. So if I turn off the Inverter it wont charge the next day but if I leave on the inverter during winter the standby current will empty the batteries if the days are short and the sky is cloudy. If I turn off the inverter so as not to waste the battery because I dont expect good weather and I'm going to be away it wint charge but there is still a current draw from the Growatt that will empty the battery. Am I correct on these points? Thanks for your help.

 

[Seabhac]

If there is nothing connected to the battery pack and it goes to 0 SoC in one day then there's something wrong with your batteries.
You should monitor the individual cell voltages at 100% charge and at 50% charge to see if they are all within ~30mV. It could be you have a single bad cell.

I'll have to look into this, I thought the system was healthy. When there was ample sun it charged and ballanced correctly. Or so I thought.

 

[AshleyL]

Thanks for the info. So if I turn off the Inverter it wont charge the next day but if I leave on the inverter during winter the standby current will empty the batteries if the days are short and the sky is cloudy. If I turn off the inverter so as not to waste the battery because I dont expect good weather and I'm going to be away it wint charge but there is still a current draw from the Growatt that will empty the battery. Am I correct on these points? Thanks for your help.

If you don't use Lithium Communication mode, you will encounter problem triggering the recharge/rebulk.

If you use USE mode, the battery voltage need to be 1.5v - 2.0v lower than the set float voltage for the growatt inverter to rebulk charge the battery next day.

On the other hand, if you use LI Comm mode, you better hope the BMS is "accurate". Tell us, what is the battery BMS?

 

[Kid Solar]

With the inverter switch turned off. It won't restart the MPPT's the next morning. Unless you reached floating charge on the previous day.

My SPF 5000 ES turns on automatically every morning and starts charging the battery. It gets triggered by the panel voltage going over 120v.

It does this if the battery is at any charge level. I am using a growatt battery with coms.

The switch is in the off position.

It uses less power in this mode as the AC is shut down.

After a couple of hours charging I flip the switch and my loads come on when there's more generation than I'm using to top the battery up.

Works really well, my system is basically automated now. The settings within the inverter allow ac charging time and load time etc. The only thing I do is turn the inverter off at night when the battery gets low as I don't have all my panels up just yet and need another battery when they are added.

 

[Seabhac]

If you don't use Lithium Communication mode, you will encounter problem triggering the recharge/rebulk.

If you use USE mode, the battery voltage need to be 1.5v - 2.0v lower than the set float voltage for the growatt inverter to rebulk charge the battery next day.

On the other hand, if you use LI Comm mode, you better hope the BMS is "accurate". Tell us, what is the battery BMS?

The Battery BMS is Ovekill Solar.

 

[Seabhac]

My SPF 5000 ES turns on automatically every morning and starts charging the battery. It gets triggered by the panel voltage going over 120v.

It does this if the battery is at any charge level. I am using a growatt battery with coms.

The switch is in the off position.

It uses less power in this mode as the AC is shut down.

After a couple of hours charging I flip the switch and my loads come on when there's more generation than I'm using to top the battery up.

Works really well, my system is basically automated now. The settings within the inverter allow ac charging time and load time etc. The only thing I do is turn the inverter off at night when the battery gets low as I don't have all my panels up just yet and need another battery when they are added.

I expected the Growatt to charge the battery when there was sunlight even if the inverter was off and the voltage was up from the panels. I'm getting good Voltage, not alot of current on a cloudy day but it should be enough to keep the batteries charged with no loads on them. What could cause it to not charge? It seems to be draining. The BMS shows a small drain. And of course the charger doesn't start in the morning.

 

[timselectric]

Thanks for the info. So if I turn off the Inverter it wont charge the next day but if I leave on the inverter during winter the standby current will empty the batteries if the days are short and the sky is cloudy. If I turn off the inverter so as not to waste the battery because I dont expect good weather and I'm going to be away it wint charge but there is still a current draw from the Growatt that will empty the battery. Am I correct on these points? Thanks for your help.

Yes, that's pretty much the situation.

 

[Seabhac]

Anyhow thanks for the replies, I'm not beside the battery the set up at the moment so I cant check the settings and the individual cells. But will do soon.

 

[timselectric]

My SPF 5000 ES turns on automatically every morning and starts charging the battery. It gets triggered by the panel voltage going over 120v.

It does this if the battery is at any charge level. I am using a growatt battery with coms.

The switch is in the off position.

It uses less power in this mode as the AC is shut down.

After a couple of hours charging I flip the switch and my loads come on when there's more generation than I'm using to top the battery up.

Works really well, my system is basically automated now. The settings within the inverter allow ac charging time and load time etc. The only thing I do is turn the inverter off at night when the battery gets low as I don't have all my panels up just yet and need another battery when they are added.

Mine does too, if it reached float charge on the previous day.
But not, if it didn't.
I think that there was a firmware update that addressed it. But I don't update anything, unless I absolutely have to.

 

[timselectric]

You could use "power saving" mode (setting #4).
Less draw on the battery, when no loads.

 

[Seabhac]

Mine does too, if it reached float charge on the previous day.
But not, if it didn't.
I think that there was a firmware update that addressed it. But I don't update anything, unless I absolutely have to.

The thing is here in the west of Ireland my batteries will rarely get much of a charge on a winters day unless it's sunny and even then the day is short so they wont fully charge. If I had the inverter off for 4 days and it was slowly charging it would fully charge but alas its not how things are. I have a charger for a windmill that charges some lead acid batteries from a single solar panel and thats always charged.

 

[Seabhac]

You could use "power saving" mode (setting #4).
Less draw on the battery, when no loads.

I wonder what the draw would be when in power saving mode and no loads, I'll give that a try. I need to have another look at understanding the settings. I thought I had it set up well enough when the days were longer but obviously not well enough for winter. I also use a generator, I have it left in Utility mode, I see there are also other modes but I doubt the way I have it set for the Genie effects it switching on and off in the morning or it draining.

 

[Seabhac]

I have one more question, why does a Lifepo4 bank need float mode? I would have thought charging and ballancing at full charge would be enough?

 

[timselectric]

The thing is here in the west of Ireland my batteries will rarely get much of a charge on a winters day unless it's sunny and even then the day is short so they wont fully charge. If I had the inverter off for 4 days and it was slowly charging it would fully charge but alas its not how things are. I have a charger for a windmill that charges some lead acid batteries from a single solar panel and thats always charged.

Winter is the same, here.
It's been 3 months since solar got me to 100% charge. But I should get there, today or tomorrow. And then I'll be fine until some time in November, again.

 

[timselectric]

I have one more question, why does a Lifepo4 bank need float mode?

It doesn't.
But having bulk and float charging modes, allows faster charging at a higher bulk voltage. And then floating at a easy balancing voltage.

I would have thought charging and ballancing at full charge would be enough?

It is, but not as efficient sometimes.

 

[Seabhac]

It doesn't.
But having bulk and float charging modes, allows faster charging at a higher bulk voltage. And then floating at a easy balancing voltage.

It is, but not as efficient sometimes.

I'll have to look into this more.

 

[AshleyL]

The Battery BMS is Ovekill Solar.

Ah crap, no BMS communication with the inverter then.

So, which mode you use? USE or US2 mode?

USE = there is float, however the battery voltage needs to be 2v lower than your set float voltage, otherwise, there will be no solar recharging next day.

US2 = no float, when battery voltage reach CV value, it stops charging immediately.

 

[Kid Solar]

I expected the Growatt to charge the battery when there was sunlight even if the inverter was off and the voltage was up from the panels.

Mine does. It gets woken up at 6am when voltage rises.

Inverter is off at this time.

Battery is charging.

Mine does too, if it reached float charge on the previous day.
But not, if it didn't.

Works for me irrespective of charge state or conditions from the day before.

It will wake up the battery at 0%-100%.

What would be the point of the device if it didn't wake up upon generation?

It wouldn't be automated in anyway if it didn't come on automatically.

It wouldn't work for a lot of people as they don't have enough batteries to keep the system running overnight and are not near the inverter at sunrise every morning to turn it on.

What a chore that could be.

What could cause it to not charge?

This I'm not sure.

I'm using a Growatt battery with comms to the inverter.

My setup has always behaved like this, I assumed it was normal operation lol.

I'd say it's the comms not waking your battery.

 

[timselectric]

Mine does. It gets woken up at 6am when voltage rises.

Inverter is off at this time.

Battery is charging.



Works for me irrespective of charge state or conditions from the day before.

It will wake up the battery at 0%-100%.

What would be the point of the device if it didn't wake up upon generation?

It wouldn't be automated in anyway if it didn't come on automatically.

It wouldn't work for a lot of people as they don't have enough batteries to keep the system running overnight and are not near the inverter at sunrise every morning to turn it on.

What a chore that could be.



This I'm not sure.

I'm using a Growatt battery with comms to the inverter.

My setup has always behaved like this, I assumed it was normal operation lol.

I'd say it's the comms not waking your battery.

It's probably just a different firmware version.
It's only an issue for people who turn off the inverter. So, it doesn't come up in the forum very often. I don't remember if a firmware update fixes it or not.

 

[Seabhac]

Ah crap, no BMS communication with the inverter then.

So, which mode you use? USE or US2 mode?

USE = there is float, however the battery voltage needs to be 2v lower than your set float voltage, otherwise, there will be no solar recharging next day.

US2 = no float, when battery voltage reach CV value, it stops charging immediately.

I'll have to have a look later when I'm over there. I thought it would be ok to have the overkill solar switch off the supply to the battery without need for coms with the Growatt when the battery wad full.. The overkill solar does the balancing also. The way USE setting is programmed, ie no charging the next day for example is strange. Why is it like that? For US2 what does CV voltage stand for?

 

[Seabhac]

Mine does. It gets woken up at 6am when voltage rises.

Inverter is off at this time.

Battery is charging.



Works for me irrespective of charge state or conditions from the day before.

It will wake up the battery at 0%-100%.

What would be the point of the device if it didn't wake up upon generation?

It wouldn't be automated in anyway if it didn't come on automatically.

It wouldn't work for a lot of people as they don't have enough batteries to keep the system running overnight and are not near the inverter at sunrise every morning to turn it on.

What a chore that could be.



This I'm not sure.

I'm using a Growatt battery with comms to the inverter.

My setup has always behaved like this, I assumed it was normal operation lol.

I'd say it's the comms not waking your battery.

My BMS doesn't have coms with the growatt.

 

[Kid Solar]

firmware

My firmware is

067011.04
068011.04

My BMS doesn't have coms with the growatt.

Damn, that's probably it.