Hello,

I'm a newbie to renewable energy and solar.
I have installed a 2.7 KW 48 v system with 6 panels 450 W each, Growatt SPF 5000 es inverter, and 4 Lead-acid batteries

Everything is running smoothly, except that the inverter is discharging the batteries to 50 v after a full charge even without a load.

When there is no source for charging even if there is no load, the voltage is being dropped to 50 V. As it seems for the inverter the maximum voltage for the batteries should be 50 v. 

 

Below are the settings

1- sub

2- 60

3- APL

4- dls

5- FLD ( I also tried USE)

6- dls

7- dls

8- 230

9- 50

10- 4

11- 40

12- 48

13- 56

14- snu

15- OFF

16- OFF

17- OFF

18- dls

19- 58.4

20- 56

21- 43.6

Any idea why this is happening?

@haissamx Your settings are wrong according with what I see on your battery. is it just one battery 12 V or is it two in parallel to give you 44 V

 

I have 4 batteries (same model) 200 AH 12 v each

How are they connected ? are they connected in parallel ? or are they connected in series? Do you have a catalogue of your batteries?

They are connected in series. I will try to find the catalogue of the batteries. 

 

 

So theoretically according to what I see in the photo of the battery you have boost at 57,6 V and floating at 53.6 V 

Also in my opinion I think your charging current is a bit on the high side. but again need to look at the OEM manual/catalogue to see what are the recommended settings according to the original equipment manufacture.

Try to get the values bellow from the OEM

 

• Charging cut off voltage point:
• Discharging cut off voltage point:
• Recommend charge/discharge current = ?? A * N  

Edited January 18, 20223 yr by Antonio de Sa

Okay i will try to get these from the information from the battery manufacturer. Meanwhile, can you recommend what are the best settings for the inverter to ensure smooth and efficient performance?

 

13 minutes ago, haissamx said:

Okay i will try to get these from the information from the battery manufacturer. Meanwhile, can you recommend what are the best settings for the inverter to ensure smooth and efficient performance?

 

Difficult without knowing what are the battery OEM recommended settings. another thing is does your battery have an BMS? that is very important.

Running a battery without BMS is not recommended. though one can set parameters on the inverter it's always recommended to have a BMS 

 

 

5 hours ago, haissamx said:

Everything is running smoothly, except that the inverter is discharging the batteries to 50 v after a full charge even without a load.

If you mean that the battery voltage relaxes to 50.0 V after being charged, this is fairly normal, except that one would hope that the relax to a bit higher than 50.0 V. 50.8 V (12.7 V x 4) or higher would be better. Are they getting to float stage? I.e. is the charge complete by the end of a typical day?

43.6 V is very low for the low battery cutoff voltage, if you have regular load shedding. It should be up around 48 V, to preserve the life of the battery.

Hello friends,

I'm new here in this forum, and hope I can contribute, and also learning for you.

I was looking through several documents, guidelines from manufacturers, etc... unfortunately there are many stories and it makes me also confused.

I have about the same installation, 4x 12V batteries in serie, all are 200Ah, GEL deep cycle.

Here is what I configured:

Bulk charge voltage: 56v

Floating charge voltage: 54v

Low voltage alarm: 46v

Low voltage shutdown: 44v

I assume I'm pretty close to what it should be (according guidelines), but I would like your opinion(s)

Thanks, regards

Geert

 

 

 

13 hours ago, geert said:

I assume I'm pretty close to what it should be (according guidelines), but I would like your opinion(s)

It really depends on the model of gel battery that you are using. Different manufacturers recommend different values.

13 hours ago, geert said:

Low voltage alarm: 46v

Low voltage shutdown: 44v

Those are very low value for South Africa, where load shedding is fairly frequent. The above are OK for a "once a year" event, but for regular load shedding, you want to stop discharging at around 48 V (roughly 50% SOC). Regular discharging to 44 V will quickly ruin a lead acid battery.

18 hours ago, Coulomb said:

If you mean that the battery voltage relaxes to 50.0 V after being charged, this is fairly normal, except that one would hope that the relax to a bit higher than 50.0 V. 50.8 V (12.7 V x 4) or higher would be better. Are they getting to float stage? I.e. is the charge complete by the end of a typical day?

43.6 V is very low for the low battery cutoff voltage, if you have regular load shedding. It should be up around 48 V, to preserve the life of the battery.

Yes the voltage of batteries is settling on 50 V. When there is power to charge (from pv or grid), the batteries voltage are getting to the float voltage set.

so it seems 50 V is the voltage of batteries in 100% charge state right?

the max that I allow the batteries voltage to drop is to 47 V. When it hits this number, I switch to main.

 

Thank you for your reply.

Edited January 19, 20223 yr by haissamx

2 hours ago, haissamx said:

it seems 50 V is the voltage of batteries in 100% charge state right?

The rested voltage, yes. But a healthy, fully charged lead acid module will rest at a higher voltage, 12.7 to 12.9 V per nominally 12 V module, so 50.8 - 51.6 V. But a small load can easily blow away a few tenths of a volt per 12 V module.

Hi Coulomb,

Thank you for your help and the good information.

I checked with the seller, indeed, ratings vary a lot, depending of the type and brand.

here I share the info they gave me for my type of battery: (because it was not mentioned on the battery itself - some Chinese stuff)

One thing they emphasized: don't go under 48v (4x12v batteries in series), choose your own depth of discharge, preferable to a 50% limit (lifecycle depends on this)

they advised me:

bulk charge: 57,6v

floating: 54v

recommended charge current: up to 30 A

Hi everyone I am a newbie 

 

I have a 5kw li battery system my battery use to last about 8 hours with minimal load.

 

Until we had a 12 hour power outage in my area, my battery drained itself and went into sleep mode (according to the solar technician) 

 

My battery only lasts 3h30m now on minimal load 

 

I am told that li batteries are not proun to fault especially since nothing dramatic has happened to it physically.

 

I don't have BMS, where would I get that? 

 

Why are my batteries only lasting 3h30min now ? 

 

I have set my inverter settings to default.

With the exception of the battery stop charging voltage when grid is available which I put on 58v from 54v as default 58v is in range with the manufacturer guidelines.

21 hours ago, Corezality said:

I have a 5kw li battery system my battery use to last about 8 hours with minimal load.

...

I don't have BMS, where would I get that? 

So this is a home made 5 kWh LFP battery, made from bare cells?

Sorry, I know nothing about commercial BMS for DIY batteries.

Quote

Why are my batteries only lasting 3h30min now ? 

Probably at least one cell is badly out of balance with others. It's not good to leave the battery in this state.

Do you have a power supply that you can use to bring up the low cells? Charge them until the voltage, when rested or at least at very low load or charge, are about the same voltage as the others. It's best to do this when the battery is nearly full or nearly empty.

21 hours ago, Corezality said:

I have set my inverter settings to default.

That's probably not great. LFP is a reasonable, but not great match for lead acid as far as charge voltages go.

Is your battery 15S, 16S, or perhaps 8S? Or perhaps it's not even LFP chemistry at all? All you told is is that it's one of the Lithium chemistries.

Edited January 14, 20232 yr by Coulomb