Voltage drop very fast on load

[acdoctor]

What was the load, lights and refrigerator?
That is very close to the C20 discharge rate.
From 100% charge you can run that for 9 hours to the 46 to 48 volts.

 

[Montanat]

You mean to say the same amperage screen you have referenced before that was 20 amps.This time was showing 11 amps?

Yes. The screen was 11amps discharging load. The clamp meter showed 1.6amps on the inverter output cable (my AC clamp not DC).

Inveter Voltage was around 51v on pins + screen + batteries terminals.
Output voltage was 229v.

It was fridge, freezer, 42"TV, résistance heater, some lamps, total drawing = 11amps.
I didn't go to 20amps load just 11a.
If I want to load 20a I turn on the second resistance heater (attached pic).

Now I did a recharge test:
Charging on screen was 8amps, clamp meter on input cable of the inveter showed 3.3amps, voltage on inveter was 53v and increasing.

Again I'm using my AC clamp.

 

[acdoctor]

I would love to see a picture of the electrical data plate from that heater.

 

[Montanat]

I would love to see a picture of the electrical data plate from that heater.

1 résistance is 400w. 2 are 800w

 

[acdoctor]

So 400 watts / 229 volts is 1.75 amps.
1.6 amps x 229 volts is 366.4 watts
11 amps x 51 volts is 561 watts x .95 efficiency is 533 watts
I suppose fridge and freezer were not running at the time. Then the 533 watts may be believable.
I think the meter is off a little, the scale is 600 amps so it’s not very accurate that close to zero.
I think you about have it as good as you can with what you have. I think your batteries are a bit small for your needs or maybe your expectations.

 

[Montanat]

So 400 watts / 229 volts is 1.75 amps.
1.6 amps x 229 volts is 366.4 watts
11 amps x 51 volts is 561 watts x .95 efficiency is 533 watts
I suppose fridge and freezer were not running at the time. Then the 533 watts may be believable.
I think the meter is off a little, the scale is 600 amps so it’s not very accurate that close to zero.
I think you about have it as good as you can with what you have. I think your batteries are a bit small for your needs or maybe your expectations.

Did a test on the heater.
Inverter screen showed:
1 résistance 350w / 10a
2 résistance 750w / 18a

Anyways I don't think I will get more than 4 hours AC in the summer. My AC draws 850 watts, with cutoff at 46v i will get 4 hours.

I'm trying to get solar panels 4x545w, still have problem with the neighbours (building where I live is 5 floors), they don't allow panels on the roof no more place. And if I install the panels at the balcony I won't get any sun, only daylight.

 

[acdoctor]

Those are some big panels. All of this said where will you put them?
In a good location just 2 of them should make a big difference. Where are you located?

 

[Montanat]

Those are some big panels. All of this said where will you put them?
In a good location just 2 of them should make a big difference. Where are you located?

Beirut /Lebanon. 2x545w are enough? I won't get 100% power out of 2 to power AC, fridge, freezer, TV, washing machine all together. All Those are rated around 2100w

 

[acdoctor]

So you are about the same latitude as I am. But no 1 kw of panels won’t carry all of that but it would cover A/C load.
I have high humidity that affects solar production a little in the summer. I have 6.1 kw of panels the array is 10 feet x 40 feet. In the summer I produce 25 to 30 kw a day.

 

[Montanat]

So you are about the same latitude as I am. But no 1 kw of panels won’t carry all of that but it would cover A/C load.
I have high humidity that affects solar production a little in the summer. I have 6.1 kw of panels the array is 10 feet x 40 feet. In the summer I produce 25 to 30 kw a day.

That's a Waw. If I want to do this I need the full block of buldings near me lol.
Do you advise bi facial or mono panels?

 

[acdoctor]

Bi facial only benefit you if they are mounted on a frame where you can look at the back of the panels. If you mount them on a angled roof for example with just a few inches between them and the roof there is no benefit.

 

[Montanat]

Bi facial only benefit you if they are mounted on a frame where you can look at the back of the panels. If you mount them on a angled roof for example with just a few inches between them and the roof there is no benefit.

Yes in think I will mount them with 4 meters above roof floor.
And I think my battery problem is described in this pic (attached). External battery charger (64v-20amps) is needed.

 

[BarryE]

Hi. I bought a brand new 5000w inverter (Chinese Soer) + brand new 4x200a tubular Indian lead acid batteries. It's a 48v / 800amp setup. No solar panel, only grid for recharging.

I see 54v float when electricity is on and when it goes off voltage drop immediately to 53.2v without any load on the batteries at all.

In batteries mode (when electricity goes off) i tried 1300w load and the voltage of batteries dropped from 53.2v to 48.2v immediately.
I switched off that load after 10 seconds , the voltage went back to 50.5v.

Checking the batteries with a voltmeter there is one of them always 0.07v lower than the rest on both float and load and rest mode.
Example of Batteries voltage like this : 12.72v / 12.71v / 12.74v / 12.64v is that low one.

Inverter is installed 4 meters away from the electricity board with 12mm wires. Batteries under it connected together in series with 2x6mm wires.

I'm new to the inverter batteries thing, I need to know if dropping this much and fast under this load is normal and if that battery which is always lower than the rest by 0.07v is defected or not.

Thank you

When the battery is being charged, the charger "pulls up" the Voltage. This is normal and when the charger is turned off again the battery Voltage will slowly settle back to it's nominal Voltage - that will depend on the state of charge.
Don't be worried about Voltage variation whilst charging. It would be helpful to have an Ammeter to monitor current into and out of the battery. This will enable you to determine when the battery is full and understand the "normal" Voltages. Assuming that your batteries are Lead Acid type, the charge current will reduce slowly over time as the battery approaches full charge and will level off at a small value - perhaps around 1 Amp when on float.
If you then remove the charge and wait for the Voltage to settle you can establish a "Normal" resting Voltage. If the batteries are healty this will be a little higher than the nominal 4 x 12V - probably around 50V
If you then draw current from the battery into a load this will cause a small drop in Voltage that will mostly be recovered when the load is removed, except for a small drop due to the amount discharged.