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Battery dropping fast to 50v

ghostman

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Apr 13, 2022
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Hi,
my off-grid system consists of 14 solar panels 410 W, Voltronic 48v 5300w Inverter and 12x Leader LDR INV TT 220AH/12v set in 3 parallel banks of 4 batteries each.
I ran the 230V output from the inverter directly into my electrical panel.
This system is online for less than 1 week.
Bulk Charging voltage is set to 56.4v and Floating Charging voltage to 54v.
I don't have an issue during the day where the load can go up to 2.5kw where power is taken directly from the solar panels without the battery intervention.
But when the sun is down, battery drops fast to 50v (in few minutes) and stabilizes there and start dropping gradually to reach around 47.5 around sun set.
Load at night is around 800w.
I'm worried about this instant drop, is it normal? I also noticed that after battery drops to 50v, if I charge it using grid power it goes up rapidly back to 54v, is this also normal?
Any thoughts on this?
 
50v seems normal for FLA.
So I shouldn't worry much about it? what about the fast charge from 50v to 54v, is this also normal?
I was worried when you said "weak battery" in your previous reply lol, so we can assume this is not the case?
 
Hi,
my off-grid system consists of 14 solar panels 410 W, Voltronic 48v 5300w Inverter and 12x Leader LDR INV TT 220AH/12v set in 3 parallel banks of 4 batteries each.
I found this https://www.bdtradeinfo.com/product/d/362/leader-heavy-duty-220ah-ips-battery - e.g. lead acid.
4s3p = 660ah @ 48v =~ 31kwh at 100% DOD. Say 15kwh at 50% DOD.

I ran the 230V output from the inverter directly into my electrical panel.
This system is online for less than 1 week.
Bulk Charging voltage is set to 56.4v and Floating Charging voltage to 54v.
That's 14.1v bulk and 13.5v float.

I don't have an issue during the day where the load can go up to 2.5kw where power is taken directly from the solar panels without the battery intervention.
But when the sun is down, battery drops fast to 50v (in few minutes) and stabilizes there and start dropping gradually to reach around 47.5 around sun set.
This doesn't sound good. It's true that bulk charging will raise the voltage above the battery voltage to allow current to flow - but that should be around 1v - e.g. shows 55v which charging but drops to 54v when charging is turned off - 'kind of thing'.

56v -> 50v would be 14.0v/battery to 12.5v/battery after charging stops - maybe this is normal for lead-acid? I'm not a lead-acid expert as all my stuff is lithium-ion.

Load at night is around 800w.
15,000w (see above) to 50% DOD / 800w = 18.75hrs runtime.


I'm worried about this instant drop, is it normal? I also noticed that after battery drops to 50v, if I charge it using grid power it goes up rapidly back to 54v, is this also normal?
Any thoughts on this?
If you have a volt meter, maybe start by measuring the voltage 'at the battery itself' to confirm what you think is happening is really happening.

Do you have specs (voltage range specs)? Maybe contact the distributor for this if you don't have it / confirm bulk/float recommendations.
 
12.6 is full resting charge voltage. If memory serves me.
So 50.4v should be perfect.
I can see a small load dropping it to 50v, easily.
As long as the discharge going down from there, seems gradual, based on load.
I would think it is fine.
But maybe someone else who is running FLA , on a daily basis. Can confirm this.
 
I found this https://www.bdtradeinfo.com/product/d/362/leader-heavy-duty-220ah-ips-battery - e.g. lead acid.
4s3p = 660ah @ 48v =~ 31kwh at 100% DOD. Say 15kwh at 50% DOD.


That's 14.1v bulk and 13.5v float.


This doesn't sound good. It's true that bulk charging will raise the voltage above the battery voltage to allow current to flow - but that should be around 1v - e.g. shows 55v which charging but drops to 54v when charging is turned off - 'kind of thing'.

56v -> 50v would be 14.0v/battery to 12.5v/battery after charging stops - maybe this is normal for lead-acid? I'm not a lead-acid expert as all my stuff is lithium-ion.


15,000w (see above) to 50% DOD / 800w = 18.75hrs runtime.



If you have a volt meter, maybe start by measuring the voltage 'at the battery itself' to confirm what you think is happening is really happening.

Do you have specs (voltage range specs)? Maybe contact the distributor for this if you don't have it / confirm bulk/float recommendations.
As shown in the picture, boost voltage (I assume this is bulk) range is 14.4-14.8v and float range is 13.4-13.8v
 

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This doesn't sound good. It's true that bulk charging will raise the voltage above the battery voltage to allow current to flow - but that should be around 1v - e.g. shows 55v which charging but drops to 54v when charging is turned off - 'kind of thing'.
Can you please elaborate more on this point? I didn't get what do you mean by it.
 
Those are voltages while charging.
As I remember.
Resting voltages are much lower.
And discharging voltages are even lower than that.
 
Correct
Should never go below 50% with lead acid batteries.
The issue is that in the inverter's parameters, if I specified battery type as FLA, I cannot change the Low DC cut-off voltage, it is fixed to 42v, which is pretty low. I think I have to change the battery type to User-Defined, and manually set the value of cut-off voltage to 48v.
 
The issue is that in the inverter's parameters, if I specified battery type as FLA, I cannot change the Low DC cut-off voltage, it is fixed to 42v, which is pretty low. I think I have to change the battery type to User-Defined, and manually set the value of cut-off voltage to 48v.
Just set the "back to utility " at 48v.
 
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