Is 13.3 Volts or 13.6 Volts the defacto voltage after charging and then immediately loaded LiFePO4 battery (12.8 V 280 AH)

[tsuru]

Have a 12.8 V 280 AH LiFePO4 battery that is barely 2 months old. I did not at first pay that close enough nor document voltages on it, but charged it up to where it appeared to be full with a LiFePO4 Battery charger of 14.6 volts and 60 amp capacity.

What I'm noticing different within weeks of building this whole thing up and nothing else changing, is that I can't seem to get thru the night and not loose the inverter due to low battery. After any charge, it drops from 14.6 volts to 13.3 volts. I've seen YouTube videos of folks that show photos of everything and it seems 13.6 volts is the defacto voltage after charging. Why do I only get 13.3 volts? And not 13.6 volts? Or is this 'normal' having 13.3 volts? Or is there something I am doing wrong? OR, worst case, is this new battery already failing as the manufacturer doesn't seem to give me straight answers it seems. Thanks in advance.

 

[mikefitz]

Why do I only get 13.3 volts? And not 13.6 volts?

How are you measuring voltage, what make is the 280Ah battery, Renogy perhaps?
Are you measuring the voltage with the battery under load ?
Is the inverter permantly connected and switched on?
What make and model is the inverter?
What is the load on the system.?
How are you charging the battery, what equipment?
How are you determining the battery is fully charged?

Even a small load on the battery will reduce the voltage from the 'completely full' value.
The fact that the battery will not meet the night time loads suggests that either the battery is not being charged correctly, or the load is too high for the batteries capacity.

 

[Mattb4]

100% full charge resting voltage would be 13.6vDC. Often, when new, LifePO4 batteries are not balanced and high runner cells will cause the BMS to trip and 100% charge will not be reached. Backing off from 14.6vDC to 14.2vDC for a few cycles can help or leaving your battery charger on for longer periods of time even if it gives a full charge indication.

However 13.3vDC at rest should indicate 80%+ capacity. If you are reaching low voltage cutoff at night what is the load on the battery? 280ah at 80% =224ah or ~ 2400wh usable.

 

[tsuru]

Well received two answers that I will respond to.

First, for the first week to 10 days of having my solar system built and up, and with the exact same everything meaning the panels never changed (800 Watts - 4x200), the 60 Amp MPPT never changed the inverter (BougeRV 3,000 Watt) never changed and the battery (Eco-worthy 12.8 V 280 AH) never changed and all equipment brand new, nothing used.

And, the loads were the same, two refrigerators, my internet router, my TV (which is nearly always just in standby as don't watch much over a full weeks period), and my computer and monitor, which is on or off depending on the day but most all days are just about the same. I get up, check email, might read a little news, then nothing till later in the day or evening. Inside temps of my home have been pretty steady as well. So I call that like No Change.

Battery is not Renogy (not impressed with that company whatsoever for several reasons) and measuring the voltage with a digital voltmeter, which I have two, and get nearly identical readings with.

I am measuring the voltage under load but the load is the inverter showing 87 watts time frames, not when both refrigerators are running on.
And all equipment is turned on and has been as I say, the same setup and running the same way since day one.

Inverter is a 3,000 Watt BougeRV. Load stated above. Purchased a 14.6 V 60 Amp charger which is adjustable, meaning voltage up to 14.6 V and current up to 60 Amps.

Fully charged to me seems to mean that I run the Battery charger at 50 Amps from 9 PM at night (when there is the least load being placed on the battery / inverter) until 10 AM in the morning. And I've done that a few times too since purchase.

So the night time load has not changed since the first 7-10 days (I didn't write down the exact date this changed but approx), and assume the battery has been fully charged after charging it up on the first couple days with no load.

Do I need to run the battery charger several nights as above to then have a fully charged battery? AND, why then when I first set this whole thing up did it run fine all those first days after just one night on high amperage charge? Had assumed it was charged and can't see what on earth has happened with nothing changing!!

Another person said to charge the battery at 14.2 volts so will try that next.

Thank you.

 

[Suijkerbuijk]

Have a 12.8 V 280 AH LiFePO4 battery that is barely 2 months old. I did not at first pay that close enough nor document voltages on it, but charged it up to where it appeared to be full with a LiFePO4 Battery charger of 14.6 volts and 60 amp capacity.

What I'm noticing different within weeks of building this whole thing up and nothing else changing, is that I can't seem to get thru the night and not loose the inverter due to low battery. After any charge, it drops from 14.6 volts to 13.3 volts. I've seen YouTube videos of folks that show photos of everything and it seems 13.6 volts is the defacto voltage after charging. Why do I only get 13.3 volts? And not 13.6 volts? Or is this 'normal' having 13.3 volts? Or is there something I am doing wrong? OR, worst case, is this new battery already failing as the manufacturer doesn't seem to give me straight answers it seems. Thanks in advance.

Rest vs load

Rest is about 13.6 volt
Slow load is about 13.5
Load is about 13.3 volt
So if you use a inverter that is 24/7 on its a load
Switch the inverter of both will have the same volts

You can see it on my systeem
The 13.3 have a inverter on that is running 24/7 (not eco mode)
The 13.5 have not
If the battery are full the non inverter will stay on 13.5 volt.
The inverter go to 13.4 volt

 

[mikefitz]

charged to me seems to mean that I run the Battery charger at 50 Amps from 9 PM at night (when there is the least load being placed on the battery / inverter) until 10 AM in the morning.

One would hope that is enough to charge, but what is the battery charger profile? What is the absorption period, is there a float charge ?
The battery charger settings and model would be useful .
As requested the model of of solar charger and setting would help .
What instrument are you using to measure voltages?


It seems that the battery needs a capacity test to confirm its not the problem. It it possible, after charging with the 60 amp charger overnight with no other load on the battery, to carry out the following tests:
Disconnect the charger and measure battery volts with a multimeter.
Load the battery with a constant known load via the inverter, perhaps a 1000 watt heater.
Time the run time of the battery.

 

[tsuru]

Charger purchased on Amazon for about $120: https://www.amazon.com/dp/B09Z25WQPY?psc=1&ref=ppx_yo2ov_dt_b_product_details

Measuring with a Fluke DVM, probably one of the most accurate DVMs on the market.

Performing the battery tests suggested means taking my computer system down and I'm not too crazy about doing that however if nothing else can be done but that, I will do that.

And I'm going to try a high current 14.2 V (vs 14.6 V) as suggested, overnight charge which will run from 9 PM to 10 AM next morning.

 

[time2roll]

13.30 loaded after charging is reasonably normal. Might hang at 13.4-13.5 if resting no load. I also recommend 14.0 to 14.2 charging.
Ultimately need a second battery or even two more.

 

[tsuru]

Running charger now at 14.2 Volts. Been contemplating purchasing another battery like a 12.8 V 300 AH. Have the Eco-Worthy 12.8 V 280 AH battery presently. Tough trying to decide to purchase a battery for $50 to $100 less than some other 300 AH batteries, but can't bring myself to it. Just sitting on this damn fence post and need a good swift kick in the butt to buy another battery! LOL Wish I knew batteries better.

 

[tsuru]

It appears that charging my battery at 14.2 volt (vs 14.6) seems, seems to have an improvement. Jury is still out, but something seems a bit better now. Although back on the charger again tonight as don't want my entire system going down for bringing the battery to a low voltage.

 

[time2roll]

It appears that charging my battery at 14.2 volt (vs 14.6) seems, seems to have an improvement. Jury is still out, but something seems a bit better now. Although back on the charger again tonight as don't want my entire system going down for bringing the battery to a low voltage.

The charge is not linear. 14.2 will get the battery to 100% with even a short absorption time. Worst case 99% charged.

 

[Mattb4]

It appears that charging my battery at 14.2 volt (vs 14.6) seems, seems to have an improvement. Jury is still out, but something seems a bit better now. Although back on the charger again tonight as don't want my entire system going down for bringing the battery to a low voltage.

You did not mention how much load you put on it overnight.

Something also to consider is if a large load (such as a pump or compressor) cycles on when the battery is at a low state of capacity. The resulting voltage slump can cause your inverter to trip out on low voltage. Once it does the battery voltage jumps back up to resting voltage corresponding to actual capacity left.

 

[Suijkerbuijk]

You did not mention how much load you put on it overnight.

Something also to consider is if a large load (such as a pump or compressor) cycles on when the battery is at a low state of capacity. The resulting voltage slump can cause your inverter to trip out on low voltage. Once it does the battery voltage jumps back up to resting voltage corresponding to actual capacity left.

Wil not happens if you not adjust the inverter.
A inverter program run on a lead battery profile .
The low volt on that is 9.3 volts on a 12 volt inverter.
The low point of lipo4 is 10volt (100% bms shutdown)
So really the inverter wil not shutdown on that moment.

If people program the inverter on 12.8-12.9-13.0 volt shutdown. (Safety reason )
But only if somtings els is connect on the same 12 volt connection and have a big pull .(Other Inverter)
Or .
Is a inverter is in eco mode ( wat is stupid to do ) than yes it can ( eco mode use a pulse to see if somtings need power and set the inverter on if there is a power draw on that moment)
Reason i do not use eco mode.
A stupid fan do not run it go on and of on the same puls .
And low power stuf will be damaged thanks to that.
(I think)

I do not thing people use the eco mode if you are off grid house for the reasons like a phone charger and more wat you connect in home .

I do talk about Victron unit .
Other unit i do not know .

For the rest again i do not see a problem with his battery.

Lithiumbatterijspanning

Keheng biedt op maat gemaakte oplossingen, van 12 V tot hoogspanningsbatterijen, en biedt een alles-in-één service, van energieopslag thuis tot commerciële en industriële energieopslag.

www.lithiumbatterytech.com

See link with Google Chrome and translate.
Small part out of it .

The LiFePO4 cell has a discharge termination voltage of 2.5 V, a float voltage of 3.65 V and a nominal voltage of 3.2 V.

Other link
a vs b cell.

How to Distinguish Grade A and Grade B LiFePO4 Prismatic battery Cell?

This article answers readers' questions about how to distinguish between A and B cell and how to differentiate between A and b batteries

www.lithiumbatterytech.com

b cell wil never have the same performance like a cell.

 

[tsuru]

You did not mention how much load you put on it overnight.

Something also to consider is if a large load (such as a pump or compressor) cycles on when the battery is at a low state of capacity. The resulting voltage slump can cause your inverter to trip out on low voltage. Once it does the battery voltage jumps back up to resting voltage corresponding to actual capacity left.

This is what I have on the system:
1 Internet Router ~ 20 watts
1 Computer system ~ 90 watts on standby at night or less actually
1 Refrigerator that may come on during the night ~110 Watts
1 Refrigerator that may come on during the night ~ 120 Watts
1 TV system / DVR / etc that is off but on standby ~ 30 Watts

That is all. So really only if both fridges come on at the same time during the night for lets say 1/2 hour (?) it would pull total of 380 Watts, but then drops off quite a bit after fridges power back off. House is cool at night too, so they are not subjected to 100+ temps all night long whatsoever.

And I really thing estimating 90 watts for the Computer is really high. Maybe as low as 50 Watts