LiFePO4 battery shut off 14.6V

Alice2021

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Oct 12, 2021
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I have a 1500W pure sine wave inverter,which run by the lithium batteries.It can run my fridge very well,only trouble with TV, it usually shut off about 15 minutes.
I can turn it off and back on then it is fine for a little while. This seems to only happen when my batteries are at full charge. The display panel shows the input voltage is well within the parameters of the inverter.
I contact the battery supplier, the battery working range is 10V-14.6V , inverter working range is 9.5V-16V.And the inverter shut off about 14.6V, I have contacted with inverter supplier and they said the battery goes to full charge protection,not the inverter problem,is that right ?Any one has this same problem?
 

ericgrand

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Maybe a little bit more details on the batteries and BMS? it maybe the BMS which is triggering a high current protection. 1500W over 12V battery bank is above 100Amps... Any bad connection would also trigger a low voltage at inverter input under load.
 

Alice2021

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I think the connections are well,because My fridge works well by this inverter,only when I watch TV, the inverter shut off and restart some minutes later.I talk with the inverter supplier,they suggest me to stop charge when I watch TV, or change another lead acid battery.But my lithium battery supplier said my battery is no problem,why I should change the battery. The inverter works range is 9.5-16V,why it shut off at 14.6v?
 

ericgrand

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No answer to the questions, no way to help you...What is your battery brand? BMS? Charger? Inverter? picture of the connections?
Also, 14.6 volts for a LFP battery is full charge at 3.65V per cell. So if your inverter stops under load with a battery at such voltage, that means you are exceeding a limit somewhere...
 

Alice2021

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I do not have pictures in hand,in fact,I have used this inverter this whole summer on the hill, run by fridge and microwave oven , shop vac very well,only problem when I watch TV. I like the inverter very much.
When the lithium battery full charge,will it shut off by itself and will not output DC, right ? I am very confused
 

ericgrand

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If you don't want to provide the required details, then there is no way to help you...
 

Steve_S

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Alice, we NEED the Make & Model number of the Inverter, the Battery Make Model etc, links to the products. We cannot help you bake a cake without knowing what ingredients we are working with.
 

time2roll

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Is this an inverter/charger that is charging an LFP battery?
Yes the LFP may block additional charging at 14.6 or more.
 

Alice2021

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The battery is hooked to a charge controller which connects to my solar panels. When the battery is fully charged the charge controller limits the amount of power that is fed to the batteries. The charge controller monitors the amount of power in the batteries, it stops charging the batteries when they reach 14.6V. When they get below 14.6V the charge controller allows more power from the solar panels to go into the batteries to keep them fully charged. The inverter works fine as long as my batteries are not fully charged ,but once my battery full charge at 14.6V, the inverter stop working.
 

time2roll

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I assume something is wrong with the inverter.
Consider reducing the charging voltage of the solar controller.
The battery will also live longer.

Are you certain the controller equalization has been disabled?
 

740GLE

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Easy solution, don’t use your TV. Sounds like that is the only time the inverter shuts off when you are using the TV. Problem solved!!
 

evad

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Is it possible that the BMS is shutting off the inverter ? Is this a problem at night when the battery is not being charged ?
 

Alice2021

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Is it possible that the BMS is shutting off the inverter ? Is this a problem at night when the battery is not being charged ?
No problem in the night, only in the day time,when the battery is full charged
 

DJSmiley

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It all points towards a too high voltage to me.

As said by others, 14.6V = 3.65V / cell.

Any higher and the battery BMS shutsdown. In reality, BMS shutdown will occur earlier, since most cells are not equally. A BMS shuts down if a single cell exceeds 3.65V. So with 3.62V for a cell, and 3.66V for another, it still will trip OVP, while the total voltage is still <14.6V

During daytime only, when the battery is fully charged leads towards your solar controller. My guess it's not set properly.

Which solar controller do you have and how is it configured?

I personally don't like 14.6V. Too high imho for the lifespan of a LFP cell, and too great risk of tripping OVP due to cell inbalance (which there ALWAYS is, even though its only a few mV)

I'd set it to 14.2 or so, 14.4V maximum. Leaves some room for cell inbalance.
And 14.2V is still 99.99% or so, so there is no real benefit in terms of capacity to go to 14.6V. (you won't even notice)
Some people go even lower, which does increase the life of the cells, without much loss of usable capacity. (14.0V will still be 99% or so)

The inverter doesn't shutdown or fail, it's most likely the BMS of the battery


Ow and suggestion: Always mention at least brand/model of the involved equipment (Inverter, solar controller in this case), and preferably the settings. Now it's just guessing based on the information you're providing, with settings and models we can exactly point out the issue (this setting is wrong, this is a know issue with this model/brand, I had the same issue, you need to change xx on this) and so on.
 
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Short_Shot

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Agree.

You should not be charging your batteries to 14.6v on a regular basis.

Even though this is "full charge" voltage, the BMS is also programmed to disable charging at this point and might (probably) also be shutting down discharge simultaneously.

Your chargers should not be configured to output 14.6v.

Now you'll probably say "well I want my battery at full charge!" And you'd be right to say so.

However the difference between 14.6v and 14.2v is actually effectively nothing. Even if you charge them all the way to 3.65v (14.6 total) the cells will settle to about 3.55v (sometimes less) at full charge, which is 14.2v or less.

This will represent a fraction of a percent of capacity of difference if you only take it to 14.2 to start with.

In fact, at ~13.4 volts total your battery is over 99% charged, assuming good cell balance.

13.8 to 14.2 is a good range to charge a lfp4 battery in my opinion and many others.
 

Alice2021

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Thanks for all of your help,I will try to make some changes on the set in the following days.
 

Supervstech

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When you say, “only problem is using the TV”
What else is running? Just the TV?
 

Texas-Mark

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As others noted, it sounds like the charge voltage is too high. It works ok with the fridge because that loads the batteries down more than the TV.
 
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