PowerQueen 300AH 12v

[MikeRo55]

I recently purchased a Power Queen 300ah 12v.
When I received it the voltage was 13.19. After putting it on a LifePo4 6 Amp charger for two days the voltage is now at 13.15.
I changed chargers and used a 20 Amp charger from another system. When the charge is connected it shows 14.6v. But as soon as I disconnect the charger the voltage reads 13.15. From what I can see in online charts that seem low for a fully charged battery.
Any recommendations? Should it return to normal after several cycles of charging discharging?
Or, is this possibly defective?
From this chart here I was expecting 14.4

LifePo4 battery state of charge chart - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

www.bing.com

Update,
I put a parasitic load on it, an inverter doing nothing for 24 hours. After that I put a small 6 amp LifePO4 charger and let it run until it said it was charged. After completing it was showing 13.35. the PQ state of charge states that a fully charged battery is anything > 13.30. So, perhaps it is ok!

Thanks,
Mike

 

[Tomthumb62]

A fully charged 12v lifepo4 will read about 13.2v when settled at rest with no loads or charging for about 24 hours. Though it will often settle down to that voltage within an hour or so.

So your new lifepo4 is nearly fully charged. Why isn’t it at full capacity at 13.2v? Because that’s what you tend to get with a cheap battery…the cells are usually poorly balanced. Unless your battery has a Bluetooth BMS that you can read the individual cell voltages, then you can only guess that the cells are out of balance. Or you can cut open the top of the battery and test the cells manually, but that will ruin your plastic battery case.

What I’ve been told you can do to try to rectify this imbalance issue (I can almost guarantee this the problem because it’s so common) is to put a bench power supply on the battery at 13.8v and leave it there for 24 hours. Then remove the power supply, let the battery rest for at least a couple of hours (with no loads or other charging source) and measure the voltage again with your multimeter. If it’s gone up but not much (the max you’ll get is about 13.25-13.3v), then put it on the bench supply for another 24 hours. Keep repeating until it reaches and settles at 13.2v, then just use the battery for a while and see if the resting voltage of a fully charged battery (using your regular charger or solar charge controller) still hovers around 13.2v.

FYI, the Victron IP22 12/30 charger is an excellent one. It’s fully programmable and also has a bench power supply mode to use as I suggested above. Retails for about $200 but I found it open box for about $150 on eBay, comes with a full warranty.

 

[Lt.Dan]

I changed chargers and used a 20 Amp charger from another system. When the charge is connected it shows 14.6v. But as soon as I disconnect the charger the voltage reads 13.15.

As soon as you connect it, there must be one cell hitting HVD, causing the battery to go open-cicuit, which shows the 14.6v. As soon as you remove the charger, it shows the real pack voltage of 13.2v.

From what I can see in online charts that seem low for a fully charged battery.
Any recommendations? Should it return to normal after several cycles of charging discharging?
Or, is this possibly defective?
From this chart here I was expecting 14.4

LifePo4 battery state of charge chart - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

www.bing.com

Thanks,
Mike

The cells are out of balance severely. I recommend like @Tomthumb62 Said, except hold it as high of a voltage as you can without HVD occurring. Then over time you slowly raise the voltage until you get to ~14v. This might take days or even weeks depending on the balancing current of the BMS.

 

[MikeRo55]

A fully charged 12v lifepo4 will read about 13.2v when settled at rest with no loads or charging for about 24 hours. Though it will often settle down to that voltage within an hour or so.

So your new lifepo4 is nearly fully charged. Why isn’t it at full capacity at 13.2v? Because that’s what you tend to get with a cheap battery…the cells are usually poorly balanced. Unless your battery has a Bluetooth BMS that you can read the individual cell voltages, then you can only guess that the cells are out of balance. Or you can cut open the top of the battery and test the cells manually, but that will ruin your plastic battery case.

What I’ve been told you can do to try to rectify this imbalance issue (I can almost guarantee this the problem because it’s so common) is to put a bench power supply on the battery at 13.8v and leave it there for 24 hours. Then remove the power supply, let the battery rest for at least a couple of hours (with no loads or other charging source) and measure the voltage again with your multimeter. If it’s gone up but not much (the max you’ll get is about 13.25-13.3v), then put it on the bench supply for another 24 hours. Keep repeating until it reaches and settles at 13.2v, then just use the battery for a while and see if the resting voltage of a fully charged battery (using your regular charger or solar charge controller) still hovers around 13.2v.

FYI, the Victron IP22 12/30 charger is an excellent one. It’s fully programmable and also has a bench power supply mode to use as I suggested above. Retails for about $200 but I found it open box for about $150 on eBay, comes with a full warranty.

Thanks for the good advice

 

[Starex]

13.15 is so close to 13.2 you should consider the possibility that it’s caused by a error in the meter you’re using to measure, temperature variations ( immediately after charging, the battery will be warmer than ambient), a bms that’s balancing circuits are very slow.
I’d quit trying to fix the problem by beating charge into it and just put it in service and check it after a few cycles.

 

[Starex]

What I’ve been told you can do to try to rectify this imbalance issue (I can almost guarantee this the problem because it’s so common) is to put a bench power supply on the battery at 13.8v and leave it there for 24 hours.

Never use a bench power supply on a full or nearly full lifepo4 battery, unless you want to use the battery as a heater.
That’s the absolute worst thing to do, especially if you suspect that there may be a bad bms in the battery.

 

[Lt.Dan]

Never use a bench power supply on a full or nearly full lifepo4 battery, unless you want to use the battery as a heater.
That’s the absolute worst thing to do, especially if you suspect that there may be a bad bms in the battery.

This is 100% false, I'm sorry.

We aren't suspecting a bad BMS because it is properly disconnecting at HVD.

And just my opinion, but 13.2v is NOT full charge. It's barely 3.3v (if they are all perfectly balanced, which this battery is clearly not). 13.6v is 99-100% charged at 3.4v per cell.

 

[Tomthumb62]

And just my opinion, but 13.2v is NOT full charge.

But I’ve been told that a resting lifepo4 will settle out at 13.2-13.3v after reaching 13.8-14.6v (or 3.45-3.65v per cell). My experience corroborates this, but I’m certainly still learning. Are you seeing higher than that, at rest for 24 hours, with no loads/charging?

 

[Lt.Dan]

But I’ve been told that a resting lifepo4 will settle out at 13.2-13.3v after reaching 13.8-14.6v (or 3.45-3.65v per cell). My experience corroborates this, but I’m certainly still learning. Are you seeing higher than that, at rest for 24 hours, with no loads/charging?

Mine have settled to 3.36-3.38v (13.4-13.5v) after several days, but I chalk that up to BMS draw or something. Even if 13.2v is the resting voltage after 24hrs, the OP is seeing that immediately after removing his charger. Its definitely not full.

 

[Tomthumb62]

Even if 13.2v is the resting voltage after 24hrs, the OP is seeing that immediately after removing his charger. Its definitely not full.

Ah I missed that part. Yeah I agree completely.

Severely unbalanced cells is the lottery game you play when you buy these ultra cheap lifepo4 batteries.

 

[McKravitts]

We aren't suspecting a bad BMS because it is properly disconnecting at HVD.

I didn't know that a single parameter (HVD) was all that is necessary to diagnose all functions of a BMS.
Please provide some refferences that support that idea.

 

[Starex]

This is 100% false, I'm sorry.

You’re advising someone to put a bench power supply on a battery with no high current disconnect?
A battery that you already decided is defective.
That’s 100 % dangerous!

 

[Lt.Dan]

I didn't know that a single parameter (HVD) was all that is necessary to diagnose all functions of a BMS.
Please provide some refferences that support that idea.

Well if HVD is working correctly, then the mosfets are operating as intended. What other functions do you need to verify in this instance?

Never use a bench power supply on a full or nearly full lifepo4 battery, unless you want to use the battery as a heater.

Pleae provide some refferences that supports that idea. When the voltage peaks and trips HVD, the BMS will turn off charging and prevent damage. Even if the BMS failed, its not like a lead acid where it will generate heat.

You’re advising someone to put a bench power supply on a battery with no high current disconnect?
A battery that you already decided is defective.
That’s 100 % dangerous!

Who said the battery doesn't have a high current disconnect? And what power supply does the average guy have that is going to trip a 100a or 200a BMS for high current????

Setting a power supply to 13.4v and it trickle milliamps into a battery over several days or weeks is not dangerous.

I never decided the battery was defective. Please post where I said that. I simply stated the battery is out of balance, and provided the instructions to the OP on how to fix that themselves.

Please provided references to support that it is dangerous.

Either way, I'm over this thread, if OP wants to deal with sending it back, then go ahead. I've tried ?‍

 

[McKravitts]

Well if HVD is working correctly, then the mosfets are operating as intended. What other functions do you need to verify in this instance?

How about the sensors, transistors, ic and the plethora of components that control the mosfets?

 

[Starex]

Well if HVD is working correctly, then the mosfets are operating as intended. What other functions do you need to verify in this.

Well if HVD is working correctly, then the mosfets are operating as intended. What other functions do you need to verify in this instance?

Pleae provide some refferences that supports that idea. When the voltage peaks and trips HVD, the BMS will turn off charging and prevent damage. Even if the BMS failed, its not like a lead acid where it will generate heat.



Who said the battery doesn't have a high current disconnect? And what power supply does the average guy have that is going to trip a 100a or 200a BMS for high current????

Setting a power supply to 13.4v and it trickle milliamps into a battery over several days or weeks is not dangerous.

I never decided the battery was defective. Please post where I said that. I simply stated the battery is out of balance, and provided the instructions to the OP on how to fix that themselves.

Please provided references to support that it is dangerous.

Either way, I'm over this thread, if OP wants to deal with sending it back, then go ahead. I've tried ?‍

Setting a power supply to 13.4v and it trickle milliamps into a battery over several days or weeks is not dangerous.

That’s a far more reasonable advice.

Please provided references to support that it is dangerous.

Contact any manufacturer or supplier and ask them what type of charger they recommend. Using a bench power supply will void the warranty in many cases.
Simply put, they don’t trust customers when it comes to safety.
They can’t be legally shipped without a caution label.
If you’re old enough you should remember the news articles about li batteries causing fires.
I agree that they are a lot safer now, but why take a chance.
Power queen has a 5 year warranty on batteries.

 

[McKravitts]

There is another confusing issue about full charge capacity.
What exactly does charged to full capacity mean?
End uses could care less about how much charge they can jam into a battery but how much usefull charge they can get out.
I've found that I only get full discharge capacity if I keep my batteries on a float charge of about 3.5 volts/cell.
If they sit idle for any substantial length of time that voltage drops and with it capacity.
I'd guess manufacturers spec battery capacity based on a battery that has been maintained with a float charge.

The cost of maintaining a float charge is small.
What''s a better buy?

A cheap$300.00 battery of 100AH capacity that'll give you say 5000 cycles but must be maintained with a float charge.

or a more expensive $400.00 battery of 100AH capacity that'll give you 5000 cycles and only has to be charge "toped off" every week.

 

[Tomthumb62]

A cheap$300.00 battery of 100AH capacity that'll give you say 5000 cycles but must be maintained with a float charge.

or a more expensive $400.00 battery of 100AH capacity that'll give you 5000 cycles and only has to be charge "toped off" every week.

No lifepo4 battery, cheap or not, should need to be on constant float charge or even topped off every week. They should hold most of their charge for a month to six months (or more), depending upon the power used by the BMS to maintain itself.

But you describe cheap vs expensive AGM batteries well.

 

[MikeRo55]

13.15 is so close to 13.2 you should consider the possibility that it’s caused by a error in the meter you’re using to measure, temperature variations ( immediately after charging, the battery will be warmer than ambient), a bms that’s balancing circuits are very slow.
I’d quit trying to fix the problem by beating charge into it and just put it in service and check it after a few cycles.

Thanks for the good advice, It is now at 13.35 and I am just going to build me solar charger system and start using it. I'll check it after a week or so of use.

 

[MikeRo55]

Ah I missed that part. Yeah I agree completely.

Severely unbalanced cells is the lottery game you play when you buy these ultra cheap lifepo4 batteries.

I bought this specific battery brand because Will Prowse recommended it. When you say buying these Cheap batteries, is there an expensive one that you would recommend is better?

 

[McKravitts]

No lifepo4 battery, cheap or not, should need to be on constant float charge or even topped off every week. They should hold most of their charge for a month to six months (or more), depending upon the power used by the BMS to maintain itself.

But you describe cheap vs expensive AGM batteries well.

I can't imagine how supplying a float voltage, if only to power the bms, could in any way damage a battery.

Perhaps there are great batteries that can hold full charge for 6 months without float voltage applied, but is the cost worth the convenience?