Which Charge profile is ok for LifePo4?

[Wapst]

Hi Everyone
I have a 12.8v 4s 190ah battery... well 2 390aH Lifepo4

120 overkill bms

3.2v nominal
3.65 max / 14.6v pack
190aH
1c discharge rating


the inverter i have has an AC transfer switch and charger built in.
it only has 4 fixed charging profiles, which are:

Battery Type and Voltage Setting (Bulk/Absorption/Float)​

Flooded: 14.4V / 14.4V / 13.5V​

GEL: 14.2V / 14.2V / 13.8V​

AGM: 14.3V / 14.3V / 13.4V​

Fixed: 13.5 Vdc fixed voltage​

Will's published profiles are:
12V LiFePO4 Battery w/ BMS:

• Absorption: 14.5V
• Float: 13.6V
• Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc)

Is the Flooded Profile OK or will that cause some type of issue? better option? There is also a Solar charge controller in the mix that is configurable,,

Thanks in advance!

 

[newbostonconst]

"Gel" looks best for a Lifepo4 battery with 4 cells. 14.2/4=3.55
You battery description is a little hard to read. Do you have a BMS?

I would double check the charger voltage with a good voltage meter.

I think "Flooded" is to high....there isn't must to gain going that high except a 100 percent chance of damaging a cell if they go out of balance.

 

[Wapst]

"Gel" looks best for a Lifepo4 battery with 4 cells. 14.2/4=3.55
You battery description is a little hard to read. Do you have a BMS?

Hi, Yes -- sorry wasnt more specific. it has the overkill BMS

 

[John Frum]

I would go with flooded as long as doesn't try to "equalize" your lifepo4 cells.
That would not be good for them.
14.6 volts is max charge voltage for lifepo4.

 

[Dhopewell]

Hi Everyone
I have a 12.8v 4s 190ah battery... well 2 390aH Lifepo4

120 overkill bms

3.2v nominal
3.65 max / 14.6v pack
190aH
1c discharge rating


the inverter i have has an AC transfer switch and charger built in.
it only has 4 fixed charging profiles, which are:

Battery Type and Voltage Setting (Bulk/Absorption/Float)​

Flooded: 14.4V / 14.4V / 13.5V​

GEL: 14.2V / 14.2V / 13.8V​

AGM: 14.3V / 14.3V / 13.4V​

Fixed: 13.5 Vdc fixed voltage​

Will's published profiles are:
12V LiFePO4 Battery w/ BMS:

• Absorption: 14.5V
• Float: 13.6V
• Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc)

Is the Flooded Profile OK or will that cause some type of issue? better option? There is also a Solar charge controller in the mix that is configurable,,

Thanks in advance!

There may not be a right answer but there is a “best for you” answer. Other than the too high 13.8 float those all look ok if you trust your bms, Its helpful to keep in mind that LifePo is very good at absorbing charge, even at low voltage differences. Fresh cells will probably reach >95% SOC during constant current phase, which means those profile voltages never kick in or if they do your bms triggers shortly thereafter and interrupts the charge process.

So the best approach is to try the profiles on a “realistic to you” charge cycle, then use the profile that does what you need at the lowest possible voltage. Unless you want to cycle your batteries all the way between 100%-0% to get every bit of capacity you may find you never need to go above 13.5v. Happy testing!

 

[Gazoo]

If I had to pick I would choose the AGM setting simply because it has the lowest float voltage. There isn't much capacity to be gained charging between 14.3 and 14.6 volts and I would be concerned about the 13.8 float voltage. However if you are cycling your batteries often then the float voltage isn't a big concern.

 

[newbostonconst]

If I had to pick I would choose the AGM setting simply because it has the lowest float voltage. There isn't much capacity to be gained charging between 14.3 and 14.6 volts and I would be concerned about the 13.8 float voltage. However if you are cycling your batteries often then the float voltage isn't a big concern.

Lifepo4 takes power and tops out in minutes once charged. The Gel setting has the lowest overall voltage. Float isn't really relative on a Lifepo4 battery. Voltage is the killer of the battery IMHO, don't supply them more then they need because they will spike quickly.

 

[John Frum]

Voltage is the killer of the battery IMHO, don't supply them more then they need because they will spike quickly.

Are you running a bms with a sensible high cell cutoff?
By sensible I mean ~3.7 volts.
If charging at 3.65 volts per cell or lower I would expect the charge fets to open within a second of the high cell reaching the cutoff voltage.
Further to that I would expect that the high cell would settle to a voltage within spec fairly quickly.
Probably faster than the balance function could bring it into spec.
Are you seeing something different?

 

[Deleted member 9967]

Hi Everyone
I have a 12.8v 4s 190ah battery... well 2 390aH Lifepo4

120 overkill bms

3.2v nominal
3.65 max / 14.6v pack
190aH
1c discharge rating


the inverter i have has an AC transfer switch and charger built in.
it only has 4 fixed charging profiles, which are:

Battery Type and Voltage Setting (Bulk/Absorption/Float)​

Flooded: 14.4V / 14.4V / 13.5V​

GEL: 14.2V / 14.2V / 13.8V​

AGM: 14.3V / 14.3V / 13.4V​

Fixed: 13.5 Vdc fixed voltage​

Will's published profiles are:
12V LiFePO4 Battery w/ BMS:

• Absorption: 14.5V
• Float: 13.6V
• Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc)

Is the Flooded Profile OK or will that cause some type of issue? better option? There is also a Solar charge controller in the mix that is configurable,,

Thanks in advance!

I have been trying to find this out for days now.
I am glad you asked and got different replies LOL.
Thanks for your thread.

 

[wlfpck1]

I am having a similar question. I have a DIY 12V 90ah battery (3.2V cells). Am wondering what the best Boost and Float charge voltages should be. Can someone describe the difference? Right now I have my Boost and Float voltage at 14.4V since that is what I understand full charge to be. I wouldn't want my charge controller to stop charging if the battery isn't full. Thanks!

 

[Deleted member 9967]

I am having a similar question. I have a DIY 12V 90ah battery (3.2V cells). Am wondering what the best Boost and Float charge voltages should be. Can someone describe the difference? Right now I have my Boost and Float voltage at 14.4V since that is what I understand full charge to be. I wouldn't want my charge controller to stop charging if the battery isn't full. Thanks!

Lifepo batteries don't do well being floated.
Unlike lead acid which loves to be floated.
Once at full charge, try to use the battery soon after. Like within 24 hours preferably.
Many of us only charge to 3.4 or 3.5 per cell.
Doing this also increases the life pan of the cells. Sometimes even doubling the life span.
So bet "float" would be 14 to 13.6 volts.
As for "boost". If you mean level of charge. Then lifepo can easily take 1C. Or in your case, 90 amps charge. So you could charge it in one hour. However it is better if you do a 0.5 C [45 amps] or even 0.2C [18 amps.

Hopefully this helps you out.

 

[Dzl]

Float isn't really relative with a Lifepo4 battery.

What makes you say this? Where have you read this?

 

[Alber C]

You need to find out your BMS configuration on charging part. But normally a 4S LiFePo4 will be 14.6v fully charged by each cell. And each cell is 3.65 volt. When you have a bms. it will manage the voltage. If single cell reached to 3.65. the battery will be fully charged. In this way, you 'd better use Flooded to charge it. don't worry about over charged. BMS will manage it.

 

[Download7]

Further to the conversation I'm leaning towards using the AGM setting on my inverter/charger instead of the LiFePo4 setting because of the lower voltages, does this sound like a good or bad idea?

 

[Deleted member 9967]

Further to the conversation I'm leaning towards using the AGM setting on my inverter/charger instead of the LiFePo4 setting because of the lower voltages, does this sound like a good or bad idea?








View attachment 31431

You have lifepo batteries? NEVER use lead acid settings.
AGM is for AGM. Gel is for gel. Lifepo is for lifepo. Heck, you shouldn't even mix lithium settings.
Lots of reasons for this. Google it for more info. But it is not safe or healthy for many reasons.

 

[Download7]

I have xuba 280ah LiFePo4 cells. Further up in this thread there is talk about using AGM settings for the lower voltages and now you're saying it's crazy, what's changed?

 

[Download7]

I copied this from RELiON LITHIUM IRON PHOSPHATE (LiFePO4) BATTERIES charging PDF

"Charging Source: Lead-Acid Battery Chargers
Most lead-acid battery chargers can be used with LiFePO4 batteries as long as they are within the appropriate voltage guidelines.
AGM and Gel algorithms typically fall within the LiFePO4 voltage requirements. The voltage for flooded battery charging algorithms
are often higher than LiFePO4 requirements, which will result in the BMS disconnecting the battery at the end of the charge cycle
and possibly result in the charger displaying an error code. If this happens, it is generally a good practice to replace your charger for
one with a LiFePO4 charge profile. Since the BMS protects the battery, using lead-acid chargers will typically not damage the battery"


I have those smart BMSs from AliExpress with the Bluetooth adapter. I'm thinking it will be fine to use the AGM settings on my charger for the lower voltages and I was just wondering what other people's opinions were before I wrecked something...

 

[Gazoo]

I have xuba 280ah LiFePo4 cells. Further up in this thread there is talk about using AGM settings for the lower voltages and now you're saying it's crazy, what's changed?

Nothing. You will be fine using any of the AGM settings. You can experiment with GEL USA and the A.G.M settings to see which one you like better. It depends on your usage and how often you will be cycling the cells.

 

[Deleted member 9967]

I have xuba 280ah LiFePo4 cells. Further up in this thread there is talk about using AGM settings for the lower voltages and now you're saying it's crazy, what's changed?

I have tried it and yes it works. But as I paid almost $1200 for my batteries I would rather not have taken the risk is all. It is simply not worth destroying my batteries.
But hey, if you have money to throw away then go for it.
The ONLY other suggestion I would have is that if you have OCD as I do then you won't mind checking them every 5 minutes to make sure they do not do a runaway on you is all.
But there is a reason for the settings. Otherwise they would never had made them.
Just my thoughts on this.

 

[Gazoo]

I have those smart BMSs from AliExpress with the Bluetooth adapter. I'm thinking it will be fine to use the AGM settings on my charger for the lower voltages and I was just wondering what other people's opinions were before I wrecked something...

I don't recall if you had parallel top balanced your cells. If you did the inverter/charger should cut off charge before the BMS does. In other words there should be no runners at the top. My Delta at the top is less than 100mv's when fully charged. That will change some as I am using low C rates.

When discharging I have a slightly weak cell. So my delta is .5 volts. When the BMS cuts off my lowest cell is 2.5 volts and my highest is 3 volts. So if using an inverter charger my LVD would have to be set slightly above 23 volts since I have an 8S battery, and that is the voltage of my pack when the BMS cuts off. I have not found any inverter/chargers that have that high of a LVD except programmable ones like Samlex.

There has been a lot of talk about keeping the cells between the knees. The sweet spot of my pack is between 25.35 and 27.25. That gives me apx. 250ah's of usable capacity. Since my use is for emergency back up power, which means long storage, my usable capacity will actually be less.