Lost in the lifepo4 woods

[DDale]

Hi all.
I just switched from lead acid batteries to lifepo4, 2x 280ah in parallel, ooycyoo 60a charge controler and im having problems. Controller set at 13.4 charge (full) and on li setting for lifepo4 and at 12v
The controller shows to get the batterys to 80 - 100% but then it just drops, at 20% i shut it down.
While at about 100% i turned the new inverter on and tryed it out for about 3 minutes to make sure it works.
The batt. Volts dropped to about 50% (3 min @500 watts).
With nothing on but the charge controler i let it charge back up to around 80%
Within about an hour with the c controller still going it dropped to 20%. so at this point i don't know if it's the batterys or charge controler or both :-(
Any help would be much appreciated

 

[ScrotusGobbleBottom]

2x 280ah in parallel

What does this mean? Are you using DIY Eve 280k cells or something similar?

 

[ScrotusGobbleBottom]

Do they look like this?

 

[yabert]

The batt. Volts dropped to about 50% (3 min @500 watts).

Look at discharge curve comparison between lead and lifepo4
With lifepo4 cells, the voltage can be hard to link to SOC.

 

[DDale]

No. Im useing ecoworthy 280 amp batteries, 2 in parallel

 

[DDale]

What does this mean? Are you using DIY Eve 280k cells or something similar?

Im having enough problems with 2 batteries.lol no way i want to try building them

 

[Andrewr05]

No. Im useing ecoworthy 280 amp batteries, 2 in parallel

You should always start any threat that you create with as much information as you possibly can.

I would rather be thought of as a nerd who overshares information then be stuck in a situation where you might not be providing enough information from the get-go.

 

[740GLE]

How long have you ever let the charger bring the batteries up to full charge?

At 13.4v the charger should feed full tilt for hours on end until it tapers off. That’s only 3.35v per cell, it needs a longer time at that voltage with little current to bring up to full.

Who recommended that lifepo charger?

 

[Rednecktek]

Controller set at 13.4 charge (full) and on li setting for lifepo4 and at 12v

That's too low to charge LFP batteries full, set it to 14.4v if you can.

The other thing to know about the SOC % on your controller is that it's based on voltage of the battery. That works great for lead acids, but because the curve on LFP is so flat, the difference between 100% full and 20% full is about half a volt. You'll need a proper shunt involved to know exactly how much you have in your batteries.

Because of the combination of the low voltage charging and the SOC meter being voltage based, and the battery's natural reserve capacity, you're probably only getting maybe 30% of your battery capacity at best.

 

[ScrotusGobbleBottom]

Im having enough problems with 2 batteries.lol no way i want to try building them

I was hoping that you werent charging 2 )3.2v batteries with 13V.
I figured that was a good place to start

 

[ScrotusGobbleBottom]

As others have mentioned, Getting the state of charge or SOC percentage from a charge controller or inverter that only sees the voltage of your battery is NEVER going to be accurate with LifePo4. The discharge cure is so flat that it would be impossible.
Also, previous poster was right. Charge to 14 - 14.4.

Somehow tho, I do not think this is the end of the story.

 

[740GLE]

Also what is the PV panels feeding the SCC?

700w-1000w of PV?

Have you seen a consistent 60amps from the SCC?

 

[DDale]

Update: im still having the same problem with these ecoworthy 12v 280ah batteries (2 in parallel) ive charged them with solar & 20 amp batterie charger, the problem is im not seeing hardly any run time from them. My setup is (all new) except the solar panels which I've been looking for replacements for (2x 12v 280ah ecoworthy batteries, renogy 3000 watt inverter, ooycyoo 60amp mppt charge controler) with 5' eh hot / ground 0/1 copper wire from batteries to inverter, with appropriate buss bars & breakers + copper lugs.
I've had the batterys up to full ( the ecoworthy company recommends 13.46 volts = full, with everything turned off i checked the voltage after a few hrs - it only dropped a little....to 90% if that's a little. So i ran a 10watt light, a 25watt tv & 5 watt ph charger through the inverter... (Intermediately) The batteries dropped from around 90% to 30% in maybe 5 hours.
I got way better service out of my smaller lead acid batteries.
Next im going to use only 1 battery at a time and see what that does.
At this point i wish id staying with lead acid

 

[Rednecktek]

A couple thoughts:

So i ran a 10watt light, a 25watt tv & 5 watt ph charger through the inverter... (Intermediately) The batteries dropped from around 90% to 30% in maybe 5 hours.

Where are you getting the 30% number from? If you're using anything but a shunt it's being based on the voltages which are worthless for LFP batteries because the charge curve is so flat. I.E. 14v is 100% but 13.6v is pretty dead.

I've had the batterys up to full ( the ecoworthy company recommends 13.46 volts = full, with everything turned off i checked the voltage after a few hrs -

If you're only getting to 13.5v you're just beginning the charging. That's only 3.37v per cell that aren't fully topped out until 3.6v. In short, your battery isn't being fully charged so you're measuring from a dead-ish battery.

20 amp batterie charger,

OK, considering a 20a charger for LFP, and 560Ah of capacity, that's going to be at least 28 hours to fully charge those batteries. Pre-built batteries have a long history of having unbalanced cells and BMS's that only balance while the battery is actually charging, so throw the batteries on the charger and just leave them there for a few days to get them really topped up AND give the BMS's a chance to spend some quality time balancing. At least 72 hours if possible, THEN let them sit a couple hours and re-test them.

When you test them, don't go off the reading from the SCC or BMS reading. The SCC is lying because it thinks everything is lead acid and the BMS (if you have bluetooth access to it) will need a few full cycles to figure out what it's doing. Get a shunt involved (the Aili's are a good cost effective option if you don't want to spring for a $$Victron$$) or a Kill-A-Watt on the inverter and run your loads until the inverter trips out on low voltage. That's going to give you a FAR more accurate read on what your system can provide.