Did I get two bad chins?

[Blakes]

TLDR; new chins 200ah in parallel after a couple of partly sunny days have charged from 13.1v to 13.2v.

Ok so I got a couple of new chins 200ah batteries from Amazon a couple of days ago. They were both at 13.1v out of the box. I have a new renogy rover 60amp CC and set the user settings to what the chins manual said. The CC charged my old optima agm batteries just fine for a couple of days.

I have five 100w renogy mono panels that are in series and worked fine for years.

The last couple of days have been partly cloudy with only 3-4 hours of full sun.

No load on the batteries other than the CC and cheap Amazon 12v meter.

Would this be "normal" for these batteries to have only increased .1v in two partly cloudy days of charging? The CC showed 300w charge for maybe 3-4 hours each day then ~ 100w ish.

 

[sunshine_eggo]

@ 13.1V, they're likely around 30-40% SoC.

You need to put 3,584Wh into them. I'm seeing that you put about 900-1200Wh/day, so you're about 1/2 to 2/3 of the way there.

LFP voltage curve is very very flat. 13.2V is about 70%-80%.. a 0.1V change for ~40% increase in SoC. You're also charging at a low C rate.

Sounds like you need another 1-2 days of ~300W of charging.

 

[Blakes]

@ 13.1V, they're likely around 30-40% SoC.

You need to put 3,584Wh into them. I'm seeing that you put about 900-1200Wh/day, so you're about 1/2 to 2/3 of the way there.

LFP voltage curve is very very flat. 13.2V is about 70%-80%.. a 0.1V change for ~40% increase in SoC. You're also charging at a low C rate.

Sounds like you need another 1-2 days of ~300W of charging.

Thanks

Thats kinda what I was thinking.

I have never had lithium batteries before.

I simply have not had time to 'deep dive' into this forum as I've been too busy with life and building my offgrid log cabin that I live in.

 

[Tulex]

Couldn't help but think the title sounded like the start of a bad joke.
"Peter Griffin and Demi Lovato walk into a bar...."

 

[Horsefly]

Couldn't help but think the title sounded like the start of a bad joke.
"Peter Griffin and Demi Lovato walk into a bar...."

Yeah, my first thought was that the title was worded badly. Two bad chins would be better called a bad double chin. ?

 

[Blakes]

Update

So after a few days The two 12v 200ah chins batteries finally reached float. My renogy app actually said float and the voltage was at 13.8.

I put a ~300W load on the inverter and in 30 minutes the volts dropped to 13.1v. The CC started charging immediately after the load was placed on the inverter. I powered off the inverter and the batteries showed 13.2v

Is that normal?

According to the chins manual, the batteries are at like 40% SOC.

Pic of the manual.

 

[sunshine_eggo]

Those numbers are pretty atypical, and they're for charging/discharging, not resting. Most go by these for resting:



Can you reach 14.4V without triggering BMS charge cut-off?

 

[Blakes]

Those numbers are pretty atypical, and they're for charging/discharging, not resting. Most go by these for resting:

View attachment 153065

Can you reach 14.4V without triggering BMS charge cut-off?

I have the boost voltage set in the renogy app at 14.4v.

We had some decent sun today and the CC actually stopped charging. These batteries don't have BT, so I can't see the BMS.

I decided to reapply the 300w load and now it's down to 13.0v. This is while the CC is charging at like 50w due to little sun.

 

[Blakes]

So after reading a lot on here..
I did get two bad chins.

I'm gonna drain them all the way, charge up one more time and see what happens....

 

[Blakes]

I happened to receive the chins 4amp charger yesterday evening.

I discharged the batteries down to 12.9v, then ran my generator all night. They were at 14.6v this morning when I woke up.

Applied a ~1000w load to them and within 10 minutes the are currently at 13.0v.

I'm planning to keep the ~1000w load on them until the BMS shuts them down.

Is any if this correct or normal guys? These are my first LifeP04 batteries.

 

[meetyg]

I happened to receive the chins 4amp charger yesterday evening.

I discharged the batteries down to 12.9v, then ran my generator all night. They were at 14.6v this morning when I woke up.

Applied a ~1000w load to them and within 10 minutes the are currently at 13.0v.

I'm planning to keep the ~1000w load on them until the BMS shuts them down.

Is any if this correct or normal guys? These are my first LifeP04 batteries.

Disregard the voltage when load is applied. 13v sounds pretty good to me. You need to remember that Lifepo4 has a fairly flat discharge curve for around 80% of its capacity. So they might be at 13 or so volts for most of the discharge.

 

[TacomaJoe]

I don't like voltage readings when it comes to battery SOC. Even their chart has three different SOC numbers for the same voltage.

You have 400Ah capacity in parallel. That means it will take 100 hours for the 4A charger to get them charged. Your solar, with good sun, will be two days. If they are fully charged, your 1000W load should run about 5 hours.

I really like a shunt meter. It will tell you exactly how much is going in or coming out, and let you know the SOC.

 

[Grimmster]

+1 on using a shunt. The curve of a LiFePO4 is just too extreme on the ends and flat in the middle to really tell anything about SOC other than you're about > 90% or < 20%.

The chart in the Chins manual doesn't seem very accurate either. I just got a CHINS 12V 100A, it arrived at just under 13.2V, which according to the manual should mean about 20% but when I charged it it only took 42Ah in, which more closely fits this chart:

 

[Grimmster]

I happened to receive the chins 4amp charger yesterday evening.

I discharged the batteries down to 12.9v, then ran my generator all night. They were at 14.6v this morning when I woke up.

Applied a ~1000w load to them and within 10 minutes the are currently at 13.0v.

I'm planning to keep the ~1000w load on them until the BMS shuts them down.

Is any if this correct or normal guys? These are my first LifeP04 batteries.

Isn't 14.6V a bit high if they are at rest? How long had they been off the charger when you measured 14.6?

13V with the load, right? V will typically drop 0.5-0.7 under load.

 

[Blakes]

Isn't 14.6V a bit high if they are at rest? How long had they been off the charger when you measured 14.6?

13V with the load, right? V will typically drop 0.5-0.7 under load.

I think when I measured 14.6v it was still on the 4amp chins charger.

These are on my secondary array which is just topping off my primary array to keep the AGMs happier.

I've been running them at night. Seems that under a ~500w load they will sit at 13.0 volts for at least 5 hours.

I think they may actually be ok, but the voltage numbers chins puts in the manual are just flat wrong....

 

[Tomthumb62]

Seems that under a ~500w load they will sit at 13.0 volts for at least 5 hours.

You cannot measure any meaningful voltage reading of lithium while under load. Ignore the number.

To get a meaningful number, remove all loads and charging sources, wait a few hours and then measure voltage.

 

[Blakes]

You cannot measure any meaningful voltage reading of lithium while under load. Ignore the number.

To get a meaningful number, remove all loads and charging sources, wait a few hours and then measure voltage.

Yup

Right now the sun has basically set and neither array is making any power.

Cheap Amazon volt meter shows 13.6v on the chins.

My 8 renogy 200ah AGMs are reading 50.6v in a 4S2P config.

I'm about to flip the switch and drain these chins until the BMS cuts them off...

 

[Blakes]

They immediately went from 13.6v to 13.0v under 500w load.

 

[Skypower]

Get a good coulomb meter. Voltage is only a rough estimate and primary only reasonable close at rest. Victon shunt is very good but there are others good enough;
Charge-Discharge Multi Tester, DROK 0-120V 400A DC Voltmeter Coulometer, Battery Monitor with LCD Screen, Measuring Volt Amp Temp Power Capacity Timing Monitor for RV, Boat, E-Bike https://a.co/d/dTjdOm8

 

[Blakes]

Get a good coulomb meter. Voltage is only a rough estimate and primary only reasonable close at rest. Victon shunt is very good but there are others good enough;
Charge-Discharge Multi Tester, DROK 0-120V 400A DC Voltmeter Coulometer, Battery Monitor with LCD Screen, Measuring Volt Amp Temp Power Capacity Timing Monitor for RV, Boat, E-Bike https://a.co/d/dTjdOm8

Ya, I need to look into this.

I live 100% offgrid for the past 6 years and love messing with this stuff.