Is My Battery Toast?

[rykelo]

Hi Everyone,

I bought a "160ah" Lithium battery that has been underwhelming in terms of performance, and I'm wondering all of your thoughts on how I should proceed.

Throughout the summer, the battery was just able to make it through the night, but it couldn't handle the load put on it by my trailer (running a refrigerator and LED lights) for more than one consecutive cloudy day.

Even after several days straight of sun, the battery would never hold more than 80% charge (by 3pm), and it always dropped to 60% going into the night (by 8pm same day).

Now that the battery is disconnected from all loads for the season, I thought I'd see how it's holding charge, and I was able to get it to 80% charging in utility mode. I disconnected utility power and left the Growatt inverter powered on, and the charge dropped to 50% by the next day.

I think by battery is a dud. Does anyone have ideas on where to buy a replacement? I've heard on Ali Express you can get 100ah for $300, though I haven't found anything like that in my searches. Nor would I know how to properly configure the battery to work with my 24v Growatt.

Any ideas would be appreciated!

Thanks,

Ryan

 

[Goboatingnow]

Does your BMS show cell balance status. ?

 

[Supervstech]

What are the charge settings in your controller?

 

[Supervstech]

How many watts of solar do you have?

 

[rykelo]

Does your BMS show cell balance status. ?

No

 

[rykelo]

How many watts of solar do you have?

440W X 3 in parallel. The Growatt often throws a high bus voltage error on sunny days, even after adding a switch to remove 1 of the panels from the array on sunny days (but I use all 3 on cloudy/overcast).

 

[100 Proof]

How are you measuring State-of-Charge?

 

[rykelo]

What are the charge settings in your controller?

Charge and Floating voltage are both set to 28.4V.

 

[Goboatingnow]

No

It could be you have gross imbalance a bms should should cell values.

 

[rykelo]

How are you measuring State-of-Charge?

The Growatt shows battery voltage while it's powered on.

 

[100 Proof]

Charge and Floating voltage are both set to 28.4V.

If you are floating your battery at 28.4V, you may have damaged it by overcharging it.

 

[Goboatingnow]

If you are floating your battery at 28.4V, you may have damaged it by overcharging it.

If you have a 24 v system are you wiring 2x12 batteries in series. Cell imbalance is worse in series strings.

 

[Supervstech]

I would lower the float to 27.6V
Ok to keep absorb at 28.4, however some out of balance cells can still trigger overvoltage.
The overvoltage likely is due to the bms limiting charging.
You need a larger bank, or additional load to keep the battery from

 

[lexio]

you have 160 a = 1920 watt

growat 45*24 = 1080 watt
ad fridge 700 watt a day
led 50 watt

 

[MisterSandals]

Now that the battery is disconnected from all loads for the season, I thought I'd see how it's holding charge, and I was able to get it to 80% charging in utility mode. I disconnected utility power and left the Growatt inverter powered on, and the charge dropped to 50% by the next day.

How did you figure that is was 80% charged? By voltage from the inverter while under load?
What is the idle draw from the Growatt?
How much power does your refrigerator and LED lights use "by the next day"?

I suspect you might be reading too much into surface charge, assuming that 28.4V is 100%. The surface charge may be less than 1% of total capacity and you could still be virtually at 100% when voltage is around 27V-27.5V.

 

[MisterSandals]

you have 160 a = 1920 watt

growat 45*24 = 1080 watt
ad fridge 700 watt a day
led 50 watt

160A x 24V = 3840Wh (watt hours)

45W? x 24h = 1080Wh
700Wh (per day)
LED 50Wh? per day? As in 5W x 10h?

If so, 1080Wh + 700Wh + 50Wh = 1830Wh

1830Wh / 3840Wh = 47% used which sounds like the 50% you are seeing.

 

[lexio]

- 10 % what you will not use stay between 3.0v and 3.50v
and -10 % snobbler effect

what i say is that those all in one units use a lot of energie

Idle 'no load' Consumption: Specs vs Your Personal Observation

In this thread, I hope to consolidate personal observations/measurements on inverter standby consumption. Specifically whether your observations are inline with what is stated on the datasheet, along with anything else you consider relevant, interesting, good or bad. With time--if this thread...

diysolarforum.com

so what you need to do is make a energie audit buy your self a shunt and then you will know more

 

[MisterSandals]

snobbler effect

I think something might be off in the translation to english:

Snobbler - Urban Dictionary​

https://www.urbandictionary.com › define › term=Snob...
Someone who snores and slobbers simultaneously while sleeping. I would let my dog in at nights but he is a snobbler.

 

[Supervstech]

If you are floating your battery at 28.4V, you may have damaged it by overcharging it.

Unlikely to damage the cells, but the bms could fail from frequent high voltage disconnect.
A cell can reach 100%SOC at 3.4V, but it can safely reach 3.65 without damage.
If the bms is working, 28.4 shouldn't hurt the cells.

 

[lexio]

I think something might be off in the translation to english:

Snobbler - Urban Dictionary​

https://www.urbandictionary.com › define › term=Snob...
Someone who snores and slobbers simultaneously while sleeping. I would let my dog in at nights but he is a snobbler.

snoobler

diysolarforum.com

sorry you are right