Battery SOC minimum %

Diabolix said:
Mine is set to 40%, two Hubble AM5's.
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i have mine at 35 for now, want them to work a bit after the firmware update, they been reporting in very weird to solar-assist , in a few weeks i'll put them back to 40%
 
chrisc said:
60%. During the past 12 months, it has never fallen below 62%

As a result, a battery which is now 3 years old has completed 219 cycles so should last a long time

12 x 550 watt panels
4 x 5100 wH batteries
7.2 kWh inverter

Incoming AC is switched off from September to April
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You're right, at the rate you're going, it will take 83 years to get to 6000 cycles and then still have 80% capacity left.
 
I'm curious.
Given the timelines and degradation of normal use, will it be worth it if you stop at 30-40% vs 10% or even 5%?
In 10/15 years time, will capacity and technology and cost not have improved?
And are you leaving e.g 30/20/10% of use on the table and paying Eskom for it?
 
kolaval said:
I'm curious.
Given the timelines and degradation of normal use, will it be worth it if you stop at 30-40% vs 10% or even 5%?
In 10/15 years time, will capacity and technology and cost not have improved?
And are you leaving e.g 30/20/10% of use on the table and paying Eskom for it?
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No it makes fokkal difference. Use all the battery that you paid for. The manufacturer cycle count tests go to 0% and its still 6000 cycles to 80% SOH.
 
wingnut771 said:
No it makes fokkal difference. Use all the battery that you paid for. The manufacturer cycle count tests go to 0% and its still 6000 cycles to 80% SOH.
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Any facts to back this up?

You are saying a battery that depletes to 0% vs one that depletes to 80% will last just as long and it will make fokkal difference.

Sure buddy
 
Enzo Matrix said:
Any facts to back this up?

You are saying a battery that depletes to 0% vs one that depletes to 80% will last just as long and it will make fokkal difference.

Sure buddy
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As mentioned earlier, calendar aging is a thing so will most likely still have 80% SOH after 15 years even if you don't use your battery at all.

Why dont you have a look at one of the cell manufacturers spec sheet?
 
20% for me - BMS cutoff is 15% but i can extend it if i switch to voltage mode
 
I think the data for the battery cycles will depend on your BMS. On mine it does not show up anywhere. With Victron you can pull some reports and there is one called VRM Dynamic ESS report. It can only do about 3 month periods per report. On this report it shows battery cycles but I suspect it's a calculated figure rather than a reading from the BMS.

Below is a sample of a 92 day period.

1766070626750.png

1766070666622.png
 
A cycle test for a 3.2V 100Ah LiFePO4 cell evaluates its longevity and capacity retention over hundreds or thousands of charge-discharge repetitions. The test typically follows industry standards (e.g., IEC 62619 or UN38.3) to determine when a battery reaches its "End of Life," usually defined as the point where capacity drops to 80% of its original rating.
1. Standard Cycle Procedure
A single cycle in a laboratory test generally consists of four sequential phases:
  • Constant Current (CC) Charge: The cell is charged at a standard rate, typically 0.5C (50A), until it reaches the upper cut-off voltage of 3.65V.
  • Constant Voltage (CV) Charge: The voltage is held at 3.65V while the current gradually tapers down. Charging stops once the current falls to a minimum threshold (e.g., 0.02C or 2A).
  • Rest Period: The cell sits idle for 10 to 60 minutes to allow chemical and thermal stabilization before discharging.
  • Discharge: The cell is discharged at a constant rate (e.g., 0.5C or 1C) until it reaches the lower cut-off voltage, typically 2.5V for a full 100% Depth of Discharge (DoD) test.
 
kolaval said:
I'm curious.
Given the timelines and degradation of normal use, will it be worth it if you stop at 30-40% vs 10% or even 5%?
In 10/15 years time, will capacity and technology and cost not have improved?
And are you leaving e.g 30/20/10% of use on the table and paying Eskom for it?
Click to expand...

I don’t understand the logic.

You bought the thing to do a job so use it to its full capacity and get the most out of your investment.

Wasting 40+% of battery every day to make it last 5% longer makes zero sense.
 
How hard you run your batteries also makes fokkal difference to the capacity:
1766072452674.png
 
SauRoNZA said:
If anything I would think the 25-degrees is the most important part.

Pretty sure mine being in the garage and running quite hot in summer isn’t great for them.
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Indeed. Its all about 25c. Install an aircon.
 
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