Battery Discharge Cycles

[Mark]

Good Day, I want to make sure if my calculations are correct. I added a Dyness PowerBlock Max 16kWh battery to the database. Please just check if my Discharge Cycles are correct below:

[hotline_oh]

Dear Mark,

Thank you for your inquiry.

Since you cannot enter 8,000 cycles at 70% EOL (DoD), enter 10,000 cycles at 60% EOL (DoD) (and have the remaining values calculated).

[Mark]

When I try to change the value at 60% DOD to 10000 and do the Calculate cycles then that value just returns back to the values that it was. Nothing changes.

Also please give me the formula to determine a batteries DOD at 60% from the datasheet.

[Mark]

Any feedback on my post?

[hotline_oh]

Dear Mark,

We apologise: for lithium iron phosphate batteries, the reference value used to calculate discharge cycles is not a DoD of 60% (as with lead-acid batteries), but a DoD of 40%.

You can simply enter these four values manually:

We are still awaiting feedback from our development department regarding the formula.

[Mark]

Thanks, please share with me as soon as you get that formula.

[Mark]

Any feedback yet on the formula?

[hotline_oh]

Dear Mark,

Thank you for your message.

For lithium iron phosphate batteries, the reference value used to calculate discharge cycles is based on a DoD of 40%. This results in the following factors for the discharge cycles:

DoD	Value
0.2	2.206563
0.4	1
0.6	0.598166
0.8	0.397315

[Mark]

Good Day, my question was actually, what the formula is to calculate the battery DOD at 40%. As per below, it does not reflect what you are getting.

 

[Mark]

Any feedback yet on my question above?

[hotline_oh]

Dear Mark,

Thank you for your message.

The formula is correct, but the exponent (0.55) is not a standard constant; it varies depending on the battery type and even within a single battery type. PV*SOL Premium uses a value of 1.3278; this value models lithium iron phosphate batteries with sufficient accuracy. Unfortunately, we are unable to model higher accuracy (using variable exponents).