Poor solar performance

[upnorthandpersonal]

Results of actual cycle tests on LiFePO4 (Winston 40Ah cell):
https://agronomy.emu.ee/wp-content/uploads/2017/05/Vol15SP1_Papezova.pdf

"Two tests with 1,000 and 1,400 discharge cycles were performed at two four-cell batteries of the type WB-LYP40AHA Winston Battery during one-year period of time. The lifetime of the first battery with 100% DOD relative to 80% of the nominal capacity of the worst cell was set to 950 cycles. The lifetime of the second battery with a DOD of 50% relative to 80% of the nominal capacity of the worst cell was calculated on 3800 cycles according to the measurement results."

 

[Ryang]

View attachment 10457

Its actually 3.25 nominal, 3.65 full. Try doing user setting and match mine. Set limits at 14.7v if it lets you, if not 14.8v.

Thanks Ped.

Yes that’s the defualt LI profile. I just assumed it was correct. When in LI mode there Re only 3 things you can set.

I’ve gone to user and set the parameters manually. It has straight away changed the battery monitor to numbers which look a lot more correct.

Thanks!

I guess tomorrow, in some sun, will be a better judge.

 

[Ryang]

Could also be the battery is shagged. I will get the monitor installed tomorrow even if it’s not at length and mounted correctly.

 

[Ped]

Results of actual cycle tests on LiFePO4 (Winston 40Ah cell):
https://agronomy.emu.ee/wp-content/uploads/2017/05/Vol15SP1_Papezova.pdf

"Two tests with 1,000 and 1,400 discharge cycles were performed at two four-cell batteries of the type WB-LYP40AHA Winston Battery during one-year period of time. The lifetime of the first battery with 100% DOD relative to 80% of the nominal capacity of the worst cell was set to 950 cycles. The lifetime of the second battery with a DOD of 50% relative to 80% of the nominal capacity of the worst cell was calculated on 3800 cycles according to the measurement results."

Thats 100% dod though. Not simply charging to 100%. Theres broad agreement not to discharge to 0%. And that doing so is detrimental to cycle life.

Could also be the battery is shagged. I will get the monitor installed tomorrow even if it’s not at length and mounted correctly.

I didnt want to say it...lets hope not.

If it makes you more confortable drop my figures by .1-.2v

 

[Ryang]

Okay well the battery monitor is in and setup and now the results are .

bad news. The battery is shagged. It lasted for 74amps only. Didn’t get through the night. It was fully charged and set at 120amp, battery is at 11v and apparently has 46amp left...



so the question is, what now. Should I open the box and try to balance the cells and see if they come good?

I am also going to swap out battery 2 and see how it goes.

 

[Ped]

Yes if you were never getting to 14.6v the cells were never balancing. I thought you had 2x 120ah? What brand of battery and BMS specs? Top voltage might depend on that.


Charge them to 14.6v (or top spec) and hold that for several hours. The resistance goes up at very end so the current will drop to zero.

Did solar production change at all?

 

[Ryang]

I took out acbattery to test them 1 by 1. I’ll swap that back in at some point.

very overcast cloudy rainy day so I can’t really comment on the solar.

this is how noob I was, brought 2x120 off eBay for a steal, chucked them in as they said a straight replacement for agm. Suspect they aren’t able to be wired in series.

So the plan is to pull out the cells and create a single battery with 1 bms using the 8 cells.

problem is with corona virus we are livingoff the grid now so it’s very hard to play with your power as it’s very vital