My build thread

[Zwy]

That delta isn't a runner, it's a stragler.
Average cell voltage in the battery is 3.519v and the stragler is at 3.348v

I have one like that. Eventually it will balance but takes time. Last winter when I ran down between 5% and 20% for extended periods, it did the same on first recharge cycles at the top. Delta isn't as bad as that, top cells were at 3.50V while the stragler sat at 3.39V.

 

[timselectric]

It's still stuck at 3.342v
This is what it always does. It'll be stuck for a while and then all of a sudden it will take off and balance.
I actually thought that it was something in the BMS, last year. But I switched the cell to a different position and the issue moved with it. So it's definitely the cell. But I can't even guess what is going on with it.
I'll probably replace it one day. When my OCD can't take it anymore. lol

 

[OffGridForGood]

HA !
My OCD is worse than your OCD !
My crappy cell has been bothering me for a few years, and finally I ordered some extra cells to deal with it...watch the problem just move to a slightly less crappy cell and continue to Torment me !! Aghhhhhhhhhhhhhhhhh

 

[ksmithaz1]

Correction, I see tonight we only used 134 Kwh from grid in December, the 404 Kwh was in the column to the left in SA and is Battery Discharge for the month.


With the correct grid usage for the year of 152 Kwh, the cost would be $300/year for meter charge and $27 for the Kwh used comes to $327 per year. That makes the cost of grid power $2.15/Kwh.

Those are high priced Kwh.

Don't worry, you'll never need the grid, until you disconnect it, and TSHTF. -- Murphy

 

[OffGridForGood]

...and $300 per year is cheap back up system...no maintenance required

 

[Madcodger]

What is this "grid" of which you people speak? Blasphemy!

 

[JJJJ]

What is this "grid" of which you people speak? Blasphemy!

LOL. Yet a number of us need to deal with another four letter word. Snow

 

[Zwy]

Don't worry, you'll never need the grid, until you disconnect it, and TSHTF. -- Murphy

If TSHTF occurs, grid probably would be down anyway.

Some look at life as a glass half empty, some look at it as half full.

 

[Zwy]

...and $300 per year is cheap back up system...no maintenance required

It won't get cheaper as time goes by, the recent rate increases combined with increasing meter charges show the utilities will continue to increase rates and fees.

My utility can't increase the price per Kwh for 5 years now as part of the agreement with the state utility board. They can however add other fees such as the renewable energy fee per Kwh used and increase fees already in place. Those are the unknowns.

Using the thought of "and $300 per year is cheap back up system" then why install any solar? After all, the cost per Kwh from grid increases for every Kwh produced from your personal solar system. This is why we see meter charges keep increasing, it reduces the incentive for load reduction and using solar or wind on the personal level.

As for my shop, the cost of any solar system is 100% deductible using depreciation. Thus any power not purchased from grid is free energy. On that same subject though, the cost of utilities is also 100% deductible. Is it a wash or is it more profit? It depends on the timeline. But if I do fully retire (highly doubtful) then I guess I'd have free electrical power for my own use.

 

[JJJJ]

During a recent power outage having access to an alternative source of power brought a smile to my wife’s face.

Worth every penny!

 

[OffGridForGood]

Using the thought of "and $300 per year is cheap back up system" then why install any solar?

What would be the back up system to the grid if you have no solar no batteries no inverters? Then you are just dependent on the grid - vunerable.
Using the grid as the back up adds one more layer to the alternatives available:
PV
Battery
Grid
Prime Generator - wired into the sytem
Dual fuel supply storage
Secondary Generator - Generator plug wired, tested and ready.
EV V2L

For this area the grid is lower cost per kWh then the generators. If that ever changes, then the grid can be last instead of in the middle of the back-up systems.

 

[Zwy]

What would be the back up system to the grid if you have no solar no batteries no inverters? Then you are just dependent on the grid - vunerable.
Using the grid as the back up adds one more layer to the alternatives available:
PV
Battery
Grid
Prime Generator - wired into the sytem
Dual fuel supply storage
Secondary Generator - Generator plug wired, tested and ready.
EV V2L

For this area the grid is lower cost per kWh then the generators. If that ever changes, then the grid can be last instead of in the middle of the back-up systems.

I know you read this.

With the correct grid usage for the year of 152 Kwh, the cost would be $300/year for meter charge and $27 for the Kwh used comes to $327 per year. That makes the cost of grid power $2.15/Kwh.
Those are high priced Kwh.

 

[OffGridForGood]

yeah but for a few hundred bucks a year, I will keep the 'back up system' for now.
Maybe after some more PV installation I will feel differently, I only have 13kW of PV right now, and with the tall trees on the East property line near the shop, I get zip from the sun until 10:00 most of the winter.
The next array is going on my new barn - it sits up on higher ground and is farther west of the shop area, so will get early morning sun, and will add a lot of PV to my system.

 

[Zwy]

For me, a $7K generator depreciated out over 7 years is $1K per year writeoff and if in a 35% tax bracket (Social Security taxes and income tax) comes to $350/year. Government pays for the generator over time.

You own a business, it is a no brainer when it comes to solar/ generators and getting off grid if you can produce enough power when you need it. If you need to run a 50 HP air compressor, then you should stay on grid power.

 

[Skypower]

My OCD got the most of me on New Year’s Day. I took it to bulk voltage, temporarily set float to same and gave that straggler(3.4) a good jump with a power supply to teach it a lesson. It needed a surprising number of little provocations over the period of a hour before it decided to play along. Even the 2amp JK was having difficulty. Probably because of large number incomplete cycles not reaching full charge. Ironically this is my newest battery, most contributing and only Eve cells.
Considering turning off the JK’s balance function and use a A30 voltage module+ 5 Amp Heltec for this one battery if the problem continues. That balancer setup was flawless on my first battery (2P 16S) before I dumped the Daly, split it into two batteries and two JK’s, so I know it has a lot of balance power. I have a 4amp Neey that I could try too, which is quicker for lower delta levels.

 

[timselectric]

That stubborn straggler is stuck. It's increased by only 3 mv .
I'm probably gonna put the bench top power supply on it.
My patience is running out. lol

 

[Skypower]

That stubborn straggler is stuck. It's increased by only 3 mv .
I'm probably gonna put the bench top power supply on it.
My patience is running out. lol

Tell it who’s boss

 

[timselectric]

System in standby, waiting for the storm to end.



This is one of those times when it's good to have the grid for backup.

 

[OffGridForGood]

And a Genny fueled & waiting - JUST IN CASE
Hope all you guys in the storm-path are okay, stay safe.

 

[timselectric]

All good now.
#5 was the straggler.
And it was stubborn. I had to bring out the bigger power supply.

 

[Skypower]

The crazy thing is, if you disconnect that battery from the main buss(no load) and use an internal resistance meter on the cells, you’ll most likely find that not only are all the cells exactly the same but, the same as the day you first commissioned them.

 

[sunshine_eggo]

The crazy thing is, if you disconnect that battery from the main buss(no load) and use an internal resistance meter on the cells, you’ll most likely find that not only are all the cells exactly the same but, the same as the day you first commissioned them.

Internal resistance is not the biggest influence on balance. It's self-discharge.

Internal resistance forces the cell voltage to rise more than the others thus increasing the Wh needed to charge it, but it takes on the exact same Ah as the other cells.

In 2021, I purchased nine 280Ah EVE cells from Amy Wan. Eight of them were incredibly well matched, but the 9th was a comparative turd. All tested identically on a YR-1030.

I charged all cells up to 3.65V @ 20A with a 4A tail current (limitation of equipment) and let them sit for five months. After 5 months, the 8 "matched" cells needed only 300-700mAh to return them to full charge by the same criteria. The 9th cell required 3100mAh. Again, all nine tested identical on a YR-1030.

ALL cells were well within the 1%/month spec, but they clearly wouldn't play nicely. That 9th cell working with 7 of the others would need regular balancing.

 

[timselectric]

It took 384wh to get it balanced with the others.
But I shouldn't complain. I have purchased 128 cells so far (80 in use), and this is the only one that stands out. It's like a tire with a very slow leak that just needs a few pounds of air, every six months. It's not quite annoying enough to warrant replacement.

 

[Skypower]

I’m kinda regretting not going to 18S and if needed, cull out a few ringers from each battery after a couple of years. So far the YR meter hasn’t indicated anything in the regards of battery health but it sure was good at telling me about connection and cable quality. Capacity test is the last word for batteries. I use to think that the straggler was the strongest(more capacity) or had more resistance to accepting charge, but I can buy the idea of self discharging too.
Presently I’m charging to 100%. I suspect that the cell that has the issue will be normal and another might be a tad disruptive. That seems to be the playbook of the past.

 

[timselectric]

Self discharge is the only thing that makes sense, in my case.
During normal daily cycles the BMS can handle it, easily.
But spending a long time in a lower SOC, it's compounded every day.