No magic smoke, but no $ savings because I played with AC charging.

[marke.e]

1 full cycle is when you discharge the capacity of the battery and it can be in any combination of charge discharge cycles ie 100-0 x1, or 100-50 x2, 100-75 4x

 

[ksmithaz1]

1 full cycle is when you discharge the capacity of the battery and it can be in any combination of charge discharge cycles ie 100-0 x1, or 100-50 x2, 100-75 4x

That is incorrect. By DEFINITION 1 FULL cycle is when you discharge from 100 to 0 and back to 100. 100 to 50 to 100 to 50 to 100 is two HALF cycles. You can not make the assumption that the "wear and tear" on the overall component / chemistry is the same no matter how you treat it. This would be true of any storage medium.

For example if you ran a liquid fuel tank dry every time before you re-filled it, you could put additional stress on an in-tank pump that might die sooner. If you always kept it full you would create additional weight that might factor in on seals at the bottom of the tank, or create strange hydraulic pressure scenarios on other plumbing items.

You just don't know until you have actual real world test data over the expected lifetime of the product. We are actually just starting to get some useful data on this front, it will be interesting. Early data from tesla seems to indicate people who slow charge at home and keep it generally topped off won't lose very much range/capacity over a 10 year period, but we don't have good aggregation of intermediate charge-discharge cycles. From the LifePO front the chemistry is still fairly new.

 

[Hedges]

One of my problems with "% charging" is if you are not supposed to go below 20%, then you mis-calibrated. Whatever was 20 needs to be zero (0). My amplifier goes all the way to 11. Yours only goes to 10. Meh. I'm not in "Spinal Tap" I don't need to go to 11 . The battery 0-100% should be calculated to optimize total energy thruput on the device. I would like to see a rating as above: 0-100 @ 6000 full cycles. This should be whatever the point is that maximized total energy in/out.

For example if you ran a liquid fuel tank dry every time before you re-filled it, you could put additional stress on an in-tank pump that might die sooner. If you always kept it full you would create additional weight that might factor in on seals at the bottom of the tank, or create strange hydraulic pressure scenarios on other plumbing items.

If my motorcycle sputters to a stop because I ran out of gas, I just reach down and flip the valve over to "Reserve."

The full capacity of ESS or EV is how car you can go until the lights go out or you roll to a stop.
You might choose to stop with 10% ~ 20% remaining then recharge because you get more cycle life and value, but you've got that reserve in case you need it.

 

[Quattrohead]

That is incorrect. By DEFINITION 1 FULL cycle is when you discharge from 100 to 0 and back to 100

I never use 0-100% of my batteries but they are still counting cycles.

 

[ksmithaz1]

If my motorcycle sputters to a stop because I ran out of gas, I just reach down and flip the valve over to "Reserve."

Oops, already did that 20 min ago, no gas station in site! To my point, gravity feed on a bike changes the paradigm. Pushed that B about 3 miles.

The full capacity of ESS or EV is how car you can go until the lights go out or you roll to a stop.
You might choose to stop with 10% ~ 20% remaining then recharge because you get more cycle life and value, but you've got that reserve in case you need it.

Agree. None the less, testing/ratings should be based on 100-0-100, whatever those numbers might actually indicate on the battery in question is another question altogether. The percentages and ratings are actually derived thru experimentation/optimization, that are decidedly not real world conditions.

 

[ksmithaz1]

I never use 0-100% of my batteries but they are still counting cycles.

Yea, I think mine increment every shift even if very small.

 

[robbob2112]

If my motorcycle sputters to a stop because I ran out of gas, I just reach down and flip the valve over to "Reserve."

The full capacity of ESS or EV is how car you can go until the lights go out or you roll to a stop.
You might choose to stop with 10% ~ 20% remaining then recharge because you get more cycle life and value, but you've got that reserve in case you need it.

And if you forget to flip the switch back when you fill it up then sputter again you feel like an idiot and have to hitchhike or call someone to bring you gas.

Don't ask me how I know this.

I generally only use the top 25% of my battery and top it up everyday. According to the paperwork that came with it that should get me 15 years with only a 10% loss. Deeper discharge means more loss. Higher C rate charge or discharge means lower life.

At least all the paperwork says it... but who has a 15 year old LiFePO4 battery laying around and knows it wasn't abused to check this? Raise your hand high so I can see it over the monitor.

 

[plympton]

At least all the paperwork says it... but who has a 15 year old LiFePO4 battery laying around and knows it wasn't abused to check this? Raise your hand high so I can see it over the monitor.

Had to hunt it down, but this guy! https://marinehowto.com/happy-15th-birthday-to-my-lifepo4-battery/

 

[Brucey]

Had to hunt it down, but this guy! https://marinehowto.com/happy-15th-birthday-to-my-lifepo4-battery/

Those Winston/Thundersky cells are premium priced but certainly seem to have withstood the rest of time

@Daddy Tanuki

 

[Daddy Tanuki]

personally I think that the BMS should be counting the number of watts used and anytime the total number hits the capacity of the cells that should count as one cycle so basically it should be able to calculate the used wattage and even if you recharge before full it should keep the used amount in memory until it resets, so if the cell is good for 10 watts of energy once it uses 10 watts that is one cycle regardless of if it uses 100 watts in one night and gets recharged to full the following morning, or every three days as it uses the 100 watts.

 

[Brucey]

personally I think that the BMS should be counting the number of watts used and anytime the total number hits the capacity of the cells that should count as one cycle so basically it should be able to calculate the used wattage and even if you recharge before full it should keep the used amount in memory until it resets, so if the cell is good for 10 watts of energy once it uses 10 watts that is one cycle regardless of if it uses 100 watts in one night and gets recharged to full the following morning, or every three days as it uses the 100 watts.

in think that's how the Victron smartshunts calculate it:

 

[Daddy Tanuki]

in think that's how the Victron smartshunts calculate it:

View attachment 217884

thats how magnum and bogart do it as well, but the bms's obviously do not or they would tally much closer to the shunt based battery monitors.

 

[automatikdonn]

Not a magic smoke post, but a newbie error I made, hope to educate other newbies.

I went live with Solar and Batteries in November of 23.

I had several thoughts in my head, re batteries.

1 - It's cool to run off batteries
2 - I need to fully cycle batteries, to keep them healthy

1 is correct, 2 is not so much, at least with Lithium Iron Phosphate.

So I ran off batteries as much as possible. When they got low, because December and January solar sucked, I would charge them back up with grid.

Then I run off batteries.

Well, stupid me, neglected to take conversion losses into account, so while it was fun, I wasted $ and my electric bills really didn't change, somewhat due to charging new EVs, but also related to all that back and forth with the batteries.

I really want my batteries for UPS of the house. I have 12 LIfePower4s, connected to my 18 KPV set up for whole home backup. 50% SOC would carry me for more than a day, in case of an outage and no solar.

So that is where I have my settings now, 50% when on grid, let the system do its thing. NO more playing with charging, discharging, percentages, etc.

I have had the direct opposite experience - my bill has went down by 80% doing exactly what you are doing. However during the crappy months I saw no savings. So over the course of the year it works out to about 65% total savings and I am off grid only - no feeding to the grid at all (for now)

 

[D71]

personally I think that the BMS should be counting the number of watts used and anytime the total number hits the capacity of the cells that should count as one cycle so basically it should be able to calculate the used wattage and even if you recharge before full it should keep the used amount in memory until it resets, so if the cell is good for 10 watts of energy once it uses 10 watts that is one cycle regardless of if it uses 100 watts in one night and gets recharged to full the following morning, or every three days as it uses the 100 watts.

You have a valid point. After a year of using my emergency system it has 6 cycles on it for batteries. Notice if it drops below 50% and recharge then logs a cycle. If charge it over and over before then seems to never log next cycle. That 80% to 100% charge part is always the slowest.
Never ran my batteries down below 20%.

Like most want more so …… it is in the works. I feel the ancient - neglected grid will be more problematic in the future. Be nice if new green deal was concerned with upgrading transformers that will be failing in near future. I assure everyone the new transformers will not last as long as the old transformers have lasted.

The replacement transformers will no doubt be chinese. Again they - new replacement transformers won’t last long.

Like OP want batteries - my system as emergency backup. The grid if rebuilt as reliable as it was in days gone by will still be my go to. It - local grid cost me ~$1400 a year. Nothing can beat that when it works properly.