Lithium Battery Life

[Dolby]

This has probably been asked a lot, but I'll go again :

In an inverter/UPS that is always plugged in - do batteries degrade with cycles (ie shedding where it is used) or just the fact being plugged in ?
In other words, if load shedding stopped tomorrow and my inverter/UPS is plugged in - will it degrade simply by being plugged in and not using cycles?

 

[1am7h30n3]

I'm no expert, but I think it will degrade slowly just by sitting and being maintained at charge. (Possibly for longest life and least degradation it would need to be cycled every x months?). I think it will degrade faster if you cycle regularly though.

 

[Mike Hoxbig]

There's various schools of thought. Not using cycles is not an issue, but generally it's best not to keep it 100% charged if you're not going to discharge.

If you're not going to discharge, then keeping it at for eg. 80-90% will help extend it's life...

 

[Tomtomtom]

All batteries degrade just from time because they are basically chemical sandwiches and there's always reactions underway.

For lead acid, they sulfate and lose capacity even faster if stored below 100% charge, hence "float" chargers.

For lithium it's almost the opposite - best to store at more like 50-90%, not fully charged.

Degredation is faster at high temperature as well, regardless of chemistry.

 

[SauRoNZA]

I don’t understand the notion of people buying batteries and then NOT using them so they can live longer and continue to NOT use them.

Murder the things to the extremes of their capacities and then buy more/new ones.

I swear people spend more time and effort calculating all this kak than actually getting any benefit from the things.

 

[Dolby]

I don’t understand the notion of people buying batteries and then NOT using them so they can live longer and continue to NOT use them.

Murder the things to the extremes of their capacities and then buy more/new ones.

I swear people spend more time and effort calculating all this kak than actually getting any benefit from the things.

So if they stop all load shedding tomorrow, I should rather keep it plugged it and just let it degrade over time even if no power issues ?

That's an odd answer :/

 

[SauRoNZA]

So if they stop all load shedding tomorrow, I should rather keep it plugged it and just let it degrade over time even if no power issues ?

That's an odd answer :/

I’m saying either way, whichever way it goes it’s likely going to make a 1% paper value difference to the lifetime health of the device and not affect you in any meaningful way.

It’s simply not worth worrying about.

One thing that is worth worrying about is to make sure it’s charged fully before you unplug it and then charge it again every six months or so because discharged lithium batteries living in your cupboard become completely dead lithium batteries very quickly.

 

[Tomtomtom]

I don’t understand the notion of people buying batteries and then NOT using them

BL (before loadshedding) this was the whole point of a UPS - standing by hopefully never needing to be used.

Then the one day you did need to use it you discovered the battery survived only 10 seconds because it'd been roasting in the box for 5 years.

 

[SauRoNZA]

BL (before loadshedding) this was the whole point of a UPS - standing by hopefully never needing to be used.

Then the one day you did need to use it you discover the battery survives only 10 seconds because it's been roasting in the box for 5 years.

The point of a UPS was always to be powered on inline with a device you wanted to keep powered in case of a power outage.

Buying one and keeping it in a box was never going to work for a great many reasons.

Load shedding or otherwise.

 

[Dolby]

I'm no expert, but I think it will degrade slowly just by sitting and being maintained at charge. (Possibly for longest life and least degradation it would need to be cycled every x months?). I think it will degrade faster if you cycle regularly though.

That is what I think - but again, I'm not an expert .

If I leave it plugged in continually and we start on 01 January and by 31 December I've used 500 cycles - I should be 80% health
If I leave it plugged in continually and we start on 01 January and by 31 December I've used 250 cycles - will I be 90% health?
If I leave it plugged in continually and we start on 01 January and by 31 December I've used 0 cycles - will I be 95% health?

Question was basically cycles vs continual charge - what is more damaging if I had to choose

 

[Tomtomtom]

Buying one and keeping it in a box was never going to work for a great many reasons.

Oh lol, misunderstanding - I mean the case of the ups itself, online and working but never discharging.

As to OP, if it's lead acid, don't unplug it - the device will have a float charger necessary to keep the battery going.

 

[SauRoNZA]

Oh lol, misunderstanding - I mean the box of the ups, online and working but never discharging.

As to OP, if it's lead acid, don't unplug it - the device will have a float charger necessary to keep the battery going.

That’s another thing, since load shedding the term “UPS” has changed radically in the eyes of most.

To the laymen it means a thing that will keep my stuff on after the power goes out. To an IT nerd it’s a box that allows me to shut my stuff down in a couple of minutes before accepting my fate that there now is no more power.

The amount of stories I can tell you about people buying completely the wrong thing for their needs is probably approaching a hundred for me personally now.

But I was speaking purely in the here and now, not before Load Shedding.

 

[SauRoNZA]

That is what I think - but again, I'm not an expert .

If I leave it plugged in continually and we start on 01 January and by 31 December I've used 500 cycles - I should be 80% health
If I leave it plugged in continually and we start on 01 January and by 31 December I've used 250 cycles - will I be 90% health?
If I leave it plugged in continually and we start on 01 January and by 31 December I've used 0 cycles - will I be 95% health?

Question was basically cycles vs continual charge - what is more damaging if I had to choose

How have you used any cycles if it hasn’t discharged?

How would it use any cycles if it wasn’t plugged in?

Neither is consuming cycles really.

Discharging it through use would consume cycles but there’s also a very line between when that is necessary, good or even bad.

I’ve discharged to 15% almost every day for the past 8 months and I’m on 100% battery health.

It honestly is not worth worrying about. Just use the thing as you need to use it.

 

[Dolby]

How have you used any cycles if it hasn’t discharged?

It's really only hypothetical and for me to understand the best way forward.

I'm keeping it plugged in 100% and I'm expecting it to give out 2-3 years - but would be curious as to how battery health would be affected if all next year was stage 1 or all was stage 6 - or shedding just stopped altogether

 

[SauRoNZA]

It's really only hypothetical and for me to understand the best way forward.

I'm keeping it plugged in 100% and I'm expecting it to give out 2-3 years - but would be curious as to how battery health would be affected if all next year was stage 1 or all was stage 6 - or shedding just stopped altogether

Well start logging your data and you can report back in 3-5 years.

Either which way it will degrade with time, that’s a given.

 

[neoprema]

Plugged in (load) or no load, or charge or no charge - the life will start going after some time.

There are things you can do to make it last longer though, which is why so many laptops and phones these days have smart algorithms for charging. The other day my Macbook over 2 days just REFUSED to charge when plugged into power - it just said "Not Charging" and it let itself go to like 50% and then decided to charge again like normal. From what i've read online its part of the battery conditioning to extend its life.

Also sometimes I notice my phone won't charge when put on the wireless charger until around 3am.

I guess its quite a complex thing to keep these batteries at peak performance, prob more so than just a "should i unplug it when not in use" thing..?

 

[Mystic Twilight]

So if they stop all load shedding tomorrow, I should rather keep it plugged it and just let it degrade over time even if no power issues ?

That's an odd answer :/

You charge it up to about 80% capacity and then disconnect it for long term storage, occasionally connecting it up to top it back to 80%. Same way as to how new cell phones are charged and stored to preserve battery life.

 

[chrisc]

I do not understand the correlation between battery voltage and the State Of Charge indicator

There are 4 LEDs indicating the SOC thus:

1 - 0% to 25%
2 - 25% to 50%
3 - 50% to 75%
4 - 75% to 100%

The lithium battery I am using states that the maximum voltage charge is 54.6V
Float charge is 52.5V

The voltage shown on the inverter display and is verified by a Fluke meter is 53.9V
When there is load-shedding, the battery may drop to 52.9V

At the end of load-shedding, lights 1 and 2 are on,
After a 3 or 4 hour charge, the voltage is shown to be 53.1V
Yet only 3 LEDs illuminate

If I increase the charge voltage to 55V, then 4 lights come on but the "over limit" light comes on, so I reduced it to 54.6V

I sent an email to the sales agent and factory. Neither replied

 

[neoprema]

Also just an FYI - i find the DJI Drone batteries to be interesting. If you store them long without use the manual says they'll at some point get warm because there's an internal circuit that will "discharge" them to a preset amount for long-term storage by generating heat. I wonder if any other batteries do that?

 

[Tomtomtom]

If I leave it plugged in continually and we start on 01 January and by 31 December I've used 0 cycles - will I be 95% health?

Something like that. As sauron says, it's not going to be worth worrying about. But maybe it would be 98% condition instead of 95% if you charged it carefully to 80% and stored it.

Only time I can imagine you don't want it on the charger is if there's a lot of heat. Over about 50 degrees C is bad for lithium.

Edit: assuming the charger / BMS are properly designed and do not overcharge.