Loadshedding affordable battery setup?

[Park@82]

You said a cycle is 100 to 0 and back to 100. So if you are only half discharging then that is only half a cycle so life expectancy doesn't change, you just take twice as long to get there.

I'm not sure if I understand your criticism correctly.

I said a full cycle is 100 to 0 and back to 100.

Im not sure how else to define a full cycle.

I could add that 100 to 20 and back to 100 can also be called a cycle but not a full cycle?

If you look at that DOD vs discharge cycles form battery university as an example, a DOD of 100% gets you 600 cycles (600 x 100 = 60000) vs a DOD of 80% and you'll get 900 cycles (80 x 900 = 72000).

It seems clear that discharging to 20% (80% DOD) will give you a lot more of usable capacity (12000%).

Unless I'm missing something?

 

[leon.davibe]

I'm not sure if I understand your criticism correctly.

I said a full cycle is 100 to 0 and back to 100.

Im not sure how else to define a full cycle.

I could add that 100 to 20 and back to 100 can also be called a cycle but not a full cycle?

If you look at that DOD vs discharge cycles form battery university as an example, a DOD of 100% gets you 600 cycles (600 x 100 = 60000) vs a DOD of 80% and you'll get 900 cycles (80 x 900 = 72000).

It seems clear that discharging to 20% (80% DOD) will give you a lot more of usable capacity (12000%).

Unless I'm missing something?

The lithium-ion they refer to is a different chemistry combo

The combo that gives you those cycles is often the 3.7v cells

The lifep04 gives more cycles and is 3.2v cells

Then you also get LTO cells
That are 2.3v cells and they claim does even more and also love charging fast, but no models with this available afaik

That's just 3 of the many many different chem compositions

 

[wingnut771]

I'm not sure if I understand your criticism correctly.

I said a full cycle is 100 to 0 and back to 100.

Im not sure how else to define a full cycle.

I could add that 100 to 20 and back to 100 can also be called a cycle but not a full cycle?

If you look at that DOD vs discharge cycles form battery university as an example, a DOD of 100% gets you 600 cycles (600 x 100 = 60000) vs a DOD of 80% and you'll get 900 cycles (80 x 900 = 72000).

It seems clear that discharging to 20% (80% DOD) will give you a lot more of usable capacity (12000%).

Unless I'm missing something?

I wasn't critiquing the "what is a cycle" definition, just the "shallow discharges to prolong life" part. Its true in a way I guess but 3000 cycles is 10 years, and that's without extending anything. Anyway, let me read it again tomorrow as I'm not thinking clearly now.

Like I said earlier, that 600 cycles from battery university is outdated imho, I know for a fact when the hubble s100 first came out it said 2000 cycles at 100% DOD.

I'm not following your maths in the bold part.

 

[wingnut771]

The lithium-ion they refer to is a different chemistry combo

The combo that gives you those cycles is often the 3.7v cells

The lifep04 gives more cycles and is 3.2v cells

Then you also get LTO cells
That are 2.3v cells and they claim does even more and also love charging fast

That's just 3 of the many many different chem compositions

No no don't you come here complicating things now.

 

[leon.davibe]

A lithium isn't a lithium

But most of the ones we see in solar is lifep04 based

Also not all 3.7v cells are that low cycle count

I think the type hubble uses in the am2 is 3.7v and they also claim way higher cycles so rules of thumbs is kinda hard when it comes to lithium gotta find the specs on the specific one

 

[wingnut771]

A lithium isn't a lithium

But most of the ones we see in solar is lifep04 based

Also not all 3.7v cells are that low cycle count

I think the type hubble uses in the am2 is 3.7v and they also claim way higher cycles so rules of thumbs is kinda hard when it comes to lithium gotta find the specs on the specific one

We call everything here lithium. Its just you that's hung up.

 

[leon.davibe]

Thanks. That is form my blog site. I'm still actively editing it and I want to add some additional information.

Sizing power stations / inverter trolley solutions - South African Consumer

What is a power station / inverter trolley / inverter battery box/ solar generator? It is a portable enclosure that typically houses a battery, an inverter, and a charger. It looks like loadshedding is here to stay and you may have decided that you would like a portable solution that would be...

southafricanconsumer.co.za

This is how I came up with that statement:

I looked at this:

BU-808: How to Prolong Lithium-based Batteries

Manufacturers take a conservative approach and specify the life of Li-ion in most consumer products as being between 300 and 500 discharge/charge cycles.…

batteryuniversity.com

(see attachment I'm posting form the mybb app)

It shows number of cycles going up as depth of discharge goes down on both NMC and LFP.

Unless I missunderstood? View attachment 1480715

Reading the post and yes so far it is doing a great job of not getting to technical or just keep it in a way of explaining that makes sense often with too much info a person can get lost

Some constructive criticism
The cycles

one part that nobody mentions is that when they talk about cycles on lithium

the claim is that after said cycles you would still be left with 80% capacity if you had a 5kw battery you would now essentially have a 4kw battery but still usable

Not sure if the cycles on a lead acid has the same asterisk

Kinda like with solar panels

So after 20 years the panels ain't useless ,they will only deliver say 80% of it's rated output

 

[leon.davibe]

I wasn't critiquing the "what is a cycle" definition, just the "shallow discharges to prolong life" part. Its true in a way I guess but 3000 cycles is 10 years, and that's without extending anything. Anyway, let me read it again tomorrow as I'm not thinking clearly now.

Like I said earlier, that 600 cycles from battery university is outdated imho, I know for a fact when the hubble s100 first came out it said 2000 cycles at 100% DOD.

I'm not following your maths in the bold part.

Not if you cycle it three times a day

Sure If you have solar panels to sustain during the day and essentially skip two cycles yes then it is

And naturally if shedding is suspended the math changes

 

[wingnut771]

Reading the post and yes so far it is doing a great job of not getting to technical or just keep it in a way of explaining that makes sense often with too much info a person can get lost

Some constructive criticism
The cycles

one part that nobody mentions is that when they talk about cycles on lithium

the claim is that after said cycles you would still be left with 80% capacity if you had a 5kw battery you would now essentially have a 4kw battery but still usable

Not sure if the cycles on a lead acid has the same asterisk

Kinda like with solar panels

So after 20 years the panels ain't useless ,they will only deliver say 80% of it's rated output

No, lead acids are a door stop or a big paper weight after their cycles, send it to scrap for a few bob.

 

[wingnut771]

Not if you cycle it three times a day

Sure If you have solar panels to sustain during the day and essentially skip two cycles yes then it is

And naturally if shedding is suspended the math changes

How do you go from 100 - 0 - 100 three times a day?

 

[Park@82]

...

I'm not following your maths in the bold part.

Please correct me if I am wrong but this is how I understand it:

Lets say that you have a 1000Wh battery.

And lets say that the battery is rated for 600 cycles at 100% DOD and 900 cycles at 80% DOD
(as in the example from battery university)

At 100% DOD you got 600 000Wh (600 x 1000) out of the battery.

At 80% DOD you got 720 000Wh (900 x 800) out of the same battery.

You got 120 000Wh more when you used a DOD of 80%.

As you pointed out, Scott's lifepower bronze batteries are rated for 2000 cycles at 80% DOD. We don't know how many cycles it would get at 100% DOD perhaps it could be 1500 Cycles who knows. The point I was trying to make is that you should try to oversize the battery so that you avoid using 100% DOD.

Edit
I guess it doesn't make a huge difference on LFP but with NCM (which many of these power stations still use) it makes a difference because of the very limited cycles that you start with.

 

[wingnut771]

Hey @Park@82, I've had a go, the stuff in bold are my additions/corrections. Hope it's okay? Feels like we're going down a rabbit hole


What you should know:

Batteries:

Typically three types of batteries are commonly used in power stations/inverter trolley:

Lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LiFePO4(LFP)) or lead acid (Flooded/SLA/AGM/Gel) (Lead acid are generally used only in some the trolley solutions because they are a lot heavier). Each battery chemistry has pros and cons but one major difference is the amount of charge cycles that are supported by each type of battery. NMC is more popular in the portable type as they have a higher energy density therefore lighter than the LFP type. LFP type you can find marketed as "lead acid replacements" as their voltage is similar to lead acid and can be used with the same lead acid charger.

Note that the life expectancy in terms of cycles is affected by how deep you discharge a battery. The less deeply you discharge it, the more cycles you can expect to get from them. For this reason, it is a good idea to make sure that the power station that you opt for has more watt hours (Wh) of available power than the amount you would actually be using, so that you don’t deplete it all the way to 0% before recharging it.

Generally lead acid batteries can only be discharged to 50% before permanent damage occurs. Lead acids also take a long time to charge so you might not have enough time between sessions to fully recharge again damaging the battery. Because of this, the weight, the very limited cycles and charging time, I would avoid lead acid batteries if your budget allows it. LFP/NMC can be discharged to 0% (some only allow to 10% or 20%) and doesn't suffer like lead acid. With lithium batteries one should aim to have around 20% battery left when you are done using it as it's good to leave a buffer at the bottom in case you run out as some lithium battery's internal BMS (battery management system) will switch the battery off to protect itself if it gets too low basically disabling your system (inverter trolley type(that was designed for lead acid)) and you will need an external power source (another small 12V alarm/gate motor type) to "wake it up" again by "jump starting" its like what you do with a flat battery in your car with jumper cables. It would also be good practice not to charge it all the way to 100% but that may be too cumbersome for most users and I won’t discuss it here. This only applies to entry level trolley's as the settings can't be changed, higher end ones don't suffer this "issue".

 

[wingnut771]

Please correct me if I am wrong but this is how I understand it:

Lets say that you have a 1000Wh battery.

And lets say that the battery is rated for 600 cycles at 100% DOD and 900 cycles at 80% DOD
(as in the example from battery university)

At 100% DOD you got 600 000Wh (600 x 1000) out of the battery.

At 80% DOD you got 720 000Wh (900 x 800) out of the same battery.

You got 120 000Wh more when you used a DOD of 80%.

As you pointed out, Scott's lifepower bronze batteries are rated for 2000 cycles at 80% DOD. We don't know how many cycles it would get at 100% DOD perhaps it could be 1500 Cycles who knows. The point I was trying to make is that you should try to oversize the battery so that you avoid using 100% DOD.

Edit
I guess it doesn't make a huge difference on LFP but with NCM (which many of these power stations still use) it makes a difference because of the very limited cycles that you start with.

I understand now.

Yeah, with NMC I would try use the 20-80% rule where possible.

 

[Park@82]

Hey @Park@82, I've had a go, the stuff in bold are my additions/corrections. Hope it's okay? Feels like we're going down a rabbit hole


What you should know:

Batteries:

Typically three types of batteries are commonly used in power stations/inverter trolley:

Lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LiFePO4(LFP)) or lead acid (Flooded/SLA/AGM/Gel) (Lead acid are generally used only in some the trolley solutions because they are a lot heavier). Each battery chemistry has pros and cons but one major difference is the amount of charge cycles that are supported by each type of battery. NMC is more popular in the portable type as they have a higher energy density therefore lighter than the LFP type. LFP type you can find marketed as "lead acid replacements" as their voltage is similar to lead acid and can be used with the same lead acid charger.

Note that the life expectancy in terms of cycles is affected by how deep you discharge a battery. The less deeply you discharge it, the more cycles you can expect to get from them. For this reason, it is a good idea to make sure that the power station that you opt for has more watt hours (Wh) of available power than the amount you would actually be using, so that you don’t deplete it all the way to 0% before recharging it.

Generally lead acid batteries can only be discharged to 50% before permanent damage occurs. Lead acids also take a long time to charge so you might not have enough time between sessions to fully recharge again damaging the battery. Because of this, the weight, the very limited cycles and charging time, I would avoid lead acid batteries if your budget allows it. LFP/NMC can be discharged to 0% (some only allow to 10% or 20%) and doesn't suffer like lead acid. With lithium batteries one should aim to have around 20% battery left when you are done using it as it's good to leave a buffer at the bottom in case you run out as some lithium battery's internal BMS (battery management system) will switch the battery off to protect itself if it gets too low basically disabling your system (inverter trolley type(that was designed for lead acid)) and you will need an external power source (another small 12V alarm/gate motor type) to "wake it up" again by "jump starting" its like what you do with a flat battery in your car with jumper cables. It would also be good practice not to charge it all the way to 100% but that may be too cumbersome for most users and I won’t discuss it here. This only applies to entry level trolley's as the settings can't be changed, higher end ones don't suffer this "issue".

Thank you Mr. Ill definitely use some of that. Just need to read through again make sure I understand. I'm trying not to go down too many rabit holes with BMS and discharge rates and I did reccomend that people avoid lead acid.

I want tannie Sarie who wants to watch 7nde laan with her inverter to be able to follow along and not get lost when she hears that you may need to jump start your battery.

 

[Park@82]

Hey @Park@82, NMC is more popular in the portable type as they have a higher energy density therefore lighter than the LFP type.

It is true that NMC is popular at the moment but the market is moving towards LFP at such a rapid pace that I think by next year NCM will not longer be so popular anymore. Ecoflow, Bluetti and even the local Gizzu brand are all moving to LFP.

I have heard that that NMC has a higher energy density but If you look at the actual Wh and weight of LFP vs NCM in portable power stations this is negligible and I don't think I need to mention it.

e.g.
The Ecoflow River Max (NCM) has a capacity of 576Wh and weighs 7.7kg.
VS
River 2 Max (LFP) has 512Wh and it weighs only 6kg.

 

[wingnut771]

It is true that NMC is popular at the moment but the market is moving towards LFP at such a rapid pace that I think by next year NCM will not longer be so popular anymore. Ecoflow, Bluetti and even the local Gizzu brand are all moving to LFP.

I have heard that that NMC has a higher energy decency but If you look at the actual Wh and weight of LFP vs NCM in portable power stations this is negligible and I don't think I need to mention it.

e.g.
The Ecoflow River Max (NCM) has a capacity of 576Wh and weighs 7.7kg.
VS
River 2 Max (LFP) has 512Wh and it weighs only 6kg.

I feel like a dinosaur like battery university.

 

[Park@82]

Hey @Park@82 It would also be good practice not to charge it all the way to 100% but that may be too cumbersome for most users and I won’t discuss it here.

I kinda want to keep this part in because some power stations like my Ecoflows (NCM) allows me to set the charge and discharge levels. I try to keep mine to 20% - 80% but in case of emergency I can set it to 0 -100 (e.g. I was without power from Monday afternoon until Wednesday afternoon and wanted more capacity.)

 

[Park@82]

Hey @Park@82, LFP type you can find marketed as "lead acid replacements" as their voltage is similar to lead acid and can be used with the same lead acid charger.

Ill be using this part "LFP are also often marketed as "lead acid replacements" as their voltage is similar to lead acid." but I am not saying that people can use lead acid chargers because I am still not 100% certain about how pulsing would affect them...

 

[Park@82]

hey @wingnut771

I asked chatrgpt to "combine the following into one coherent paragraph: Note that the life expectancy in terms of cycles can be affected by how deep you discharge a battery. The less deeply you discharge it, the more cycles you can expect to get from them. For this reason, it is a good idea to make sure that the power station that you opt for has more watt hours (Wh) of available power than the amount you would be using, so that you don't deplete it all the way to 0% before recharging it. With lithium batteries it is a good idea to aim to have around 20% battery left after you have used it. It would also be good practice not to charge it all the way to 100% but that may be too cumbersome for most users, and I won't discuss that here. This is more applicable to NCM than LFP because LFP has way more cycles.

It gave me this:

When considering the life expectancy of a battery in terms of cycles, it's important to keep in mind that the depth of discharge can have an impact. The less deeply a battery is discharged, the more cycles can be expected from it. To ensure a longer lifespan, it's a good idea to select a power station with more watt hours of available power than what you typically use, so that you avoid completely depleting it before recharging. With lithium batteries, it's recommended to aim for having around 20% battery left after use. While it's also good practice not to charge the battery all the way to 100%, this may be inconvenient for most users, and it's not discussed here. This advice is especially relevant to NCM batteries, as LFP batteries have a significantly higher number of cycles.

Seems better. Thoughts?

 

[leon.davibe]

How do you go from 100 - 0 - 100 three times a day?

By living a normal lifestyle on a battery that is just enough ah for your needs

ie i cycle about 80dod on 7.5kwh
In 4hrs stint

So can just imagine someone with a 5kw can easily do it if lifestyle isn't adjusted for load shedding
especially with stage 6
Without panels ie only battery backup