AchmatK
Honorary Master
The pylontech batteries are now rated at 90% DOD.
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Question of the Day: How do you normally pay for purchases in stores?
Tesla Powerwall vs generators - South African pricing compared
- Thread starter Jamie McKane
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I recently bought a replacement LA gel battery for my home UPS, just looked up its specs
100Ah, 12V, 800 cycles at 50% DOD
It cost about R3k if I remember correctly.
So:
(3000 x 1000) / (100 x 12 x 0.5 x 800) = R 6.25 / kWh Cycle
Just for interest sake.
Looks like I got ripped off
100Ah, 12V, 800 cycles at 50% DOD
It cost about R3k if I remember correctly.
So:
(3000 x 1000) / (100 x 12 x 0.5 x 800) = R 6.25 / kWh Cycle
Just for interest sake.
Looks like I got ripped off
Speedster
Honorary Master
60% is the guaranteed remaining capacity after 6000 cycles.
wingnut771
Honorary Master
Sorry, my bad that's more like it.
With LFP, there is no battery life, as after it gets to 60% the curve flattens and lasts almost indefinitely within reason.
wingnut771
Honorary Master
I was being generous with the LA comparison. What normally happens with LA is one battery in the bank breaks, breaking all the others, then have to replace after 600 cycles.I recently bought a replacement LA gel battery for my home UPS, just looked up its specs
100Ah, 12V, 800 cycles at 50% DOD
It cost about R3k if I remember correctly.
So:
(3000 x 1000) / (100 x 12 x 0.5 x 800) = R 6.25 / kWh Cycle
Just for interest sake.
Looks like I got ripped off
Um.. I doubt if any battery manufacturer is going to guarantee anything like that, given that battery performance is so sensitive to environmental factors like temperature etc, as well as the way the battery is used (which is why they quote different numbers of cycles for different depths of discharge).
I think what is meant by the 60% is that they only quote the number of cycles to the point that battery only can hold 60% of it's original rated capacity each cycle (so it's a measure of the battery's deterioration)? If I remember, that is just a different way of quoting the life in number of cycles (this was all some time ago for me), not all battery specs were given in that way. Which sounds like the a good way to provide the spec. For eg, if you cycle the battery till its absolutely stuffed and get a large number of cycles, that doesnt tell us that the last thousand or so cycles only could deliver say 5 % of the original capacity, during each cycle?
Speedster
Honorary Master
As you mentioned earlier, you haven't been keeping up to date with developments in the battery industry. Here's a quote directly from the Pylontech warranty, and it is pretty standard for most battery manufacturers nowadays.
I doubt it lasts indefinitely
It's more or less the same technology as a laptop battery and those don't last forever.
Admittedly battery technology is advancing fast though.
Probably the state of the art in lithium batteries are electric car batteries these days. I was vaguely interested in the BMW i3 a while ago, I think they quoted 15 yrs or something? But the actual thing to think about is the deterioration in capacity as the number of cycles increases.
This whole subject is going to become more and more relevant, so I suppose we should all spend some time learning more about it.
For example when buying an electric car, one is essentially just buying the battery, so understanding the state of that battery and being able to evaluate it's condition, and compare that to other similar cars is going to be important.
The same is equally true for a home solar system, I think.
SauRoNZA
Honorary Master
And there in lies the thing for me.
Long and decent warranty. Very little in the way of space used and no maintenance required.
If I convert my geyser to solar and install the Powerwall with all the panels in the world I'm likely looking at 250k.
250k / 10 years / 12 months = R2083
That's more or less what I spend on electricity now, except the real benefit will be that I can now smash my air conditions all day every day without much of the stress of cost and still have enough power left overnight to run the one in the bedroom which I now only ever use briefly when it's unbearably hot or cold.
In fact had I gone solar the very next thing I would consider installing would be a central air type setup.
The only problem is I don't have the 250k upfront right now, which is what makes sense of it. If I have to do it on a loan basis it's not going to be as affordable.
Of course throw an electric car into the mix down the line and suddenly it becomes cheap as chips.
Zophos
Expert Member
wingnut771
Honorary Master
That's why I said within reason. End of life with LFP, the battery is still usable, with LA it's not. The only reason they replace them in electric cars is because of range. This is what 2nd life batteries are. They can still last the life of the car, it's just they won't drive as far. This isn't an issue with home storage.I doubt it lasts indefinitely
It's more or less the same technology as a laptop battery and those don't last forever.
Admittedly battery technology is advancing fast though.
Probably the state of the art in lithium batteries are electric car batteries these days. I was vaguely interested in the BMW i3 a while ago, I think they quoted 15 yrs or something? But the actual thing to think about is the deterioration in capacity as the number of cycles increases.
This whole subject is going to become more and more relevant, so I suppose we should all spend some time learning more about it.
For example when buying an electric car, one is essentially just buying the battery, so understanding the state of that battery and being able to evaluate it's condition, and compare that to other similar cars is going to be important.
The same is equally true for a home solar system, I think.
Laptop batteries are not LFP. LFP is more bulky and has a much lower energy density than cobalt which is what tesla uses.
There are better chemistries becoming available like lithium titanate, which is about 22000 cycles at the moment.
Aeon Battery - Zenaji
zenaji.com
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Just be careful of the startup current spikes of aircons, they might overwhelm the Powerall inverter.
I documented a similar issue here where a fridge (similar technology to an aircon) was overwhelming a small inverter at my sisters' place. https://powersaving.co.za/alternative-power/inverter-overload/
wingnut771
Honorary Master
That's why you do an energy audit first measuring your peaks before speccing your inverter.
Ja but the problem is that most people do not have the equipment that can detect these extremely fast current and voltage spikes. In the article I linked above, those measurements were taken with a power quality meter that cost R100k and that was when the Rand was R11 to the USD.
My company at the time just happened to sell those meters and offer those services, which was why I was able to collect that data.
So It's actually quite hard to do that in practice.
wingnut771
Honorary Master
An efergy device should work.
Efergy Home Energy Monitors: Electricity Usage Power Monitor
Efergy Home Energy Monitors allow you to monitor your energy use and cost in real-time, set budgets, view and download historic consumption data.
efergy.com
Ellies Efergy E2 Energy Monitor
Wireless Energy Monitoring System Instantly See Cost of Using Energy in Your Home Views Your Daily, Weekly, Monthly or Average Data Discover & Reduce Your Carbon Footprint
www.futurama.co.za
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Geoff.D
Honorary Master
The Tesla Powerwal is basically the same technology used in their cars, with a built-in charger and inverter.I doubt it lasts indefinitely
It's more or less the same technology as a laptop battery and those don't last forever.
Admittedly battery technology is advancing fast though.
Probably the state of the art in lithium batteries are electric car batteries these days. I was vaguely interested in the BMW i3 a while ago, I think they quoted 15 yrs or something? But the actual thing to think about is the deterioration in capacity as the number of cycles increases.
This whole subject is going to become more and more relevant, so I suppose we should all spend some time learning more about it.
For example when buying an electric car, one is essentially just buying the battery, so understanding the state of that battery and being able to evaluate it's condition, and compare that to other similar cars is going to be important.
The same is equally true for a home solar system, I think.
The Powerwall is designed to charge quickly, as are the car batteries, and run until 100% discharged.
Other Li xxxxx batteries are sort of customised to the application of providing backup power from a variety of charging sources (grid AC, Solar, Wind, Generator, etc), controlled by some or other power managment system.
