Does battery weight matter?

[Tomtomtom]

I'm yet to see a LA battery that gives anywhere near 300 cycles at 100% DoD.

I'm not saying this is a fair example but it's definitely a proof of concept:

Trojan Battery | Home

Trojan Battery Company is a pioneer in deep cycle battery technology, introducing generations of deep cycle flooded lead acid, lithium-ion, and AES AGM batteries.

www.trojanbattery.com

> 5000 cycles at < 40% DoD. Not bad.

 

[wingnut771]

Has anybody here run a lithium battery beyond the cycle life that put on the sticker? Do they just die ? Do they lose capacity?

Like hubble s-100A +- 4000cycles what happens after that?

Nothing really, it just has less capacity but is still usable. LA is unusable except for powering a 15W router.

 

[AchmatK]

Has anybody here run a lithium battery beyond the cycle life that put on the sticker? Do they just die ? Do they lose capacity?

Like hubble s-100A +- 4000cycles what happens after that?

Here's the thing. They don't just die.

After 10 years I expect my battery to still be able to provide 60 to 70% of its rated capacity. After 20 years it might be 25% but not entirely dead.

So my 20kWh battery bank might be a 5kWh battery bank eventually. Not just a dead weight and I'm sure I could use it for other applications for a good few years after that.

 

[Speedster]

Has anybody here run a lithium battery beyond the cycle life that put on the sticker? Do they just die ? Do they lose capacity?

Like hubble s-100A +- 4000cycles what happens after that?

Cycle life for lithium systems are in excess of 3000 (for the cheaper ones). Cycling them once per day will take 8 years. The higher rated ones are at 6000 cycles, that's more than 16 years. There was a team at one of the universities in Aus who ran long-term continuous tests on a range of batteries and their results showed that lithium battery capacity drops off linearly over time. So at 4000 cycles those batteries will have say 60% of their capacity left (I think they're NMC?) and this will continue to decrease as you use them more.

 

[AchmatK]

Cycle life for lithium systems are in excess of 3000 (for the cheaper ones). Cycling them once per day will take 8 years. The higher rated ones are at 6000 cycles, that's more than 16 years. There was a team at one of the universities in Aus who ran long-term continuous tests on a range of batteries and their results showed that lithium battery capacity drops off linearly over time. So at 4000 cycles those batteries will have say 60% of their capacity left (I think they're NMC?) and this will continue to decrease as you use them more.

One thing to remember about the Australian tests is that they are running their tests at 1C charge and discharge rates which also impacts on capacity and cycles.

I'm discharging mine on average of 0.2C but charge for an hour at 0.45c but only really in summer during the middle of the day. Most times my charge rate is under 0.3C

 

[zll]

Two points.

1. This doesn't answer my question about what to do if you're only in the house for a couple years. For many people talking 5-10+ years with these things is just irrelevant because they're not looking that long-term.

2. As @AchmatK has pointed out and I can attest to, the real problem is that gate motors/alarms etc. simply don't have fast enough chargers to tolerate < ~90% grid availability. Whatever your chemistry, you will run into trouble sooner or later at continuous stage 6+. I'm first putting in an external solar charger and then I'll look at lithium.

1. Why are you talking in terms of years when lead-acid will get burnt through in a few short months in our current situation? I literally helped my neighbours who were having the exact same issue by telling them where to go get LI batteries that work with their alarm systems (yes, I also shared this information because their alarms were waking me up).

Also, if you spend R850-R1000 and it goes onto the next person, who cares if it solved the problem? As I demonstrated, you'll still be burning through literally at least R1000 per year at the current state of load shedding buying lead acid (at least that was my experience). Or you buy one (edit) LI at the same price, and then the next person to move in when you move out gets the benefit of it until it dies.

Finally, unless you are a vampire or don't sleep, most people would happily pay more for a solution that doesn't die in the middle of the night and wake them up and make them tired for work the next day, unless they are so broke that they can't afford that. That being said, I would rather suffer without an alarm for a few months and save up to buy an LI battery than keep throwing money into the bottomless pit that are lead acid batteries.

2. Yes, but you still increase the length of time your alarm/gate works by going with LI over LA, even if it doesn't charge up to it's full capacity with the ridiculous amount of load shedding slots we currently have.

 

[Tomtomtom]

What sized lead acid battery bank is needed to accept this charge?

Yeah. Your charge is bigger than my charge.
Don't think anyone here advocating lead-acid for your power station.

Incandescents are used in ovens and fireplaces because new tech can't handle the heat. The only place where LA still has any merit for consumers is in starting cars/bikes.

LEDs could be used with light pipes to make it work. Maybe in some ovens they do. I think a better reason is that an oven is supposed to get hot, so the inefficiency of incandescent -- the selling-point of LED -- is moot. If not an advantage.

LA is unusable except for powering a 15W router.

Looks like we now have cars, bikes, and 15 W routers. What next?

Edit: datacentres? I know there's noise about going lithium along with going green / off grid entirely, but for a non-newsworthy new build with classic transfer-to-diesel-generator design I'm gonna guess it's still mostly LA?

 

[Tomtomtom]

2. Yes, but you still increase the length of time your alarm/gate works by going with LI over LA, even if it doesn't charge up to it's full capacity with the ridiculous amount of load shedding slots we currently have.

At continuous stage 6/7, it'll zig-zag down to zero over a while (weeks, months?) and you'll have upset neighbours again. Good news is they could hook up an external charger, but they'll probably just chuck it.

I think we have a real problem on our hands with this, and I agree throwing batteries at it is not the solution.

 

[Speedster]

One thing to remember about the Australian tests is that they are running their tests at 1C charge and discharge rates which also impacts on capacity and cycles.

I'm discharging mine on average of 0.2C but charge for an hour at 0.45c but only really in summer during the middle of the day. Most times my charge rate is under 0.3C

I think I read somewhere that they tested the batteries as per their published specs but your point stands, their results are close to worst case. Nobody is running their batteries at anything even close to 0.5C constantly, whether charge or discharge. We mostly average probably around 0.2C with some peaks here and there.

 

[PsyWulf]

I'm not saying this is a fair example but it's definitely a proof of concept:

Trojan Battery | Home

Trojan Battery Company is a pioneer in deep cycle battery technology, introducing generations of deep cycle flooded lead acid, lithium-ion, and AES AGM batteries.

www.trojanbattery.com

View attachment 1444411

> 5000 cycles at < 40% DoD. Not bad.

at C20
If you charge faster you're raising internal resistance
If you discharge faster you're cutting available capacity

If you can discharge Lead batteries only 40% over 20hours - kudos to you on your giant lead farm

 

[AchmatK]

I think I read somewhere that they tested the batteries as per their published specs but your point stands, their results are close to worst case. Nobody is running their batteries at anything even close to 0.5C constantly, whether charge or discharge. We mostly average probably around 0.2C with some peaks here and there.

Actually a lot less than that.

I have the inverter AC running which runs the whole night and even then it's 0.07C discharge rate.

 

[Koosvanwyk]

For example, my 4.8kw narada battery has about 9000 cycles at 60% DOD. Currently Ive used about 3500 cycles. That means I will start seeing a loss of capacity after another 5500 cycles.

The end of life of a Lithium battery is defined as when the raining capacity (Ah) reaches 80% of its original design capacity. So if all is perfect the battery will already have lost 20% of its capacity over those 9000 cycles. So you wont be seeing a loss of capacity only after another 5500 cycles, you are already seeing it.

It you have access to an accurate SOH reading (from the BMS directly) you can easily determine the remaining capacity (and capacity lost) during the 3500 cycles that you have used.

 

[Koosvanwyk]

LEDs could be used with light pipes to make it work. Maybe in some ovens they do. I think a better reason is that an oven is supposed to get hot, so the inefficiency of incandescent -- the selling-point of LED -- is moot.

Just for shits and giggles, I recently invested in a A++ Siemens oven, the lights are LEDs.