Maintaining battery long term

Hi,
I got my 8.2 GE battery installed last week, added to 5kW PV with GE 5 hybrid inverter. So far the system behaves as it should, without me having constrained too much, e.g. EV charger and immersion discharges the battery.

Now, what I need to know are a couple of things:

• from my experience with EV batteries, the usual advice is "don't leave the battery at 100%". But my home battery seems to stay at or close to 100% for extended periods. Obviously it is summer, and that will change come autumn/winter. But what is the general consensus, is this something that I would need to be concerned?
• and the second is the result of the previous question. If I need to maintain the battery long term, is there a way that I can only charge it and maintain 50% charge for example? I know that I can set grid charging to certain %, but that is not what I'm looking for.
  Any input would be appreciated!

rio911 This is something I've been meaning to ask. I'm going on holiday in a couple of weeks so would like to know the best state to leave the battery in. Is it best to charge to 100% and let the overnight house drain it to 80% and then charge back to 100% or is it better to cycle between 60-80% for example.

rio911 What you mean long term. Battery have 10 years warranty and in your case 80000kw charging capacity.
I would say that battery (cells) will least 15 years no problem. Keep battery cool and reduce charging power to 1.5kw or 2 so battery will not get hot when on charge.
And yes better to keep battery while on holiday at max 80% SOC. It will increase charging cycles battery can run.

But TBH there is no option to charge battery to 80% or something im missing?

2 points to mention here:

100% is not a true 100%, these batteries have a top and bottom buffer.

They also use LFP technology in the cells so actually don't mind going to 100% as much as Li-ion. Also charging to 100% is helpful for the BMS to keep the state of charge 'calibrated' 👍🏻

With the waranty given both in terms of time and total throughput, battery lifetime is not anything I worry about. Far more pressing issues short term, mainly reducing our grid usage of very expensive electricity. JMHO

Thanks all for the replies!
I will try and cover as much as I can:

• Long term would be something beyond the warranty. And by the way, the GE battery warranty is 10years and unlimited throughput for the 8.2kWh (I'm still not sure what that means and if that has an impact on the performance of 70% or how that works).
• @HipHopAst The battery capacity is 8200Wh (reported on my system as 8.19kWh/160Ah). Cold is not batteries best friend, but I get your point about the charging speed. Mine currently shows charging power as 1629W, but I'm pretty sure that I have seen it charge at more than that. So, maybe there is a setting I'm missing or not working?
• @Tom_P how do you know the battery chemistry? But LFP or Li-Ion it is pretty much the same guideline according to Tesla battery management.
• @Tom_P do you know the buffer sizes? As a home battery I very much doubt that is has anything large to spare and I haven't been able to find anything specific.

And by the lack of guidance, I'm assuming there is no way to limit the BMS SOC% 🙁

rio911
" But LFP or Li-Ion it is pretty much the same guideline according to Tesla battery management."
Actually it's not. Tesla recommend that LFPs are regularly charged to 100%(weekly), whereas Li-ion batteries are not.
I wouldn't draw many comparisons though..the Tesla packs have sophisticated thermal management that isn't present in GivEnergy packs, for example.
Don't overthink this...let the system do its thing. The way that I look at it is that in 10 years an 8kW pack will probably be considered tiny and will cost a third of what's available at that time.

rio911 Yes cold and warm is enemy of the battery.
What i try to say that avoid hot and cub zero temperatures as well.
Around 20C would be ideal. don't let battery go over 40C and fall below 10C and should be fine.
I didnt open battery pack yet but hopefully there are some decent cells.
Most popular are EVE and they are rated for 3500 charging cycles from 0 to 100 (that's 10 years) but if you reduce to 80% capacity its life time will extend to well over 5k. Of course big impact to that is charging current. Hopefully in 10years time price of 8kw battery will drop by half to £1.5k
Fun fact that if you will build your own battery pack it will cost you half for what you paying for AIO system.

For my pennies worth I think 10 years will be a lifetime in battery technology. I remember buying a memory card for my camera that was 32mb, now 32gb is the norm. PV panels are a fraction of their original cost also. 10 years ago a car had say 20kWh battery now 50-60 for the same money. With the whole world looking for better batteries and a fortune to be made from inventing one I would expect a 80kWh to be around in 10 years for the same money or an 8kWh to be a tenth the price. I'm pretty sure the batteries will in fact outgrow the solar panels output by quite some margin!

rio911 Mine currently shows charging power as 1629W

On the web portal Inverter - Settings - Battery Options, you can set the charge and discharge power from 0-100% (ie 0 to 2600/3600W depending on inverter model).

CARLMW There will always be new tech to bump the price too - my current DSLR takes CFexpress cards - in 2020 a 120Gb one cost £175 - same manufacturer (Sony) about the same size today is £204 , A CF card (My other camera takes these) of the same size is about £120 (Sandisk)
Sd card same size and Sandisk is £30.
Depending on the tech will determine the cost in a lot of ways. No doubt battery tech will be similar, and like memory cards it will be the speed that makes the difference,

anglefire your right of course it’s like tv’s they just keep making bigger ones, curved ones, 3d, 8k etc. to get people to pay more. I think it’s about what people want vs what they need however and once batteries can charge / discharge 2-3 times faster and have the same kind of capacity increase, what comes after will be of little consequence for most people. Very few people actually need a memory card as fast as yours or a car that does 180mph but there will still be a market for them. In the future the average solar PV owner will be an electric Ford Focus driver, doing the average 40km commute stuck in traffic however. All new builds now have charge points and after 2025 heat pumps rather than gas. I think the solar PV market is about to explode driving prices down massively once production ramps up in a year or two!

I think it cost/price will remain the same imho. Demand will outstrip supply (like it is now) and this will keep prices constant despite production process efficiencies etc, plus of course, there is only so much raw material in the earth to start with so mining the resources required will get more and more difficult.

I also believe that once ICE vehicles are stopped that it won't be long before the cost per mile will be fairly similar to what it costs in petrol/diesel. There is only so much electricy to go around after all!! Night time rates etc will disappear as everyone charges their cars at night will equalise the demand over industry/household use during the day.

Ra

"Demand will outstrip supply (like it is now) and this will keep prices constant despite production process efficiencies"
Unlikely, given that lithium battery costs have reduced by 97% over the last 30 years. Yes, there was a pike in 2021, but that matched the COVID pandemic.
https://www.economist.com/graphic-detail/2021/03/31/lithium-battery-costs-have-fallen-by-98-in-three-decades

"There is only so much electricy to go around after all!!!
Which happens to be the very first myth busted on the National Grid website.
https://www.nationalgrid.com/stories/journey-to-net-zero/5-myths-about-electric-vehicles-busted

Zakalwe Are we supposed to believe people in positions of power now? 😆 We won't be using as much power just like the NHS will be getting £350m a week

Ra

"Are we supposed to believe people in positions of power now? 😆 We won't be using as much power just like the NHS will be getting £350m a week"
That's a heck of a conclusion that you've jumped to.
When discussing a subject I always find it useful to see what the main stakeholders and experts in the field say about the subject, rather than some rando off the Internet (or, indeed a politician with a vested interest). In this case, the National Grid most definitely qualify as those experts.
I've been following their Future Energy Scenario documents that they publish every year. I'm guessing that this will be the first time that you've heard of the FES....

CARLMW if batteries use tech that's abundant then yes expect a price drop, but with the metal's in your modern batteries then no, tesla have indeed squeezed about 30% off manufacture costs "Labour + Materials". expect the price to stay the same with demand 6mts wait from the manufacture from an order today.
silicone sand is cheap as chips, so it's why pricing as drop on PV panels and SD cards.

bottom line, when battery tech drops nickel for some else, is when battery's will have a big drop in price.