5.2 vs 8.2 Battery

I'm still waiting on a 5.2 battery, but have the option of an 8.2 right now.
Just want to check whether I have this right...
The 5.2kW has a depth of discharge of 80%, which means it has a usable rating of 4.1kW
The 8.2kW contains a pair of 5.2kW (total power 10.4kW) which again have a DoD of 80%, i.e. 2 x 4.1kW but are branded as an 8.2kW with 100% DoD.
Is that correct? If so, some questions...

• Is there actually a 5.2 with 90% DoD? Does that constitute a v2 of the 5.2? (this is not mentioned on the factsheet, but I've seen it referenced in the forum)
• If so, then I'm guessing that the 9.5 is two of those stuck together?
• Is there any advantage of the v2 over the v2 apart from DoD?
• Is there any advantage of choosing the double battery over, for example, starting with a single battery and doubling up later?
  Thanks!

simondoyle To answer some of your questions:

The 5.2kW has a depth of discharge of 80%, which means it has a usable rating of 4.1kW - YES
The 8.2kW contains a pair of 5.2kW (total power 10.4kW) which again have a DoD of 80%, i.e. 2 x 4.1kW but are branded as an 8.2kW with 100% DoD. - Proabably Yes

Is there actually a 5.2 with 90% DoD? Does that constitute a v2 of the 5.2? (this is not mentioned on the factsheet, but I've seen it referenced in the forum) - Not as far as I am aware, but its possible its in "development"

I am pretty certain that the 8.2 and 9.5 are more or less the same batteries but have slightly different internal Battery Management Systems (BMS). With the 9.5 having a new/better version which therefore allows access to more of the total charge. There may be some slight differences externally, but will be negligible.
Essentially 8.2 is 10.4 @ 80% DoD, 9.2 is 10.4 @ 90% DoD

It's not quite as simple as being "stuck together" but they will use a standard Lithium Iron Phosphate Cell internally which is then connected to a BMS or multiple BMS to control the batteries Depth of Discharge, State Of Charge, Temperature, Balancing Voltages and many other processes.

2 x 5.2 or 1 x 8.2 (or 9.5) mostly its going to come down to space, location and additional wiring. We originally intended for our entire system to be installed in the Loft, but once the battery arrived there was no way anyone could lift 110kg into the loft.

Both the larger batteries (8.2 and 9.5) have unlimited cycle warranties. The 2.6 and 5.2 have 26MWh & 52MWh (or the equivalent of 10,000 cycles).

If you buy the combined system Solar Panels, Inverter & Batteries in one go you get all kit excluding VAT. So adding batteries at a later date will cost you more due to VAT plus installation (also + VAT).

Unless you are a single person living at home alone and working all day you will probably find that you need more than 5.2kwh over night. I would say you are looking at about 3.5ish-5kwh per person (but that's a generalisation). We are occasionally running out of battery now with a 9.2 with 3 adults and fully charging every night on cheap rate tariff.

If your interested in what the internals look like you can check out the content by Will Prowse in USA on Youtube
https://www.youtube.com/@WillProwse

Or The Off Grid Garage in Australia
https://www.youtube.com/@OffGridGarageAustralia

They aren’t quite “double” as such (the 8.2 doesn’t have twice the cells as a 5.2)
The cells are just higher capacity in AH, you get various different sized cells it just happens to be that GE have chosen sizes that (kind of) overlap/double. I did a post on all the different versions here
There are 90% DOD ones in the wild.

I’d take the 8.2 personally if you’ve been offered it.

magician2905 Whilst absolutely everything you say here may well be correct - it's also true that the datasheets available for the 5.2 batteries since January of this year both (one from Jan, the other from May) state that it's a 90% DOD product... So it's bloody annoying when what turns up is an 80...

ianfretwell
These are direct from the website:
2.6kwh - https://www.givenergy.co.uk/pdfs/products/Version%202.0/Giv-Bat%202.6.pdf
5.2kwh - https://www.givenergy.co.uk/pdfs/products/Version%202.0/Giv-Bat%205.2.pdf
8.2kwh - https://www.givenergy.co.uk/pdfs/products/Version%202.0/Giv-Bat%208.2.pdf
9.5kwh - https://www.givenergy.co.uk/pdfs/products/Version%202.0/Giv-Bat%209.5.pdf

It's possible there are some legacy models still around that are the older specifications though. Either companies/people bought them and projects didn't go ahead or maybe some scalpers bought them looking to make a profit considering the price rises that occurred since the start of 2022.

hoggy cool nice link thanks

simondoyle As Hoggy says I would take the 8.2 I have the 5.2 from Jan 2022 and it is not quite large enough. If you have the space?

magician2905 Still annoying to have an 80% one when all year - up to those new datasheets (and I can assure you they still had the May one there last week when I was having to tell my installer about this) it stated 90%...

Almost like they're covering their tracks now!

Thanks for the input! Very helpful. I think I will try for supply of the 8.2kW if available.

I'm in Ireland, where we've just introduced a feed in tariff, which minimises the economic argument for a battery; but I'm also conscious of the FIT policy U-turn in the U.K., where it was introduced, only to be removed; I think it's better to future proof myself and not rely excessively on the FIT!

FIT in the UK was not removed retrospectively, only progressively reduced for installs after certain dates. Depends on the initial contract small print for Ireland, I guess!

I originally ordered the 5.2Kw battery with my system, but due to a shortage they couldn't get one in time for my install. I was offered the choice - either have the panels installed first with the battery coming later when stock came in, or to have a bigger battery. They put an order in for a batch of 8.2KW before christmas and they finally turned up in July! I went for the bigger battery and I haven't regretted it., especially as the weather has now turned and with little solar generation during the day I can still run most things and just top up when electricity is cheaper overnight. I'm not sure the smaller battery would have seen me through the day/evening until the cheap rate cuts in.

SimonP Thanks for the clarification! I wasn't 100% sure about that.
The FIT has been introduced here at quite a high level for launch, e.g. up to 20p per kW, but I suspect that utilities will reduce it over time, and that the larger battery might be more cost effective in the long run.
Thanks for all your input.

Just in the name of clarity it's come to light I'm not entirely correct on my "they don't have double the cells" part. The 8.2 does not have double the cells of a 5.2 because it turns out the 5.2 actually has double the cells of a 2.6 already!
So -
2.6kWh - 16x 51AH cells
5.2kWh - 32x 51AH cells in 2P16S so 102AH
8.2kWh - 16x 160AH/200AH cells (depending on if 80 or 100% DOD)

Phew, glad that's all clear as mud now!

Don’t suppose there are the same details for the 9 .5?

No, they have removed that line from the battery nameplate. If someone with GivTCP & a 9.5 would be so kind as to let me know what the "Factory" AH value is (it won't be 186AH as stated on it) we may be able to work it out. I'm 99% sure the 9.5 is 32Cells (2PS16) like the 5.2. The shot of it's insides has 4 "shelves" which are far too many for just two rows of 8 like the 8.2 has so 4 rows of 8 is much more likely.
It does mean the BMS is measuring paired cells not individual cells if that has any bearing on the issues that have been going on...

9.5 Internals -

9.5 Nameplate - ??? -

8.2 Nameplate - 16S Cells -

5.2 Nameplate - 2P16S Cells -

hoggy My 8.2 100% DOD says 2P16S as well?

Ra does it? Ah OK that's interesting. So they are presumably twin 100AH cells or thereabouts.
Have you had the weird SOC bug thing. I've been wondering why I've been spared and that would be something "different" between the packs.
Any chance of a pic of the nameplate at somepoint (redacting your Serial)

I've many things to change on the Wiki now.

hoggy

Did you get any confirmation from GivEnergy on the pack makeup?

TheDragon (GivEnergy) yes Martin confirmed it - 5.2 is 32 cells. Also mentioned the part about the BMS averaging out the cells that are doubled up.
Essentially 2x 2.6 packs doubled up.
Left me hanging on the rest but it’s looking like the 100% DOD 8.2 and the 9.5 are also 32cells

hoggy My 8.2 100% DOD also says 2P16S (and I have had the SOC problem).

Some interesting ideas here, the SoC is affecting the 32 cell battery, monitored as 16 cells.

Any more 8.2s 16S out there wish to comment on the SoC isues?

was signposted here to post my 8.2 nameplate details in case useful.
Installed beginning of November 2021:

Li+ Giv-Bat8.2,
Nominal voltage 51.2,
Rated capacity 160Ah,
Usable @25C 160Ah.
Voltage range 46.4-57.6,
Max Charge & discharge current: 80Ad.c.
100%DoD,
Protective class: IFp P48 / 174 / 133 / [2P16S]M / 0+50 / 90

SoC issues: I had many starting from January 2022, increasing in frequency over the spring. Usually this was a drop to zero (followed by an immediate charge up to the 4% reserve from the grid) from 24% but twice this happened from 48%.

After a firmware update in I think early summer I didn't see another from 48% and frequency of drops from 24% reduced - but did still happen once or twice.

HOWEVER in late July 2022 I then had a full outage following a power outage, where the inverter could not see the battery. This took almost 3 months to resolve, so I can't say for sure that things would have stayed better.

After it was restored to service early October and updated to 3008 by the engineer (i'm sure it had already had this, actually, but perhaps the power outage/issues reverted it?), it's fair to say it's still been flaky but not in the same way: the inverter has kept losing connection with the battery for hours at a time (although it appears the battery was still functioning throughout, but often these disconnects happened when the battery was already out of charge anyway).

Then, on 13th November, it suddenly started only charging/delivering up to 6kwh. I can see that on that night the SOC jumps from 80% to 100% over a 5 min period (i.e. instantly). After that I've not seen such a jump, but it now consistently only charges/delivers up to 6 instead of 8.

I have zero idea if any of the issues I'm describing are connected with the general SoC issues, or if my various woes offer any further insight into the physical make up of the different models. But I hope so 🙂

hoggy Hi Hoggy, yes!! I definitely have the SOC thing 😃