10kWh LifePO4 DIY Battery Addition..... Here is my write up.

Thanks, that’s what I was trying to work out, I wasn’t sure if a grid tied system would be worth it without solar as most info online assumes that setup.

I was thinking of timing the charge at night. The battery would live in the utility room next to the main appliances so not too difficult to manage.

The 2kw pure sine inverters I was looking at on Ali Express we’re around €200 but maybe not up to the job.

I have a A+++ heat pump dryer which barely pulls 1kw but it runs most days during winter, same for washer which is also A+++

Fair enough, looks like a lot of the videos on YouTube we’re too good to be true!

Starting small is definitely a good plan, I’ll probably try a small 2-3 panel solar setup on the shed roof and play around with that to learn how it works.

If VW enable vehicle to home for my ID3 then I’ll look into that too

We do as much as possible but I don’t get up early enough to fill the dryer after the wash - planning an over complex battery solution seems easier 😂

Does your system work during power cuts or is that an option?

Joking aside, I’d get a solar install with a hybrid inverter and add my own battery later - like most here. The problem is that I only have room for 4 panels on my roof so not enough to qualify for the grant.

Power wall type system are hard to find at a less than eye watering price (including install without solar+grant) right now and I’m guessing that most electricians wouldn’t be happy about grid connecting a diy battery.

That’s what got me thinking about a diy battery without grid connection. I have a good understanding of the concepts and how it all works but very little practical experience of which hardware combinations works best - especially BMS and inverters as the spec sheets for a lot of the gear on Ali Express can’t be trusted.

I looked at all in one battery packs but it looks like most affordable 2kWh packs don’t use LiFePo4 cells, which are the only type (of large battery) that I’d trust in my house.

I agree with you that my solution is not really practical for my uses and thanks for your answers, that’s what I was looking for.

By the way, what is it about the 200-300 euro inverters, like the ones on Ali Express, that makes them bad? It it there ability to handle inductive load or peak power demand?

Older hot tumble dryers too with clogged up fluff filters and dodgy charging plugs with damaged or poor quality cables are even worse.

It was reported last year but haven’t heard anything since - VW’s software quality and update schedule hasn’t been great. I also wonder about V2H standards and if the expensive bidirectional wall box will work with other EVs

would something like this be suitable to install inverter and batteries outside ?

@electricus, quick side note. It's defo worth your while seeing if you can really only fit 4 panels. A small shed likely fits that. We got 16 (1m wide x 1.7m high) onto a small '2 up, 2 down' house. Includes 5 of them on an extension flat roof. So I would guess it's not space that is the issue.

Maybe you already said you have other older panels or solar thermal on the roof. Or one roof is pure North (and even then it's a possible runner for a cheap DIY setup down the line). We have a few on a NW roof output is and grand up to this time if the year. Others told me that's crap in Winter but working find to this point.

Take some pics on the roof maybe and pop into into the quotes thread asking for suggestions. Some shade can be worked around with optimisers. We had vent pipes causing shade so cut them down a little in height and no more shade.

As I said, everyone to their own and if it gives you peace of mind, that's important too and I'm not having a go at you or Dublin fire brigade for that matter. In the interest of a balanced thread, here is the Dublin fire brigade warning.

Dublin Fire Brigade shares fire warning about household appliances as they highlight common mistake - Irish Mirror Online

However, I was mentioning above specifically "dish washers", and to your point about "where is your statistically more chance"...here you go.

Faulty appliances cause 43 fires a week in England, research finds (electricalcontractingnews.com)

Fridge/freezers comes in at #8 and dish washers #7 in terms of occurrences of fire, at least in 2019. However, it shouldn't be forgotten that this is a country with 60 million people. <500 fires is a small number when you are talking about potentially millions of units, and many of those units were probably poorly maintained etc. That's not to say that it's "ok", every fire could potentially be the loss of life, only that it's a small number.

but we're going a little off topic in relation to the 10Kwhr Battery addon - but yeah, always interesting to me that people won't use devices when others in the house are left on ok.

I have two questions, the first is probably for @championc .

Roughly what physical space do your 2 x 5 kwh of batteries take up once assembled and insulated?

We are trying to figure where to put them in the house/outhouses.

The second is a bigger issue but related to the efficiency AC/DC points above.

After much thought, as we have a field with a good southerly aspect, we are thinking of a ground mount, even though they are more expensive. But the best position is nearly 120m from the house. I know that most inverters these days come with standard weatherproofing and can be installed outside. And that it's more efficient to transport AC versus DC over longer distances. But then what do you do with the batteries which need to be near or in the house?

Or is the practical answer no, if you want to have a hybrid inverter and batteries, you can't put the panels down the field?

Can you put the batteries in a cabinet under the solar panels down the field? We are coastal, I'd be worried about corrosion as we get sea gales and everything rusts here.

I know the term micro inverter tends to be confused with optimisers like Tigos, but maybe they have a role for this scenario?

Thanks! And yes, I know, we probably would have to get planning permission to put them in a field...

I have received 8 of my cells so far (others stuck in post) from OYE. I topped them up to 3.67v with bench power supply. It dropped to 0.05a for few hours so believe they are near enough 100%, but when I capacity test them, the result is 135ah. Am I doing something wrong or could I have a bad capacity tester (DL24P)? Or should I be opening a dispute?

Thanks @munsterfan2, I am in Co. Down so guessing you are not close. I thought I might be doing something wrong. Low voltage cut off is 2.6, though cells are 3v at end of test, but 2.6 under load. I was testing at 20 amps. Maybe should be at 10 amps?

Dispute is looking like way to go thought.

I think issue might have been with the cables I was using. The voltages on the tester were not matching my multimeter. I have crimped up 2 sets of very short wires. Used speaker wire for voltage pins and 2.5mm for amp pins. Voltage on tester is reading much closer now to both multimeters, though test only running for 30mins. I will be keeping a close eye. I had crimped 2 sets of 2.5 together before and cables were 50cm long. Will let you know how this test goes.