Idiot's guide to a self build battery

[Mr Gus]

Sounds good, how many hours on it?

Jinx, remember this element of the kit may eventually need replacing but the second hand market thrives from install & update system inverters one of mine was bought from a member here doing the exact same thing, ..inverter bed hopping as well as troubleshooting where needed due to familiarity.

[MrPablo]

Looking at my records, the inverter was first commissioned on the 24/5/22 as a battery only setup, then solar was added on 19/8/22.
It's done very well, I wouldn't change it out if it wasn't for plans to move away from a combi boiler and the associated gas connection.

[Mr Gus]

Wow, that's clearly low mileage then

[Jinx]

If you're not fussed about getting a brand new unit, I could sell you my Solis RHI 3.6kW hybrid inverter.
I'm planning an upgrade anyway, so two birds, one stone.

PM sent

[marshman]

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[Jinx]

I’ve been asked to look into disposal for more but it’s very much on the drawing board and would require taking expanded cells and possibly burnt items, testing and sorting. I do have a few contacts from previously disposing of SLA batteries and all the paperwork it entails but need to look into LiFePO4 requirements.

SLA can be "disposed of" at pretty much any scrap yard - sorry metal recyclers and you get paid, if over a certain amount (weight) you simply sign a WEEE form and waste transfer note. Other types of battery are a different kettle of fish, or can of worms (chose your own animal and container as appropriate)

Yes we always did that for small amounts, the quantity we often had meant collection with a couple of lorries. G&P are great, they turn up with a forklift onboard but they pay poorly. City batteries (previously Vintons) are the preferred recycler now.
Strangely enough I took in a small load today and got £500/tonne
I asked, they don’t take any lithium types.

[Jinx]

Well I decided to go the blue route after all and the main parts have just turned up. I have processed a couple of packs and brought them down to 16S, will do a couple more and then see where I can fit all this stuff.



Get ready for plenty of questions!

[nowty]

Whats your capacity (kWh) going to be ?, I needs to know.

EDIT - I just noticed you mentioned they are 70Ah cells, so 4 strings of 16S are going to be around 14 kWh.

[Jinx]

Whats your capacity (kWh) going to be ?, I needs to know.

EDIT - I just noticed you mentioned they are 70Ah cells, so 4 strings of 16S are going to be around 14 kWh.

I have more than that (6) However… not too sure how many I will use first of all. I’m very tempted to use without balancing and see how they fare, keeping some back in case of failure.
Handy 12v sets are also created breaking these down, so I quite fancy making use of these somewhere, possibly a home made Jackery type product and a friend wants one for an electric scooter.

[nowty]

My cheatsheet for 16S LIFEPO4 may help you.



If your going to run without a balancer (I did for about 3 years), I would recommend you run them very conservatively, not too high and not too low. Initially balance them near the top end, then cycle them between 80% and 20%. If all is well, then you can widen out the range a bit.

But I would recommend getting a balancer sooner than later, cell voltages really rise and fall dramatically at the top and bottom ends.