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

Ints

Nothing in stock there, lead times 50-60 days now. Maybe I could have some but decided to get faster delivery so that I don't loose my cool while waiting lol. So paid this am and now we wait. So now I am not sure will I need to balance etc, have no tools for that. Do I wait and see or order balancer right away?

unkel

https://www.boards.ie/discussion/comment/121465471#Comment_121465471

Looks like the batch shipping this month has run out. I bet a lot of it is going to Ireland because of this forum 😁

Cheapest ever cells per kWh they were. The new batch is the same price, so for anyone who can wait until the end of next month for delivery, I would order them now. Remember these cells come from within the EU, so would not take any longer than if you buy cells now directly from China yourself.

slave1

Some will say it's not required but top balancing before install is something lots swear by to allow your BMS to get good grasp of battery capacity. Where are you based as likely folk around that could lend you a bench power supply (or just get one off AMZ)

Ints

Any suggestions on cheap bench power supply? Also I presume I will need breaker in between battery and Solis hybrid 5kw inverter? Any suggestions on that? And that's me set, or am I missingsomething? Sorry noob here lol

Ints

I am in Cavan town

unkel

https://www.boards.ie/discussion/comment/121465590#Comment_121465590

Power supply for what? Charging individual cells or the entire pack? These types are widely used, cheap and cheerful, you can get them in different voltage and amp ranges

https://www.amazon.co.uk/RUZIZAO-Power-Supply-Variable-Adjustable/dp/B09H7D1FDS/ref=sr_1_50_sspa?crid=1JA316PA18657&keywords=bench+power+supply&qid=1701947652&sprefix=bench+power+supply%2Caps%2C65&sr=8-50-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9idGY&psc=1

Ints

I need it for cell balancing. I presume that my inverter will charge battery after i balance them so nothing else needed?

unkel

https://www.boards.ie/discussion/comment/121465898#Comment_121465898

One of those will take several weeks to top balance your cells. If you get a decent BMS with active balancing, there is no need to top balance before you assemble the pack. Technically it is better if you did and your pack would be balanced from the start, but from a pragmatic point of view you will be losing money by not having your pack working for you straight away

Ints

Thanks for that. I will check cells before I decide, for now will order that small bench power supply. About that breaker between battery and inverter- do I need one and if yes what are the good one for the price 🤔

slave1

Ordinary rotary isolation switch will do the job, just get the proper amp one for your setup

Ints

I will have 200amp bms, so that means I need 200amp isolator?

Ints

Can anyone shed a light here. I have 5kw system with Solis 5kw hybrid inverter. Let's say panels are maxing out production at 5kwh but my house using 7kwh at the minute, will it take missing 2kwh from battery (soon to be installed) or grid?

championc

The inverter spits out it's capacity - so max 5kW and therefore 2kW from the grid if your load is 7kW

DC999

https://www.boards.ie/discussion/comment/121473963#Comment_121473963

It will pull from panels first if available, then battery (there is a max discharge limit on batteries), then grid

slave1

https://www.boards.ie/discussion/comment/121473963#Comment_121473963

No, 5kW inverter is maxed at 5kW, won't be able to supply the 7kW in that example so will 2kW shortfall from the grid

Fantana2

Considering most smart plans seem to have a three hour EV rate and a standard 12kv connection what is the optimum battery size? In this three hour window I’d like to charge the EV, run the dishwasher and heat the hot water off the immersion and charge a battery to full.

graememk

https://www.boards.ie/discussion/comment/121477924#Comment_121477924

Most inverters top out at 100 amps

That's 5kw

3hr is 15kWh, 4hr is 20kWh (useable)

Having a bit more would be nice as you could "get ahead" on the lower demand days

dermotx

https://www.boards.ie/discussion/comment/121440550#Comment_121440550

To answer my own question, it seems that the Seplos BMS 3 should work with a Solis inverter. See attached on amazon.de and post in this thread from connesha on page 27 no. 783 on 30 March this year.

In my original post I said "What think ye? Solis or JK". I meant Seplos or JK. Also I have a 3kW solis inverter not 3kWhr.

Seplos BMS.jpg

insular1

Hi all, finally got Home Assistant up and running and have linked it to the new JKBMS for the past few days. A small issue I have had the last 2 nights is that when the battery charges to full Cell 1 on Battery 1 hits the over protection voltage and stops the charge. This causes the solis inverter to alarm for 5-10 minutes before voltage settles and everything resumes as normal. Wondering if I have a bad cell of else if my OVP voltage (3.6V) is too close to my SOC100% (3.55V)? How close should all the cell voltages be at the top and bottom of the charge? I haven't done many full charge discharge cycles so wondering if this might settle out over time? Have attached the grafana chart of the event last night. Bottom graph should read battery 2 and not battery 1.

Cell voltageB1B2.jpg

graememk

https://www.boards.ie/discussion/comment/121482239#Comment_121482239

First thing Id do is reduce the charge voltage, And that should give that cell 1 time to balance out.

If the cell is weak, it should be the lowest when you are at a low state of charge (below 3v)

insular1

Generally very little difference between the Cells except at the top and bottom of the charging curve. Cell 1 is generally the highest across the board, so probably not a weak cell so?

When you say reduce the charge voltage do you mean the voltage at which the BMS registers a cell hits 100%? Or the actual voltage the Solis is charging the pack at? If the latter then would I correct in thinking that this is the "Charge OVV_Pro" setting in user defined battery settings on the solis? I might drop this from 60V to 58V tonight and see if this helps. Thanks!

graememk

https://www.boards.ie/discussion/comment/121483162#Comment_121483162

You'll only see any difference at the top or bottom. Anywhere else you'll not see it

SD_DRACULA

https://www.boards.ie/discussion/comment/121483162#Comment_121483162

As per Andy's video of the new jk firmware settings v14.13, there seems be an option to set the voltage of when the battery reads 0% and 100% maybe that can help

munsterfan2

https://www.boards.ie/discussion/comment/121374621#Comment_121374621

Just an update, replacement cell arrived. Sent back the defective cell using GLS ( 36€ shipping ). Received a full refund of the €135 for the replacement and the €36 shipping costs. Great service.

unkel

https://www.boards.ie/discussion/comment/121486495#Comment_121486495

Well done. And well done to NKON too. Excellent customer service from what seems an honest company.

Also their latest price of €60 + VAT for a 305Ah cell (about 1kWh) is the cheapest we have ever seen LiFePO4 batteries for. They sure are the ones I would be buying now. I would put aside my feelings about EVE type cells bloating and their inferior small welded terminal posts.

munsterfan2

https://www.boards.ie/discussion/comment/121486557#Comment_121486557

Me too, but with 2 EV's charging most nights, heat pump hot water, dishwasher, washing machine etc I am on the just about scraping 12KW into my battery pack in the 4 hour EV slot. Otherwise I would pick up another 15kw pack.

on_the_roots

I'm thinking of placing a NH Switch Disconnector for NH00 fuses instead of a DC Circuit Breaker between battery and inverter.

NH fuses are cheap and rated to handle DC arcs up to ~120kA , I think they would be a good protection alongside the internal battery fuse.

Any thoughts on that?

unkel

https://www.boards.ie/discussion/comment/121486590#Comment_121486590

Same here, I just about get 15kWh into my pack in 3 hours. Half of my 42kWh night slot has been taken up by the 2 EVs alone.

With the big battery I am well prepared for the next change in the utility provision system though - when we get agile tariffs. Where sometimes we will get paid to use electicricity and other times we get paid extremely well to supply electricity to the grid. Bring it on!

DC999

https://www.boards.ie/discussion/comment/121486930#Comment_121486930

Yeah, UK paid £4.20/kWh for a recent event. Or 84 times of a 5c night rate. This punter cashed in: I earned £32 in one GivBack session! - DFS for lazy people (youtube.com)

unkel

https://www.boards.ie/discussion/comment/121487346#Comment_121487346

Some creative accounting from your man there 😂