Idiot's guide to a self build battery

[Stinsy]

Just received a photo of my order prior to shipping and a testing video.

Wow how many are in there?

64

There are a few people on here who seem intent to make @nowty's battery look positively "medium sized"!

[Caesium]

I'm minded to build a third (and final!) 16S stack for about 42kWh total storage. That'd be more than enough and I like that I'd have enough redundancy to take a stack out of service at a time for maintenance, balancing, replacing cells etc, and still not overload the remaining two too much.

But probably not just yet.. out of work at the mo so need a job before I spend another £3k on this

I actually had to take half of my current stack out of service since Sunday as one of the JK-BMSs just stopped working overnight. Came to it one morning and no power. Poof. That left me with only 14kWh for a few days and it was a bit tight at the bottom end, was worried about the low voltages. The Saving Session on Monday actually helped a lot

Ordered another (from Fogstar this time, UK retailer) so I have some warranty in case it happens again. The existing one (from ali) is just going in the bin. Not worth any bother.

Also took the opportunity to upgrade it from the 0.6A balancing one to a 2A balancer, so I might even be able to manage without the separate balancer.

[Tinbum]

Came across this thread that looks very interesting. I have some Seplos BMS's but may do this instead.

https://community.openenergymonitor.org ... /16491/286

[Caesium]

Being a tinkerer who can't leave my batteries alone this sort of thing should really appeal to me. I did look at these before and decided against though, because it felt a bit too overengineered and complicated.

That's a lot of individual boards that can fail. The fewer components there are in a system the less that can go wrong. Granted, one of my JK BMSes just failed but as a one-off I'll accept that.

I can't remember if I looked at the cost of this setup but given you can get a 16-24S BMS for £160 (Fogstar; or less if you wait for China slowboats) each cell board+components would need to be not much more than £5 to be competitive, plus the controller board itself at another £5-£10 I guess?

I didn't really relish the thought of assembling 16 identical copies of the PCB; I believe JLCPCB can assemble most of it but that'll be more extra cost. Have you priced up a total for it?

[Tinbum]

Have you priced up a total for it?

No, not as of yet. Just been reading through the thread. As with a lot of these things their doesn't seem to be an idiots guide to how you actually go about doing it- their's bits and pieces all over the place.

I liked the idea of fewer cables, a small controller that is easy to mount and its easy to replace a board if you do have a fault.

[marshman]

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[Tinbum]

I think the latest version does have CAN and they do mention connection to Vicron inverters.

"The latest version of the controller uses an ESP32 and supports CANBUS, RS485, SD CARD logging, relays, SSR outputs, multiple inputs, AVR programmer and much more.
Although the hardware is complete, not all features are usable from the software, this will be developed and improved over time to make use of the hardware."

It's a bit like I said, information is all over the place. If you get in from the start you know what's going on. It's a bit like my Node-Red flows, they make perfect sense to me (most of the time- until Alexa wakes me up and tells me I've been an idiot) but to others they wouldn't without serious studying.

At the moment i have the time as I'm physically unable to do manual things.

[marshman]

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[Tinbum]

I understand about the latest version having CAN coms to the inverter but that relies on the inverter controlling the current and doing as its told. A "proper" BMS will control/limit the current if necessary - the DALY Smart BMS I am currently using does this for both charge and discharge.

Now all I need is an "open" project for a "soft start" for my heat pump and life will be good, convinced mine keeps "dipping out" with glitches on the supply, but can't track down quite what is happening ..... yet!

Yes the Seplos does that as well. I'm guessing this could as well.

I know what you mean- I think our washing machine may be having an Arduino implant soon as it's driving my wife mad. It literally has a mind of its own.

[marshman]

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