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Thank you to all that have been so very supportive in this thread, it is truly humbling ... but I have withdrawn from my course. What!?! ? I know. The course was going really well, learning was challenging but very satisfying. The problem was COVID-19. We had two people on the course test...

Simply put, >50V hurts. It won't kill you, but it doesn't tickle either. And it's not always the initial shock (⚡), though I can assure you that is quite disconcerting in and of itself, it's what you then do in reaction to it. For example, I was shocked whilst fitting some PV panels to my roof...

As @DJSmiley says, your BMS is there for 'emergencies'; you should never, in theory, reach the parameters set by your BMS in normal operation but they are there as a 'back-stop' to prevent damage to the cells if something does go wrong. 3.85V would be a reasonable balance between avoiding damage...

@fat_old_sun, nice write up. I think I have fallen fowl of this misunderstanding before. I mean, I've always known that if you draw more [than the C20 rate] then you get less, but I have been guilty of extended this further to include heavy discharges where, for example, you draw 100A for 0.5...

Starting college again after 31 years has been ... taxing; not so much free time on my hands. I'll be back on form soon enough! ;)

I thought this video explains the Puekert Effect very well, including the significant differences between lead-acid and lithium-ion.

Yeah, most people go that way, but I'm doing it with magnets...

Gravity is just the warping of space-time, once we've worked out how to 'unwarp' it, we won't need these silly contraptions. I'm almost there with my theory, just have a couple of i's to dot e.g. locally change the gravitational constant of the universe. Where's 'Q' when you need him?

Wow! "3,000kW"! That was some typo! :oops: Will is quite correct to suggest >2,000W, but it's horse for courses. My tipping point is usually 3,000W because I am balancing: The cost (and system complexity) of adding a 24V/12V converter (for a 24V system) The cost of bigger cables (for a 12V...

Not started that yet. The 'job offer' turned into more of a 'I'll put in a good word for you' type deal, which is fine, we were both very (very) drunk at the time! I've contacted the contracts manager at the company (AC Electrical, UK) but heard nothing back as yet. Don't want to come across as...

Mummy, make the bad man stop... ;)

Had my first day at college on Mon, and the second today. Week one summary: Transformers (step-up, step-down, isolation, current) and the (UK) electrical distribution system. Power factor and the AC 'Ohm's law'. Calculating inductive reactance and combined impedance in transformers. My brain...

No, it's an Amp thing. Basically if you draw C/20 Amps then you get 110AH (from a 110AH rated battery, obviously). If you draw more then you get less. Conversely, if you draw less, then you get more. This is the puekert effect. By how much depends on how much more (or less) you draw. Pulling...

Some further considerations: Your battery is far too under-specified to be drawing 167A from it (2,000W at 12V), that is why you are seeing huge voltage-drops under load. In addition, due to the puekert effect, your 110AH battery would actually become more like 50AH after drawing such loads...

Some considerations: Do not buy a grid-tie inverter (or this hybrid inverter) until you have confirmed with your local power supply company that it is suitable - you will not be allowed to grid-tie without approval. If all you want to do is go off-grid, why buy a hybrid? A 'normal'...

Very difficult to assess without knowing the specs of the panels and the inverter but some considerations: No need for a fuse and a DC breaker No need for a surge protector. What 'surges' are you expecting from a solar PV array? Lightning arrester, yes, definitely. Any panels in a series string...

I'm afraid I can't offer a definitive answer (I do not have one of these units) but it would surprise me if solar PV power was available that it didn't use this to charge your batteries, which in turn would contribute to house loads. It would be like dangling a carrot in front of a donkey. But...

In order to be fully off-grid you simply need to replenish what you use every day. You said that you are using "100 - 165 Amps [sic]" per day, that is 1,200Wh - 1,980Wh per day, let's take the average, 1,590Wh per day. In order to replenish 1,590Wh per day you would need around 400W of PV in...

I think this may actually be a typo - I don't think Will would specify what you could over-panel to. Of course, I could be wrong, but I would certainly prefer (as a consumer of his blueprints) to see what power I could actually achieve at the output rather than what I could theoretically connect...

You're paying a premium for these solar generator units because they are all-in-one and, therefore, portable. If you plan to take it out camping, or use it for a yard sale, or maybe help out an elderly relative if the grid goes down, then yes, the Bluetti makes sense. For what would essentially...

I'm not sure, tbh, I kinda imagined the opto-coupler circuitry to be something like this: Where an independent supply and ground would activate the opto-coupler and switch the device on, but that wouldn't obviously work with only a supply present on '+'.

Crikiebobs, I figured that would switch the inverter ON when the BatteryProtect activated on low voltage ... exactly the opposite of the required behaviour! But, hey, if it works, it works!

According to the manual on page 52, the '-' terminal of the opto-coupler is not grounded internally, so it must be provided with an independent ground i.e. one external to the inverter:

I thought you were using the Remote terminals? Had you also tried with the Alarm terminal? Sorry, must have missed that. Ahhh, you were using the remote terminals simply to activate the BP. Got it. So you mention ... When you say, "inverter_ext_switch_terminal" do you mean the terminal marked...

Actually just assumed (no charger, no ac-coupling etc). You know what they about assuming.... ;)

I would be considering whether a MultiPlus is right. Are you grid-tieing? Do you need AC-coupling / PowerAssist? Do you strictly need an AC charger if you have solar? The Victron Phoenix has 1200W, 1600W, 2000W and 3000W model variants and I dare say would be a lot cheaper than a Multi.

Oh, bugger!! Option 4 doesn't fail-safe. Hope Option 3 works!!

OK, I'm back. Had some very weird dreams... But anyway, I can't think of a way to 'invert' the Alarm control signal without resorting to a relay per the middle diagram in the inverter's manual. So I think you've got another two options, the first will need to be tested: 3. Test whether...

That's the wrong question. You should be asking yourself is the value the EasySolar worth €1,900 to me? And I've already posted my thoughts (considerations) on that. When I am designing a system, for myself or others, I always create three options: (1) Budget, (2) Comfortable and (3) Ideal. (1)...

Or you could simply connect OUT to '+', but this assumes that no voltage is on OUT when the BatteryProtect has activated, and that's far from certain and anyway, floating terminals are no good if you want reliable activation. Although I guess you clamp OUT to ground with a high value resister...

OK, investigation complete ... don't use the 'Remote' connections. These are solely for turning the BatteryProtect on or off i.e. just a master of/off switch. You need to use the Alarm terminal. The Alarm terminal basically provides a ground return when it activates i.e. depending on voltage IN...

You must not connect a BatteryProtect to the supply circuit of an inverter. Apparently, many BatteryProtects have been destroyed this way and, as this is clearly stated in the manual, it would be a very generous Victron to replace such units under warranty. Whilst I personally have a...

A 'lithium fire' isn't a 'fire' in the intuitive sense i.e. requires access to atmospheric oxygen in order to continue combustion. It's more of a chemical reaction between the battery's internal chemicals, an extremely exothermic chemical reaction. Like if you pour concentrated sulphuric acid...

Battery University has an interesting post about lithium fires.

Hey, I'm not trying to scare here, all I'm saying is that you have to take care when using the 'explody' types of lithium-ion. Making sure you charge with good quality components and, of course, have a solid BMS, configured correctly, the risks are minimal. But, like everything in life, all you...