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So I've been umm'ing and ahh'ing about if for a while but I finally decided to embark on a new career - I'm going to re-train as an electrician. I've worked out all the courses and 'ologies I need and have enrolled on my first course starting 13 Sep 2020: City & Guilds [2365-3] Level 3 Diploma...

@dsilver, I've given it my best shot but please exercise caution, I am not familiar with this BMS, this is just an educated guess! Xiaoxiang BMS Settings v1.0.xlsx

Generally speaking, so long as you don't exceed the PV input limits, you can over-panel any modern MPPT-based SCC and it will dynamically control the input power to whatever the output needs. For example, if you were charging a 24V battery at 20A, that's a peak power requirement of 584W (29.2V x...

Just completed my enrolment on my first course and paid my fees. No turning back now! Course starts on Mon 14 Sep 2020 and my first day in college is the following Mon 21 Sep 2020. Very excited - my plans are becoming reality! ? And, believe it or not, by pure coincidence, I met and had a few...

I learned something interesting about Victron Solar Charge Controllers (SCC) the other day. Most SCCs on the market provide two important specifications: Maximum PV Voltage and Maximum PV Power, and you can use these to correctly size your SCC to your PV array. Victron SCCs do not follow this...

@ecualibrium, I could be wrong here but I sense a possible misunderstanding between the nominal voltage of a Lithium-ion cell and its recommended charging voltage. These two things are entirely different. The nominal voltage of a LiFePO4 cell is generally between 3.2V and 3.3V (or 12.8V - 13.2V...

Quite a few questions! I'll address the questions first, then provide some general advice. You can consider your Solar Charge Controller (SCC) to have two independent 'sides', the PV side and the battery side, and never the twain meet. You could have 2,000W PV panels one side, 12V battery the...

There's a lot of misinformation and misinterpretation in this thread. Let's start with some clarifications: These cells do not need to be balanced because they are already balanced. These cells do not need to be discharged further because they are already at 30% SoC. If these are new cells...

How many times have we heard the question, "What's the best BMS for my situation?" on this forum and how many times have we responded, "Well, it depends..."? We then go on post-after-post, page-after-page talking about what BMS's are there to do, what BMS's are available, posting caveats and...

A PV panel's output is standardised to STC (Standard Test Conditions), which are 1,000Wh/m² at 25℃. According to here, right now in Dallas you are only getting around 4,250Wh/m² per day. If you assume 6 hours of 'good sun', that's 708Wh/m², so you're already down 30% just because of the time of...

All batteries have what's called a 'nominal' voltage but in truth, the voltage of most batteries vary depending on their state of charge. For example, a 12V lead-acid battery will vary from around 10V fully discharged to around 12.8V fully charged. In order to charge that battery you need to...

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...

OK, short answers: No. No. A BMS is required to balance the individual cells within a battery (a battery being a container for one or more cells). 4S means that within the battery there are four LiFePO4 cells connected in series or that the BMS supports up to four cells. An 8-cell BMS supports...

Just to clarify @smoothJoey's comment, you can use a Victron BatteryProtect with an Inverter but not in the Inverter's supply line - using the BP to control the inverter (i.e. switch it off) is a very useful automation.

Buying the cheapest possible components and shoving 10,000W of electrical energy through them. Never has that before been problematic! ;) Good luck in your quest but please, don't install these components anywhere near things you might want to keep or otherwise protect!!

LOL! When I first looked at LiFePO4 a couple of years ago, they were £2,000 for a 100AH, now you can get them for $700 (£530). All depends on the timeframe you are comparing between, I guess! ;-)

I always find that it's better to think of the fuse protecting the cable, rather than the device. For a start most devices have their own protection and thinking in this way makes you focus more on cable sizing, shorting risks etc. @FilterGuy I like your point about considering the return cable...

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

Interestingly, I would call a device that changes AC to DC a rectifier, and a device that changes DC at one voltage to DC at another voltage a converter.

I personally wouldn't trust the cheap units, heard lots of horror stores that they melt/burn even within specifications. Also, most automotive products are only rated for up to 48V, your system voltage is higher. Consider bussmann products or buy from somewhere like BlueSea.

Sounds about right, though measuring terminal voltage as an analogy of SoC for a lithium-ion battery is somewhat hit and miss. That said, I've seen 'storage SoC' recommendations from 30% - 80% so I don't think it matters too much. AFAIK, storage means forever. I mean, the battery will calendar...

Still no takers? Let's give it a day for other members to check in and if nobody volunteers, I'll do it. If I do end up doing this, however, I'm going to need a lot of help - never having actually owned a BMS before! Talk about the blind leading the blind! ?

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

I do absolutely agree with you but for one point: people come here to have their questions answered. We are not a reference book, we're a group of problem solving enthusiasts. I do agree with the concept of a knowlegebase, after all, we are all repeating mostly the same stuff to most queries...

I would recommend that you checkout some of Will's blueprints - they cover everything you need. Other considerations: You need a DC-DC charger, not a DC-DC converter, in order to charge your batteries from your van's electrical system. I would also urge you to be conservative on the current -...

You are, of course correct, but I was tailoring my response for a non-expert in lithium-ion battery management (as I presume OP is). Nothing good comes from charging a LiFePO4 to 4.2V, yes there are caveats to that in that it is technically possible, but I thought the simple answer was best in...

Personally I harness the the hawking radiation given off by my DIY micro-singularity reactor. I'll be honest, it does concern me that I do under utilise it somewhat; of the 6.24 Exa Watts of energy it produces, I only really use it for my camping kettle and charging my smartphone. I should...

If you take a look at their datasheet (for example their smaller SCCs) their 'Nominal PV Power' has a footnote, thus: Meaning that you'd need 12V + 5V = 17V before the unit will even switch on. And if you did manage to 'trick' the charger to turn on, to charge at 14.4V you'd need 15.4V on the...

Just read this on Wikipedia (so it must be true...): BUT... So I am assuming that the use of a small stainless steel fastener (weeb) connected to a large aluminium frame would generate less corrosion than if the materials were reversed.

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...