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280Ah 12v yacht domestic system

Aphers

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Nov 17, 2020
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I'm trying to put together a 12v 280Ah system without breaking the bank or over-complicating things. It's as a standalone house bank on a yacht, charged by 60A solar (and if necessary, 30A B2B from the engine/SLA). It will power the fridge, inverter for the galley, and a few smaller loads, but nothing essential. I'm planning a 3kw inverter and would try to keep continuous load to 2.5kw or less.

For charging, I'm going to trust the Epever MPPT to do its thing. The BMS will be the fallback if there's a problem.

The BMS will be protecting the smaller loads, whilst the inverter will have an alarm at 11.5v, and LVD at 10.5v. The fridge has a LVD at 10.6v.

Is this enough protection? I realise that the BMS is the only line of defence for the small loads. These will be things like laptop chargers, cabin lights, so probably 200-300w at most. Would it be worth fitting something like a battery protect set to 12v as a fallback for these loads? Also I know that the LVD built into the inverter and fridge are lower than ideal, but I can't seem to improve on that without at tripling the budget and/or making things much more complicated.

I haven't chosen a BMS yet, but with a 3kw inverter I'm considering the 300A Daly fan-assist. They appear to the pick of the bunch amongst the cheaper units, but I can't find a definitive answer on the LVD value- some sources say it's as little as 2.2v/cell- and there are plenty of dissatisfied customers out there so I wouldn't mind using something a bit more upmarket. The Daly at that spec is going to cost nearly £200 by the time I've paid taxes etc, so maybe there are better options for not much more?

As a final layer of protection, I like the idea of spending £10 on a set of four mini voltmeters, wired to each cell, so that I can actually see how they are doing in real time. Can't see it dong any harm, and when I am drawing heavy loads it will be when I am aboard.

Thanks for any feedback- I still feel very new to this and don't want to mess up.
 
Does the EPEver have load ports? If so, you can provide alarm and cut-off on many SCC that provide battery power via their load ports.

Ultimately, knowing that you've sized your system on the basis of the anticipated usage with the application of sensible operating parameters on your chargers/loads (operating INSIDE the BMS limit), AND the fact that you actually have a BMS should prevent any catastrophes. Everything else is just warm-fuzzy... and there's nothing wrong with it.
 
I haven't actually bought the Epever yet, but was planning on the Tracer 60A, partly based on Will's reviews.

Just a thought about the BMS... I reckon I could couple an Overkill with a Tyco relay... total cost might not be much more than a Daly, but higher total current capacity (500 Vs 300A), more configurable, and probably more reliable? Just need to find a UK supplier for the Overkill...
 
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