DIY or just buy premade?

[Steve Fractals]

I'm sure this has been asked countless times over the years but given prices constantly change I thought I'd ask again.

I'm currently running battery-less but about to get batteries. Tried FLA but the slow charge rate makes them unusable for me (think I was sold starter batts as deep cycle so returned them).

Anyway looking at LifePo now (wanted to wait for the new Sodium launch but think its a year off). From my research so far it seems I can build my own 48V battery with BMS for £200 cheaper than buying a pre-made. The pre-made comes with the same cells and a good BMS plus breaker etc and in a nice metal server rack case. Now £200 is still quite a saving (just cells and BMS, no breaker or case) but is it really worth it given the pre-made is warrantied as a whole unit whilst the DIY would mean warranties if any from different suppliers etc. which as we all know can cause issues with one blaming the other etc. I am a confident DIYer so my question really is, should I DIY to save £200 but have potential warranty issues or just buy the pre-made?

What are peoples thoughts?

 

[Steve_S]

If you wish to build your own batteries you will need some gear, some of which you may have already.
- Digital Multi-Meter (2 decimal places accurate)
- Wire cutters, insulation stripper,
- Small Wire Crimper for Non-Insulated O or Y Type Terminals. Ratcheting Crimper SN-06 model
- Large Crimper for Lugs, most use a Hydraulic Crimper with HEX dies
- A Small Tolls Torque Wrench
- Heat Gun for heatshrink wrap

A Charger to Initialize & Top Balance the cells, this would need to be at minimum capable of charging at 4 Volts @ 10A *
* LFP cells can charge up to 0.5C so a 100AH cell can take p to 50A Max. The lower the amperage the longer it will take and a true test of patience.

 

[SeaGal]

...wanted to wait for the new Sodium launch but think its a year off

And the rest...

From my research so far it seems I can build my own 48V battery with BMS for £200 cheaper than buying a pre-made.

You don't state the capacity. £200 off a 2kWh system is quite a saving. Less so if you're saving just £200 on 30kWh of storage.

What are peoples thoughts?

Depends so much on your experience, knowledge, what equipment you already have (as @Steve_S noted), and what interest you have in doing it. Is it the start of a potentially bigger storage system or just a one off? Do you want to DIY so you can control it with other systems more easily?

 

[MrM1]

If you have some or most of the tools (or you like buying tools) and you feel confident, I surely would. With going DIY, you know how and why it works and know how to fix it. When there's a problem, you can almost see it in your mind and usually can go right to it.

 

[MrM1]

I just recently built 2 48v 16s batteries with bms and all cables, etc. Total 560ah. Pre made would have cost upwards of $8600 (about $15.72 per Ah) for that capacity. Cost Me just under $6000 DIY (or $10.72 per Ah) .

 

[Steve Fractals]

If you wish to build your own batteries you will need some gear, some of which you may have already.
- Digital Multi-Meter (2 decimal places accurate)
- Wire cutters, insulation stripper,
- Small Wire Crimper for Non-Insulated O or Y Type Terminals. Ratcheting Crimper SN-06 model
- Large Crimper for Lugs, most use a Hydraulic Crimper with HEX dies
- A Small Tolls Torque Wrench
- Heat Gun for heatshrink wrap

A Charger to Initialize & Top Balance the cells, this would need to be at minimum capable of charging at 4 Volts @ 10A *
* LFP cells can charge up to 0.5C so a 100AH cell can take p to 50A Max. The lower the amperage the longer it will take and a true test of patience.

Got all that stuff except the charger to charge at 4 volts, so will factor that in thanks.

 

[Quattrohead]

I'm gonna say skip the charger, just use a good BMS and get the settings right.
I don't know how the supply chain is in good olde Blighty, so this make make your decision for you.
I have DIY 3 packs and saved a bunch of cash, but depending on your time and materials, it can be cost/time effective to buy a unit.

 

[Steve Fractals]

And the rest...


You don't state the capacity. £200 off a 2kWh system is quite a saving. Less so if you're saving just £200 on 30kWh of storage.


Depends so much on your experience, knowledge, what equipment you already have (as @Steve_S noted), and what interest you have in doing it. Is it the start of a potentially bigger storage system or just a one off? Do you want to DIY so you can control it with other systems more easily?

My inverter is a 6Kw so plenty of scope with that but limited space for panels so at the mo its just a 2.4KW. I plan to just build an 100ah 48v battery and so my calc is based on that saving me £200 (less now as I need a 4v charger).

I did all my system DIY from scratch including building the lean to porch to house some of my panels so I'm pretty ok with DIY. I do like to know how stuff works and from what I can see the only difference with the pre-made is the metal case and a breaker as I've already priced up with sames cells and BMS.

I'm defo leaning towards DIY esp as I can pay just £5 more per cell to get them from a really good reputable uk company rather than self import and the risk that carries. Also if I buy the BMS from them then will essentially all be warrantied by same retailer and although the metal box with breaker is nice and would be more to buy separately than I'd save on DIY, I'm not really bothered as have a nice airy cupboard to put the batteries in anyway.

 

[SeaGal]

I'm defo leaning towards DIY esp as I can pay just £5 more per cell to get them from a really good reputable uk company rather than self import and the risk that carries. Also if I buy the BMS from them then will essentially all be warrantied by same retailer and although the metal box with breaker is nice and would be more to buy separately than I'd save on DIY, I'm not really bothered as have a nice airy cupboard to put the batteries in anyway.

Is that Fogstar? Comparing their cells vs. their battery rack?

 

[Steve Fractals]

Is that Fogstar? Comparing their cells vs. their battery rack?

Yes