Anyone else gone down the lithium rabbit hole and forgotten what sleep feels like?

Started with a knackered leisure battery in my shepherd's hut, ended up spec'ing a full 200Ah Fogstar Drift setup with a Victron SmartSolar 100/20 and now I'm three weeks deep into cable gauge spreadsheets at 2am.

Running about 400W of panels on the roof (two Renogy 200W), feeding into the Fogstar via the Victron. SOC sits comfortably at 80-90% most days even through this grey British nonsense we call summer. Honestly couldn't be happier with the Fogstar — built-in BMS, solid app, no dramas.

My one nagging question: anyone paralleled two Fogstar Drifts successfully? Tempted to double up to 400Ah before winter, but I've heard mixed things about paralleling lithiums from different production batches. Worth the headache or just buy a bigger single cell to start with?

@ValleyChild oh I know this rabbit hole. Started researching a simple backup for power cuts at home, ended up with a 300Ah system on my narrowboat that I spent four months obsessing over before I bought a single cable.

The Fogstar Drift is a solid choice though — been running mine since last spring with zero complaints. One thing that actually helped me stop disappearing down spec sheets at 2am was locking in my actual loads first. Wrote everything down, ran the numbers properly, then the rest of the decisions got much easier.

The 100/20 might feel limiting once you start adding panels though. Worth thinking ahead before you're committed to the wiring layout.

SD_Sparks | Posts: 847

@ValleyChild ha, the cable gauge rabbit hole is a special kind of madness isn't it. Three weeks sounds about right before you start dreaming in milliohms.

One thing that actually helped me stop the endless spiral was just committing to the busbar approach early on - properly rated busbars at both positive and negative, then every cable run becomes its own isolated decision rather than one giant interconnected headache.

Also with the Fogstar Drift, make sure you've sorted your BMS comms with the Victron before you start pulling your hair out over cable sizing. Get the charge profile confirmed first, then work backwards from there. Saved me a good fortnight of second-guessing.

@LindaPrice87 genuinely curious what you ended up with - sounds like your sentence got cut off mid-build! 😄

BoatOllie | Posts: 312

@ValleyChild mate, I feel this in my soul. Boat refit last spring — started with "I'll just swap the starter battery" and six months later I'm cross-referencing IEC 60228 conductor ratings at half two in the morning with four browser tabs of Anderson connector comparisons open.

One thing that genuinely helped me escape the cable gauge spiral: just commit to oversizing slightly and move on. I went 35mm² for my main runs where 25mm² probably would've been fine. The marginal cost difference is nowt compared to the hours you'll lose second-guessing yourself.

The Fogstar Drift is a solid choice by the way — had no grief with mine. The Victron pairing is chef's kiss once everything's talking properly via the app. You'll get there, just maybe set a bedtime alarm before you start reading BMS discharge curves 😄

PGL_Builds | Posts: 1,203

@ValleyChild the cable gauge hole has a sub-hole waiting for you — once you've settled on your runs, you'll discover voltage drop calculators don't all agree with each other, and there goes another fortnight 😅

Genuine tip though: for a 200Ah Drift setup in a shepherd's hut, don't underestimate your negative runs. Everyone obsesses over the positive side and then throws a sketchy earth in as an afterthought. Size them identically and make sure your battery negative to chassis/busbar connection is as beefy as everything else.

Also worth double-checking whether your SmartSolar 100/20 is actually going to see 20A from your panel array — what are you putting on the input side? The Victron will handle it beautifully once it's dialled in, just want to make sure you're not leaving capacity on the table.