Battery terminal screw sizes (and depths) for Eco Worthy ECO5000W(SR) 48V AIO Inverter?

Has anyone actually managed to get a definitive answer on this? I've been going back and forth trying to figure out the correct terminal screw sizes for the Eco Worthy ECO5000W(SR) 48V AIO and the documentation is, as usual, absolutely useless.

Specifically I'm trying to work out:

• The screw diameter and thread pitch for the battery terminals
• The depth of the terminal holes so I know what bolt length to order

I've got some 95mm² cable with copper lugs ready to go and I don't want to end up with bolts that are too short and only catching a few threads, which seems like a disaster waiting to happen at those current levels.

The manual just shows a vague diagram with no actual measurements. I've searched Eco Worthy's support pages and got nowhere fast.

Has anyone pulled theirs apart or measured up? I'm also wondering whether the terminals are the same spec as some of the other AIO units floating around — a lot of these seem to come out of the same Chinese factories with slightly different badges on them.

Would M8 be a reasonable starting assumption, or are these M6? And is anyone else finding the physical build quality of the terminals a bit questionable compared to something like a Victron Multiplus? Not exactly comparing like for like on price I know, but still.

Any real-world experience with this unit appreciated — particularly if you've already wired one up and can share what worked.

@Chris1966 had the same headache with mine. From what I measured directly on the unit, the battery terminals take M8 bolts, and the thread depth is roughly 12-15mm — worth checking with a depth gauge before you go cutting cables to length.

That said, Eco Worthy's documentation is genuinely awful, so I'd strongly recommend verifying before you torque anything down. I used tinned copper lugs crimped onto 35mm² cable and M8 stainless bolts with serrated flanged nuts — no issues so far.

One thing worth noting: the terminal posts aren't massively beefy, so don't go overtightening. I've seen people crack the housing on cheaper AIO units doing exactly that.

If you've got a caliper, just measure the existing holes directly — far more reliable than anything in the manual.

@Chris1966 worth noting that even once you've got the M8 bolts sorted, the thread depth on these Chinese AIO units is often embarrassingly shallow — I stripped one on my static caravan setup by simply doing it up properly with a torque wrench. These aren't Victron terminals where you can lean on them a bit.

My recommendation: get yourself some M8 stainless button-heads rather than standard hex bolts — lower profile means less lever arm if something nudges the cable. Also use belleville washers rather than standard spring washers; they maintain clamping force as the terminal warms and cools through charge cycles.

Fogstar or wherever you're buying your cells from sometimes stock decent terminal hardware if you ask nicely. The stuff bundled with Eco Worthy units is genuinely terrible — thin plating, soft steel, basically decorative.

@Chris1966 went through exactly this saga with my van build last spring — spent a whole afternoon hunting through my bolt bins before I found anything that worked properly.

One thing nobody's mentioned yet: thread engagement matters as much as the size itself. On my unit I found that bolts over roughly 16mm length started to bottom out before clamping properly, which gave a false sense of security. Pulled it apart a week later and the connection had barely any real bite on the lug.

Worth getting yourself a thread gauge if you haven't already — absolute lifesaver for these Chinese units where the spec sheet is basically fiction. Screwfix do decent ones for a few quid.

Also double-check your lug hole diameter matches the bolt shank — some M8 lugs run slightly oversized and you end up with unwanted movement even when torqued.

Good shout from @CliveBaker on thread depth — that's caught me out before on similar units. Worth picking up a thread gauge if you haven't already; cheap from Screwfix and saves a lot of guesswork.

One thing I'd add: on my narrowboat install I use M8 copper ring terminals crimped to 35mm² cable, and I always put a stainless penny washer under the nut to spread the load across those shallow threads. Stops the lug digging in and stripping them.

Also worth checking whether your unit has the SR suffix — some batches have slightly recessed terminal blocks which means a standard bolt can bottom out before it's properly clamped. A slightly shorter M8 (12–14mm rather than 16mm) sorts that immediately.

@Chris1966 on my shepherds hut build I've connected various Chinese AIO units and the ECO5000W(SR) specifically uses M8 bolts at the battery terminals, but the critical detail nobody mentions is the washer stack matters — these terminals are often recessed and a standard M8 bolt with no washer can bottom out before it actually clamps properly.

Measure your thread depth with a depth gauge or even a drill bit before torquing down. I'd also strongly recommend copper lugs crimped properly rather than relying on bare cable ends — the terminal contact area on these units is marginal at 5kW continuous.

If you're running 16mm² or 25mm² cable (which you should be at that inverter rating), make sure your lug barrel fits the recess — some proprietary lug profiles foul the housing before seating fully.