blackrose

Yes I have a couple of extra connections on two of the battery posts, not enough to warrant another bus bar when it should be easy enough to use longer M8 bolts and a couple of washers.

Learn to ignore random boaters offering advice if they also don't understand the systems on your boat. It may be more economical to boil water using an electric kettle rather than gas, especially if you have a good solar setup, good batteries and the sun is/or has been shining. However, it might be much more impractical to use the electric kettle if your boat's electrical system doesn't support such use. *sorry I forgot you were on shore power!

No. Where did you read that by the way?

I hadn't thought about studding and a nut. But what I want to avoid is whatever goes into the battery turning as I tighten the cable ring terminals down. That's what happens with the Fogstar posts as you tighten the top bolt, so you need another 20mm open ended spanner to hold the post in position as you tighten the top bolt. Wouldn't that also be the case with studding - the stud would try to turn as you tighten/or undo the nut? Isn't a longer M8 stainless bolt better and you can just take up any excess length if necessary with a couple of plain washers + spring washer?

It depends on how your window apertures were cut by the builder and how the windows were installed. Plus the type of window. One of my 15" portholes started leaking a couple of years ago so I took it out and discovered that the aperture in the cabin side was so large that there was only about 5mm overlap from the window frame. Some sort of sticky foam tape had been used, I'm not sure exactly what it was but I was amazed it lasted so long because the stainless screws used to fit the window went into the wooden trim on the inside which I'm told is a common, but in my opinion a crap way of doing it. Steel and wood will thermally expand and contract at different rates so sooner or later a weak join is bound to fail. One by one I took all 14 portholes out and refitted them. Because the overlap was so thin I used a very good marine sealant (Bostik Simson MSR) rather than tape and I used small machine screws, washers and nuts (12 on each porthole) to attach the portholes to the steel rather than using the wood. They're small portholes rather than big windows so I'll be able to get them out again if I need to, but obviously not as easily as if I'd used tape. Hopefully it's a permanent fix and I won't have to unless one gets broken of course.

Agreed, and it's not a design exclusive to Fogstar LiFePo4 batteries Thanks 👍

Yes all my cables have crimp eyes, but a couple of battery terminals will need slightly longer bolts than the ones supplied with the Fogstar battery terminals as there are a few ring eyes connected. On those terminals I've put the big ring eyes direct to the battery under the terminals and smaller ones on top.

You were both right of course. The first thing I did when I got into the engine hole this morning was to check the tightness of the battery terminals. It was those horrible Fogstar terminals again. One was slightly wobbling so I tried to tighten it and snapped the stud off (again). Fortunately I was able to turn the protruding end of the stud and get it out with my fingers, which just shows how weak they are. Anyway I just used the top screw to attach the cable terminals to the battery and re-tested it with the toaster on. Does this look ok now, bearing in mind that they weren't charged equally yesterday?

There are plenty of other clear PU sealants around apart from Sikaflex. Have a look at Screwfix and Toolstation: Stixall, OB-1, Soudal Fix All, Sticks like Sh*t, CT-1, etc. I've tried quite a few of them and to be honest they're all pretty good.

So the battery terminals will give meaningful voltage readings even when connected to the other battery? Ok I'll draw a diagram with all cable lengths and I'll take voltage readings at the terminals with/without current draw and compare to the app voltages.

Ok I'll do it tomorrow thanks.

Ok thanks. I just started charging again and now I've got one battery saying it's accepting 43a and the other less than 2a? The BMS of battery 2 can't have cut off charging at 14v? Should I just stop charging until I've worked out what's going on?

I'll have to get in there tomorrow to have a look. What does (12V *and* 0V) mean?

Both batteries on toaster on. Battery 2 off, battery 1 on, toaster on. Battery 1 off, battery 2 on, toaster on.

Ok thanks Ian. I've got a Teams meeting at 4pm for 20 mins so I'll do it after that.