IanD

So a DIY series hybrid then? Good luck 🙂

You need to look at the engine (and alternator) torque/power curves -- you can't use the maximum engine power to run the alternator, because that means charging at peak power rpm (noise, wear...). Most people with engines like the Beta charge at maybe 1200rpm when moored -- not lower because of torsional vibration problems, Beta forbid this -- at which point a Beta 43 can put out about half its maximum power (22bhp). And you need some power to drive the prop when cruising (e.g. about 4bhp at this rpm) which leaves 18bhp absolute maximum for the alternators. If these are 50% efficient (normal for automotive ones like the Iskra) this gives a maximum alternator output power limit for charging of 9bhp (less than 7kW), or about 20% of the maximum engine power... Any narrowboat only ever uses a tiny fraction of the maximum engine power when cruising on a canal, measurements have shown that typically about 3kW/4bhp is required. Since propeller power goes up as the cube of rpm (actually, a bit faster), a Beta 43 propped to absorb 43bhp at 2800rpm (maximum power) will put 4bhp into the prop at about 1250rpm.

1) Correct. 2) Well done. 3) Probably not a bucket of worms you want to open given by what happened last time that argument was tried. 4) Don't mention dog poo bags either... 😉

You could cut a circular hole out around the taps using a hole saw in a drill, then plug the hole with a glued-in circular offcut the right size -- I've done this before when a hole was drilled in the wrong place...

If you have a legal means of disposing of said compost -- some boaters do, many don't (or didn't)... 😉

The smallest engine that Beta fit big/dual high-current alternators on is the Beta 43, IIRC the smaller ones don't have crankshaft nose pulley attachments (splined shaft?) that can take the lateral load of the big/dual polyvee pulleys...

If your engine is 14hp flat out you've got no chance of driving big alternators like this anyway, look at the "bhp absorbed" and "torque" curves I posted...

Two years ago (late 2020) Beta quoted me £670 on top of the standard engine price for 2 24V 80A alternators with brush boxes fitted, including pulleys and belts -- not much point fitting the 100A ones for charging at 1200rpm, see curves I provided. To fit a big 48V 100A alternator like the Balmar the quote was £570 (including special pulleys and belts and testing) PLUS the cost of the alternator.

Sounds a bit like snake oil but it seems there may be some real science behind it... https://wrccontrols.com/pages/fire-safety-sticks-more-information It doesn't fit into the conventional categories of pressurised liquid/power/foam/gas extinguishers which could be why it's not approved, even though it seems to work extremely well it doesn't tick any of the required boxes e.g. BSS. Or it could all be bunkum, difficult to be sure... 😉

Masochism?

Maybe because the DC terminals are PCB mounted, and with a single thick cable there's more risk of stress from the cable causing damage, either from the cable or the bigger tag/stud needing more torque to tighten it down?

I looked at that in the past too (before it disappeared) and asked Beta about it. They said there was almost no demand because it was *very* expensive, and that two 100A 24V alternators in series with standard polyvee pulleys/belts did the same job for a fraction of the cost...

Even with that, an alternator outputting 8kW means something like 15hp through the belt, which is a *lot* of torque -- might need a 10V or 12V belt (IIRC Beta use 6V for big alterators) as well as an idler pulley. I talked to Beta at length about this when I was looking at fitting a single big alternator...

A single alternator that can put out 8kW is probably going to need wider than normal polyvee belts/pulleys to prevent belt slip and probably an idler wheel to increase the belt wrap angle -- see what Integrel do, for example.

Always good to have a backup, especially if it's cheap 😉

Indeed it's not that difficult. Or Beta can just supply the brush boxes (with holes for wires to external regulator) which you swap for the ones with the regulators in, which at least gives a temporary backup option (swap them back!) if your external regulator dies... 😉 Don't forget that you can't just drop high-current alternators in, you also need the polyvee pulleys and belts to drive them if the engine doesn't already have these fitted. Beta also recommend using pulleys with over-running clutches fitted to reduce transient belt loads and wear, and these are only available in a limited range of sizes.