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Beta B43 'missing' occasionally (with the answer)


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I have been wondering about this apparent glitch with my engine for ages. You'll be cruising along at a steady speed and suddenly the engine will seem to 'miss' just for a second before carrying on as before. I know diesels don't misfire, so it was worrying me.

 

However, I have found out what it is, and thought I'd post it on here in case anyone else has the same thing.

 

It's the (240v) fridge compressor cutting in, and the momentary extra load on the alternator causes the engine to slow down a fraction before picking up again. So nothing to worry about.

 

I hope this is of interest.

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Fridge, pah! you should try an electric kettle. wink.png

When I first had the boat I set the tickover as slow as possible and Diana putting the kettle on stalled the engine as we were between the two Glascote locks. I tweaked the throttle stop

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In a warship, there would often be a broadcast of "Anyone wishing to start heavy machinery should first contact the SCC (Ship Control Centre)". In our boat, insert steerer for SCC and include electric kettle, coffee machine, hair dryer as heavy machinery. It works pretty well.

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I have been wondering about this apparent glitch with my engine for ages. You'll be cruising along at a steady speed and suddenly the engine will seem to 'miss' just for a second before carrying on as before. I know diesels don't misfire, so it was worrying me.

 

However, I have found out what it is, and thought I'd post it on here in case anyone else has the same thing.

 

It's the (240v) fridge compressor cutting in, and the momentary extra load on the alternator causes the engine to slow down a fraction before picking up again. So nothing to worry about.

 

I hope this is of interest.

 

Thanks for this. A most interesting insight and not one I've ever heard mentioned before.

 

It's a bit like the way my Kelvin won't rev to more than about 250rpm after starting it if the batteries are a bit flat, even if out of gear. The alternator load soaks 100% of the engine power!

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What is interesting is that this momentary glitch is indicative of the very high startup current of a fridge compressor motor. So when folks get a fridge rated at say 500w they are going to be very disappointed if they try to run it from a 500w inverter.

 

Also indicative of the large alternator fitted to Betas and its ability to deliver full output at just above idle.

Edited by nicknorman
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What is interesting is that this momentary glitch is indicative of the very high startup current of a fridge compressor motor. So when folks get a fridge rated at say 500w they are going to be very disappointed if they try to run it from a 500w inverter.

 

Also indicative of the large alternator fitted to Betas and its ability to deliver full output at just above idle.

We haven't got a beta, the venerable old BMC 1.5 based Thornycroft 90 can manage that trick too. Edited by gazza
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I found out about this last Friday. We'd just arrived at the boat for a couple of days away. I'd started the engine and switched on all the internal electrics while my wife was putting a few things into the fridge.

 

I went into the boat and realised she hadn't switched the fridge on at the 240v socket. When I did so, I heard the engine note change momentarily as the fridge started. So I switched it off and back on again at the socket a couple of times and the engine did the same thing each time.

 

I'll admit it made my day as I was becoming convinced there was something nasty getting ready to bite my wallet.

 

Later on Mrs J t P told me there was no water coming out of the taps. We had a bit of a water pump moment a few weeks ago and I thought it was that again, but then I realised in my earlier euphoria I'd forgotten to turn on the water at the tank. Doh!

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How big is your battery bank? I would assume with a larger (and well charged) bank, this would be less likely to happen.

 

Ironically it will be more apparent with a fully charged bank because the alternator will have been in idle then suddenly asked to provide some compensating current.

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Later on Mrs J t P told me there was no water coming out of the taps. We had a bit of a water pump moment a few weeks ago and I thought it was that again, but then I realised in my earlier euphoria I'd forgotten to turn on the water at the tank. Doh!

 

 

Plumbers. Hopeless, lol!!

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Ironically it will be more apparent with a fully charged bank because the alternator will have been in idle then suddenly asked to provide some compensating current.

I am sure you will be correct. I am not au fait with the workings of an alternator. I will listen out this weekend.

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