Expired Domestic Alternator

[KenK]

We moved our boat back from Stone to the K&A at Newbury over the last two weeks, couldn't have asked for better weather, shorts and tee shirt coming down the Thames.

 

Alas the weather may have been perfect but not far from Benson lock on the Thames large quantities of smoke appeared out of the engine hole and the domestic alternator warning light came on accompanied by the alarm. Managed to pull over to the side and turn off, lifted the hatch and stepped back quickly to avoid the fumes, nasty burnt plastic smell. It was fairly obvious that the domestic alternator had suffered a catastrophic failure. I managed, without burning myself, to remove the drive belt and set off to the lock, where we could tie up and investigate further.

 

Quick word with the lady lockie and she was quite happy to let us overnight on the lock landing, fortunately it has landings on both side so we were not in anyone's way. After everything had cooled down and a small quantity of alcohol had been consumed, scary when that happens on a river, I checked the alternator. It turned over by hand but bits of burnt plastic emerged from the rear, clearly goosed, this is a technical electrical term and has nothing to do with our feathered friends.

 

Fortunately I posses a Smartgauge and Smartbank system, slightly less fortunately I have never actually connected up the Smartbank, where is that Roundtoit when you need it. Thankfully I do posses a good set of Jump leads so was able to connect the Starter and Domestic batteries together, although I wasn't sure how well the relatively small 40 Amp starter alternator would cope with six 110 Amp/ Hr batteries in addition to the 90 Amp/Hr starter battery.

 

I am pleased to say the little alternator performed very well indeed especially on the Thames where we were able to run for a good distance, between Benson and Sonning it charged all the batteries to 100% according to the Smartgauge. The next two days on the K&A, even with all the stopping for the locks it still managed to maintain the charge.

 

We reached our mooring without any problems and I removed the alternator to investigate back at base. The Stator was completely burnt out, the source of the bits of burnt plastic. Checking around the ISKRA alternator isn't something most local auto factors carry parts for so I figured a new one made more sense, the dead one is ten years old.

 

Google in this case was my friend especially as Onion Bargee's (of this forum) blog popped up with the information as to type and a link to a cheap supplier, "Thank you, I lot of time saved". Quick phone call, new one on the way.

 

So what have I learnt.

 

You really do not need very large alternators.

 

Alcohol is a good antidote for fear.

 

A set of jump leads is worth having on a boat.

 

If you purchase a Smartbank it is a good idea to fit it even if you have two alternators.

 

It is worth sourcing a small drive belt in case the Starter alternator fails in a similar fashion. Disconnecting the domestic belt is easy it only drives the alternator, but the starter belt also drives the water pump. Fitting might be an issue but I seem to remember emergency belts used to be available which could be adjusted to fit.

 

Thanks again to the Lock keeper at Benson and to Onion Bargee.

 

Ken

 

Oh and if you are heading up the K&A both Fobney lock and Woolhampton are running very fast and need care.

[ditchcrawler]

http://www.ebay.co.uk/itm/like/221738722539?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108

make it what length you want

[larkshall]

Most good motor factors stock cut-to-length alternator belting, is circular in section, can be cut and joined to fit. I'd get a length for the tool box

[Iain_S]

I got a couple of metres of Fenner Powertwist at an IWA festival a few years ago. Good stuff; can be fairly slack without slippng, and oil proof (a big advantage when fitted to our local canal society SR2 )

 

Iain

[Arthur Brown]

When genuinely cruising a moderate alternator is adequate and battery friendly, 10 hours at 40 amps is 400ah and very useful. Once you want to run the engine to charge the batteries the big alternator is clearly faster therefore better.

 

I wish you success getting and fitting the replacement.

 

There are lots of things that you might want a spare for, ultimately it's down to how much cash and space you can allocate to spares and the tools needed.

[KenK]

 

When genuinely cruising a moderate alternator is adequate and battery friendly, 10 hours at 40 amps is 400ah and very useful. Once you want to run the engine to charge the batteries the big alternator is clearly faster therefore better.

 

I wish you success getting and fitting the replacement.

 

There are lots of things that you might want a spare for, ultimately it's down to how much cash and space you can allocate to spares and the tools needed.

 

Replacement alternator arrived this morning, I'll need to change the pulley but otherwise a straight swap. Good service and a hundred pounds less than either Midland Chandlers or Beta Marine.

 

Thanks for the links to the emergency drive belts, ditchcrawler and Ian-S.

 

Ken

[Arnot]

Just a couple of caveats....

 

In my experience if these big Iskra alternators go into Chernobyl mode it is almost always caused by the connection to the battery failing whilst the engine is running. The two most usual causes are;

 

1) The power stud just behind the alternator at the bottom of the engine sometimes corrodes or comes loose giving poor or intermittent connection. This is best cured by rewiring the alternator output directly to the domestic battery with 25mm or larger cable.

 

2) The output of the alternator being routed to the domestic battery through a master switch. Particularly when it is one of the little plastic jobbies with the red key. Master switches just are not intended to carry large continuous currents, overheat and then melt. The solution is to connect the alternator directly to the domestic battery (as above). Unfortunately a lot of boat safety examiners expect the alternator to be wired through a master switch for safety reasons but the alternator manufacturers dislike this for exactly the same reason. To my mind the charred remains tell the story.

 

As for not needing a large alternator, well, it depends on how you use your boat. If you cruise a lot then you don't need the large alternator, just good wiring and voltage regulation. However, if you are a live aboard a large alternator will charge a large battery in less time saving fuel, engine wear and neighbour irritation.

 

Hope this helps...

 

Arnot

[Detling]

 

As for not needing a large alternator, well, it depends on how you use your boat. If you cruise a lot then you don't need the large alternator, just good wiring and voltage regulation. However, if you are a live aboard a large alternator will charge a large battery in less time saving fuel, engine wear and neighbour irritation.

 

Hope this helps...

 

Arnot

also remember

When your batteries are over 85% (smartguage) your big alternator is probably supplying less that 20 A. Mine is into 550 my Amphour bank

[Arnot]

also remember

When your batteries are over 85% (smartguage) your big alternator is probably supplying less that 20 A. Mine is into 550 my Amphour bank

 

How much the battery demands in current terms from a given voltage source (alternator/regulator and a bit of whizz) depends on a lot of factors, battery state of charge, battery type, temperature, battery condition, wiring resistance to name but a few.

 

What you say is no doubt true for your set up but some battery systems such as AGM's and particularly traction cells, can continue to accept high currents until they are almost 100% charged. For a live aboard cruiser, this translates to significantly reduced (50%?) charging times with the resultant fuel and wear savings.

 

In addition, the use of an external regulator will tend to increase the charging current at lower speeds and when the battery is being charged which has a similar effect.

 

Hope this helps,

 

Arnot

[smileypete]

Good to have you back, Arnot.

 

cheers, Pete.

~smpt~

[Arnot]

Good to have you back, Arnot.

 

cheers, Pete.

~smpt~

Hi!

 

Thanks for that...

 

Just for the record (because I wasn't in a fit state to tell anyone at the time) I was involved in a car accident in November 2011 and sustained a brain injury. No physical injury at all but a few days after the accident I could hardly stand up on dry land let alone on a boat and at its worst, I couldn't read or write.

 

It's taken over three years to recover more or less but I'm back at work again although not able to do as many hours as I used to.

 

It's nice to see a lot of the old names still about...

 

Regards

 

Arnot

[Theo]

also remember

When your batteries are over 85% (smartguage) your big alternator is probably supplying less that 20 A. Mine is into 550 my Amphour bank

I have a 70A Bosch into 720Ah. Current cruising patterns mean that I start in the morining with about 82% on the SmartGauge. The current delivered is up at about 50A but only for 15 minutes or so. It then progressively drops.

 

N