Alternator speed (slow speed alternators)

[Sir Nibble]

This may sound strange, but here goes!

 

I fairly sure (bear with me), my engine rotates anticlockwise (no where in the manual does it state the direction of rotation!), when looking at the flywheel end of the engine to the back of the engine.

 

One of the beasts was fitted with an old alternator (not sure if its 12 or 24v) that I cannot get to work. But the alternator was fitted with a heath robinson bracket that made it face backwards (ie pulley faced the rear of the engine) and jutted out infront of the engine. This was obviously done to make the alternator rotate in an opposite direction to the engine (if you get what I mean).

 

Am I right in thinking that normally rotation is clockwise for most engines. Will I have trouble with alternators?

 

I've put a picci on my album to show it

 

Alternators are not at all fussed which direction of rotation they are driven in. Sometime the cooling fan however is. If the fan blades are disposed straight and radial, no problem, sometimes the blades are angled, you will see what I mean if you look at a few. It's not a problem and fans aren't difficult to source or change.

[Timleech]

Alternators are not at all fussed which direction of rotation they are driven in. Sometime the cooling fan however is. If the fan blades are disposed straight and radial, no problem, sometimes the blades are angled, you will see what I mean if you look at a few. It's not a problem and fans aren't difficult to source or change.

 

Last time I tried to buy a reverse rotation fan for an 11AC, a good few years ago when the 11AC was still in regular use, I was told that they had been discontinued because it had been found that the normal fan would provide enough cooling even when run backwards. That particular installation, using that principle, never gave any trouble in many hours of service. That info is, of course, worth what you paid for it and even if accurate doesn't necessarily apply to other machines.

 

I have seen alternators recently with a direction arrow cast into the end frame, yet with radial fan blades. I imagine they have offset brushes, in which case they would probably work either way but brush & slip ring life might be reduced if run the 'wrong' way?

 

Tim

[Gibbo]

 

Please tell me that the main alternator output wire is not visible in that photograph.

 

Gibbo

[DHutch]

 

 

Please tell me that the main alternator output wire is not visible in that photograph.

Gibbo

Yes they are, the two slightly thicker ones. Both red, with the neg wraped in black every 8inches.
- There about 10-15mm^2 with a cable run of about 20ft (40ft round trip) the neg output cable can be seen as the dull cable top right.
- Its not ideal but it works fine for us tbh for now. In the morning it will put 20amps for a bit, down to 16, 10, then about 4 for a while. Usally cuting back and just maintain the fridges usage by about lunchtime.

However does need some form of attention, because if nothing else the bow batteries another 35ft away really dont charge.
- The cabling from the change over switch (located by the domestic batterys) upto the bow is about 4mm^2 going another 35ft upto the bow.
- So there is enough cabling looses to basicaly prevent the bow batterys ever being charged proberbly at all (same cables used for the mains charger).
- The only way to get them up is just leave it on the mains for two days at the start of winter and then not use them all season really.

In the future im planning to run a pair of thicker cables upto the bow, and then bring the sterling alternator booster thingy into play, using the existing cables to sense the voltage. Or somthing like that. but i fell im high jacking a thread here!!



Daniel

[Alan de Enfield]

I'm getting a little confused (especially when the square roots came in to it).

 

I need to try to find a:

CAV AC7 or AC5 ?

or a Butec ?

 

I have found a Butec A100 set up (Leyland National?) on line:

Alternator £220

Charge loom £100

Regulator £30

 

Not knowing much about the cost, is this reasonable? Should I bite his arm off at this price?

 

How difficult would it be to source one via a breaker? I'm not in a massive hurry.

 

Cheers

 

I know this thread is long dead & buried, but how often does someone come on looking to charge their batteries at very low revs

 

Anyway - this guy has several AC7 generators with bracket and regulator tested and working for 125 pooonds.

 

Could be a bargain if you need one.

 

http://www.findafishingboat.com/ac7-alternator/ad-53776

[Sir Nibble]

Necromancy!

[MtB]

[WotEver]

https://youtube.com/watch?v=xos2MnVxe-c"

 

.

Edited January 22, 2016 by WotEver

[Sir Nibble]

Mind you, anyone need a slow speed 60A 24V alternator for a vintage engine this is a good chance to score and well done Alan for the heads up.

[by'eck]

I don't understand the need for a slow speed alternator on a low revving vintage engine. Suitable pulley ratio will have a typical alternator performing fine at whatever engine revs are normally needed. Also the rev range between idle and max governed will be no more, in fact likely less than a modern engine so extreemly unlikely to over rev the alternator.

 

As an example my JP2 has a 14" engine pulley driving two alternators. On a test with a large inverter load (3kW kettle) I wound up engine revs until battery drain current ceased to drop, and found to be 650 rpm = approx 3500 alternator rpm. At this point a clamp-on meter indicated 156 amps being supplied by the larger 160 amp alternator. Even at the unlikely max engine speed of 1200 rpm the alternators would only be spinning at approx 6500 rpm, well within their max safe speed.

Edited January 22, 2016 by by'eck

[OldGoat]

I've got something similar with an internal regulator - NEW = unused that I ought to get rid for similar money plus carriage...

[billh]

Video

I am certain that a Van der Graaf generator won't be 12volt , more like 500kV. and anyone touching it will be 100% necroed.

Stick with a CAV (C.A. Vandervell) . Different van....

[DHutch]

I don't understand the need for a slow speed alternator on a low revving vintage engine. Suitable pulley ratio will have a typical alternator performing fine at whatever engine revs are normally needed.

Yes and no.

 

Certainly for us, the engine speed is sufficiently low that a 'suitable ratio' cannot be achieved in a single stage. Hence you either need to seen a reduced speed alternative, or do as SNB Hasty has done, which is to have a multi-stage pulley system to get the speed high enough.

 

We typically cruse with engine speeds of around 180-250 rpm.

 

320 rpm is flat out, 350 is seen only if you can get it ventilate/cavitate significantly!

 

 

Daniel

[by'eck]

Yes and no.

 

Certainly for us, the engine speed is sufficiently low that a 'suitable ratio' cannot be achieved in a single stage. Hence you either need to seen a reduced speed alternative, or do as SNB Hasty has done, which is to have a multi-stage pulley system to get the speed high enough.

 

We typically cruse with engine speeds of around 180-250 rpm.

 

320 rpm is flat out, 350 is seen only if you can get it ventilate/cavitate significantly!

 

 

Daniel

 

Fair comment with your steam installation although I guess a jackshaft running at say three times engine speed would suffice without an outrageously high pulley ratio. It sounds like this has been the thinking with Hasty's installation.

 

In fairness though the original topic was referring to low speed diesels as was my post.

[ditchcrawler]

 

Fair comment with your steam installation although I guess a jackshaft running at say three times engine speed would suffice without an outrageously high pulley ratio. It sounds like this has been the thinking with Hasty's installation.

 

In fairness though the original topic was referring to low speed diesels as was my post.

There was a post on here some time back where the OP was running from the cam shaft of a Lister and didnt have room to get to the crankshaft without riping the bedroom wall out.

[FadeToScarlet]

Yes and no.

 

Certainly for us, the engine speed is sufficiently low that a 'suitable ratio' cannot be achieved in a single stage. Hence you either need to seen a reduced speed alternative, or do as SNB Hasty has done, which is to have a multi-stage pulley system to get the speed high enough.

 

We typically cruse with engine speeds of around 180-250 rpm.

 

320 rpm is flat out, 350 is seen only if you can get it ventilate/cavitate significantly!

 

 

Daniel

Missing a real trick, obviously a steam turbine coupled to the alternator is what's needed- silent power generation when required!