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Alternator temperature


Dr Bob

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6 minutes ago, rusty69 said:

What affect (effect) does the use of an alternator to battery charger have on the alternator temperature? I recall you have one. 

I think the quick answer is none......well actually lots.

There are 4 settings (dip switches) on the AtoB that are for different battery types. On Lead acids, these give absorption voltages from 14.0V to 14.6V and the current levels on initial charge increases from 40A to 60A across the 4 types. I am using this to give me a bit of control over the lithiums. On the US Gel battery setting, the LA absorption voltage is 14.0V. On the lithiums, it looks like this will be the termiinating voltage for 100% charge and it gives me 45A output...all the way to 95% charge (not been to 100% yet). On the gel setting I get 55A and voltage seems to be 0.1V more.

So yes, the AtoB is the thing with which I can control the current and 45A looks ok for temp but 55A was getting to 90°C...hence my question. I will stick to the 45A for now as I want to check out the termination voltage but may they go to the 55A.

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I was told NEVER to publish an equation without defining each term.

 

k  some sort of constant

A amplitude of a sine wave

Ea  Environment agency

RT  Canal and River trust when they get rid of the canals?

 

...........Dave

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6 minutes ago, dmr said:

You sound like an electronic engineer ?, there's a lot of us on this forum. Does that law apply primarily to semiconductors where temperature is a big and understood factor? I am not sure it would apply to winding varnish but do confess that I know nothing at all about this.

 

..............Dave

I've played one on TV. Yes, very applicable to the semiconductor diodes in the alternator. Not so to the winding varnish.

 

8 minutes ago, jonesthenuke said:

Can you reduce the operating temperature in any way? I have fitted some computer fans to cool the alternators on our boat. IIRC they run a lot cooler than yours, I wanted them to run cooler just to improve longevity and it was easy to accomplish.

Dr Bob should drill a small hole in the baseplate directly underneath the alternator. The water spray will cool the alternator, increasing its life and efficiency, allowing it to generate more electricity to power the bilge pump and keep the boat afloat. The clouds of steam from the engine room will convince gongoozlers he has one of them there steam narrowboats. ?

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7 minutes ago, dmr said:

You sound like an electronic engineer ?, there's a lot of us on this forum. Does that law apply primarily to semiconductors where temperature is a big and understood factor? I am not sure it would apply to winding varnish but do confess that I know nothing at all about this.

 

..............Dave

It's generally a good rule but for well designed products its unlikely to apply as stated as the designers should be using materials that are operating well below their limiting temperatures and such effects are then low. It's more likely that the temperature will affect lubricants etc and thus bearing life. Personally, though, I would not want an alternator to be updating at near 100C in normal operation.

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7 minutes ago, Dr Bob said:

I think the quick answer is none......well actually lots.

There are 4 settings (dip switches) on the AtoB that are for different battery types. On Lead acids, these give absorption voltages from 14.0V to 14.6V and the current levels on initial charge increases from 40A to 60A across the 4 types. I am using this to give me a bit of control over the lithiums. On the US Gel battery setting, the LA absorption voltage is 14.0V. On the lithiums, it looks like this will be the termiinating voltage for 100% charge and it gives me 45A output...all the way to 95% charge (not been to 100% yet). On the gel setting I get 55A and voltage seems to be 0.1V more.

So yes, the AtoB is the thing with which I can control the current and 45A looks ok for temp but 55A was getting to 90°C...hence my question. I will stick to the 45A for now as I want to check out the termination voltage but may they go to the 55A.

I knew that.

 

Did you resolve your overheating alternator problem from last year? 

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6 minutes ago, jonesthenuke said:

 

 

Can you reduce the operating temperature in any way?

See my response to Rusty a few posts of mine before. I can reduce alt output to 45A which keeps me below 80C on the hottest bit but that was the point of the OP....am I safe at 90C?

It is obvious that you cant run a 90A alternator at max output for any length of time but I cant see any info on just how much you need to reduce it to get good life. The Balmar site discusses it in detail and shows how their system reduces output via their belt manager system but that doesnt give info on what typically the current is reduced to - they just talk about %'ages but % of what? I guess 45A on a 90A alternator should be fine for 2-3 hours......but is 55A.

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16 minutes ago, LadyG said:

{\displaystyle k=Ae^{\frac {-E_{\rm {a}}}{RT}},}

 

 

12 minutes ago, dmr said:

I was told NEVER to publish an equation without defining each term.

 

k  some sort of constant

A amplitude of a sine wave

Ea  Environment agency

RT  Canal and River trust when they get rid of the canals?

 

...........Dave

So are you suggesting we 

 

Komplain (k) when(=) the A***hole eejits (Ae) remove the Environment Agency (-Ea) and the River Trust goes under (1/RT)?

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5 minutes ago, Dr Bob said:

See my response to Rusty a few posts of mine before. I can reduce alt output to 45A which keeps me below 80C on the hottest bit but that was the point of the OP....am I safe at 90C?

It is obvious that you cant run a 90A alternator at max output for any length of time but I cant see any info on just how much you need to reduce it to get good life. The Balmar site discusses it in detail and shows how their system reduces output via their belt manager system but that doesnt give info on what typically the current is reduced to - they just talk about %'ages but % of what? I guess 45A on a 90A alternator should be fine for 2-3 hours......but is 55A.

These seem quite conservative numbers. I run an 70A (nominal) A127 at 65A for hours on end and have not yet had a failure. I'd expect a 90A alternator to have better cooling.

 

 

MP.

 

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2 minutes ago, rusty69 said:

 

 

Did you resolve your overheating alternator problem from last year? 

That problem was on the starter battery alternator (a 50A one) that the AtoB was using all the time rather than sharing the duty with both alternators. I just disconnected the 50A one from the AtoB and wired it direct to the starter battery so no problem.

It is interesting that that problem had the 50A alternator operating at 50A output all the time ......and the alternator ran at 90°C. It was like that for a month or two and hasnt suffered. Been fine for the last 8 months.

 

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7 minutes ago, Dr Bob said:

See my response to Rusty a few posts of mine before. I can reduce alt output to 45A which keeps me below 80C on the hottest bit but that was the point of the OP....am I safe at 90C?

It is obvious that you cant run a 90A alternator at max output for any length of time but I cant see any info on just how much you need to reduce it to get good life. The Balmar site discusses it in detail and shows how their system reduces output via their belt manager system but that doesnt give info on what typically the current is reduced to - they just talk about %'ages but % of what? I guess 45A on a 90A alternator should be fine for 2-3 hours......but is 55A.

I was thinking by reducing the local ambient rather than reducing the current being delivered, I rather assumed you would want to maximise that.  Can you insulate the surface of the skin tanks so they reject less heat to the air near the alternator or is the engine the more significant heat source? My engine is in an engine room and the skin tanks are not close my so the problems are less significant.

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5 minutes ago, Dr Bob said:

That problem was on the starter battery alternator (a 50A one) that the AtoB was using all the time rather than sharing the duty with both alternators.

I knew that too. 

 

Smellys idea of sticking an eco fan on each alternator pointing at the other one should sort your problems. 

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3 minutes ago, MoominPapa said:

These seem quite conservative numbers. I run an 70A (nominal) A127 at 65A for hours on end and have not yet had a failure. I'd expect a 90A alternator to have better cooling.

 

 

MP.

 

....but have you measured it with an infrequent red thermometer? Every boat should have one!

 

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6 minutes ago, jonesthenuke said:

I was thinking by reducing the local ambient rather than reducing the current being delivered, I rather assumed you would want to maximise that.  Can you insulate the surface of the skin tanks so they reject less heat to the air near the alternator or is the engine the more significant heat source? My engine is in an engine room and the skin tanks are not close my so the problems are less significant.

Ah, I see.

Its in the engine hole on a cruiser stern so not easy to reduce the heat without installing fans. The skin tank is on the other side of the engine. Yes I could put a fan  on it and I am sure it would cool it. The alternator is near a bulk head so that would make it relatively simple. I will be very happy if I can run at 55A.

10 minutes ago, rusty69 said:

 

 

Smellys idea of sticking an eco fan on each alternator pointing at the other one should sort your problems. 

Can you buy a magnetic one?

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1 hour ago, rusty69 said:

What affect (effect) does the...

Affect. 

 

Your hair is affected by the wind. The effect is that it looks a mess.

 

However... you effected a fix to that problem by donning a hat. 

 

So, affect is a verb and effect is a noun. Except for when it isn’t.

 

Don’tcha love English...

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5 minutes ago, Bobbybass said:

Is that really a 90 amp alternator ?

 

Looks a bit small to me......mind you...lots of things seem small to me these days....

It does look a bit small doesn't it. Honest guv, it is 90A. The 50A starter alternator is smaller. Anyone know what make it is? Its the bog standard one supplied with the beta 43.

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8 minutes ago, Dr Bob said:

It does look a bit small doesn't it. Honest guv, it is 90A. The 50A starter alternator is smaller. Anyone know what make it is? Its the bog standard one supplied with the beta 43.

Why not send your photo to Adrian at Beta....and ask him...?

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A wee computer fan could be mounted directly behind the alternator to add extra boost to the alternators fan. But the engine compartment does need decent vents to the outside or the fans just keep recirculating  hot air.

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Probably an Iskra alternator, Czech, I think, now called Letrika. Beta have used them for ages.

Not the best I am told.

Diode pack and regulator should be good to 120 degrees C, the enamel insulation on the windings will be 150 degree stuff, it all has been for many years. I wind transformers and that's all I can buy these days.

 

But the temperatures outside will be different than the inside by quite a margin.

 

Due to the drop in output with temperature, provided that there is adequate cooling air available for the fan, the alternator should not suffer at all.

We used to run some 24v 100A truck alternators in reverse, they cooled but the wrong way, the back was hotter than the front. They survived OK.

 

The ones that are useless are the ones with aluminium stator windings.

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9 hours ago, jonesthenuke said:

 

 

I Note Tony Brook's comment on current being much higher if the delivery voltage is low, this may not be universally applicable, the Leece Neville alternators are auto current limiting so will not double in current for a 6V battery voltage.

 

 

I think this statement is not the whole truth but is near enough the truth for most purposes..

 

Yes, for years we have said alternators are self limiting for current and so they are as long as you stay within their design parameters. They still self limit when you are outside those parameters but the self limiting comes from the Watts = Amps X Volts. Unless Leece Neville have a shunt in their output so the regulator can "measure" the output current the regulator can not control it, So the question is if what Leece Neville told you is true what mechanism controls the current? Until I see a definitive explanation this comes back to the Watts thing.

 

So lets have the answer for how do they  control their current when operating way outside their design parameters.

 

5 hours ago, Boater Sam said:

The ones that are useless are the ones with aluminium stator windings.

For goodness sake, don't they ever learn. We had enough trouble with the aluminium would starters, now they   have done it to alternators as well.

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