More Alternator problems

[nicknorman]

1 minute ago, Dr Bob said:

Sea Dog/Nick

thanks for the inputs. I think I will stick with what I have now. There is a total of 140A from the 2 together and I rarely run more than 100Ahr out (<20% of capacity) so they are not going to be overworked. I now know what I will need if one of the units fail.

What worries me slightly is that currently, the small alternator seems to be doing all the work (from the temperature measurements, although clamp-meter current readings would be helpful for certainty) and is thus running at max output for a long time. If the 90A alternator was powering the domestic batteries it would be at max output for much less time. Although quite why there is this imbalance between the paralleled alternator outputs hasn’t really been explained (unless I missed it?).

[Dr Bob]

1 hour ago, nicknorman said:

What worries me slightly is that currently, the small alternator seems to be doing all the work (from the temperature measurements, although clamp-meter current readings would be helpful for certainty) and is thus running at max output for a long time. If the 90A alternator was powering the domestic batteries it would be at max output for much less time. Although quite why there is this imbalance between the paralleled alternator outputs hasn’t really been explained (unless I missed it?).

Yes Nick, I agree. Exactly the question I was asking myself. That's why I am investing in a clamp meter to see if the small one is doing the bulk of the work. If it is, then I will pose the question to Sterling, but if necessary just wire the small one directly to the start battery and only use the 90A one for the AtoB.

[Sea Dog]

10 hours ago, Dr Bob said:

Yes Nick, I agree. Exactly the question I was asking myself. That's why I am investing in a clamp meter to see if the small one is doing the bulk of the work. If it is, then I will pose the question to Sterling, but if necessary just wire the small one directly to the start battery and only use the 90A one for the AtoB.

You know my thoughts Bob - I'd have done that already.  Firstly, for fault isolation purposes; secondly because I don't think that with 90a available you need the Sterling thing anyway; thirdly because the weak link in the system is the Sterling thing.  KISS principle - Keep It Simple, Stupid. (Not you Bob, obviously - it's just a saying and Keep It Simple, Muppet doesn't make a word)

[Dr Bob]

2 minutes ago, Sea Dog said:

You know my thoughts Bob - I'd have done that already.  Firstly, for fault isolation purposes; secondly because I don't think that with 90a available you need the Sterling thing anyway; thirdly because the weak link in the system is the Sterling thing.  KISS principle - Keep It Simple, Stupid. (Not you Bob, obviously - it's just a saying and Keep It Simple, Muppet doesn't make a word)

I agree. The simplest thing at the moment is leave it as it is. If the Sterling fails, i will take it out of circuit. At the moment it is a benefit.

[ditchcrawler]

1 hour ago, Dr Bob said:

I agree. The simplest thing at the moment is leave it as it is. If the Sterling fails, i will take it out of circuit. At the moment it is a benefit.

But if the Stirling keeps going and the small alternator fails what will you do?

[Dr Bob]

40 minutes ago, ditchcrawler said:

But if the Stirling keeps going and the small alternator fails what will you do?

At the moment both alternators feed the AtoB which then charges both domestic and starter. If the 55A fails, but is mechanically ok (so the water pump is still driven) then I can take my time and get a new one, with the AtoB still charging both batteries. If it fails mechanically then I immediately need to replace it - and so will call out RCR - and let them do it.

[ditchcrawler]

3 hours ago, Dr Bob said:

At the moment both alternators feed the AtoB which then charges both domestic and starter. If the 55A fails, but is mechanically ok (so the water pump is still driven) then I can take my time and get a new one, with the AtoB still charging both batteries. If it fails mechanically then I immediately need to replace it - and so will call out RCR - and let them do it.

My point was after repairing it will you still keep the AtoB which is possibly heavily loading it, for it possibly to fail again?

[Dr Bob]

22 minutes ago, ditchcrawler said:

My point was after repairing it will you still keep the AtoB which is possibly heavily loading it, for it possibly to fail again?

Ok, now I understand.

I think the first thing  is to work out what current each alternator is giving out. If the small one is more heavily loaded - so it is delivering say 30 A and the big one only 20A then I need to talk to Sterling about how their AtoB works. I can then make a decision after that. Their AtoB will not be fit for purpose under the sale of goods act if the unit pulls more power from a smaller alternator if 2 are used together. Likely i will use the smaller one just direct to the starter battery and the AtoB for the big alternator and domestic bank.

[WotEver]

4 minutes ago, Dr Bob said:

Likely i will use the smaller one just direct to the starter battery and the AtoB for the big alternator and domestic bank.

You know that we all think that this is what you should be doing anyway, right?

[Dr Bob]

5 minutes ago, WotEver said:

You know that we all think that this is what you should be doing anyway, right?

Yes, but its not wired up that way now, is it! Maybe when the sun starts shining a bit more.

[Sea Dog]

4 minutes ago, Dr Bob said:

Ok, now I understand.

Hmm, maybe, maybe not.  If you isolate the AtoB and connect up so that your 90a alternator is feeding your domestics and your 55a iss feeding your starter battery, you'll be able to see exactly what each alternator is doing.  If all is then well, it's the AtoB that's at fault; if the 55a is still overheating, it's at fault; if the 90a is duff (and is having to be compensated for by the 55a one through the AtoB thus overheating it), you'll be able to see that.  Left in circuit, the AtoB thing could either be covering up the cause, or be the cause. 

[Dr Bob]

1 minute ago, Sea Dog said:

Hmm, maybe, maybe not.  If you isolate the AtoB and connect up so that your 90a alternator is feeding your domestics and your 55a iss feeding your starter battery, you'll be able to see exactly what each alternator is doing.  If all is then well, it's the AtoB that's at fault; if the 55a is still overheating, it's at fault; if the 90a is duff (and is having to be compensated for by the 55a one through the AtoB thus overheating it), you'll be able to see that.  Left in circuit, the AtoB thing could either be covering up the cause, or be the cause. 

No I understand what you are saying. I do.

Both alternators were checked when RCR did a service on the engine over christmas. Both seem to be putting out the right voltage. Let me check the currents and then I can make a decision. Cleaning all the dust out of the 55A one should help! I have not noticed any change in an any of the charging characteristics except when the AtoB was fitted so everything has been constant for the last 6 months. First job is to pick up the clamp meter from the marina reception!

There is quite a bit of re-wiring to do to take the AtoB out of circuit.

[rusty69]

6 minutes ago, Dr Bob said:

First job is to pick up the clamp meter from the marina reception!

Ooo exciting. New toy. Go on,go and see if its arrived yet,go on. I bet its a red one too!

[Sea Dog]

1 minute ago, Dr Bob said:

No I understand what you are saying. I do.

Both alternators were checked when RCR did a service on the engine over christmas. Both seem to be putting out the right voltage. Let me check the currents and then I can make a decision. Cleaning all the dust out of the 55A one should help! I have not noticed any change in an any of the charging characteristics except when the AtoB was fitted so everything has been constant for the last 6 months. First job is to pick up the clamp meter from the marina reception!

There is quite a bit of re-wiring to do to take the AtoB out of circuit.

Ah, now I understand your reluctance!  I expected it had been added to the system later so would be using the original alternator to battery cabling as it's feeds so these would be straightforward to remove and reconnect to their respective batteries.  I'd have wired it like that anyway, so you could connect direct in case the unit failed (or you needed to fault find!).

Unless you put the alternators on a test loads or depleted batteries, the current will be limited to what the batteries can take.  I expect your starter battery will be near as damn it full so you won't see a big current there and your domestics could be anywhere depending on your recent charge or duscharge.

[rusty69]

21 minutes ago, rusty69 said:

Ooo exciting. New toy. Go on,go and see if its arrived yet,go on. I bet its a red one too!

C'mon Dr Bob, the suspense is killing us.

Get the wrapping off, open the box ,chuck instructions to one side (cos blokes don't need instructions).

Put probes in. Check batteries. Turn on. Find something to measure (watch out duck).

Find instructions you earlier chucked,cos you can't figure out if its autoranging or not.

[Dr Bob]

1 hour ago, rusty69 said:

C'mon Dr Bob, the suspense is killing us.

Get the wrapping off, open the box ,chuck instructions to one side (cos blokes don't need instructions).

Put probes in. Check batteries. Turn on. Find something to measure (watch out duck).

Find instructions you earlier chucked,cos you can't figure out if its autoranging or not.

Yes, it's red. It's a UNI-T.

Doesn't fit round the ducks neck unfortunately. There is no current running through my little finger. I better test that with the infrequent red thermometer to see if I'm still alive otherwise I'll need to go to the doctors.

I will switch off the shore power tonight to pull some charge out of the batteries so I can test it tomorrow.

[nicknorman]

2 minutes ago, Dr Bob said:

Yes, it's red. It's a UNI-T.

Doesn't fit round the ducks neck unfortunately. There is no current running through my little finger. I better test that with the infrequent red thermometer to see if I'm still alive otherwise I'll need to go to the doctors.

I will switch off the shore power tonight to pull some charge out of the batteries so I can test it tomorrow.

If you survive the night. Just seen this...

[Amber Derv]

Hi All, just passing by looking at Alt. probs, as have had issues with a boat I am moving, (may start a thread on that).

One thing that strikes me as to the OP`s possible `problem`, i.e. Start Battery Alternator getting hot.

In the confined `box` of the engine `ole, and bearing in mind the Alternator draws air in from it`s rear, I notice the Alt. is positioned just below and in front of the ex. manifold/heat exchanger, thus probably drawing its cooling air from that area as opposed to the domestic Alt, higher and on the other side of the engine. Possible quick test may be run up and check temps. with eng. cover/boards up.

Just a thought until the amps get checked.

I have a Beta 1305 and the boat I am moving is a 1505, much the same as this but have not had cause to look/check Alt. running temps.

(Hi to Snibs who worked next door to me for `Satan` and my Alt. on a previous boat was the `Delta/Star` mod he often refers to).

[Dr Bob]

3 hours ago, nicknorman said:

If you survive the night. Just seen this...

Com'on Nick. Keep up!

Auntie Waitrose posted the news this morning on another thread! I think we all agreed it was another of Mr Putin's plots.

1 hour ago, Amber Derv said:

Hi All, just passing by looking at Alt. probs, as have had issues with a boat I am moving, (may start a thread on that).

One thing that strikes me as to the OP`s possible `problem`, i.e. Start Battery Alternator getting hot.

In the confined `box` of the engine `ole, and bearing in mind the Alternator draws air in from it`s rear, I notice the Alt. is positioned just below and in front of the ex. manifold/heat exchanger, thus probably drawing its cooling air from that area as opposed to the domestic Alt, higher and on the other side of the engine. Possible quick test may be run up and check temps. with eng. cover/boards up.

Just a thought until the amps get checked.

I have a Beta 1305 and the boat I am moving is a 1505, much the same as this but have not had cause to look/check Alt. running temps.

(Hi to Snibs who worked next door to me for `Satan` and my Alt. on a previous boat was the `Delta/Star` mod he often refers to).

Thanks Amber Derv. Welcome to the forum.

Your idea on heat is well taken. It could indeed be the problem as well as the air intakes on the alternator rather blocked with belt residue. Once we go out next - likely next week once it warms up a bit - I will try it with the boards up.

[WotEver]

6 minutes ago, Dr Bob said:

Once we go out next - likely next week once it warms up a bit - I will try it with the boards up.

Remember the first rule of fault finding... only change one thing at a time. 

[Amber Derv]

Hi again and thanks Dr Bob.

Just to add, unless the experts say otherwise regarding temps, I don`t think the 85 degrees is too excessive anyway, given the environment the Alt. operates in. Although my background is in vehicle diesels, in cars they obviously run at higher temps than our `slow` revving boats but are able to cope with the under-bonnet temps and are mostly similar to our boat alternators, bearing in mind diesels do run hotter, even with proper cooling, say 110 degrees or so. (cooling sys pressure increases boiling point), in a car down the m/way. You get cylinder temps of 3 - 400 degrees and blasting down the road at 100mph with the turbo whizzing away it can reach 800 in the cylinders!!! which the cooling sys takes care of. I know our engines in no way get this hot, but gives you the idea.

This is all just conjecture if when you get an ammeter on your kit you find a fault.

I am of the school of if it ain`t xxxx`ed, then don`t fix it! as well as it sometimes can be the silliest thing causing a fault before wading in with the spanners!

Like they say about my old Triumph, `90% of carb problems are electrical`.

Edited March 28, 2018 by Amber Derv
add a bit more

[Dr Bob]

3 minutes ago, Amber Derv said:

Hi again and thanks Dr Bob.

Just to add, unless the experts say otherwise regarding temps, I don`t think the 85 degrees is too excessive anyway, given the environment the Alt. operates in. Although my background is in vehicle diesels, in cars they obviously run at higher temps than our `slow` revving boats but are able to cope with the under-bonnet temps and are mostly similar to our boat alternators, bearing in mind diesels do run hotter, even with proper cooling, say 110 degrees or so. (cooling sys pressure increases boiling point), in a car down the m/way. You get cylinder temps of 3 - 400 degrees and blasting down the road at 100mph with the turbo whizzing away it can reach 800 in the cylinders!!! which the cooling sys takes care of. I know our engines in no way get this hot, but gives you the idea.

This is all just conjecture if when you get an ammeter on your kit you find a fault.

Thanks again. Have a greenie.

[Tumshie]

On 26/03/2018 at 23:49, rusty69 said:

The trouble trying to take Tribble temperatures with thermometers, time tells that three temperature transducers trending together totally tally. 

 

[Dr Bob]

9 hours ago, Tumshie said:

 

What's Rusty doin' round your place?

[Tony Brooks]

17 hours ago, Dr Bob said:

There is quite a bit of re-wiring to do to take the AtoB out of circuit.

Are you sure?

I think that when this problem cropped up before I said that you could probably just take the relevant alternator and battery cables off the A to B and join them or even put the pair of leads on one terminals, then do the same for the other alternator/bank. The other tong seemed to agree.

17 hours ago, Dr Bob said:

Both alternators were checked when RCR did a service on the engine over Christmas. Both seem to be putting out the right voltage.

The trouble is that voltage on its own is not a good test of alternator output but the best that can be done "in the field" unless you have a dummy load to connect to the batteries.

When alternators are tested properly they go onto a rig with an adjustable load. This allows the maximum output to be checked and then with the load very much reduced the regulated voltage can be checked. Trying to use just voltage taken on a boat with no indication of current can only rely upon informed inference.

To illustrate. Before your D+ to B+ voltage difference test  the date suggested you might have a phase down. That will slightly reduce the maximum voltage but it may still be within figures quoted for a range of alternators but it will make a far larger reduction in maximum current. So if your domestic bank was well charged when RCR tested it the voltage could well have looked OKish despite a fault.