Alternator cutting in and out

[eid]

I have a 90amp alternator connected to my leisure batteries, which has a Sterling alternator regulator fitted to it.

 

Usually, whilst charging, the voltage at the batteries is ~14.3v, going up to ~14.5v as they get full. Recently however, the voltage keeps dropping, sometimes fluctuating, other times dropping down to 13.3v and staying there. The current also goes down (to nothing at 13.3v). If left for a while it will kick in again.

 

I have tested the batteries by removing them and trying one by one. This has no effect.

 

I don't think the belt is slipping as the wheel is definitely turning as this happens. I'm also quite sure it is not overheating as I am only charging about 4amps. Also, it isn't hot.

 

I have tested the voltage between the alternator + and the chassis. The reading is the same as above.

 

I have tried increasing the revs to no effect. However, when I lower the revs to idle, the alternator kicks in again. How long it stays on seems to be random however.

 

 

Anyone have a suggestion as to what may be causing this?

[dor]

What happens if you disconnect the Sterling regulator?  It should then operate on the alternator's internal regulator.  This might only be 13.8 - 14.0V, but should be consistent.

[Jess--]

another vote to have a good check of the regulator

 

I used to have a range rover that would randomly decide the battery was fully charged at 11.3v (from inside you'd see the headlights and dash lights drop when it happened) that turned out to be the regulator built into the back of the alternator.

[eid]

11 minutes ago, dor said:

What happens if you disconnect the Sterling regulator?  It should then operate on the alternator's internal regulator.  This might only be 13.8 - 14.0V, but should be consistent.

 

1 minute ago, Jess-- said:

another vote to have a good check of the regulator

 

I used to have a range rover that would randomly decide the battery was fully charged at 11.3v (from inside you'd see the headlights and dash lights drop when it happened) that turned out to be the regulator built into the back of the alternator.

 

I'm not familiar with the regulator wiring, but I'll have a good look and do some research. Is it just a case of removing the wires from the regulator to the alternator, or more complicated than that?

 

Thank you both for your advice.

[Bod]

If this random, check for loose or broken wires, particularly any that are not fully supported.

 

Bod

[dor]

24 minutes ago, eid said:

 

 

I'm not familiar with the regulator wiring, but I'll have a good look and do some research. Is it just a case of removing the wires from the regulator to the alternator, or more complicated than that?

 

Thank you both for your advice.

It depends on the alternator, but usually the Sterling regulators are linked by a wire that comes out of the alternator rather than a connection on the case (the wire goes to one of the brushes internally).  If you disconnect this wire, the alternator will revert to the internal regulator.

[eid]

54 minutes ago, Bod said:

If this random, check for loose or broken wires, particularly any that are not fully supported.

 

Bod

This seems more suited to my skill-set. I gave them all a good wiggle. To no effect. Thanks.

39 minutes ago, dor said:

It depends on the alternator, but usually the Sterling regulators are linked by a wire that comes out of the alternator rather than a connection on the case (the wire goes to one of the brushes internally).  If you disconnect this wire, the alternator will revert to the internal regulator.

Thank you, I'll look into that. I think I have the manual here somewhere.

[GUMPY]

Is the sterling regulator an old blue coloured one?

if so then take it off and bin it they are rubbish

Just after they were released I tried 3 under warranty from sterling in the end he said it was my fault!

Never did find the real reason it didnt work.

 

ETA there is a mismatch between those controllers and some types of alternator mine was on a Nanni engine but cant remember the alternator type

Edited February 5, 2019 by Loddon

[by'eck]

3 hours ago, eid said:

I have a 90amp alternator connected to my leisure batteries, which has a Sterling alternator regulator fitted to it.

 

Usually, whilst charging, the voltage at the batteries is ~14.3v, going up to ~14.5v as they get full. Recently however, the voltage keeps dropping, sometimes fluctuating, other times dropping down to 13.3v and staying there. The current also goes down (to nothing at 13.3v). If left for a while it will kick in again.

 

I have tested the batteries by removing them and trying one by one. This has no effect.

 

I don't think the belt is slipping as the wheel is definitely turning as this happens. I'm also quite sure it is not overheating as I am only charging about 4amps. Also, it isn't hot.

 

I have tested the voltage between the alternator + and the chassis. The reading is the same as above.

 

I have tried increasing the revs to no effect. However, when I lower the revs to idle, the alternator kicks in again. How long it stays on seems to be random however.

 

 

Anyone have a suggestion as to what may be causing this?

The Sterling regulator is likely a smart one. Just like similar smart chargers it has multiple modes. One will be float with charge voltage dropping to just over a volt less than full when it decides batteries are near fully charged. The exact voltage will depend on settings as they cater for a range of battery types.  The reason it may jump back to full (absorb charge) mode is because of a sudden load on batteries whilst cruising has caused a dip in battery voltage. Situation normal in other words.

 

If you have two alternators charging the same battery bank it's even possible one the alternators, depending on internal regulator, to drop out altogether as indicated by charge light when batteries approach full charge. This is also an acceptable situation.

Edited February 5, 2019 by by'eck

[eid]

2 hours ago, Loddon said:

Is the sterling regulator an old blue coloured one?

if so then take it off and bin it they are rubbish

Just after they were released I tried 3 under warranty from sterling in the end he said it was my fault!

Never did find the real reason it didnt work.

 

ETA there is a mismatch between those controllers and some types of alternator mine was on a Nanni engine but cant remember the alternator type

It is this one:

 

 

 

39 minutes ago, by'eck said:

The Sterling regulator is likely a smart one. Just like similar smart chargers it has multiple modes. One will be float with charge voltage dropping to just over a volt less than full when it decides batteries are near fully charged. The exact voltage will depend on settings as they cater for a range of battery types.  The reason it may jump back to full (absorb charge) mode is because of a sudden load on batteries whilst cruising has caused a dip in battery voltage. Situation normal in other words.

 

If you have two alternators charging the same battery bank it's even possible one the alternators, depending on internal regulator, to drop out altogether as indicated by charge light when batteries approach full charge. This is also an acceptable situation.

 

It does seem to be dropping into float, but it is way before the batteries are fully charged, which has only started happening recently. When it decides to go back into absorb does not seem to be connected to any surge in usage either: this is all happening while I sit watching it with only a few watts being used.

 

Could it be related to old batteries? Mine are on their last legs I think.

[Keith M]

Check the sensing and supply wires to the external regulator. 

[by'eck]

eid, that looks like an early Sterling regulator. These didn't have automatic sensing of battery bank size. Instead they had a user adjustable timer via tiny dip switches inside to control how long it was in the higher voltage absorb charge mode. If it's already set to the max, which from distant memory is two hours, then there is nothing more to be done, unless you buy latest version. Otherwise set timer to max.

 

Note the timer switches are a separate set from those depicted on casing which set battery type. Worth checking they are set appropriately though.

Edited February 5, 2019 by by'eck

[Tony Brooks]

The symptoms might be related to worn or sticky brushes making intermittent contact and have nothing to do with either regulator. This would be my   second check after the  wiring and connections. I think 13.3V is about what I would expect from a freshly charged battery for a short while and the zero amps  sort of goes along with this.

[GUMPY]

5 hours ago, eid said:

It is this one:

 

 

That's the one I had, the older yellow ones are fine. Personally I wouldn't entertain one on my system, just change the internal regulator for a higher voltage one.

Edited February 5, 2019 by Loddon

[Sea Dog]

5 hours ago, eid said:

It is this one:

 

 

 

 

It doesn't look that big...

 

I'd have thought you could throw it quite a long way! 

 

(If it isn't the problem I'd be surprised )

 

 

[ditchcrawler]

1 hour ago, Sea Dog said:

 

It doesn't look that big...

 

I'd have thought you could throw it quite a long way! 

 

(If it isn't the problem I'd be surprised )

 

 

If it fails doesnt the standard regulator take over?

[GUMPY]

It did on mine.

[Boater Sam]

That’s the mk2 version, it is self setting for battery bank size, mine has always worked fine. Check it is set for the correct type of battery. 

It should/will have a temperature sensor fitted to one battery and wired into the box. Check it’s fitted correctly.

[eid]

15 hours ago, Keith M said:

Check the sensing and supply wires to the external regulator. 

Thanks, I will.

15 hours ago, by'eck said:

eid, that looks like an early Sterling regulator. These didn't have automatic sensing of battery bank size. Instead they had a user adjustable timer via tiny dip switches inside to control how long it was in the higher voltage absorb charge mode. If it's already set to the max, which from distant memory is two hours, then there is nothing more to be done, unless you buy latest version. Otherwise set timer to max.

 

Note the timer switches are a separate set from those depicted on casing which set battery type. Worth checking they are set appropriately though.

I realised last night that I have never before seen this regulator go into float mode. Or rather, the float light comes on but it stays at 14.5v.

 

14 hours ago, Tony Brooks said:

The symptoms might be related to worn or sticky brushes making intermittent contact and have nothing to do with either regulator. This would be my   second check after the  wiring and connections. I think 13.3V is about what I would expect from a freshly charged battery for a short while and the zero amps  sort of goes along with this.

This makes a lot of sense. I did check the voltage when I turned the engine off and it matched (13.3v). I assume the brushes are replaceable?

 

28 minutes ago, Boater Sam said:

That’s the mk2 version, it is self setting for battery bank size, mine has always worked fine. Check it is set for the correct type of battery. 

It should/will have a temperature sensor fitted to one battery and wired into the box. Check it’s fitted correctly.

I'm not sure it has a temperature guage. I'll check later.

 

 

Thanks all.

 

9 hours ago, Sea Dog said:

 

It doesn't look that big...

 

I'd have thought you could throw it quite a long way! 

 

(If it isn't the problem I'd be surprised )

 

 

I'd gladly do so if I can safely remove it.

[Tony Brooks]

Just now, eid said:

 

This makes a lot of sense. I did check the voltage when I turned the engine off and it matched (13.3v). I assume the brushes are replaceable?

 

 

 usually these days as part of the regulator. Unscrew the regulator but don't just pull the regulator away, you have to sort of tilt/twist it to get the brushes out of the hole.

[dor]

10 hours ago, Loddon said:

That's the one I had, the older yellow ones are fine. Personally I wouldn't entertain one on my system, just change the internal regulator for a higher voltage one.

I've changed the internal regulator on my 95A Iskra (Vetus). The original one went to 14.0V, the replacement goes to 14.6V.   Cost around £18.  As far as I can make out, it does as good a job of the Sterling; the PDAR I have always went into float after one hour, regardless of the state of charge of the batteries

[eid]

Can anyone identify this alternator; I'd like to get a manual or some instructions:

 

 

 

----------------------------------

 

ETA: Luckily there is a sticker on the alternator regulator so I was able to identify it by that. Apparently it is from a Renault Clio ?

 

 

 

Edited February 9, 2019 by eid

[eid]

While fiddling around yesterday, trying to see where all the wires went, I noticed inside the regulator a fuse. It is used to select between a pos/neg field alternator. This fuse was blown. The new one blew too.

In the installation instructions it states that the wires coming from the internal regulator brushes should measure: 1) 14v and 2) between 2 and ten volts. You should connect the Sterling wire to the non 14v one.

On testing these wires, one was ~14v and the other 10.6v. So i tried connecting the Sterling wire to the lower of these but it went into high voltage warning mode. The fuse did not blow though!

Today this wire is outputting 12v. Does anyone have any idea why this should be?

 

Thanks.

 

 

[WotEver]

@Sir Nibble?