Alternator charging problems

[Andydenn]

Hi

I'm looking for some advice, if anyone could help

I have a 5yr old NB with a beta marine 43 with the standard 175amp alternator. I switched the engine on and the voltage at the batteries was indicating 14.95v which was correct from using the multi meter. I thought that perhaps the alternator wasn't regulated properly so gave it to my partner to take to work where a new regulator was fitted. The output is now 15.2v!! The batteries were fully charged at the time. 

I have 5x 110amp domestic sealed lead acid batteries. With one battery at the bow for the bowthruster but still connected to the others.
I have load tested the batteries and all passed the test.

My question is... can the alternator be regulated down to output 14.4v? And subsequently reduced its voltage as the batteries are nearing full SOC.  Or do you think there is a fault in the system somewhere?

Apologies if I have missed any important information
Thanks 






 

[nicknorman]

We have a beta 43 with the iskra 175A alternator. I have never known it produce more than 14.6v.

 

But are you sure you are looking at the right thing? There are 2 alternators on a Beta 43, and the voltmeter on the panel shows the engine alternator / engine battery voltage, nothing to do with the 175A alternator.

 

How are you measuring the 175A alternator voltage?
 

If you are indeed looking at the engine battery/alternator voltage using the panel gauge, firstly I’d check the voltage using something else to corroborate it (handheld digital meter). And if it is corroborated, it is the small engine alternator that needs looking at.

 

Edited May 7, 2020 by nicknorman

[ditchcrawler]

Also has someone fitted an alternator controller like an Adverc ?

[Andydenn]

The victron gauge we have shows both starter and leisure voltage. I can see the starter voltage drop quite a bit when engine starting 

The high output voltage on the 175amp alternator was measured with a multi meter. We don't have any sort of external regulator/battery charger on the alternator. 

One thing I do remember is that the batteries were actually changed from open lead to sealed lead. Is it possible the previous owner has switched battery types and not adjusted the alternator? Does the alternator need adjusting when changing battery types?

 

[system 4-50]

You have no solar or you would have mentioned it.

[Andydenn]

12 minutes ago, system 4-50 said:

You have no solar or you would have mentioned it.

disconnected it for the readings 

[Tony Brooks]

Some Betas have been fitted with a Beta alternator controller. Check yours is not one of these.

[ditchcrawler]

58 minutes ago, Andydenn said:

The victron gauge we have shows both starter and leisure voltage. I can see the starter voltage drop quite a bit when engine starting 

The high output voltage on the 175amp alternator was measured with a multi meter. We don't have any sort of external regulator/battery charger on the alternator. 

One thing I do remember is that the batteries were actually changed from open lead to sealed lead. Is it possible the previous owner has switched battery types and not adjusted the alternator? Does the alternator need adjusting when changing battery types?

 

I am guessing its not  a battery sensing alternator, they aren't normally but it could explain it 

[nicknorman]

59 minutes ago, Andydenn said:

The victron gauge we have shows both starter and leisure voltage. I can see the starter voltage drop quite a bit when engine starting 

The high output voltage on the 175amp alternator was measured with a multi meter. We don't have any sort of external regulator/battery charger on the alternator. 

One thing I do remember is that the batteries were actually changed from open lead to sealed lead. Is it possible the previous owner has switched battery types and not adjusted the alternator? Does the alternator need adjusting when changing battery types?
 

Ok well that’s odd then! What happens if you put some load on the alternator, eg some lights etc (incandescent, not led)?
 

No there is no adjustment on an alternator like that, it should regulate around 14.4 to 14.5, maybe 14.6v when cold and with no load.

5 minutes ago, Tony Brooks said:

Some Betas have been fitted with a Beta alternator controller. Check yours is not one of these.

It’s only 5 years old, beta stopped fitting the controller long before that.

[sharpness]

2 hours ago, Tony Brooks said:

Some Betas have been fitted with a Beta alternator controller. Check yours is not one of these.

Those had been discontinued by 2002 when I exchanged letters with Beta about fitting one on our new engine.

[TheBiscuits]

4 hours ago, Andydenn said:

The high output voltage on the 175amp alternator was measured with a multi meter.

 

Change the batteries in the multimeter and try it again.  You can get some very odd readings caused by tired batteries in hand-held multimeters.

[Sir Nibble]

Talk to the person who changed the reg. What did they get on test? No one would return an alternator to a customer with that level of over charging.

[cuthound]

14 hours ago, TheBiscuits said:

 

Change the batteries in the multimeter and try it again.  You can get some very odd readings caused by tired batteries in hand-held multimeters.

 

This^^^, then try the voltmeter against a new AA or AAA secondary cell- it should read 1.5 volts. If it is signifi antly different your voltmeter is out of calibration.

[Detling]

On 07/05/2020 at 19:48, ditchcrawler said:

I am guessing its not  a battery sensing alternator, they aren't normally but it could explain it 

My Izusu 130A was battery sensed and I think the Beta 43 was based on it.

If OP has two little wires with spade connectors on the Alternator it could well be externally sensed as the tacho is usually fed by the engine alternator.

 

If it is external battery sensed what happens when the sense wire is disconneted / broken?

 

Edited May 9, 2020 by Detling
to ask question

[nicknorman]

1 hour ago, Detling said:

My Izusu 130A was battery sensed and I think the Beta 43 was based on it.

If OP has two little wires with spade connectors on the Alternator it could well be externally sensed as the tacho is usually fed by the engine alternator.

 

If it is external battery sensed what happens when the sense wire is disconneted / broken?

 

Our 10year old Beta 43 with 175A alternator definitely isn’t battery-sensed.

 

A battery-sensed alternator can have a variety of behaviours with the sense wire disconnected, depending on the regulator, but I think normally there is internal sensing via an internal resistor so that if the wire is disconnected, the internal voltage is used. If the wire is connected, the direct connection trumps the internal connection via the resistor.

[Tony Brooks]

I know the regulator has been changed but did anyone check all three field diodes are OK? If its a 9 diode machine a blown field diode can give high voltages even though it seems to charge.

[WotEver]

20 minutes ago, Tony Brooks said:

I know the regulator has been changed but did anyone check all three field diodes are OK? If its a 9 diode machine a blown field diode can give high voltages even though it seems to charge.

As Snib pointed out, no-one who was experienced in alternator repairs would return one charging at 15.2V. So if that’s correct then it wants slinging straight back at the repairer. 

[Tony Brooks]

24 minutes ago, WotEver said:

As Snib pointed out, no-one who was experienced in alternator repairs would return one charging at 15.2V. So if that’s correct then it wants slinging straight back at the repairer. 

I agree but we don't know who did the repair or what test equipment they have.  It is just something else that needs bearing in mind.

[Sir Nibble]

50 minutes ago, Tony Brooks said:

I agree but we don't know who did the repair or what test equipment they have.  It is just something else that needs bearing in mind.

Not worth bearing anything in mind until the op comes back with some further input.