Charging batteries

[Kalapattar]

What’s the simple way of reading alternator output using a AVO please?

[Jen-in-Wellies]

7 minutes ago, Kalapattar said:

What does  0.1 amp suggest on my nasa monitor please?

It suggests that next to no current flow is being measured. That could be for a number of reasons, that might even include a fault in the wiring to the monitor from the shunt. Other reasons include, but not exhaustively:

full charged batteries, unlikely, if the battery voltage is correct.

The shunt being installed in the wrong place, so it doesn't measure incoming current from the alternator.

The alternator being damaged.

The belt slipping.

 

Jen

4 minutes ago, Kalapattar said:

What’s the simple way of reading alternator output using a AVO please?

When you say AVO do you mean one of these?

 

For measuring current of the scale that an alternator can give out you need a DC Clamp Meter. A different thing.

Jen

[LadyG]

Calm down a bit @Kalapattar

Start by re reading all the posts, and check how well you are understanding your system. 

I struggle with this stuff, so  I have to visualise it in my head, a kind of conceptual diagram.

Have you answered all the questions?

Do you have a better understanding of why they are relevant?

 

You may find it helpfull if you put your own system to one side, make a large mug of tea and check out the learning material on Tony's website.

 Let the brain rest for an hour or so, and repeat.

 

Edited November 30, 2020 by LadyG

[ditchcrawler]

24 minutes ago, Kalapattar said:

What’s the simple way of reading alternator output using a AVO please?

The best you can do with that is measure the voltage on the B+ terminal on the back of the alternator. with the engine stopped it should read the same as the battery voltage, around 12 volts. This would indicate that the connection between the alternator and the battery is sound. When you run the engine this voltage should rise to about 13 volts quite quickly and as you batteries take charge up to 14.4 volts. More when the Adverc cuts in after 15 minutes +

 

I have just had another thought and will read the thread again. watch this space

[Slim]

I think an earlier post from you suggested you moor just above Batchworth lock. If so and if the alternator needs checking/repairing you have a handy repairer just down the road. It's on the same estate sa Watford Timer and Orbital Fasteners. . At the end of the same road. Can dig out details later if needed.

[ditchcrawler]

4 minutes ago, ditchcrawler said:

The best you can do with that is measure the voltage on the B+ terminal on the back of the alternator. with the engine stopped it should read the same as the battery voltage, around 12 volts. This would indicate that the connection between the alternator and the battery is sound. When you run the engine this voltage should rise to about 13 volts quite quickly and as you batteries take charge up to 14.4 volts. More when the Adverc cuts in after 15 minutes +

 

I have just had another thought and will read the thread again. watch this space

OK, I am back. Do you have one or two alternators on the engine?

 My thoughts ar, if there is only one your domestic batteries are fed through a split charge diode or relay. The nassa is reading the current and voltage of the domestics and the split charge system has failed.

Edited November 30, 2020 by ditchcrawler

[Kalapattar]

Ah, yes! Thanks!

Yes, meter is similar! Gunson with a digital reading 

[Kalapattar]

Ok, thanks!  split diode clicks on and off and the lights up when running engine! Should light be off?

41 minutes ago, Jen-in-Wellies said:

It suggests that next to no current flow is being measured. That could be for a number of reasons, that might even include a fault in the wiring to the monitor from the shunt. Other reasons include, but not exhaustively:

full charged batteries, unlikely, if the battery voltage is correct.

The shunt being installed in the wrong place, so it doesn't measure incoming current from the alternator.

The alternator being damaged.

The belt slipping.

 

Jen

When you say AVO do you mean one of these?

 

For measuring current of the scale that an alternator can give out you need a DC Clamp Meter. A different thing.

Jen

Ok thanks! 

[Tony Brooks]

2 hours ago, Kalapattar said:

Oops! Sorry I didn’t reply over the weekend! I tend to leave my messaging, Facebook etc alone at weekends and see what else is out there.

my lights do go out suggesting alternator is working ok! It is a process of elimination, just how the way engines and electrics work. However, I’m not an electrician! What does  0.1 amp suggest on my nasa monitor please?

 

As near as dam  it - no charge, probably just a meter inaccuracy.

 

I don't wish to be a grump but the red bit is misleading. I would suggest that phrase as its plural refers to your internal lights not the charge warning lamp (singular). That understanding would suggest the batteries are dead flat but I doubt you mean that and you are referring to the charge warning lamp.

 

The maximum voltage a battery can show is just over 13 volts and that is just for a very short time. Then it drops to about 12.8 where it stays and gradually drops as the batteries discharge.  Your 12.8 volts sounds as if your batteries are not being charged by the alternator. With a current of 0.1 amps suggest fully charged batteries or a charging fault and 12.8V suggest fully charged batteries BUT NOT with the engine running at 1000rpm+. then it should be in excess of 14.2 volts so we are back to the alternator AS LONG AS no connections have fallen off.

 

We can  explain the green part to you if you could be more specific because its a big topic for the whole boat. Basically the majority of alternators need a small current from the warning lamp to get them charging when the engine spins it up. No small current = no charge but as long as you have not misidentified an oil pressure lamp as the charge warning ,amp you have now ruled that out. You are correct to think about the drive belt but a visual inspection and thumb pressed into the longest belt run (for ordinary V belt) shoudl tell you it that's the problem. Expect about 10mm defection in the longest run when you test it. There may well be more a sits probably worn a bit but if it looks OK you can usually adjust it.

 

You may find the notes on my website helps you understand things. http://www.tb-training.co.uk

[Tony Brooks]

2 hours ago, Kalapattar said:

What’s the simple way of reading alternator output using a AVO please?

Only if you also have the high current shunt and then you need to make up some beefy cables to connect it.

 

You really need a multimeter with DC clamp meter for DC amps - AC only clamp meters are no good.

 

2 hours ago, ditchcrawler said:

OK, I am back. Do you have one or two alternators on the engine?

 My thoughts ar, if there is only one your domestic batteries are fed through a split charge diode or relay. The nassa is reading the current and voltage of the domestics and the split charge system has failed.

I agree a distinct possibility or a 1,2,both, off switch in the wrong position but I suspect the OP probably does not know what he has got.

[LadyG]

I am trying to follow this, but was completely bamboozled by post 26i

Is it possible OP  could  post afew photos ?

Tx

Edited November 30, 2020 by LadyG

[bizzard]

4 minutes ago, LadyG said:

I am trying to follow this, but was completely bamboozled by post 26i

Is it possible OP  could  post afew photos ?

Tx

Don't worry about AVO meters, they're for fuddy duddies. Just use a voltmeter and am eater.

[Alan de Enfield]

6 minutes ago, bizzard said:

Just use a voltmeter and am eater.

One like this ?

 

15 minutes ago, LadyG said:

I am trying to follow this, but was completely bamboozled by post 26i

Is it possible OP  could  post afew photos ?

Tx

An Avo is a brand / type of electrical test meter.

[Tony Brooks]

33 minutes ago, Alan de Enfield said:

 

An Avo is a brand / type of electrical test meter.

And in its day a very good one but no use on a high current circuit like starting and charging unless you have extra kit because it can only reda up to 10 amps, much like ordinary non-clamp type multimeters..

 

[Kalapattar]

On 30/11/2020 at 14:09, Alan de Enfield said:

One like this ?

 

An Avo is a brand / type of electrical test meter.

AVO actually stands for Amps, Voltage and Ohms!

mine is made by Gunson

[Tony Brooks]

16 minutes ago, Kalapattar said:

AVO actually stands for Amps, Voltage and Ohms!

mine is made by Gunson

No AVO is a trade name. You have a multimeter that can read amps, volts and ohms. In that respect its similar to an AVO but probably not as accurate. If you call it an AVO then you are not correct and will get answers that make little sense to you. A proper AVO  can come with a shunt so it can measure high currents, i bet you Gunson multi-meter does not.

[Ryeland]

AVO were based in Dover IIRC, I remember seeing the factory when I was working down there.

 

Richard