Charging woes...

[nicclark]

I'm hoping that the collective expertise might suggest a solution to my alternator and charging issues!

We've an Ocean 37, twin modern internal regulated alternators have replaced the CAV versions that were fitted. There are two battery banks - one charged by the starboard engine for starting, and the other charged by the port for domestics.

The ammeters are original and are in the high current circuit, so very large cable goes to the helm - not sure if there is a better way to do this now.

The main issue is that the newest alternator does not charge well - it's intermittent at best and I am not sure if it has been damaged by being at low speeds on the river, which is the second issue - I don't think it spins fast enough to cut in so charging is not taking place.

Both battery lights stay on when the engines run.

One Tacho, for the older and more reliable alternator, works well but the other doesn't work, or jumps a bit when a lot of throttle is applied.

Essentially, I'd like to build a reliable charging system that works at relatively low speeds and doesn't cost the earth and I am not sure where to start!

I like the look of the alternator to battery charger, but they are really expensive for our 24v system, and I don't think they would solve the speed issue.

Any ideas or experience appreciated!

 

[halcyon]

I'm hoping that the collective expertise might suggest a solution to my alternator and charging issues!

We've an Ocean 37, twin modern internal regulated alternators have replaced the CAV versions that were fitted. There are two battery banks - one charged by the starboard engine for starting, and the other charged by the port for domestics.

The ammeters are original and are in the high current circuit, so very large cable goes to the helm - not sure if there is a better way to do this now.

The main issue is that the newest alternator does not charge well - it's intermittent at best and I am not sure if it has been damaged by being at low speeds on the river, which is the second issue - I don't think it spins fast enough to cut in so charging is not taking place.

Both battery lights stay on when the engines run.

One Tacho, for the older and more reliable alternator, works well but the other doesn't work, or jumps a bit when a lot of throttle is applied.

Essentially, I'd like to build a reliable charging system that works at relatively low speeds and doesn't cost the earth and I am not sure where to start!

I like the look of the alternator to battery charger, but they are really expensive for our 24v system, and I don't think they would solve the speed issue.

Any ideas or experience appreciated!

If you put engine in neutral and run revs high, do the warning lights go out ? what voltage do you have at alternator with engine running, alternator and battery terminal.

Brian

 

[jrudge]

You need to start with basic fault finding. Is there even a fault? What is the charging voltage? Are you batteries going flat?

Alternators are designed to provide a decent output at low speed.

The ammeter would now be a shunt - running a high power cable to the helm is not the best of ideas.

If the batteries are charging then you can look at gauges. Poor earth is a fairly common culprit,

 

[peteK]

Tacho usually works off the alternater so faults are linked

 

[simonfraser]

'The ammeters are original and are in the high current circuit, so very large cable goes to the helm - not sure if there is a better way to do this now'

you may do better to start a new thread for the above, but yes
and personally i would not want to run all the power over to the helm and back

SmartShunt - Victron Energy

 

[nicclark]

Thanks for the replies so far, I'll get to the boat as soon as I can and test what is actually coming from the alternator.

 

[Montemar]

This is a very useful source of information:-
ME08

 

[nicclark]

Thanks for the replies so far.

So I had a chance to get to the boat and test output from the alternators:

Port alternator is Prestolite and less than 2 years old (but out of warranty!) output at idle 24.4v which is the voltage of the domestic bank at that time off charge. So no charging happening.

Starboard alternator is an old Bosch and outputs 28.1v at 600rpm to the start batteries.

Both battery lights stay on though?

 

[halcyon]

Thanks for the replies so far.

So I had a chance to get to the boat and test output from the alternators:

Port alternator is Prestolite and less than 2 years old (but out of warranty!) output at idle 24.4v which is the voltage of the domestic bank at that time off charge. So no charging happening.

Starboard alternator is an old Bosch and outputs 28.1v at 600rpm to the start batteries.

Both battery lights stay on though?

But did revving up the engine alter the voltage or warning lights ?

Brian

 

[nicclark]

Sorry, I should have added that! Stbd goes up to 30v, light still on. Nothing from the port, no change at high revs apart from spikes on the rev counter at higher revs.

Nic