question

@Stephen 1975 your best bet if you're looking for a smart alternator is probably a Balmar or something along those lines; I'd suggest contacting a marine parts supply store for information.

That being said, from what you describe I don't believe you have a charging problem; your statement that "the acid level shows as needs charging" indicates that, if I'm understanding what you mean correctly, your batteries are on their way out and need to be replaced soon. The fact that they show 14.4v when charging just means that your alternator is doing its job; the problem appears to be that they're not holding their charge, which is a sure indication that they need replacement.

Hi @Stephen 1975

I'd hate to see you go out and buy a new charger, or even abandon your batts straight off. All might still be well.

You don't actually say how low your Vbat goes. But pb's are very 'reactive'. They're either pushing or pulling a chemical process. Under charge they may show 14.4V. A moment later with no charge and a load applied they may show 12.0V. Same state of charge.

If you could leave them overnight to complete the chemistry, they should settle to a standing V of ~12.6V if fully charged.

I've never had much luck testing sg, perhaps because the chemical reaction takes so long to complete. Much preferred is the 'tail' current, where you compare the A they're accepting with their Ah capacity. For me, 2% is getting close, 1% would mean they're done. That's dependent on V too, but if that charge levels off they'll usually be finished.

So don't go jumping at shadows, just get to know them a little better.

You may not be able to measure A, but it's important. Not to say that every last little piece of blue kit will have it onboard, but the option of adding it is always there.