Tony Brooks

It would be more accurate to measure the volt drop across the joint under stating current.

Sorry Brian, my bad.

I am not sure that is correct. The ILLUSTRATED one uses screws to clamp the cable into the fitting. The better type that definitely are compliant are those with a stud where the two screws are.

That is not what he was describing. The "blade" was/is spring-loaded and set at the angle of the post face. The toll was placed over the post and twisted so the blade SCRAPED the corrosion off. there was no cutting of the post. Oh, and by the way it is perfectly possible to burn a new post onto the old post base if the post has burned away, but you do need to know what you are doing and have the posts moulds and lead available. It takes less than five minutes, but I suppose at today's labour rates a new battery may be more economic.

So you can get your finger under the clamps to ensure the dressing is fully sealing any gap between the post and terminal, can you. if you can, the clamp has been fitted too high on the post or it is the wrong clamp. 1. Two people (me and Tracy) have told you are incorrect, and both of us have had over 60 years in the motor and marine trade (probably in the case of Tracy). You readily discount ll the training and experience on the basis of "I have not had a problem". That is not a valid argument against all the lead acids battery installations., it is a sample size of one against probably millions. That last time this came up, you were debunked by others with experience in other industries. You will note that I have talked bout terminal dressing, with Vaseline being just one that is most likely to be available on a boat. I have also said the OP can dress or not dress, but if she does not, then the service life of the connection may well be shorter before more attention is required.

Once again, this misinformation rears its head. This was discussed at length not long ago when more than one professional explained how it was used when assembling joints on high current busbars and other applications. Yes Vaseline is an insulator so if the OP and you wish to substitute terminal dressing that looks exactly like red Vaseline or terminal grease (as issued to the UK armed forces) then fine, but they are all insulators in their own right, but that is not their purpose. If no terminal dressing is used then and very slight leak of acid or acid fumes through the post to cell lid seal will penetrate the small gaps between the post and clamp/terminal and create a very hard, black oxide type coating that really is insulating. This works its way across the whole surface and the engine will fail to start, giving machine-gunning and/or other "flat battery" symptoms. Negative terminals are particularly affected by this. If the dressing is cleaned off, all will appear well for a time, but the time period before a problem occurs is likely to be much reduced. Even now with much better post to cell lid sealing one still sees the area around the post, terminal and lead badly corroded with typically white, yellow, or bluish growths. This is normally the result of acid/acid fume leaks, so it can still be a problem. Just because you or I have an idea fixed in our minds does not make it correct, especially when it is contradicted by others with similar training and experience. The OP can take whatever advice she chooses, but dressing the terminals or not will make no difference to solving the problem, it may make the time before the next problem shorter

FWIW I understand that you can use the load output on many solar controllers to charge the start battery. perhaps someone who has done this can confirm, deny or elucidate. That gives you more solar output to charge the domestic bank during the winter, because the start battery is only discharged by a very few Ah on each start's so is nearly always very well charged (providing the engine and battery are in good order). Otherwise, I think for a lot of the time you will be wasting potential solar output. The exceptionally easy life starter batteries have is why that cheapo battery lasted 8 years.

The point that I think you may be missing is that unless you understand and monitor the battery charging you will destroy and expensive battery all but as fast as a cheap one. Unfortunately, we/I don't know if you do understand and monitor your battery charging so the only option is to advise you to buy an open, lead acid battery of the same size and terminal position as the ones you have now. This is so it fits into your existing battery cradle. If you buy a lead-carbon or AGM battery, it will cost more and may not last any longer. As far as lead acid batteries are concerned, it is far easier for an ordinary boater to test open cell batteries for faults than any sealed battery, although sealed ones seem to be favoured by many boaters who have difficulty accessing their batteries, yours look easy to access. I would not buy via either major online buying sites because you don't know who is doing the selling or if such technical data they supply is true. I used a specialist battery supplier with their own website. I think it was Advanced Battery Supplies, but there are others.

I think he is referring to the BMEA requirements and probably the ISOs. I think the BSS says something about that as well. So probably not a strict legal requirement, but something that should be adhered to. If the boat is within scope of the RCD/RCR then if it was questioned I think it would be difficult to justify it as being compliant.

Having another look, I think you are probably correct. It looks a mess. Further looking shows the batteries are rated at 60ah and 540 A EN, so I suppose that is 540A CCA. To try to answer the original question, just one of those should start the OPs engine as long as it is kept adequately charged. Further to Blackrose's post. I can see what looks like a substantial heat sink below the blue casing, so if it is a slit charge diode it is likely to be a passive one. That in turn means there is a very good chance that it is restricting the charging to all the batteries, however, this depends upon the type of alternator and how it and other charging components are wired.