Is it the batteries?

[Goldie]

OK, disclaimer here; electrics are not my thing so please be gentle!

When using the electric windlass, the engine revs now drop noticeably and if at idle rpm to begin with, to the point that the engine sounds less than smooth. This only started happening recently and otherwise, the engine (Beta 50) is absolutely fine. I’m assuming that the drop in revs is due to increased load on the alternator. As this is recent behaviour, could it be that the batteries are on their way out and the windlass is asking more than they can provide leaving the alternator (120 amp Balmar) to try and take up the slack? Battery (windlass is on the eng start battery) is 105ah AGM dating from 2015 or 2016 so far from new!

As I said, I’m asking the question on the back of very little electrical knowledge! Thank you.

 

[Boater Sam]

You could well be correct. I am assuming it is a 12v battery.
Charge the battery fully, until it is still at 12.8v after an hour off charge or till the charge going in is only1% of the rated battery capacity, again letting it stand for an hour before reading.
If it drops below 12.6 in an hour its a good bet it is dying.

 

[trevbouy]

First step, go through all the terminals especially the battery and check them for corrosion.

 

[Alex_Blackwood]

OK, disclaimer here; electrics are not my thing so please be gentle!

When using the electric windlass, the engine revs now drop noticeably and if at idle rpm to begin with, to the point that the engine sounds less than smooth. This only started happening recently and otherwise, the engine (Beta 50) is absolutely fine. I’m assuming that the drop in revs is due to increased load on the alternator. As this is recent behaviour, could it be that the batteries are on their way out and the windlass is asking more than they can provide leaving the alternator (120 amp Balmar) to try and take up the slack? Battery (windlass is on the eng start battery) is 105ah AGM dating from 2015 or 2016 so far from new!

As I said, I’m asking the question on the back of very little electrical knowledge! Thank you.

I am not an expert on AGM batteries but at that age I would think that it may well be on its way out. Its had a good life!

 

[rotrax]

In a previous life I was involved in extensive dynomometer testing of motor vehicles. For a sophisticated-at the time-car like a Jaguar XJ6 with ALL electrical items in use, the recorded BHP would drop by 4-5. This was the amount of energy required to drive the large Lucas alternator. When providing maximum output it became highly magnetic and did not wish to rotate.

As a simple fix, engage neutral and raise RPM TO 1500-1750 when using the windlass.

This should alleviate the symptoms.

 

[Goldie]

Thanks all, for the replies so far.

Boater Sam. The test is underway right now.

Trevbouy. All checked and looking good.

Alex_Blackwood. Agreed. It’ll be replaced as a precautionary measure at the next port of call.

Rotrax. That’s exactly what we’re doing, thanks.

 

[Neeves]

If you have a battery retail specialist nearby they can test your battery. Here they don't charge, its a simple test and does not take long, - its good PR.

Do you have a battery switch that allows you to switch the house bank to engine start (as a back up). If so - start the engine on the house bank and the windlass should then also be switched to the house bank - try windlass.

I would have thought if the engine start battery was dying you would have noticed issues with starting the engine - as mention check the wiring for the windlass - is may have nothing to do with the battery - I see you have checked the wiring (have you checked the circuit breaker for the windlass - depends on location but they can corrode)

Jonathan

 

[Goldie]

If you have a battery retail specialist nearby they can test your battery. Here they don't charge, its a simple test and does not take long, - its good PR.

Do you have a battery switch that allows you to switch the house bank to engine start (as a back up). If so - start the engine on the house bank and the windlass should then also be switched to the house bank - try windlass.

I would have thought if the engine start battery was dying you would have noticed issues with starting the engine - as mention check the wiring for the windlass - is may have nothing to do with the battery - I see you have checked the wiring (have you checked the circuit breaker for the windlass - depends on location but they can corrode)

Jonathan

No battery specialist close by (currently at anchor) but I will get a test when I can. Tbh, I think replacing the battery at that age probably makes sense anyway. Circuit breaker appears fine. I have a button that temporarily pairs eng and domestic batteries for eng starting if required thanks.

 

[Farmer Piles]

BBL, Cornwall Battery Centre up at Threemilestone Industrial Estate are very good - my first choice stop for batteries. Their Avon range are very good value but I would probably opt for a higher spec.

 

[Alex_Blackwood]

No battery specialist close by (currently at anchor) but I will get a test when I can. Tbh, I think replacing the battery at that age probably makes sense anyway. Circuit breaker appears fine. I have a button that temporarily pairs eng and domestic batteries for eng starting if required thanks.

A quick simple check for an engine start battery, is to put a multimeter across the terminals and start the engine. The voltage will drop to around 9 volts (Ish) and with a good battery should recover almost immediately the engine starts. If the voltage takes a bit of time to come back up the battery is duff.

 

[Goldie]

BBL, Cornwall Battery Centre up at Threemilestone Industrial Estate are very good - my first choice stop for batteries. Their Avon range are very good value but I would probably opt for a higher spec.

Thanks, and I’d go there if the boat was at home but at the moment, both boat and I are 1000nm away. I have them in mind for when I return to UK later this year as I’ll probably replace my domestic bank (same age, 2015/6) before I head away again.

 

[MontyMariner]

105ah AGM dating from 2015 or 2016

8 or 9 years old, sounds like they have given you good service, treat yourself.

"When using the electric windlass, the engine revs now drop noticeably and if at idle rpm to begin with, to the point that the engine sounds less than smooth"

Using the windlass with the engine on tickover means that the alternator isn't putting out much to replenish the current being sucked by the windlass. You should put the revs up to at least a fast tickover for the alternator to start working.

 

[William_H]

As said any deterioration of the engine start battery will show up a slow cranking of the engine. Failure to start the engine will be more serious than symptoms so far observed. As OP has back up facility for engine start he should carry on as is. But yes possible failure of battery at that age. Possible failure of engine battery if engine fails to start first try. ol'will

 

[Big John]

I have found the Topdon BT100 hand held battery tester very reliable in giving good results as to the state of the battery. https://www.ebay.co.uk/itm/233679172965?chn=ps&_ul=GB&_trkparms=ispr=1&amdata=enc:1JVLIIWZ8QVWi8ZMUjwcDKA9&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&mkscid=101&itemid=233679172965&targetid=1816181028659&device=c&mktype=pla&googleloc=9044859&poi=&campaignid=19090194174&mkgroupid=147009364227&rlsatarget=pla-1816181028659&abcId=9303860&merchantid=6995734&gad_source=1&gclid=EAIaIQobChMIu4WflPr6hAMV3pJQBh2m0Qe9EAQYASABEgLfLfD_BwE
It is very reasonably priced and very easy to use. Clear LCD screen gives results. Watch the video.

 

[Goldie]

I have found the Topdon BT100 hand held battery tester very reliable in giving good results as to the state of the battery. https://www.ebay.co.uk/itm/233679172965?chn=ps&_ul=GB&_trkparms=ispr=1&amdata=enc:1JVLIIWZ8QVWi8ZMUjwcDKA9&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&mkscid=101&itemid=233679172965&targetid=1816181028659&device=c&mktype=pla&googleloc=9044859&poi=&campaignid=19090194174&mkgroupid=147009364227&rlsatarget=pla-1816181028659&abcId=9303860&merchantid=6995734&gad_source=1&gclid=EAIaIQobChMIu4WflPr6hAMV3pJQBh2m0Qe9EAQYASABEgLfLfD_BwE
It is very reasonably priced and very easy to use. Clear LCD screen gives results. Watch the video.

So simple that even I could understand it . I’m going to replace the battery anyway, but that could be a useful tool to have in the locker. Thanks.