Alternator and or battery problems.

[ianc1200]

Last year I had a brand new Yanmar 2YM15 installed in my Crabber, at the same time two new leisure type batteries.

At an early point I pressed the wrong button on the panel & the engine ran briefly without the electrics on.

Some time later, concerned whether I had damaged the alternator, I thought I saw a 14.9V reading on the engine panel, but this didn't occur again.

The batteries have a 0/1/2/both rotary type switch, and being new to me, I mistakenly was running the engine charging the starter battery only, but not charging the domestic.

I realised this whilst on holiday when the chartplotter failed to work - we rarely use the internal lights, and their being no other draw than echo/VHF/chartplotter.

Having realised the mistake, I checked the domestic battery with a digital voltmeter, and found barely 6V.

However, the battery charged back up, and later in the season the engine would start via this domestic battery on it's own after not being used for several weeks.

I noticed early in the autumn when charged up at home the domestic would quickly get to 14.9V, and assuming it was it poor condition, I bought another. Yesterday I charged the starter battery on the home Halfords charger (having done so several times during the winter & OK), it too quickly got to 14.9. Both the old domestic and the starter have lost the green tinge to the viewing eye which I understands is an indication of being in good condition. (both had it though at the end of the season).

I intend buying another starter battery, but the question is whether the alternator could be damaged?

Should I run the engines, with the two new batteries, and if the panel reading goes above 14.5V have the alternator checked out?

Or should I take a reading off the output again to check whether too high?

The boat is out of the water for a few more weeks, I'm wondering whether it should be removed for checking in any case.

Any views welcomed, and thanks for reading a long post.

 

[black mercury]

I would install the two batteries as normal and run the engine. Put your voltmeter across the terminals of one battery with the switch set to both and check the voltage. It should stay between 13 and 14.5 depending on what you have switched on at the time. If it stays constant and stays below 14.5 or so I would not worry too much about the alternator. Most modern alternators are protected if the circuit is disconnected from them when they are running. Seems like the batteries are gone.

 

[William_H]

It is likely that the regulator is attached to the alternator. it may suit you therefor to remove the alternator for a check by an auto electrician shop. (before relaunch) Occasionally regulators do go bad and produce too much charge voltage. As said it should be nearer 14v or less.
If you do not remove the alternator then you should check the charge voltage of the batteries after a little running of engine. Let it all settle down. Voltage should again be around 14v. Make sure your voltmeter is accurate. A flat battery in a multimeter can show high reading. A penel meter might simply be inaccurate.
If the batteries are open cell then keep a check on fluid level. Any rapid loss of fluid after a lot of engine running is a sure sign of over voltage charge. good luck olewill

 

[skipmac]

Be aware that checking battery voltage to determine the state of the battery should be done after the battery has had time to stabilize. Short, quick but not definitive test, charge the batteries fully, either by the home charger or by the engine. Disconnect all the loads from the batteries, let sit a few hours or overnight and check the voltage. A good, fully charged battery should check about 12.6V.

A better check, again on a charged battery that has been allowed to rest, is to use a hydrometer to test each cell. Only cost a couple of pounds or so and will identify any bad cells.

Alternator voltage outputs can be >14V but 14.9 does sound a bit high. Could possibly cook the batteries if run that way too long. Have you checked the water levels?

Another and very definitive check on the battery condition is to run a load test. Start with a fully charged battery and attach a load to the battery. Should pick a load that is no more than 10% of the battery's total amp hour capacity. Hook up the load and periodically measure the voltage at the battery. Stop with the voltage drops below 11V Take the amps of the load X the number of hours and that will give you the battery's actual capacity. If your battery is rated at 100 amp hours, you attach a 5 amp load and it runs for 18 hours then your battery is giving you 90 amp hours or 90% of its rated output.

These are the simplified versions but should be enough to get you going.

PS
Checking the accuracy of your meter is a good idea.

 

[john_morris_uk]

Checking the accuracy of the meter is an obvious first choice for me. An alternator working properly (without any fancy charge controller modifying the regulator) will produce between 13.8 and 14.5 volts across the battery terminals. 14.9 is not far off and with a slightly dodgy meter measuring there might be nothing wrong at all.

I wouldn't be going to the trouble of removing the alternator just yet. If you can start and run the engine for a few momements while the boat is ashore, it's a very easy job to turn everything on and check what the voltage is on the batteries. Borrow another meter to cross check the reading and report back?

 

[theoldsalt]

"At an early point I pressed the wrong button on the panel & the engine ran briefly without the electrics on."

It sounds as if the starter motor supply does not go through the battery selector switch otherwise this could not happen. I purpose of this switch is to isolate the batteries from all (with one or two exceptions like solar or wind genny) equipment.

If I am right why is it wired this way?

 

[ghostlymoron]

"At an early point I pressed the wrong button on the panel & the engine ran briefly without the electrics on."
This just illustrates to me the shortcomings of the 1-2-B switch. Fit a VSR.

 

[William_H]

Be aware that checking battery voltage to determine the state of the battery should be done after the battery has had time to stabilize. Short, quick but not definitive test, charge the batteries fully, either by the home charger or by the engine. Disconnect all the loads from the batteries, let sit a few hours or overnight and check the voltage. A good, fully charged battery should check about 12.6V.

A better check, again on a charged battery that has been allowed to rest, is to use a hydrometer to test each cell. Only cost a couple of pounds or so and will identify any bad cells.

Alternator voltage outputs can be >14V but 14.9 does sound a bit high. Could possibly cook the batteries if run that way too long. Have you checked the water levels?

Another and very definitive check on the battery condition is to run a load test. Start with a fully charged battery and attach a load to the battery. Should pick a load that is no more than 10% of the battery's total amp hour capacity. Hook up the load and periodically measure the voltage at the battery. Stop with the voltage drops below 11V Take the amps of the load X the number of hours and that will give you the battery's actual capacity. If your battery is rated at 100 amp hours, you attach a 5 amp load and it runs for 18 hours then your battery is giving you 90 amp hours or 90% of its rated output.

These are the simplified versions but should be enough to get you going.

PS
Checking the accuracy of your meter is a good idea.

Skipmac is right about a test of the battery capacity test but do not expect to get anything like 90% of the manufacturers claimed AH rating out of it. I would say 50% is good less than 10% is no good. olewill

 

[Plevier]

Skipmac is right about a test of the battery capacity test but do not expect to get anything like 90% of the manufacturers claimed AH rating out of it. I would say 50% is good less than 10% is no good. olewill

It's harder than you might think to run a reasonably accurate capacity test. We had very fancy controlled constant current loads (there is a bit of a trend towards constant power now rather than constant current), temperature monitoring and control and so on, and of course the batteries were carefully charged before the test, and even then you get quite a lot of variation even with new batteries off the production line.

Subject to all that, the normal criterion for a battery in a fairly critical application is to fail it if capacity falls below 80% of what it should be when tested at a rate similar to its normal duty. That of course may be considerably different from its nominal capacity which may be specified at 8, 10, 20 or various other discharge times in hours, normally 20 for vehicle and "leisure" batteries. 80% is used because it shows enough deterioration that the battery may show significantly reduced reliability i.e. chance of rapid failure before the next test, usually annual. Most boat owners would push it a lot further I'm sure, but I'd be inclined to scrap at around 50% capacity for a service battery for cruising, 10% is really risking it.

Aircraft batteries doing combined starting and safety critical reserve duty are normally tested for 3 hour capacity which might be typically 60-75% of the 20 hour rating (rough figures from memory, not gospel) depending on the battery type, again with an 80% pass criterion.

There may well be a standard for testing commercial ship batteries but I've never encountered it, we only made vehicle, standby (telecoms, UPS, lighting etc) and aircraft batteries. Submarine batteries were another group company!

Starter batteries are usually tested in garages for voltage drop at high current rather than capacity. and can sometimes pass even with little low rate capacity left. Translation from these results to capacity does not have a good accuracy record.

 

[GrahamM376]

Checking the accuracy of the meter is an obvious first choice for me.

+1

Our analogue panel meter is around 0.3 volts out compared to BM1 digital battery meters.

 

[skipmac]

Skipmac is right about a test of the battery capacity test but do not expect to get anything like 90% of the manufacturers claimed AH rating out of it. I would say 50% is good less than 10% is no good. olewill

This may be correct on some batteries but reports I have read from marine electricians that have done extensive testing on batteries and chargers have found that some brands of deep cycle batteries actually gave more than the rated amp hour capacity. A couple that come to mind are Trojan T105s and the Rolls Royce equivalent.

 

[skipmac]

It's harder than you might think to run a reasonably accurate capacity test. We had very fancy controlled constant current loads (there is a bit of a trend towards constant power now rather than constant current), temperature monitoring and control and so on, and of course the batteries were carefully charged before the test, and even then you get quite a lot of variation even with new batteries off the production line.

Would concur completely. So many variables in the actual state of charge, time at rest, temperature and variations in the construction between batteries even of the same lot will give significant variations in test results. However I would say that in the world of boats a difference of a few percent in capacity tests are not critical. After all, you have a power failure in a boat you usually (no not always) have some options and time to figure out a solution. On the other hand, same problem in aviation is a bit more pressing.

Starter batteries are usually tested in garages for voltage drop at high current rather than capacity. and can sometimes pass even with little low rate capacity left. Translation from these results to capacity does not have a good accuracy record.

Have had this experience many times in cars. Starts just fine for years then with no warning one day it's dead (always of course when I'm late for something). The only time I have gotten any forewarning that the starting battery was approaching dead would be if I happened to park for a while with the stereo running or use the interior lights for a while only to discover that a relatively small load had depleted the battery and I was stranded.

By the way, I'm seeing another example of linguistic differences from the opposite sides of the pond. Over here batteries of concern in boating are start batteries designed for high current, short time loads and deep cycle batteries designed for long term, smaller current draw loads and to tolerate a deeper discharge without damage. So what is this leisure battery see mentioned? That the UK version of deep cycle?

 

[Plevier]

A leisure battery is a marketing concept to persuade people they are getting a deep cycle battery at low price, there is no real definition of it.
What usually happens is that it will use automotive plates, hopefully heavy ones maybe up to 2mm thick if you're lucky, more likely 1-1.5 (car batteries are typically 0.8), and different separators, maybe enveloped to catch the sediment.
It should be a bit better for cycling than a staright automotive but it is not a deep cycle battery.
OK for starting duties too but usually lower CCA (because of higher resistance separators and maybe thicker plates) than a normal auto battery of same Ah.

 

[skipmac]

A leisure battery is a marketing concept to persuade people they are getting a deep cycle battery at low price, there is no real definition of it.
What usually happens is that it will use automotive plates, hopefully heavy ones maybe up to 2mm thick if you're lucky, more likely 1-1.5 (car batteries are typically 0.8), and different separators, maybe enveloped to catch the sediment.
It should be a bit better for cycling than a staright automotive but it is not a deep cycle battery.
OK for starting duties too but usually lower CCA (because of higher resistance separators and maybe thicker plates) than a normal auto battery of same Ah.

Ah yes, marketing. We have a bit of that over here as well. And don't you just love it.