Are my house batteries dead?

webcraft

webcraft

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Let them get a little low, but they started the webasto without starting the engine. Voltage on the (basic) panel meter showed a little over 12. But - when I went into the shutdown sequence the voltage plunged to 8 volts and the lights died.

Subsequently the meter rose back to just over 12. But application of any load - even the cabin lights - resulted in plummeting voltage.

Currently on a pontoon running the engine and the heater. Domestic Bank is charging at 14.2 V

Going to switch the heater off now and continue charging for 30 min. Any tests I can do before biting the bullet and getting new batteries?

- W
 
webcraft said:
Going to switch the heater off now and continue charging for 30 min. Any tests I can do before biting the bullet and getting new batteries?
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How are you charging them? 30 mins doesn't seem very long at all on the alternator. Nor is 14.2V very high. Do you have shorepower charging in any form?
 
Are the batteries topped up?
It will take longer than 30 mins to fully charge the batteries - as said above better with a mains charger to get them fully charged then you could do a load test on them.
 
Just on the alternator. They've had an hour now, that's all I used to do for a top-up when I hadn't had to run the engine for a couple of days. There is a wind genny as well.

Perhaps I have just let them get too low and they are savable.
I don't have a shore power charger.
How long do you reckon I should charge the batteries on the alternator (2x110AH) to get them fully charged?

- W
 
Can you borrow a charger from somewhere?

Depending on your alternator, you may never have been bringing your batteries right up to "full" level.

webcraft said:
Just on the alternator. They've had an hour now, that's all I used to do for a top-up when I hadn't had to run the engine for a couple of days. There is a wind genny as well.

Perhaps I have just let them get too low and they are savable.

How long do you reckon I should charge the batteries on the alternator (2x110AH) to get them fully charged?

- W
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Once you have finished charging the batteries disconnect them and leave for a few hours to let the voltage settle. Then measure the terminal voltage - fully charged should be 12.7V - 50% charged 12.2V - fully discharged 11.9V. This will tell how much they are charged.
 
webcraft said:
Just on the alternator. They've had an hour now, that's all I used to do for a top-up when I hadn't had to run the engine for a couple of days. There is a wind genny as well.

Perhaps I have just let them get too low and they are savable.
I don't have a shore power charger.
How long do you reckon I should charge the batteries on the alternator (2x110AH) to get them fully charged?

- W
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It depnds on the current ( amps) you are pushing into them. It could take maybe 10 hours or longer. This is why you need a good automatic battery charger. One with an output of at least 15 amps.
 
It would be good to know the current.
14.2 is low, it suggests either a weak alternator, voltage drop in wiring, or fairly low charge level in the batteries.
What voltage does the windmill get them to?

It might be useful to check the voltage at the alternator.
 
I've just put a new battery in the multimeter and it's showing a voltage at the battery terminals of 14.37 while charging from the alternator.

I think there is no doubt I let the batteries run down too far - several hours heater operation, instruments Inc. Plotter, plus cabin lights, charging phones etc for five days and only ran the engine for less than two hours in that time, plus maybe 16 or so good hours of wind genny input.

I'll run the engine for a couple more hours then let the batteries rest and check the voltage in a few hours - difficult to forgo the heating in this weather though!

Problem is compounded by wanting to change the fuel filters but not wanting to do so unless I have lots of battery power for bleeding purposes... the last thing I want to do is run the engine start battery down as well.

- W
 
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I think what is confusing me is that in the past if the panel vmeter has been 'in the green' (ie showing over 12V) then there have been no problems, even enough power to use the domestic Bank for engine start if necessary.

This trip, once it was down to 12V any load caused a massive dip, though if left to recover back to 12V over a few minutes it would run a GPS and cabin lights.

Hoping a good long charge will rescue the situation, any further advice/suggestions welcome. Would rather spend £200 on cruising than on batteries then going home because holiday budget exhausted!

Excuse the extensive posting, it's a wet Sunday in Mallaig, 'nuff said!

- W
 
webcraft said:
I've just put a new battery in the multimeter and it's showing a voltage at the battery terminals of 14.37 while charging from the alternator.

I think there is no doubt I let the batteries run down too far - several hours heater operation, instruments Inc. Plotter, plus cabin lights, charging phones etc for five days and only ran the engine for less than two hours in that time, plus maybe 16 or so good hours of wind genny input.

I'll run the engine for a couple more hours then let the batteries rest and check the voltage in a few hours - difficult to forgo the heating in this weather though!

Problem is compounded by wanting to change the fuel filters but not wanting to do so unless I have lots of battery power for bleeding purposes... the last thing I want to do is run the engine start battery down as well.

- W
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Why do you want to change the fuel filters? If it’s a time based change, then forget it until you’ve got access to shore power and a battery charger. Different if you’ve got blocked (or suspect you’ve got) blocked/clogged filters. Can’t you use the lift pump lever to bleed the fuel system anyhow? It shouldn’t need bleeding all the way through to the injectors; just to the secondary filter.
 
duncan99210 said:
Why do you want to change the fuel filters? If it’s a time based change, then forget it until you’ve got access to shore power and a battery charger. Different if you’ve got blocked (or suspect you’ve got) blocked/clogged filters. Can’t you use the lift pump lever to bleed the fuel system anyhow? It shouldn’t need bleeding all the way through to the injectors; just to the secondary filter.
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Had a very rough passage from Tobermory to Canna, which obviously shook the diesel up more than a bit. Ran the engine for ten minutes to motor in and pick up a mooring. Float bowl on the primary filter was full of emulsified gunk.

Drained the bowl, and since then when running the engine it has been reluctant to start and has died a few times. In fact I thought we might have to sail in here yesterday.

It could be a bit of air, as I had to slacken the filter slightly to encourage the bowl to drain, but a filter change seems a sensible precaution - think the last time may heve been over five years ago!

After another hour charging voltage at the terminals is up to 14.45

- W
 
webcraft said:
I think what is confusing me is that in the past if the panel vmeter has been 'in the green' (ie showing over 12V) then there have been no problems, even enough power to use the domestic Bank for engine start if necessary.

This trip, once it was down to 12V any load caused a massive dip, though if left to recover back to 12V over a few minutes it would run a GPS and cabin lights.

Hoping a good long charge will rescue the situation, any further advice/suggestions welcome. Would rather spend £200 on cruising than on batteries then going home because holiday budget exhausted!

Excuse the extensive posting, it's a wet Sunday in Mallaig, 'nuff said!

- W
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Once you are down to 12V, the current from the heater will tend to create a serious dip in voltage. I think there can be a vicious circle, the glowplug drops the volts to the point the heater won't start, so it aborts and tries again, so the glowplug is used a lot.

Personally I don't think a battery should be condemned without first holding it at over 14.2V for either many hours or long enough for the current into it to drop to say 1A for a 100A battery. Even then it's only 'fairly charged' not '100% charged'.
 
lw395 said:
Once you are down to 12V, the current from the heater will tend to create a serious dip in voltage. I think there can be a vicious circle, the glowplug drops the volts to the point the heater won't start, so it aborts and tries again, so the glowplug is used a lot.

Personally I don't think a battery should be condemned without first holding it at over 14.2V for either many hours or long enough for the current into it to drop to say 1A for a 100A battery. Even then it's only 'fairly charged' not '100% charged'.
Click to expand...
Excuse my ignorance, can I use the multimeter to measure the current going into the battery?

- W
 
webcraft said:
Excuse my ignorance, can I use the multimeter to measure the current going into the battery?

- W
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Yes, one battery at a time, if the multimeter has a 10A scale. Probably a separate socket on the meter?
LEave the other battery connected. There must never be no batteries connected to the alternator.
Remove the + lead from the battery and put the multimeter across the gap to complete the circuit.
If you do this too early in charging, it might over-range.
The meter's shunt will have some small resistance, reducing the current a little, but it is a good indication.
Be fairly quick about it, the leads etc may get warm.
If you're not sure this makes sense, probably best left alone?

Make sure plenty of ventillation, thre could be a small spark or two. If you can hear the batteries gassing a lot don't do it.
 
Glenlivet said:
So you set off on a cruise with flat house batteries and fuel filters which you haven’t changed for five years?

Asking for trouble :confused:
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Not really. The house batteries weren't flat, they became flat after several days use and - obviously - not enough charging. They are always topped up when setting off, tx to the wind genny.

And - I only change fuel filters if there is a reason. I put all my fuel in through a filter funnel, but a very rough passage has shown me it is time to siphon the sludge from the tank sump again.

And anyway. It is much easier to fix stuff while away on a pontoon in a place with services than it is on a swinging mooring in the middle of nowhere, and I carry all the necessary spares and tools. Also, it's a sailing boat, and all that side of things is working.

I don't regard this as 'trouble', if I did then I might consider swallowing the anchor. One of the best definitions I have seen of cruising is 'fixing boats in strange places'

- W
 
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