Overcharging batteries

[CFarr]

Hi
Well, got the boat at last, hand over next Monday.
She's in need of some basic tlc that we can sort with a bit of graft and a bit more dosh but there is an electrical problem I hope someone can help me with.

From the survey;
'Battery level monitoring indicators were seen operational at the chart table but noted
indicating that the batteries are being overcharged when the alternator is running or
battery charger is switched on'.

It goes on to suggest 'some investigation'
Can anyone tell me what I should be looking for/doing?
I know quite a bit about a lot of things but, electrics, well lets say I'm on the bottom rung of the learning ladder.
I want to take her out for a run as soon as i can get down to her but don't want to boil the batteries on our maiden voyage.

Cheers

 

[VicS]

Hi
Well, got the boat at last, hand over next Monday.
She's in need of some basic tlc that we can sort with a bit of graft and a bit more dosh but there is an electrical problem I hope someone can help me with.

From the survey;
'Battery level monitoring indicators were seen operational at the chart table but noted
indicating that the batteries are being overcharged when the alternator is running or
battery charger is switched on'.

It goes on to suggest 'some investigation'
Can anyone tell me what I should be looking for/doing?
I know quite a bit about a lot of things but, electrics, well lets say I'm on the bottom rung of the learning ladder.
I want to take her out for a run as soon as i can get down to her but don't want to boil the batteries on our maiden voyage.

Cheers

Overcharging by the alternator is not too difficult to understand, due to a defective regulator or disconnected sensing wire if applicable.

Its not so easy to understand how the batteries are being overcharged by the battery charger.

I think a little more information /investigation is needed into how/what the battery monitoring indicators are.

 

[halcyon]

From the survey;
'Battery level monitoring indicators were seen operational at the chart table but noted
indicating that the batteries are being overcharged when the alternator is running or
battery charger is switched on'.

What boat is it ?, can you expand on battery level monitoring, what is it, look like ?

Brian

 

[William_H]

What comes to my mind is that it has a volt meter at the fuse panel. This is reading high with engine running or charger operating.
Both alternators with smart charge regulators and modern batter chargers charge at a relatively high voltage to get a faster charge.
This should reduce after some time when batteries are charged to around 14 volts. It is possible that your surveyor was not familiar with this type of charging. he would expect 13.75 to 14v.
However the volt meter may be inaccurate and would e worth comparing with a digital volt meter. (multimeter)
Ultimately if your batteries are being overcharged they will use a lot of water. So you should check fluid level and top up if necessary. If so check frequently. Of course if they are sealed batteries then you can't check and overcharge can kill them.
So it is hard to advise. Survey might be just covering a doubt or just padding the words to justify his bill or he may be on to something of importance.
Good luck with the new boat and do check the charge voltage. Initially using battery charger. However it is unlikely both alternator regulator and battery charger have developed separate faults with same symptoms. Conceivably battery is stuffed of course but if it starts engine it is probably fine. olewill

 

[CFarr]

Thank you for you replies.
I too thought it was funny to see overcharging from both alternator and charger but don't yet know enough to be sure.

The voltmeters are 'voltwatch' and the batteries were new last year and little used and I believe the boat is connected to shore power constantly.

I'll try and insert an image here but have had little luck previously.

The text beneath the photo reads;
'Battery overcharge warning lights indicating batteries are being overcharged.
Although not evident from this picture intermittently both warning lights were seen
illuminated during the examination'

I'm over 5 hours away from the boat so trying to glean as much info as poss in order to minimize problems once there.
I'll need to invest in a multimeter I suppose, any recommendation?

FYI The yacht is a Sigma 362

Cheers

 

[halcyon]

I'll try and insert an image here but have had little luck previously.

Picture not there.

Is the display a series of LED's?

First job is check what the battery voltages are, when you arrive at the boat without turning on the batteries, with engine running, and battery charger running, also note what make and model the battery charger is.

Try Maplin, look around for a clamp meter, allows you to check amperage without removing a cable, plus normal multimeter functions, on offer around £20-30.

Brian

 

[CFarr]

Picture not there.

Is the display a series of LED's?

Yes, a row of 10 starting with '!!' And '!' On the left and finishing with '!' On the right.
There are two of them side by side.

I'll check what you recommend when I'm next down.
Many many thanks.

 

[VicS]

Yes, a row of 10 starting with '!!' And '!' On the left and finishing with '!' On the right.
There are two of them side by side.

I'll check what you recommend when I'm next down.
Many many thanks.

Dunno why your Dropbox picture does not appear

Its here anyway https://www.dropbox.com/s/8nz8yp6o4pik5et/2013-05-29 07.45.18.jpg

Dunno why you have two or what the switch does

Website for Voltwatch at http://www.attfield.dircon.co.uk/voltwatch.html

The first things to do are to check the voltages as Halcyon suggests and to check the voltages with a decent multimeter or voltmeter when charging to see what they really are.

My guess is that the Voltwatch indicators are falsely indicating overcharge. They are calibrated to indicate overcharge at anything above 14.45, which is not all that high.

 

[Richard10002]

My surveyor measured each battery voltage at rest and with the engine running. To say that they are "overcharging" based on a few LEDs is possibly misleading.

As has been said..... Get a simple multimeter and measure the voltages across each battery when you get on board, before starting the engine or charger. Then measure them again when the engine is running, then again with the charger running.

Voltage at rest between about 12V and 12.8V is fine. Voltage when charging if less than about 14.8V is fine to start with. My charger pumps in 15.6V for a few seconds then settles at 15V for bulk charging, (on its highest normal setting).

If its charging at much over 15V for any length of time, something may be wrong.

This all assumes a 12 V system. Double everything if it's a 24V system.

 

[halcyon]

My surveyor measured each battery voltage at rest and with the engine running. To say that they are "overcharging" based on a few LEDs is possibly misleading.

As has been said..... Get a simple multimeter and measure the voltages across each battery when you get on board, before starting the engine or charger. Then measure them again when the engine is running, then again with the charger running.

Voltage at rest between about 12V and 12.8V is fine. Voltage when charging if less than about 14.8V is fine to start with. My charger pumps in 15.6V for a few seconds then settles at 15V for bulk charging, (on its highest normal setting).

The display shows a red above 14.4 volt, so in the operating range of some mains chargers.

If new batteries, you can see 13.0 - 13.1 volt when at rest, over time ( could be years ) this will fall to 12.7 - 12.8 volt, then as the battery ages it will fall below this range.

Don't buy a cheap £2 meter, got one for checking for a voltage on the boat, not accurate to 0.4 of a volt .

Brian

 

[William_H]

Don't buy a cheap £2 meter, got one for checking for a voltage on the boat, not accurate to 0.4 of a volt .

Brian

I would tend to disagree with this simple adage. Digital volt meters even cheap ones tend to be very accurate. They use essentially the same circuitry and voltage reference as an expensive multimeter.
Indeed if I was concerned about accuracy then I would buy 3 cheap DVM and compare rather than an expensive one. olewill the cheap skate

 

[halcyon]

I would tend to disagree with this simple adage. Digital volt meters even cheap ones tend to be very accurate. They use essentially the same circuitry and voltage reference as an expensive multimeter.
Indeed if I was concerned about accuracy then I would buy 3 cheap DVM and compare rather than an expensive one. olewill the cheap skate

If you read back I was talking about £20-30 for a clamp meter, if Maplin had one on offer, but say a £10 multimeter is normally a better bet than £2 one from Ebay, the one I use for work is £300 new but a different use.