Batteries...yes batteries again....

[Bobbybass]

Hi..

 

I have studied recent comments with great interest, and also the excellent batteryfaq.org site

I acquired my boat last year (so I'm learning) and it has 3 110ah consumer batteries, a large alternator (standard one was replaced with 120A if I recall) and 2 x 120w solar cells. The batteries are monitored with a Sterling battery management panel.

Now...bear in mind...I'm LEARNING.

The previous owner left me a note that I should try and get the Sterling (amps in/out) to indicate down to '000.00) after a days cruising to show the battereis were charged. He also said to try and get the Sterling to indicate at least 12.4 volts before retiring for the night and not to let it drop below 12.2 volts.

The battereis were new when I bought the boat.

Even after a full day..I only got it down to 3 - 4 amps...never the 000.00 that the previous owner mentioned....but they would show an alernator charge voltage of 14.2 volts on the Sterling and a positive (14 volts) needle swing on the conventional voltmeter (dial type on Beta panel)

I see from the graph on the 'batteries faq' site...that at 70 degree electrolyte temperature the previous owner was 'on the money' as the graph says 12.643 volts for 100% SOC and 12.238 volts for 50% SOC

So far...so good...

I returned to the boat this spring...and the solar cells had been charging and the Sterling panel read 14.8 volts on the unloaded batteries.

We cruised for about 7 hours...the meter read 3 amps charging in...and at days end..the batteries read 14.8 volts with a load (lights invertor)

Over the next few days..the battery voltage didn't read below 12.8 volts...even with hours of watching TV.

This continued for several weeks..then they started to 'drop off'.

The Sterling registered 13 volts alternator charging...and the conventional voltmeter needle ( Beta panel) now sits in the middle and sometimes heads down towarde the 12 volt reading)

It now takes a long time to put a charge in the batteries and then they last for a very much shorter time than they did before.

Although they do show 12.7 volt fully charge..which is still about right according to the batteryfaq site...they drop to 12.2 volts (50%) after only a few hours.

 

I think that I will need to replace the batteries before next seasons cruising...but I wonder if they have suffered due to the solar cells overcharging ?

THere is a charge control unit on the cells...and they seem to be reading the correct voltage..ie 17volts from the solar cell...before the regulator....14.2 volts on the Sterling panel when in full sunlight and charging...(checked on my Whitegold meter as well)

Do I need to visit the boat more regularly during the 'lay up' period and run appliances to draw from the batteries..?

I think its the initial 14.8 volt reading that worries me...nothing I read mentions voltage readings in this range ?

Obviously..the charging voltage should not be reading 13 volts now....I assume..it should be reading 14.2 volts when the batteries are at 50% SOC..and the standard meter shouldn't be sitting in this range either.?

The solar cell reading is only 13volts in full sunlight as well..?

Is it just a fact of life that I will be replacing them once a year ?

Do I need to make changes ?

 

Thanks.....

Bob.

Edited November 19, 2009 by Bobbybass

[RobinJ]

I acquired my boat last year (so I'm learning) and it has 3 110ah consumer batteries, a large alternator (standard one was replaced with 120A if I recall) and 2 x 120w solar cells. The batteries are monitored with a Sterling battery management panel.

..

I returned to the boat this spring...and the solar cells had been charging and the Sterling panel read 14.8 volts on the unloaded batteries.

We cruised for about 7 hours...the meter read 3 amps charging in...and at days end..the batteries read 14.8 volts with a load (lights invertor)

Over the next few days..the battery voltage didn't read below 12.8 volts...even with hours of watching TV.

This continued for several weeks..then they started to 'drop off'.

The Sterling registered 13 volts alternator charging...and the conventional voltmeter needle ( Beta panel) now sits in the middle and sometimes heads down towarde the 12 volt reading)

It now takes a long time to put a charge in the batteries and then they last for a very much shorter time than they did before.

Although they do show 12.7 volt fully charge..which is still about right according to the batteryfaq site...they drop to 12.2 volts (50%) after only a few hours.

If the batteries are only a year old, that seems a bit premature for failure?

When did you last check the electrolyte level? or are they sealed?

It may be worth disconnecting the batteries and checking each one in turn to see how they perform. You may just have a problem with one which is loading the rest.

Whenever you use an efficient system which is designed to keep the batteries at maximum capacity, you also have to maintain the batteries in peak condition too, so that involves a regular check on electrolyte and connections etc. Using solar or wind charging can make the situation worse as the batteres will not get a rest, even though they may be on 'trickle' charge, add up the hours and its a lot of energy!

[Tony Brooks]

Hi..

 

I have studied recent comments with great interest, and also the excellent batteryfaq.org site

I acquired my boat last year (so I'm learning) and it has 3 110ah consumer batteries, a large alternator (standard one was replaced with 120A if I recall) and 2 x 120w solar cells. The batteries are monitored with a Sterling battery management panel.

Now...bear in mind...I'm LEARNING.

The previous owner left me a note that I should try and get the Sterling (amps in/out) to indicate down to '000.00) after a days cruising to show the battereis were charged. He also said to try and get the Sterling to indicate at least 12.4 volts before retiring for the night and not to let it drop below 12.2 volts.

The battereis were new when I bought the boat.

Even after a full day..I only got it down to 3 - 4 amps...never the 000.00 that the previous owner mentioned....but they would show an alernator charge voltage of 14.2 volts on the Sterling and a positive (14 volts) needle swing on the conventional voltmeter (dial type on Beta panel)

I see from the graph on the 'batteries faq' site...that at 70 degree electrolyte temperature the previous owner was 'on the money' as the graph says 12.643 volts for 100% SOC and 12.238 volts for 50% SOC

So far...so good...

I returned to the boat this spring...and the solar cells had been charging and the Sterling panel read 14.8 volts on the unloaded batteries.

We cruised for about 7 hours...the meter read 3 amps charging in...and at days end..the batteries read 14.8 volts with a load (lights invertor)

Over the next few days..the battery voltage didn't read below 12.8 volts...even with hours of watching TV.

This continued for several weeks..then they started to 'drop off'.

The Sterling registered 13 volts alternator charging...and the conventional voltmeter needle ( Beta panel) now sits in the middle and sometimes heads down towarde the 12 volt reading)

It now takes a long time to put a charge in the batteries and then they last for a very much shorter time than they did before.

Although they do show 12.7 volt fully charge..which is still about right according to the batteryfaq site...they drop to 12.2 volts (50%) after only a few hours.

 

I think that I will need to replace the batteries before next seasons cruising...but I wonder if they have suffered due to the solar cells overcharging ?

THere is a charge control unit on the cells...and they seem to be reading the correct voltage..ie 17volts from the solar cell...before the regulator....14.2 volts on the Sterling panel when in full sunlight and charging...(checked on my Whitegold meter as well)

Do I need to visit the boat more regularly during the 'lay up' period and run appliances to draw from the batteries..?

I think its the initial 14.8 volt reading that worries me...nothing I read mentions voltage readings in this range ?

Obviously..the charging voltage should not be reading 13 volts now....I assume..it should be reading 14.2 volts when the batteries are at 50% SOC..and the standard meter shouldn't be sitting in this range either.?

The solar cell reading is only 13volts in full sunlight as well..?

Is it just a fact of life that I will be replacing them once a year ?

Do I need to make changes ?

 

Thanks.....

Bob.

 

 

I would just make two more observations.

 

Last spring I found my 60w solar panel was "charging" at 15 volts with 15 volts on the batteries but as the controller I chose is supposed to go through an equalisation period every 30 days I am sure that is all I saw, the higher equalisation voltage. The be thing to do is to consult the manual to see if yours does equalisation now and again. I would only worry if it did it for hours on end.

 

Secondly (acknowledge Gibbo) your research should have thrown up the fact that batteries need between 10% and 40%+ more electricity put back in than you took out to bring them back to the same state of charge and it varies with battery type/make/construction/age/temperature and so on. This means that any battery "state of charge" meter will become more and more inaccurate as far as state of charge if it relies on counting amps out and the counting them back in. If you want this sort of information then I fear that you need a Smartguage.

 

I suspect that your alternator may have lost a diode so we need the charging voltage at both the alternator output terminal and across the batteries at the end of a cruise when less than 10 amps are being produced. It would be a good idea to disconnect the controller whilst you measure this with a meter NOT the gauges on the boat.

[Bobbybass]

If the batteries are only a year old, that seems a bit premature for failure?

When did you last check the electrolyte level? or are they sealed?

It may be worth disconnecting the batteries and checking each one in turn to see how they perform. You may just have a problem with one which is loading the rest.

Whenever you use an efficient system which is designed to keep the batteries at maximum capacity, you also have to maintain the batteries in peak condition too, so that involves a regular check on electrolyte and connections etc. Using solar or wind charging can make the situation worse as the batteres will not get a rest, even though they may be on 'trickle' charge, add up the hours and its a lot of energy!

 

Hi again...THe electrolyte level is just below the filler neck. Hydrometer ( ?) reading is the same on all cells and is in the green zone.

THe charge voltage though...is only 13 volts on solar....alternator...or land based Sterling battery charger ?

It was about 14.2 volts last year....

I'll follow you advice and try each one separatley in case its just one battery causing problems...

Thanks for your thoughts.

Bob

Edited November 19, 2009 by Bobbybass

[Nickhlx]

Hi again...THe electrolyte level is just below the filler neck. Hydrometer ( ?) reading is the same on all cells and is in the green zone.

THe charge voltage though...is only 13 volts on solar....alternator...or land based Sterling battery charger ?

It was about 14.2 volts last year....

I'll follow you advice and try each one separatley in case its just one battery causing problems...

Thanks for your thoughts.

Bob

 

You will need to isolate one end of each battery to test each battery of course - all should be very close ...

 

Nick

[Sir Nibble]

This sounds to me like a lack of charge. I hate to keep coming back to what is becoming a bit of a hobby horse of mine but I cannot help but wonder if that alternator is being under driven.

[nb Innisfree]

14.8v for a long float charge sounds a bit excessive to me, 13v sounds better. High voltage caused positive plate corrosion perhaps?

[Sir Nibble]

Edited 'cos I'm just too busy to get into another one of these. Who ya gonna call? ARNOT!

Edited November 19, 2009 by Sir Nibble

[Bobbybass]

This sounds to me like a lack of charge. I hate to keep coming back to what is becoming a bit of a hobby horse of mine but I cannot help but wonder if that alternator is being under driven.

 

Hi..the alternator was fine last year...guess it could be duff......but don't forget...I'm getting the same affect (13 volts now) from the battery charger when on shore power...and the solar cells...

Keep 'em coming...thanks...

 

Bob

Edited November 19, 2009 by Bobbybass

[Tony Brooks]

Hi..the alternator was fine last year...guess it could be duff......but don't forget...I'm getting the same affect (13 volts now) from the battery charger when on shore power...and the solar cells...

Keep 'em coming...thanks...

 

Bob

 

 

But have you confirmed that figure using an accurate meter at the battery terminals?

[Sir Nibble]

Not just that, if the voltage is low regardless of charging source then that suggests the system is stuck in the bulk charge stage, that is to say the charging source is giving its maximum but is unable to lift the voltage further because the batteries are so flat. I accept the alternator is probably fine, but by "underdriven" I mean it is not spinning fast enough at canal speeds. Your 120A alternator may in fact be topping out at 20A. What happens to the charge if you rev the engine harder?

[Bobbybass]

Not just that, if the voltage is low regardless of charging source then that suggests the system is stuck in the bulk charge stage, that is to say the charging source is giving its maximum but is unable to lift the voltage further because the batteries are so flat. I accept the alternator is probably fine, but by "underdriven" I mean it is not spinning fast enough at canal speeds. Your 120A alternator may in fact be topping out at 20A. What happens to the charge if you rev the engine harder?

 

Hi..thanks again...

if I rev the engine faster...the maximum voltage is the same...only 13 volts...although the Sterling will register around 100 amps being put back into the batteries at initial startup. This drops down to 45 amps over the next hour and then goes slowly down until it 'bottoms at about 3/ 4 amps after many hours.

THe hydrometer reading is in the green...so the batteries aren't flat...

You're missing out on the 32 amp land line powered battery charger....which only goes to 13 volts now despite it going to 14.2 volts last year.

Yes..I have checked the battery terminal voltage using my separate Whitegold meter...and it agrees with the panel readings.

I think..the batteries are just sh****d out....

My question really... ..is there are a basic problem with me leaving the batteries on trickle solar charge for months ?

Will it happen again ?

Cheers.

Bob

[smileypete]

Hi..thanks again...

if I rev the engine faster...the maximum voltage is the same...only 13 volts...although the Sterling will register around 100 amps being put back into the batteries at initial startup. This drops down to 45 amps over the next hour and then goes slowly down until it 'bottoms at about 3/ 4 amps after many hours.

What is the charge voltage at the battery terminals read with a meter, when the charge current is at 100 amps, then 45 amps, then 3 or 4 amps?

 

You're missing out on the 32 amp land line powered battery charger....which only goes to 13 volts now despite it going to 14.2 volts last year.

What is the charger current when the voltage at the battery terminals is 13V?

 

When you say...

 

Hi..thanks again...

I returned to the boat this spring...and the solar cells had been charging and the Sterling panel read 14.8 volts on the unloaded batteries.

...if the batteries are getting 14.8V for months on end this definitely won't do them any good!

 

A trickle charge is usually a tiny constant current charge, just enough to get them up to 13.8v.

 

cheers,

Pete.

Edited November 19, 2009 by smileypete

[Nickhlx]

What is the charge voltage at the battery terminals read with a meter, when the charge current is at 100 amps, then 45 amps, then 3 or 4 amps?

 

 

What is the charger current when the voltage at the battery terminals is 13V?

 

When you say...

 

 

...if the batteries are getting 14.8V for months on end this definitely won't do them any good!

 

A trickle charge is usually a tiny constant current charge, just enough to get them up to 13.8v.

 

cheers,

Pete.

 

 

My bike battery is charged at 14.3 volts, measured at the battery terminals. I would have thought on a big battery, that could take a bit more than 13.8 for an overnight charger - agree if its on permanent float charge, 13.8 would be more appropriate - many service vehicles ( and reps cars) though, whose engines are running all day every day, will be charging at 14.0 or a bit above...

 

Nick

[Arnot]

Edited 'cos I'm just too busy to get into another one of these. Who ya gonna call? ARNOT!

Just a thought, have you checked the fanbelt?

 

Regards

 

Arnot

[Gibbo]

I'd take a guess that this is a measurement problem.

 

Nothing else really makes any sense.

[Tony Brooks]

I'd take a guess that this is a measurement problem.

 

Nothing else really makes any sense.

 

 

That was my initial thought but now, as the OP has failed to give us the actual sp.g. readings and only said "in the green" if a battery has a partially shorted cell that the panel is covering up but which forces all charges to remain in bulk charge. However I would expect a serviceable alternator to produce more than 13 volts in that case.

[smileypete]

The previous owner left me a note that I should try and get the Sterling (amps in/out) to indicate down to '000.00) after a days cruising to show the battereis were charged. He also said to try and get the Sterling to indicate at least 12.4 volts before retiring for the night and not to let it drop below 12.2 volts.

The battereis were new when I bought the boat.

Even after a full day..I only got it down to 3 - 4 amps...never the 000.00 that the previous owner mentioned....but they would show an alernator charge voltage of 14.2 volts on the Sterling and a positive (14 volts) needle swing on the conventional voltmeter (dial type on Beta panel)

I expect you may mean 3-4 amp hours as the Sterling unit is an amp hour counter? Taken together with the 14.2V end of charge voltage it looks like the batteries may have been a bit under charged.

 

The battery FAQ gives a good definition for end of charge for a normal healthy battery: (clicky)

 

If the batteries were new when you bought the boat maybe previous owner had issues too.

 

Although they do show 12.7 volt fully charge..which is still about right according to the batteryfaq site...they drop to 12.2 volts (50%) after only a few hours.

True, but right after the end of charge, the battery voltage can be artificially higher due to 'surface charge'. There's more about this in the battery FAQ.

 

I think you've done very well to get as far as you have learning about things, better than most people, though there may be a few more 'gotchas' to understand.

 

To get help with charging problems, it's best to quote battery terminal voltage and charging current too and different phases of charging, as one without the other is only half of the story and not much good on it's own.

 

cheers,

Pete.