Dead batteries - do I have a charge problem...

[ckris]

Sorry for yet another post about battery management, I have just spent many hours going over previous posts and researching on t’interweb and I now feel much better educated, but still a little confused.

We have a house battery bank of 2 x 110AH Varta leisure batteries and a 3rd identical battery used as the engine start. These are controlled through a 1-2-both-off switch which is used to direct which bank is connected for both charging and draw (ie no relay or split charging diode). We had a new engine installed 2 years ago, a Volvo D1-30 with a 115A alternator. When the new engine was installed the old split charging diode and Adverc regulator was removed, the engineer told us the diode was not man enough for the bigger alternator (fair enough) and the Adverc would not be needed with new alternator and could damage it (never convinced about this).

Anyway, all has been OK until last weekend when both batteries in the house bank died, they were about 3 years old so could be just their time or maybe we didn’t look after them well enough over the winter lay up (we put them on trickle charge for a day every 6ish weeks over the winter). Before deciding what to replace them with I did some tests at the weekend with a multimeter. The voltage at the (dead) house bank is 14.2 volts when this bank is selected with the engine running. When switched to charge the good engine start battery the voltage was also 14.2 volts (on that battery), we left the engine running for over 2 hours charging the engine battery and the voltage stayed at 14.2 volts, long after the point I would have expected it to be fully charged.

So, I’m thinking that 14.2 volts may not have been enough to fully charge our batteries which may have reduced their life, we are not on shorepower and typically run the engine for 1.5 hours/day when we are on board with the occasional longer run. Does this sound likely?

Conversely, I was surprised that the charge voltage stays at 14.2 and does not ever appear to reduce to a float charge – is it possible we have been overcharging the batteries?

Does anyone know what type of alternator this is likely to be, all I can find is a serial number with no make or model number? Is it possible it is fixed to permanently regulate at 14.2 v or could there be a fault somewhere? Would re-fitting the Adverc help and is there any danger it could damage the alternator (assuming I check with Adverc first that it is compatable)?

Finally, I know fitting a battery monitor would help understand what is going on and that is next on my list, then will be looking at maybe a VSR. Before that I need to replace the house batteries and want to understand if we have a problem before deciding whether to get cheap or expensive batteries (another thorny conundrum!).

Thanks in advance if any kind soul can offer advice...

Chris

 

[halcyon]

Sorry for yet another post about battery management, I have just spent many hours going over previous posts and researching on t’interweb and I now feel much better educated, but still a little confused.

The alternator is regulating at 14.2 volt, nothing wrong, not a bad recharge level. It is poosible that the adverc may not have been suitable, maybe the regulator and brush gear are one integral unit.

Get the batteries checked at the dealer before replacing them, it may be that they have surface charge only, and require a full bench charge to pull them up.

Brian

 

[MoodySabre]

I flattened a house battery last year with a fridge and anchor light etc on overnight - down to 4 volts so my charger wouldn't look at it. Took it back to where I had bought it the year before and he stuck it on a Sterling charger which recovered it and it has been fine ever since. At £85 a pop don't give up on them yet - 3 years isn't that long for a good battery. It needs a good multi-phase charger when it is that knacked.

 

[Chris_Robb]

Sorry for yet another post about battery management, I have just spent many hours going over previous posts and researching on t’interweb and I now feel much better educated, but still a little confused.

We have a house battery bank of 2 x 110AH Varta leisure batteries and a 3rd identical battery used as the engine start. These are controlled through a 1-2-both-off switch which is used to direct which bank is connected for both charging and draw (ie no relay or split charging diode). We had a new engine installed 2 years ago, a Volvo D1-30 with a 115A alternator. When the new engine was installed the old split charging diode and Adverc regulator was removed, the engineer told us the diode was not man enough for the bigger alternator (fair enough) and the Adverc would not be needed with new alternator and could damage it (never convinced about this).

Anyway, all has been OK until last weekend when both batteries in the house bank died, they were about 3 years old so could be just their time or maybe we didn’t look after them well enough over the winter lay up (we put them on trickle charge for a day every 6ish weeks over the winter). Before deciding what to replace them with I did some tests at the weekend with a multimeter. The voltage at the (dead) house bank is 14.2 volts when this bank is selected with the engine running. When switched to charge the good engine start battery the voltage was also 14.2 volts (on that battery), we left the engine running for over 2 hours charging the engine battery and the voltage stayed at 14.2 volts, long after the point I would have expected it to be fully charged.

So, I’m thinking that 14.2 volts may not have been enough to fully charge our batteries which may have reduced their life, we are not on shorepower and typically run the engine for 1.5 hours/day when we are on board with the occasional longer run. Does this sound likely?

Conversely, I was surprised that the charge voltage stays at 14.2 and does not ever appear to reduce to a float charge – is it possible we have been overcharging the batteries?

Does anyone know what type of alternator this is likely to be, all I can find is a serial number with no make or model number? Is it possible it is fixed to permanently regulate at 14.2 v or could there be a fault somewhere? Would re-fitting the Adverc help and is there any danger it could damage the alternator (assuming I check with Adverc first that it is compatable)?

Finally, I know fitting a battery monitor would help understand what is going on and that is next on my list, then will be looking at maybe a VSR. Before that I need to replace the house batteries and want to understand if we have a problem before deciding whether to get cheap or expensive batteries (another thorny conundrum!).

Thanks in advance if any kind soul can offer advice...

Chris

Chris, a number of points.

1. What was the resting state of the battery - you should see around 12.7V

2. The voltage on charging the batteries of 14.2 is on the low side for rapid chargiung (and this is where the Sterling comes into its own - charging up to 14.8) But it would not have ruined the batteries.

3. Why do you say they are dead?- they appear to be accepting charge - look at 1 above and test when you arrive at the boat. If the batteries are around 12.7 - or even 12.3 or so, then they are not dead. If that is the case then I would suspect the connections. If you put a light on and then switch on a high ampage unit (fridge) does it make the lamp go dim? If the light gies dim, suspect the main battery connections.

4. I have recently install a new alternator - it also charges to 14.2, which with open lead acid is far too low. I also have a sterling which charges to 14.8 and pumps in almost 100 amps for a long time. Suggest you get a NASA Battery monitor which will help - showing Voltage and amps.

5. 1 2 both switch is fine - so long as you remember not to leave on both overnight!

 

[theforeman]

i replaced my old alternator last year with a 90 amp jobbie. at the same time i fitted an adverc regulator. the new regime charged away at 14.4 volts constantly. the adverc is supposed to boost the charge to that level for a time and then drop to 13.8 volts for
a " resting " period. i thought the adverc was broken so disconnected it. alternator still charged at 14.4 volts.
i spoke to adverc. they said if the alternator was charging at 14.4 volts that was fine. the adverc regulator was not " working " because its purpose was to boost the charging output not to reduce it, it could not reduce the charge rate.
the system appears to have worked well all last season. the house batteries have sat on the garage bench all winter at 12.8 and 12.9 volts with the occasional charge up and very little self discharge.
you will find the people at adverc more than helpful if you phone them.

 

[Playtime]

Have you checked the water level in the batteries (assuming they are not 'maintenance free')? If the water has been used up by overcharging, the batteries will appear 'dead' although it might be possible to resurrect them if they have not been left too long.

I would refit the Adverc assuming the unit you have is OK for the alternator - check with Adverc - as said above they are very helpful. You will probably need their advice about modifying the connection to the field/brushes anyway.

Adverc charge regime gives 14.2V for the first 5 minutes before boosting the charge to 14.5 or 14.6 for 20 mins and then back to 14.2V for a similar period. It repeats this 3 times before reverting to a float charge around 13.8V (assuming the battery is fully charged).

 

[RAI]

Test the specific gravity with a hydrometer, if they are wet cells.

 

[ckris]

Many thanks for all the replies, much appreciated.

Battery symptoms were: lights went dim , was surprised to see 11.something volts on house bank so we ran the engine for 4 hours (at 14.2v). Within 5 mins the lights were going dim again and voltage on batteries still very low. So, ran engine again for 2 hours then disconnected the house bank (separating the 2 batteries) and left overnight. Next morning one battery was 12.6v, the other 11.5v, great I thought just one battery is knacked. So I connected only the higher voltage battery to make a single battery house bank but within 5 mins lights were dim and it was down to 11.something volts. Subsequent attempts to charge that battery have had same result. The engine start battery is behaving normally with a resting voltage of 12.6+. Have checked water levels and plates appear to be covered. Hadn’t crossed my mind that house batteries might be recoverable but will definitely take them along to be checked before buying new ones. Had forgotten about possibility of checking with a hydrometer, have never done this before but will give it a go if just for my education, if I can get hold of one.

I’m more confused about the alternator, I always assumed it would have a built in regulator that sensed the voltage at the alternator output and would do kind of the same as an external smart regulator but with a less aggressive charge voltage and without the cycling – ie always assumed it would drop to a float charge voltage of 13.something volts once batteries charged. If it stays fixed at 14.2v how does this prevent over-charging ?

Ref the 1-2-both-off switch, I’m OK with this except I understand that if it is inadvertently switched to off whilst engine is running the alternator will be damaged – this is only reason I am thinking of a splitting diode or VSR sometime in the future.

Chris

 

[pampas]

Do you have a ammeter fitted?

 

[Playtime]

It looks like you are going to have to replace both domestic batteries. However, before you do, it would be worth taking them home and giving them a good long charge with a mains charger (a cheapo car charger will do). Also, as suggested, get a hydrometer (from Halfords or other car accessories shop - they are not expensive) and test the batteries before and after charge.

It is possible that there is something wrong with the charging or wiring on the boat (and the batteries will be recoverable) but I suspect from the symptoms you have described, that both batteries are now knacked.

The question remains - why? It might be worth pondering this some more to avoid the same problem with the new ones

BTW - how old were they?

 

[Ruffles]

In my (limited to 2 makes) experience of 'leisure' batteries I reckon they need a slightly higher charging voltage than standard wet cells. I personally will not be buying one again.

I find they charge ok on a powerful bench charger but struggle direct from my alternator.

 

[RAI]

Sounds like dead batteries. The hydrometer will probably show at least one of the cells is dead, even when the battery has been charged for a long time.

If you plan to change the switching arrangement, look at using a voltage sensitive relay instead of diodes. The diodes insert a resistance and hence voltage drop.

If you only run the engine for relatively short periods, it might be worth getting one of Sterling's products (or similar) to get smart charging. You will need to know what kind of terminals your alternator provides. My new Yanmar has an alternator that cannot be externally controlled, but Sterling has a neat fix for that.

If you go for the Sterling solution, you don't need diodes or VSR, as the unit provides separate outputs for starter and domestic batteries.

 

[Chris_Robb]

Many thanks for all the replies, much appreciated.


I’m more confused about the alternator, I always assumed it would have a built in regulator that sensed the voltage at the alternator output and would do kind of the same as an external smart regulator but with a less aggressive charge voltage and without the cycling – ie always assumed it would drop to a float charge voltage of 13.something volts once batteries charged. If it stays fixed at 14.2v how does this prevent over-charging ?

Ref the 1-2-both-off switch, I’m OK with this except I understand that if it is inadvertently switched to off whilst engine is running the alternator will be damaged – this is only reason I am thinking of a splitting diode or VSR sometime in the future.

Chris

1-2 bith switch - you are correct - best way to go is the VSR - forget the diode splitter (voltage drop) - Halcyon runs a company called KDD - look at his blog - I had one on my last boat - very good.

Re the Alternator, I am also somewhat confused on the alternator voltage issue. I have just replaced an old alternator 55a/h that naturally charged at a useless 13.8 volts. I installed a Sterling which boosted the charge voltage to 14.8. When the batteries were well and truly charged the Sterling would presumably stop boosting as the voltage would drop down to around 13.8.

With my new alternator (a 110 ah Prestolite form Adverc) this seems to charge at 14.2 without the Sterling, but as above with the Sterling. I have not run it long enough to check the float voltages yet, but I assume that they will not drop below 14.2 ie the natural output of the alternator.

So my question is - is 14.2 too high a voltage for 24 hours of motoring in a hot climate????

 

[RAI]

The Sterling alternator to battery charger drops the volts to 13.6 to 13.8 volts when it decides the batteries are fully charged. All the details are on the Sterling web site.

 

[Chris_Robb]

The Sterling alternator to battery charger drops the volts to 13.6 to 13.8 volts when it decides the batteries are fully charged. All the details are on the Sterling web site.

That is indeed what they try to do, but if the alternators natural output is 14.2 it cannot override it. The controller is a voltage booster, it cannot reduce the alternators natural output.

 

[RAI]

That is indeed what they try to do, but if the alternators natural output is 14.2 it cannot override it. The controller is a voltage booster, it cannot reduce the alternators natural output.

It is more than that, read the literature on Sterling's website. I have one and the voltage on the house bank comes down from 15 volts to 13.6 volts when the batteries are fully charged. The alternator outputs 14.4 volts.

 

[lenseman]

. . . Battery symptoms were: lights went dim , was surprised to see 11.something volts on house bank so we ran the engine for 4 hours (at 14.2v). Within 5 mins the lights were going dim again and voltage on batteries still very low. So, ran engine again for 2 hours then disconnected the house bank (separating the 2 batteries) and left overnight. Next morning one battery was 12.6v, the other 11.5v, great I thought just one battery is knacked. So I connected only the higher voltage battery to make a single battery house bank but within 5 mins lights were dim and it was down to 11.something volts. Subsequent attempts to charge that battery have had same result. . . .

Within the text above just might be a clue?

I don't think your batteries are knackered at all [says he, sticking his neck out]!

The clue is in the words "lights went dim" inferring a sudden drop in voltage and not on one battery but both, most unusual to have both fail at the same time!!

I would like to suggest a test which you might like to consider as I think you might have HR on your house bank supply line and the test involves a single 12-volt test lamp or a small electrical meter measuring volts on every part of the circuit. You will need to check the voltage 'across' every joint from charging circuit to and including battery bank earth and all earth returns from the charging circuit. This test has to be conducted BEFORE removal of any battery or alternator as the very removal can and often masks the fault.

Give me a call on my land-line and I can explain much easier and in greater detail. Might save you the cost of two or more leisure batteries plus all the hassle of removal for testing!

In a previous life, I used to work for the RAC as their resident engineer who specialised in charging circuits and vehicle electronics. A HR fault in its various guises is far more common that people realise.

xxxxxxx

 

[Chris_Robb]

It is more than that, read the literature on Sterling's website. I have one and the voltage on the house bank comes down from 15 volts to 13.6 volts when the batteries are fully charged. The alternator outputs 14.4 volts.

I also have one - the basic Sterling Alternator booster. Fundamentally no controller, Sterling - or adverc , or any of the others, can reduce the voltage below that of the alternator itself. The way to test the actual output is to disconnect the white wire, which leaves the alternator to its own regulation.

I cannot see how you achieve the voltage reduction. One thought is that you may have a Splitting Diode, which is effectively reducing the current by .5V or more, as the alternator's natural regulator does not sence battery voltage.

 

[lenseman]

. . . I find they charge ok on a powerful bench charger but struggle direct from my alternator.

See my reply in message 17 above as it possibly applies to your yacht too.

I don't know any 'bench' battery chargers which give anything like the output of a correctly installed alternator?

 

[RAI]

I cannot see how you achieve the voltage reduction. One thought is that you may have a Splitting Diode, which is effectively reducing the current by .5V or more, as the alternator's natural regulator does not sence battery voltage.

I have no diodes. I have no idea how the Sterling alternator to battery charger works. Certainly an amplifier to get from 14.4 to 15.0 volts. But mine does drop the voltage to 13.6 - 13.8 volts when the batteries are fully charged.