How much Solar v Batteries? What do you have?

[peterboat]

31 minutes ago, Tony Brooks said:

I should have added to my post above (97) that in many cases the cost of any form of alternator "enhancer" would produce better results if used to buy solar so the engine can be shut off early in the day at about 80% fully charged and the solar being left to do the rest.

Exactly this

[nb Innisfree]

3 hours ago, Mike the Boilerman said:

Something I notice repeatedly about batteries is they seem to degrade to about 50%-60% of new capacity fairly quickly when not treated correctly, then the degradation stops. There seems to be no technical explanation for this but in my experience over many decades and boats, this is what happens.

If the reduced capacity is still enough for the use to which they are being put, then yes the user will claim 'they are fine'. 

I reckon it's because some folk are under the false impression that new batteries has cured a problem when in fact the prob was down to poor charging. They then carry on blithely, luxuriating in seemingly perfect batts not realising that irreparable damage is usually done in batts early life. 

[WotEver]

23 hours ago, Dr Bob said:

Our set up was pretty typical with 400Ahrs and only a very small inverter - fridge was 12V and electrical appliances (hair driers, curling tongues, coffee machines etc) only used on shore power.

Yet you say...

 

3 hours ago, Dr Bob said:

My batteries lasted 5 years+ with no problems whatsoever - and it was not frugal use

Looks pretty frugal to me, compared to a lot of narrowboat liveaboards. 

Most of the stuff you say would only be used on hookup are used daily by many CC liveaboards . 

3 hours ago, Dr Bob said:

If I was mislead and the SoC was 80% not 100% when charged then the batteries would have died long ago

This isn't the case, I don't know why you keep repeating it. 

[WotEver]

5 hours ago, Tony Brooks said:

Plus what looks like suspect battery and charging knowledge upon which you base your ideas.

There is no doubt about this. To state that the final absorption charge from 80% to 100% can be completed within an hour by using a magic box clearly demonstrates a lack of understanding of lead acid battery charging. 

[WotEver]

3 hours ago, cereal tiller said:

Having installed quite a lot of Sterling Alternator Regulators over several Decades I do believe that they Do improve bulk charging times and generally improve Battery performance and longevity.

I don't believe anyone here has suggested otherwise. What we have said is that once you get past bulk they won't do much if anything, and to suggest that they'll reduce absorption from around 6 hours to less than an hour is nonsense. 

[Tony Brooks]

1 hour ago, WotEver said:

I don't believe anyone here has suggested otherwise. What we have said is that once you get past bulk they won't do much if anything, and to suggest that they'll reduce absorption from around 6 hours to less than an hour is nonsense. 

In my view NO magic box can do anything during the bulk phase which I define as the time during the early part of charging where the alternator's voltage regulator has yet to come into play. I would define absorption on an alternator as the earlier part of charging when the regulator is working but the amps are still fairly high - say above 10 to 15 amps, and float (not that there is such a thing on the majority of alternator systems) as the time the   charging current is dropping below that figure and falling.

During the period I describe as bulk the alternator will be outputting its maximum wattage with the currant and voltage varying to maintain that wattage. NO device, not even an A to B can get more watts of charge into a battery that it is being supplied with. With very discharged batteries this period could be well over an hour but  perhaps more usually between 15 and 30 minutes.

After that period, what I define as absorption, the advanced controllers and the A to B can do something and cause more current to flow into the batteries by elevating the charging voltage but the degree of elevation is very limited or even non-existent on modern alternators so the degree to which the charging time can be shortened is also  limited - especially if the device pulses the elevated voltage at about a 50% cycle ratio.  Even less if the device is fitted with battery temperature monitoring at this time of year and may be a bit more in winter.

In short during the early and late periods of charging such devices can have little or any effect.

Its the extravagant advertising claims and similar claims from some users that we are questioning. In some cases I  have been able to magically improve charging by simply replacing a length of cable or swapping a split charge diode for a split charge relay. However we know that can't have any material effect because it does not cost into three figures and there are no marketing half/quarter truths to support it.

Edited July 18, 2017 by Tony Brooks

[MtB]

2 hours ago, Tony Brooks said:

I should have added to my post above (97) that in many cases the cost of any form of alternator "enhancer" would produce better results if used to buy solar so the engine can be shut off early in the day at about 80% fully charged and the solar being left to do the rest.

 

Except in November, December, January and February.

[rusty69]

2 minutes ago, Mike the Boilerman said:

 

Except in November, December, January and February.

Depends where the boat is

[Dr Bob]

5 hours ago, Tony Brooks said:

Then there is the question of the true state of charge when you started engine charging. I have seen no re4sted voltage readings that would give this information with some degree of accuracy.

 

There seems to be a theme from a number of you here that I dont know what I am talking about - and that my SoC was much lower than I was thinking (particularly Wotever)....ie I was keeping it between 80-100%. Also Mike referred to total capacity in one of his posts.

I did monitor voltage at rest as I have said on a couple of posts. If you have 12.8V (almost) and it doesnt go below 12.5V then things are fine. I managed the system to keep it at these levels most of the time although the accuracy of the voltage measurement I have no idea of. Rest means a couple of hours with no load - I did test this now and again. Each morning you could see the voltage under load and see that everything was normal. I probably had enough information after the 5 years to build a model (like Smartguage) for what that is worth.

In terms of capacity I did check from time to time the amps in/out versus voltage at rest and was happy that I wasnt loosing capacity big time.

Ref your other post, spending £350 on solar will be very advantageous for the summer (and certainly better than an AtoB - if you have space) but very little advantage in the winter.....and winter is when you need the power as your existing solar will not be working nearly as well. I am very surprised you made that recommendation.

Edited July 18, 2017 by Dr Bob
had an extra 'k' in the text....oops!

[WotEver]

55 minutes ago, Tony Brooks said:

In short during the early and late periods of charging such devices can have little or any effect.

Yes, absolutely. 

Whatever we want to call the 'stages' of charge (although, as you say, these aren't clearly defined with a solus alternator) no magic box can substantially change the time taken for the early constant current stage or the latter part of the constant voltage stage (over 80% SoC). 

[WotEver]

10 minutes ago, Dr Bob said:

There seems to be a theme from a number of you here that I dont know what I am talking about - and that my SoC was much lower than I was thinking...

Yep. Purely based on your description of charging for less than an hour. There are only two explanations...

• You were only discharged by a few % when you commenced charging or
• You were only charging up to around 80%. 

It is simply impossible to charge a lead acid battery from 80% or less to 100% in less than an hour as you claimed. 

[Dr Bob]

4 hours ago, dmr said:

There a fair bit of crap getting posted on this thread, I might write something later, but its a sunny day and there's big maintenance to get done.

Standard cheapo leisures are good for about 300 cycles (down to about 50%). No matter how well one maintains then they are unlikely to do much better than this. If not looked after then its a lot less than 300 and as Mike says they do appear to go down to a low capacity and then stick there.

If batteries last 5 years that's because either they have not done many cycles or the owner is happy to live with hugely reduced capacity.

..............Dave

What is a cycle? Is it is 100% down to 50% and back up again?

It is certainly not 100% down to 80-90% and up to 100% again as over a 5 year period  we must have done 1500 cycles. To me, looking after your batteries is to try and not fall below 80% which means having a big battery bank. On the yacht we could only afford 400 Ahrs (to keep weight down). On our NB we have 700Ahrs.

If you run from 100% down to 50% and back all the time, then you will knacker them. Surely that is common sense?

On the yacht our batteries lasted 5 years because of the SoC I kept them in, not because of reduced  capacity.

[WotEver]

2 minutes ago, Dr Bob said:

What is a cycle? Is it is 100% down to 50% and back up again?

Or 100% down to 60% and back up again. Or 100% to 70%, or 80%, or 90%. 

Battery manufacturers quote the number of cycles versus DoD. One of the reasons Trojans are popular is that they have a very good cycle life down to 60% or lower DoD. 

[Dr Bob]

7 minutes ago, WotEver said:

Or 100% down to 60% and back up again. Or 100% to 70%, or 80%, or 90%. 

Battery manufacturers quote the number of cycles versus DoD. One of the reasons Trojans are popular is that they have a very good cycle life down to 60% or lower DoD. 

I was actually asking the question as I am intrested in understanding the answer? I know 100% down to 50% will knacker a battery (but after 300 cycles or less?) and 100% down to 80-90% is pretty frugal (???) but then long life.

What is the effect of 100 to 60%, 100 to 70% etc? You guys seem to profess to be the experts? All I know is how to keep bog standard wet lead acids in good shape and dont profess to know more. I do see the adverts saying 600 cycles, 1200 cycles and upwards.

[rusty69]

6 minutes ago, Dr Bob said:

You guys seem to profess to be the experts?

Im not sure anyone is proffessing to be a battery expert, just some knowledgeable boaters(not me, i hasten to add)  trying to help out another boater. 

The advice is free to ignore should you disagree with it. 

 

Edited July 18, 2017 by rusty69

[WotEver]

7 minutes ago, Dr Bob said:

I was actually asking the question as I am intrested in understanding the answer?

I assumed that to be the case which is why I answered you. 

8 minutes ago, Dr Bob said:

What is the effect of 100 to 60%, 100 to 70% etc?

You need to check out the published figures for the particular battery in question. The lower the DoD the greater the number of cycles but there is no 'one size fits all'. All batteries differ. 

See the graph bottom left of page 2 of this PDF as an example:

http://www.trojanbattery.com/pdf/datasheets/T105RE_TrojanRE_Data_Sheets.pdf

[nb Innisfree]

44 minutes ago, Dr Bob said:

I probably had enough information after the 5 years to build a model (like Smartguage) for what that is worth.

 

[WotEver]

Yes, made me smile too. 

[Dr Bob]

7 minutes ago, WotEver said:

I assumed that to be the case which is why I answered you. 

You need to check out the published figures for the particular battery in question. The lower the DoD the greater the number of cycles but there is no 'one size fits all'. All batteries differ. 

See the graph bottom left of page 2 of this PDF as an example:

http://www.trojanbattery.com/pdf/datasheets/T105RE_TrojanRE_Data_Sheets.pdf

Ah, very useful. So for a 100-50% cycle, these Trojans will do 1500 and for 100-80% they will do almost 3 times more. I will do a bit of searching on wet lead acids. This is why I was always told to not drop below 80% when we first started sailing.

[nb Innisfree]

8 minutes ago, nb Innisfree said:

 

 

7 minutes ago, WotEver said:

Yes, made me smile too. 

I meant to add another quote in which Dr Bob said some posters were professing to be experts but I can't find it at the mo. 

Edited July 18, 2017 by nb Innisfree

[WotEver]

1 hour ago, nb Innisfree said:

I meant to add another quote in which Dr Bob said some posters were professing to be experts but I can't find it at the mo. 

Well now, Chris Gibson IS an expert (world-renowned) but sadly he's no longer around here. I learnt a lot from him. 

(Post 114 btw)

[nb Innisfree]

2 minutes ago, WotEver said:

Well now, Chris Gibson IS an expert (world-renowned) but sadly he's no longer around here. I learnt a lot from him. 

(Post 114 btw)

I miss Gibbo''s posts. 

ETA: Can't do multiple quotes on my phone anyway. 

Edited July 18, 2017 by nb Innisfree

[WotEver]

Just now, nb Innisfree said:

I miss Gibbo''s posts. 

If you frequent Facebook his posts there are in much the same vein but uncensored

[nb Innisfree]

1 minute ago, WotEver said:

If you frequent Facebook his posts there are in much the same vein but uncensored

Facebook... Arrgghh! 

[cereal tiller]

1 hour ago, rusty69 said:

Im not sure anyone is proffessing to be a battery expert, just some knowledgeable boaters(not me, i hasten to add)  trying to help out another boater. 

The advice is free to ignore should you disagree with it. 

 

I always agree with your advice Rusty,only then do I ignore it