Battery Capacity/Charging

[Meandering]

I am due to take possession of my new lined sailaway at the end of the month to start the fitting out and would very much appreciate some advice from the specialists who contribute to this forum relating to battery capacity and charging.

 

I have undertaken an initial power audit, using my best estimates for winter and summer demand based on the planned installation. These have come out with a daily consumption of 118 and 85 A/hr per day for Winter and Summer respectively. My problem now is with the sizing of the battery bank and recharging of the batteries.

 

In my research I have read the “Narrowboat Builder’s Book” 3rd edition which advises (on page 59) that you only realise some 30% of the batteries apparent capacity and that I should therefore multiply my audit figure by 3 to size the battery bank. However, at the Crick boat show this week I discussed this with three different battery suppliers at the show how basically said this was old data and new batteries would supply their full stated amp hours. I doubt this correct, are we talking apples and pears?

 

As a second but related question, I have just read the “Alternator Paralleler” topic and as this is 2009/2010 based, do the modern chargers incorporate this feature now? I will be fitting a Victron MultiPlus 12/3000/120. As I don’t have the full technical spec for this yet (and would not necessarily understand the finer points anyway) can you advice?

[Richard10002]

The generally accepted rule is that you shouldn't allow your batteries to fall below 50% state of charge, and the Smartguage site suggests a charger which will supply around 35% of battery capacity, but that most users tend to be a bit conservative, and have a 25% charger.

 

http://www.smartgauge.co.uk/50percent.html

 

http://www.smartgauge.co.uk/chargesize.html

 

Say you want at least a couple of days without needing to charge in winter, this suggests a bank of at least 500Ah. Your Victron charger at 120A is just under 25% of the bank size, which is probably OK.

 

Someone with more expertise will be along soon.

[Robbo]

I am due to take possession of my new lined sailaway at the end of the month to start the fitting out and would very much appreciate some advice from the specialists who contribute to this forum relating to battery capacity and charging.

 

Buy this book; http://www.amazon.co.uk/gp/product/B006QA720O/ref=as_li_ss_tl?ie=UTF8&tag=robbs1956pont-21&linkCode=as2&camp=1634&creative=19450&creativeASIN=B006QA720O (although the Kindle/online sample is worth reading as you get a good idea).

 

And also read this; http://www.victronenergy.com/orderbook/

[system 4-50]

I am due to take possession of my new lined sailaway at the end of the month to start the fitting out and

Nothing to do with your post but - get the outside painted asap if you haven't already! Its the number one priority for a sailaway.

 

 

 

[Meandering]

Buy this book; http://www.amazon.co.uk/gp/product/B006QA720O/ref=as_li_ss_tl?ie=UTF8&tag=robbs1956pont-21&linkCode=as2&camp=1634&creative=19450&creativeASIN=B006QA720O (although the Kindle/online sample is worth reading as you get a good idea).

 

And also read this; http://www.victronenergy.com/orderbook/

 

Thanks for the links!

[Keeping Up]

... at the Crick boat show this week I discussed this with three different battery suppliers at the show how basically said this was old data and new batteries would supply their full stated amp hours. I doubt this correct, are we talking apples and pears?

 

It sounds to me more like talking bull$hit - but I would just love to be proved wrong.

 

Read the links in Richard100000002's post, they explain things extremely well.

[Richard10002]

Richard100000002.

 

:)

[Proper Job]

............In my research I have read the “Narrowboat Builder’s Book” 3rd edition which advises (on page 59) that you only realise some 30% of the batteries apparent capacity and that I should therefore multiply my audit figure by 3 to size the battery bank. .

 

The 30% figure is probably based on a charging regime of not allowing the batteries to discharge below 50% capacity and charging up to 80% is fairly easy, whilst squeezing in the last 20% takes exponentially longer (relatively speaking).

 

If you can work between 50-80% capacity, with the odd charge up to 100% now and again, you should be able to expect a fairly good life expectancy from your batteries.

 

What is your expected usage pattern? ie. live a board, leisure only, bit of both?

[Chris Pink]

I am due to take possession of my new lined sailaway at the end of the month to start the fitting out and would very much appreciate some advice from the specialists who contribute to this forum relating to battery capacity and charging.

 

I have undertaken an initial power audit, using my best estimates for winter and summer demand based on the planned installation. These have come out with a daily consumption of 118 and 85 A/hr per day for Winter and Summer respectively. My problem now is with the sizing of the battery bank and recharging of the batteries.

 

In my research I have read the “Narrowboat Builder’s Book” 3rd edition which advises (on page 59) that you only realise some 30% of the batteries apparent capacity and that I should therefore multiply my audit figure by 3 to size the battery bank. However, at the Crick boat show this week I discussed this with three different battery suppliers at the show how basically said this was old data and new batteries would supply their full stated amp hours. I doubt this correct, are we talking apples and pears?

 

As a second but related question, I have just read the “Alternator Paralleler” topic and as this is 2009/2010 based, do the modern chargers incorporate this feature now? I will be fitting a Victron MultiPlus 12/3000/120. As I don’t have the full technical spec for this yet (and would not necessarily understand the finer points anyway) can you advice?

 

My suggestion for your usage would be 4 x US2200 6V batteries giving a total capacity of 460 Ah (20H rate) This matches your usage and charger.

 

A common mistake (see another thread) is to fit too large a bank and not charge it properly. You want to aim for two hours a day with a once a week 6-8 hour charge.

 

The Smartgauge site is, in my opinion, biased towards leisure use. I assume from your power audit you are a liveaboard.

 

The Victron document (in a pinned thread somewhere) will give you a basic grounding in battery care and liveaboard power generation.

 

Your related question; you are confusing alternators and battery charger. They are independent systems (although they do the same job). The technology is the same as 2009.

[nicknorman]

I am due to take possession of my new lined sailaway at the end of the month to start the fitting out and would very much appreciate some advice from the specialists who contribute to this forum relating to battery capacity and charging.

 

I have undertaken an initial power audit, using my best estimates for winter and summer demand based on the planned installation. These have come out with a daily consumption of 118 and 85 A/hr per day for Winter and Summer respectively. My problem now is with the sizing of the battery bank and recharging of the batteries.

 

In my research I have read the Narrowboat Builders Book 3rd edition which advises (on page 59) that you only realise some 30% of the batteries apparent capacity and that I should therefore multiply my audit figure by 3 to size the battery bank. However, at the Crick boat show this week I discussed this with three different battery suppliers at the show how basically said this was old data and new batteries would supply their full stated amp hours. I doubt this correct, are we talking apples and pears?

 

As a second but related question, I have just read the Alternator Paralleler topic and as this is 2009/2010 based, do the modern chargers incorporate this feature now? I will be fitting a Victron MultiPlus 12/3000/120. As I dont have the full technical spec for this yet (and would not necessarily understand the finer points anyway) can you advice?

As others have suggested, we really need to know more about your intended usage. Live aboard or leisure use? Boat continuously cruising or mostly in a marina /permanent mooring? Shore power mostly available or not? If CCing, how long to spend tied up before a decent day's cruising?

 

You have done the power audit which is great, you just need to publish the boat usage audit to complement it!

 

On the subject of battery types, there is a wide range of specs/technologies and prices for a given AH rating. For leisure use I think it is generally agreed that fairly cheap batteries that will not last that many cycles, nor tolerate deep discharge well, are best, with the expectation to replace them every few years. For live aboard use away from shore power, more expensive deeper cycle and higher cycle batteries may be a good idea, but with more expensive batteries comes more responsibility to keep them in good condition - the consequences of not doing so being a very expensive replacement.

Edited June 8, 2012 by nicknorman

[Robbo]

Thanks for the links!

 

The Boatowners manual does go into quite some detail, but the Victron book is slightly more upto date with the battery technology (mainly Optima spiral cell is missing from the manual).

 

Summing the different types of batteries are....

 

Leisure; Good for if have shore power and therefore used very little. (also cheap)

Traction; Cheapest overall for amp hours over lifetime, but take longer to take a charge (thicker metal) so may not be as cheap as first thought and need maintenance.

Gel & AGM; Next cheapest overall, don't need maintenance and can take a quicker charge than Traction so reducing costs if charging from engine/genny. Needs compatible charger and alternator?

Optima; Good for bow and anchor batteries due to wide range of charging voltages. (Not done much research on these though).

[Grace and Favour]

I would also suggest the OP fits some Solar panels, which will make a super job of providing the float charge for the batteries, (and will do the job rather quietly too!)

[Robbo]

I would also suggest the OP fits some Solar panels, which will make a super job of providing the float charge for the batteries, (and will do the job rather quietly too!)

 

It's suggested that to not plan the alternator or charger size with solar panels in mind.

[Grace and Favour]

It's suggested that to not plan the alternator or charger size with solar panels in mind.

 

'appen you're right, Robbo

[Meandering]

Thank you all for your useful comments and links!

Edited June 9, 2012 by Meandering