Batteries and Charging

[blackrat779]

Hi,

My first post after lurking for some time and trying to absorb information.

From a new person's perspective and not owning a boat yet, there is a lot of what could be good information on the forums about batteries and charging but also quite a lot that contradicts it. Is there a good book or reliable source of information that is the bible or go to reference for these topics?

It appears that many people are struggling with maintaining their batteries and trashing brand new batteries very quickly through a lack of knowledge or over-reliance on one form of reading. Have I got this right? For those who are getting it right, what is the answer?

Thanks for reading this

BR 

[rusty69]

Heres a freebie to get you started 

 

https://www.victronenergy.com/upload/documents/Book-Energy-Unlimited-EN.pdf

[Robbo]

Also look up Nigel Calders book, you can see the first chapter at Amazon..

 

https://www.amazon.co.uk/gp/aw/d/B0147TM944/ref=tmm_kin_title_0?ie=UTF8&qid=1509611877&sr=8-1

[Alan de Enfield]

18 minutes ago, blackrat779 said:

For those who are getting it right, what is the answer?

The principles are remarkably simple :

"Put back, each day, 20% more Ah than you have used"

The problems, arguments and discussions all revolve around the best way of measuring this.

There are a number of methods, eg, you can do it the 'hard way' and get good results, or the 'easy way' and get less accurate results. You can climb in your engine hole and measure the SG of each battery cell morning and night, or you can 'press a button' on a gauge and get an approximate result.

Many of the people who 'get it right' don't worry about it and just replace their batteries every year - batteries are disposable -  its only about £1 per week per battery, and you'll get £10 back on each battery from the 'scrap-man'.

Edited November 2, 2017 by Alan de Enfield

[Tony Brooks]

The problem with your question is that there are no definitive answers about the subject. It is even arguable that we do not yet fully understand  how our lead acid batteries work. Then there is the large range of battery types and construction even before you consider the almost infinite ways boaters and others use their batteries. If you have  a look at my website that I wrote as a free resource to try to help and advise actual and potential  ordinary (as in non-expert) boaters you will see there is no definitive battery advice. Only examples of how to do the basic "calculations" so you stand some chance of understanding what you need to in order to minimise battery problems and get an optimum battery life. This is deliberate because there are no right or wrong answers to the question. It is also a very large question because to get the best from your batteries you MUST start with assessing your  electrical requirements, from that battery bank size, and then sorting out the charging. This then feeds back to electrical demand until you develop a suitable balance. Even then a suitable balance is likely to be different for different people.

Just be wary of commercial offerings like the above link, there is always the danger that any such text will make more of the company's products than those from other companies.

The  battery "guidelines" are simple enough:

1. Install at least 25% more battery capacity than you calculate you need (to allow for some loss of capacity caused by sulphation)..

2. Try to avoid discharging below about 50% of charge (to maximise cyclic life).

3. Recharge as fully as you can as soon as you have discharged the batteries (to minimise the rate of sulphation).

4. Install some form of battery monitoring. (so you can comply with 2 and 3 above).

5. Learn how to use the battery monitoring equipment and FULLY UNDERSTAND its weak spots.

Yes you do have it right and if you look at the questions you will see fairly large scale unwillingness to answer questions (typical excuse - "I can't do a power audit) and then take advice.

Personally I get by well enough with a voltmeter and decent  ammeter to monitor my batteries. The voltmeter will tell me when 2 above comes into play BUT when and the conditions I read it under are important. That is usually first thing in the morning or last thing at night with no solar input and no other loads drawing power. 3 above is accomplished by having solar charging and running the engine every day when I have no shore powered charger. Others may use a generator. I then keep charging until the  charging amps are around 1% to 2% of battery capacity so with a split charge system and 430Ah of battery capacity I try to charge until the current drops to about 10 amps with no significant electrical loads.

 

PS - Alan's put back in 20% more than you have taken out is again only a guide. The figures I obtained on line suggest anything between 10% and 40% depending upon battery construction, temperature and condition and those tend to be unknown. This is avoided by the 1% to 2% of battery capacity charging current thing.

Edited November 2, 2017 by Tony Brooks

[smileypete]

6 hours ago, blackrat779 said:

Hi,

My first post after lurking for some time and trying to absorb information.

From a new person's perspective and not owning a boat yet, there is a lot of what could be good information on the forums about batteries and charging but also quite a lot that contradicts it. Is there a good book or reliable source of information that is the bible or go to reference for these topics?

It appears that many people are struggling with maintaining their batteries and trashing brand new batteries very quickly through a lack of knowledge or over-reliance on one form of reading. Have I got this right? For those who are getting it right, what is the answer?

Thanks for reading this

BR 

I think we can all agree that you need an ammeter to best tell when the batteries are fully charged.

[WotEver]

6 minutes ago, smileypete said:

I think we can all agree that you need an ammeter to best tell when the batteries are fully charged.

Or a hydrometer. 

Or a refractometer. 

[dmr]

Keeping batteries charged whilst living full time on a boat on the English waterways in winter is a pretty minority activity and so, to my knowledge, nobody has written a book about it. Even worse there are many styles of boat living and several ways to charge batteries and almost nobody has a good appreciation of all of this.

There are some people about with lots of knowledge about batteries and electricity but I suspect most of those would be very surprised if they tried to live on a boat in the winter.

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

[mrsmelly]

37 minutes ago, dmr said:

Keeping batteries charged whilst living full time on a boat on the English waterways in winter is a pretty minority activity and so, to my knowledge, nobody has written a book about it. Even worse there are many styles of boat living and several ways to charge batteries and almost nobody has a good appreciation of all of this.

There are some people about with lots of knowledge about batteries and electricity but I suspect most of those would be very surprised if they tried to live on a boat in the winter.

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

Well put. Speaking as one of those minority that do exactly what you say full time including winters I firmly believe its totally impossible to " precisely " answer the batteries/charging question. Sufffice to say over our umpteen off grid winters over the years charging as often as possible as high as possible will make the batteries last longer. However you will not save a penny on running costs as add up the extra fuel to " lookafter " your batteries and oil changes and wear on the engine and you may as well just buy batteries more often.

[blackrat779]

Thank you to everyone for your replies on my questions.

It looks as though there is no simple answer and it just depends on your circumstances and set up. It's my intention to constantly cruise throughout the year and not rely on shore power.

As I mentioned, I haven't got a boat yet but it will be secondhand. To some extent I will inherit the problems that come with whatever system is already installed and will have to adapt my strategy to suit. I guess learning as much as I can (thanks for the links) and reading the posts here will set me up to have a good idea about the system I inherit. BTW do surveys cover electrics? Will they tell you the current state of the system? ie batteries are on their way out, alternator isn't man enough for the job, a hamster has eaten through the battery leads?

Thanks again,

BR  

[Tony Brooks]

Answer to survey question - almost 100% certain they will not and not be able to without taking the batteries off the boat for a testing taking many hours. They should report on damaged wiring or anything glaringly obvious though.

Probably the best advice until you start to get a feel for how things pan out is to forget about all those electrical "gadgets" we never needed 50 or so years ago and stick with things like a car radio & CD player. Keep well away from large inverters but a small (say 150 watt) one for charging things like phones you can not get a 12V charger for and maybe a hand held vacuum cleaner is OK. Stick with car adaptors for things like phone charging and running a laptop where possible.

Once you get an idea about how  well you can charge your batteries then its the time to add more modern convinieences.

Edited November 3, 2017 by Tony Brooks

[blackrat779]

1 minute ago, Tony Brooks said:

Answer to survey question - almost 100% certain they will not and not be able to without taking the batteries off the boat for a testing taking many hours. They should report on damaged wiring or anything glaringly obvious though.

Thanks Tony. Are there any simple/quick tests a prospective owner can do to try and reduce the risk?

Cheers,

BR  

[nicknorman]

2 minutes ago, blackrat779 said:

Thanks Tony. Are there any simple/quick tests a prospective owner can do to try and reduce the risk?

Cheers,

BR  

I’m not sure that the condition of the batteries matters too much in a survey. Hopefully it would not make a difference between buying and not buying a boat as they are a consumable. It would be like deciding whether to buy or not buy a boat depending on how much diesel was in the tank.

Harder to fix is the infrastructure so I’d want to know the details of the equipment fitted eg alternator(s) size, inverter model, number of batteries that can be accommodated space-wise, details of any solar etc. charging equipment, monitoring equipment and general tidiness and beefyness of the wiring.

You can only tell the condition of the battery bank by discharging until it loses voltage, and that takes many hours - hopefully.

[Tony Brooks]

Practically no, not until its yours, unless you can get your hands on a very expensive commercial battery tester and some time. It would b cheaper to buy new batteries. In fact I would say budget for new batteries and if you do not need them its a win.

If they are open wet cell batteries a hydrometer will give you some idea but in far too many boats it will mean taking the batteries out. Sample each cell and note the colour of the ACID and the where the float settles. Put a decimal point after the first to numbers so 1100 becomes 11.00. If any cell does not have clear acid in it then that battery is probably faulty. If any two cells differ by more than 0.03 then the battery is probably faulty but try recharging before condemning it. Take a voltage voltage reading and look up the state of charge that corresponds to plus the state of charge indicated by the hydrometer readings. If they differ significantly with the hydrometer reading the lower one then the battery has lost a lot of capacity to sulphation.

For any battery type inspect the ends  - if they are bowing out the battery has lost a lot of capacity and is probably on its last legs.

Sealed batteries fully charging and removing from use. Allow to stand for several hours or overnight and then  measure and not the voltage. Allow to stand for a week or so and measure the voltage. If both voltages are not virtually the same the battery has an internal short circuit so is faulty.  Fully recharge again and put a known load on the battery. Monitor the voltage and time it takes to drop to (not sure about this figure but I think 10.8 volts is correct). Then the load in amps multiplied by the time in hours will give a fair idea about the actual battery capacity. If its more than 50% of what is on the label the battery is probably OK for further use but with the reduced capacity. Less than 50% and its probably time for a new one.

THIS IS THE ONLY TIME YOU WOULD EVEN CONSIDER DISCHARGING THE BATTERY TO SUCH A LOW OFF LOAD VOLTAGE. In everyday use try not to discharge below about 12.2 to 12.3 volts for optimum battery life and recharge ASAP.

 

 

[mrsmelly]

As a quicky. I bought this boat just under 3 years ago and didn't even look at the batteries when we checked the boat out. Bought boat same day and went to collect it with a complete set of new leisure batteries as I would then know their history from that date. As Nick says they shouldn't come into thinking on boat purchase they are just like diesel.

[Alan de Enfield]

40 minutes ago, blackrat779 said:

It looks as though there is no simple answer and it just depends on your circumstances and set up. It's my intention to constantly cruise throughout the year and not rely on shore power.

 

It may be only be a guide, but asking questions of the seller may help a little to establish how robust the systems are :

What was the previous ‘use of  the boat’ ?

Was it leisure use ?

Was it used only at weekends & back to the marina and ‘mains electric’ before the batteries went flat ?

Did it ‘go-out’ for weeks / months on end ?

Was it a ‘liveaboard’ ?

Was it a liveabord in a marina, never moved and always plugged into the mains electric ?

Did it CC ?

Is there a washing machine on board ?

Is there a generator on board ?

 

It is only an assumption, but better than just a guess - if it was previously a ‘regularly used, away from the mains electricity for some considerable  time’ boat, it SHOULD be robust enough to do the same for you – unless you intend to ‘go-overboard’ with additional heavy usage electric gadgets,

[smileypete]

2 hours ago, blackrat779 said:

Thank you to everyone for your replies on my questions.

It looks as though there is no simple answer and it just depends on your circumstances and set up. It's my intention to constantly cruise throughout the year and not rely on shore power.

As I mentioned, I haven't got a boat yet but it will be secondhand. To some extent I will inherit the problems that come with whatever system is already installed and will have to adapt my strategy to suit. I guess learning as much as I can (thanks for the links) and reading the posts here will set me up to have a good idea about the system I inherit. BTW do surveys cover electrics? Will they tell you the current state of the system? ie batteries are on their way out, alternator isn't man enough for the job, a hamster has eaten through the battery leads?

If you can be a very light user, at least initially, then it's hard to go wrong.

Very light user being water pump, a few LED lights, phone charging and a bit of lappie/small tv use.

Try and do without a fridge, run a twin tub from a small inverter while running the engine or a genny.

Solar is great and a 'good fit' for running a fridge, but there's precious little now until spring.

Edited November 3, 2017 by smileypete

[nb Innisfree]

It has to be remembered that living off grid 24/7 and trying to recharge to 100% SoC is impossible unless batteries are isolated from any load, in other words don'  use them just charge them! otherwise it takes more hours to charge than is available. The only option is to do a managed retreat to eventual death of batteries, much like life really! 

[bizzard]

No need for a fridge now its cold. Make a bottomless box with lid and with a few vent holes in it. Place the box on the cold steel of the front well or wherever on cold steel outside in the shade. To be honest a fridge is not really needed at all, even in summer as most folk shop at least a couple of times a week, so if fresh food is bought it will easily last a couple of days or so if kept in cool place, even milk. Keep a tin of Marvel powdered milk handy.  Electric fridges will cause you great extra expense and electrical anxiety to run, requiring more batteries, big inverters, bigger wires, gauges, monitors and pills and medication for uncontrolable anxiety spasms and sleepless nights. A gas fridge eliminates most of that though.

Preferably, for extra coolness line the inside of the box and lid with aluminium sheet.

Edited November 3, 2017 by bizzard

[nicknorman]

Just now, bizzard said:

No need for a fridge now its cold. Make a bottomless box with lid and with a few vent holes in it. Place the box on the cold steel of the front well or wherever on cold steel outside in the shade. To be honest a fridge is not really needed at all, even in summer as most folk shop at least a couple of times a week, so if fresh food is bought it will easily last a couple of days or so if kept in cool place, even milk. Keep a tin of Marvel powdered milk handy.  Electric fridges will cause you great extra expense and electrical anxiety to run, requiring more batteries, big inverters, bigger wires, gauges, monitors and pills and medication for uncontrolable anxiety spasms and sleepless nights. A gas fridge eliminates most of that though.

And don’t forget the hair shirt and daily whippings with nettles.

[bizzard]

6 minutes ago, nicknorman said:

And don’t forget the hair shirt and daily whippings with nettles.

Zactly, very exhilarating.

[Dr Bob]

One input I would give a prospective buyer is to be aware that on older boats, the alternator may not be good enough. There is a huge amount of info on this forum on power and batteries but little has been discussed on the number of old alternators out there. You are going to struggle to charge well with an 'old style' alternator. Gibbo's script on 'alternator chargers' (on his SG web site) is a good description http://www.smartgauge.co.uk/controllers.html 

In 2005 we bought a new lumpy water yacht. The max voltage the alternator put out on charging was 13.9V (a new volvo penta). This year we bought a 15 year old NB and that alternator put out a max of 13.9V (beta 43). Seems to fit Gibbo's description on boats built in the early 2000's. There must be many many boats out there with alternators designed to recharge starter batteries and not recharge depleted live aboard's batteries well. Our current boat was ok at charging as it has plenty of solar so for the first few months it was possible to keep it full(ish). Our answer was to fit a Sterling AtoB unit which is great (we fitted one to the Volvo as well) and we are charging far far better. If you are buying an old boat, have a look at the charging voltage – as long as its not been on shore power – you could ask your surveyor to do this.

[Naughty Cal]

1 hour ago, Dr Bob said:

One input I would give a prospective buyer is to be aware that on older boats, the alternator may not be good enough. There is a huge amount of info on this forum on power and batteries but little has been discussed on the number of old alternators out there. You are going to struggle to charge well with an 'old style' alternator. Gibbo's script on 'alternator chargers' (on his SG web site) is a good description http://www.smartgauge.co.uk/controllers.html 

In 2005 we bought a new lumpy water yacht. The max voltage the alternator put out on charging was 13.9V (a new volvo penta). This year we bought a 15 year old NB and that alternator put out a max of 13.9V (beta 43). Seems to fit Gibbo's description on boats built in the early 2000's. There must be many many boats out there with alternators designed to recharge starter batteries and not recharge depleted live aboard's batteries well. Our current boat was ok at charging as it has plenty of solar so for the first few months it was possible to keep it full(ish). Our answer was to fit a Sterling AtoB unit which is great (we fitted one to the Volvo as well) and we are charging far far better. If you are buying an old boat, have a look at the charging voltage – as long as its not been on shore power – you could ask your surveyor to do this.

Our old VP alternator only ever charged to 13.8V. 

Our "new" Prestolite one charges to a much higher voltage to 14.6V which the batteries seem to appreciate.

[Dr Bob]

Its not just me then! Probably a few more 'poor' alternators out there. Yep, its nice to get to 14.6V now.

[dmr]

Alternator controllers like the Adverc and Sterling are designed for exactly this reason, they set the charging voltage to exactly the desired value whilst different alternators use different voltages. They also provide temperature compensation and this can be surprisingly large in winter, and also do battery sensing.

Sadly that great battery guru, Gibbo, had a big downer on them, most likely because he was marketing one of his products as an alternative to controllers, and so many people think they are not required with modern alternators.

Bizarrely many people are happy to fit the Sterling A to B because this is not seen as an alternator controller even though it does exactly the same thing in a more expensive and complicated way.

rant over

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