How Much Battery Power

[Maverick]

Just back from wkend up the Macclesfield canal which was brill however:-- After adding a new 110ah battery to my 100ah leisure one I thought I would have the power needed to run my 12v electrolux fridge, shower pump, water pump and 240v TV off inverter (2hrs per night max)

 

As the batteries were fully charged as we set off, the first day & night just provided our needs with virtually zero power left the next morning.

 

Day 2 saw 4hrs travelling but that evening the inverter alarm sounded after only 20mts of TV and the fridge went off an hour later.

 

It appears either I hadnt travelled enough to fully charge them on day 2 or the alternator isnt out putting enough charge to charge them fast enough.

 

Glad to say my Isolater switches worked fine and my starter battery was ok.

 

Any one any suggestions to get me through a weekends boating?

Edited April 16, 2007 by Maverick

[blackrose]

Just back from wkend up the Macclesfield canal which was brill however:-- After adding a new 110ah battery to my 100ah leisure one I thought I would have the power needed to run my 12v electrolux fridge, shower pump, water pump and 240v TV off inverter (2hrs per night max)

 

As the batteries were fully charged as we set off, the first day & night just provided our needs with virtually zero power left the next morning.

 

Day 2 saw 4hrs travelling but that evening the inverter alarm sounded after only 20mts of TV and the fridge went off an hour later.

 

It appears either I hadnt travelled enough to fully charge them on day 2 or the alternator isnt out putting enough charge to charge them fast enough.

 

Glad to say my Isolater switches worked fine and my starter battery was ok.

 

Any one any suggestions to get me through a weekends boating?

 

So you have 210 A/h of domestics in total? Doesn't sound enough for your requirements to me.

 

Possible solutions: More batteries, more charging, less DC consumption (the fridge is a killer - switch it off at night), try an external alternator controller if you don't already have one fitted.

[John Orentas]

Hi Maverick.

 

Fitting more batteries is not the answer, batteries only store energy they don't produce any. Your problem is most certainly the fridge, you must run it permanently on gas. The inefficiency of these things when running on electric' is incredible. There have been many threads about this question but suffice to say that whether on 230 or 12 volts they consume 100 and 95 watts that is a CONSTANT 8 amps at 12 volts no electrical system is going to sustain that.

 

I have had several of these over the years, the first thing I do when I buy one is cut every inch of electrical cable out of them. The good news, they work great on gas.

[Maverick]

Hi Maverick.

 

Fitting more batteries is not the answer, batteries only store energy they don't produce any. Your problem is most certainly the fridge, you must run it permanently on gas. The inefficiency of these things when running on electric' is incredible. There have been many threads about this question but suffice to say that whether on 230 or 12 volts they consume 100 and 95 watts that is a CONSTANT 8 amps at 12 volts no electrical system is going to sustain that.

 

I have had several of these over the years, the first thing I do when I buy one is cut every inch of electrical cable out of them. The good news, they work great on gas.

 

Hi John, thanks for the constructive advice. The fridge is brand new and I had decided to connect it to gas as there is a short branch of pipe which has been blanked off from a previous installation which should make the job pretty easy.

However when I went to my local chandlers to obtain the neccessary rubber pipe and joint required I was told I could no longer connect a fridge to Gas or my insurance would be void as a gas fridge was not listed on the BSS.

 

I spoke to some friends at our marina who have just had a new boat built and they told me they couldnt have a gas fridge installed as they were now banned on new boats.

 

I doubt my alternator is outputting enough charge to cope with more batteries anyway and dont want the trouble and expense of purchasing a larger one. Looks like I'm stuffed either way.

 

So you have 210 A/h of domestics in total? Doesn't sound enough for your requirements to me.

 

Possible solutions: More batteries, more charging, less DC consumption (the fridge is a killer - switch it off at night), try an external alternator controller if you don't already have one fitted.

 

Hi dont think switching the fridge off overnight is an option. Boats get pretty warm inside over the summer and cant have me bacon going off.

 

The charging system has a diode in place (little square box like a indicater flasher box on cars???) which I think is to aid charging. Anyone tell me more about what these diodes actually do?

[John Orentas]

Hi Mav.

 

As you describe your 'diode' I think you will find it is a split charge rely, it's function is to separate your domestic from starter batteries when the engine is not running (therefore not charging). But don't try and simply modify your electrics to power this fridge, it will cost a lot of money and will never be satisfactory.

 

I could be wrong but I believe that the Electrolux fridge is now permitted, though not advised? The BSS have got themselves into a real mess over this. I have been trying to look it up in their book but it reads as though it has been written by a lawyer rather than an engineer. Lots of people on here will give you advice on here but most will be contradictory, traders who sell electric fridges will tell you to buy a new fridge and so on.

 

I will leave it at that for now.

 

P.S in the longer term that relay is not up to the job you will need something bigger.

[stuart]

You could also look at those fancy alt. regulators which claim to put higher charge into your existing banks. Not used one myself.

[Maverick]

Hi Mav.

 

As you describe your 'diode' I think you will find it is a split charge rely, it's function is to separate your domestic from starter batteries when the engine is not running (therefore not charging). But don't try and simply modify your electrics to power this fridge, it will cost a lot of money and will never be satisfactory.

 

I could be wrong but I believe that the Electrolux fridge is now permitted, though not advised? The BSS have got themselves into a real mess over this. I have been trying to look it up in their book but it reads as though it has been written by a lawyer rather than an engineer. Lots of people on here will give you advice on here but most will be contradictory, traders who sell electric fridges will tell you to buy a new fridge and so on.

 

I will leave it at that for now.

 

P.S in the longer term that relay is not up to the job you will need something bigger.

 

Thanks John. Modern boats may have half a dozen or more batteries etc and all the bells and whistles to run a 12v fridge. My old boat doesn't, and I really have no option but to connect my fridge to gas due to costs.

 

I'm sure the BSS is giving advice and regulations with the best possible reasons in mind eg safety, but sometimes its just not always practical or feasible. I'll do my best not to die of carbon monoxide poisoning or explosion but I'm going to connect it up to gas.

 

Now wher did I put that lump hammer???? Dont moor to close!

Edited April 16, 2007 by Maverick

[Djuwenda]

You could also look at those fancy alt. regulators which claim to put higher charge into your existing banks. Not used one myself.

 

 

Actually I am thinking about getting one, but would love to hear other people's view first.

[Billypownall]

Hi Maverick.

 

Fitting more batteries is not the answer, batteries only store energy they don't produce any. Your problem is most certainly the fridge, you must run it permanently on gas. The inefficiency of these things when running on electric' is incredible. There have been many threads about this question but suffice to say that whether on 230 or 12 volts they consume 100 and 95 watts that is a CONSTANT 8 amps at 12 volts no electrical system is going to sustain that.

 

I have had several of these over the years, the first thing I do when I buy one is cut every inch of electrical cable out of them. The good news, they work great on gas.

Something does not add up here. These fridges do take 8 amps but ours only works for 30% of the time. This means 70 to 80 amps in 24 hours. 210 amps worth of batteries is a bit thin but should be enough if running 4-5 hours a day. I doubt you are getting enough charge and an alternator regulator might be the answer. Maybe the alternator is not turning over fast enough.Ours does not give out maximum charge until the engine is running at 1600 rpm. One trick is to make sure the fridge is full,cans of ale will do it and turn it up to maximum while the engine is running (5 on ours) and down to minimum when you moor.True we have 2 alternators and larger batteries but our electric fridge works fine and I wouldn't fancy gas at all.

[Keeping Up]

As a rule of thumb, you rarely manage to get more than half the stated battery capacity. That's partly because you can never actually manage to charge them fully, partly because you can't discharge them fully either, and partly for various technical reasons too. If the batteries together are nominally 210 Amp-hour, even if they are both in perfect condition you'd be lucky to get more than 100 Amp-hours from them. So if the fridge takes 80 Amp-hours in a day, there's not much left for anything else.

[Audi Fan]

I saw a bloke on Blue Peter (it's still going y'know) and he was recommending that we all fill our fridges with house bricks !!

The theory is that they store the cold unlike the air they replace, which escapes when you open the door.

 

House bricks is a little extreme, but it's definitely worth filling the fridge up with something even if it's just bottled water.

You also need good circulation around the back of the fridge to help it's efficiency

[Theo]

Hi Maverick.

 

Fitting more batteries is not the answer, batteries only store energy they don't produce any. Your problem is most certainly the fridge, you must run it permanently on gas. The inefficiency of these things when running on electric' is incredible. There have been many threads about this question but suffice to say that whether on 230 or 12 volts they consume 100 and 95 watts that is a CONSTANT 8 amps at 12 volts no electrical system is going to sustain that.

 

I have had several of these over the years, the first thing I do when I buy one is cut every inch of electrical cable out of them. The good news, they work great on gas.

 

Although I would prefer to bow to your greater experience that is not what my sister and her husband have found with Blake. They run a 12V fridge constantly when they are on the boat and when I have borrowed it, went on a 10 day cruise to London and up to Bishops Stortford and did not give the fridge a second thought. It was blooming hot too!

 

And we ran a 240 fan off the inverter for most of the night.

 

The hire boats that I have used did not have any problems either.

 

Nick

[John Orentas]

Although I would prefer to bow to your greater experience that is not what my sister and her husband have found with Blake. They run a 12V fridge constantly when they are on the boat and when I have borrowed it, went on a 10 day cruise to London and up to Bishops Stortford and did not give the fridge a second thought. It was blooming hot too!

 

And we ran a 240 fan off the inverter for most of the night.

 

The hire boats that I have used did not have any problems either.

 

Nick

 

 

I have been specifically talking about the Electrolux absorbtion type fridges when run from 12 volts. Models typ. 212.

 

Compressor type fridges are an entirely different matter.

[DHutch]

I think there is some confusion here.

 

Maverick seams to have an Electrolux ABSOBTION Fridge, Or '3-way' fridge (runs on gas/12v/240v).

- These are incredably ineffencnt when running of electricity (or gas, infact) compaired to normal COMPRESSOR fridges.

- And certainly the earlyer/cheeper vesions had/have little or no thermal regulation on the electrical modes, inparticualr the 12v mode, which was only really ment to be used when driving you caravan between sites. So they tend to draw a goodly amount of electricty, often continuasly non-stop all day.

 

edit: post crossed with johns

 

 

Daniel

Edited April 17, 2007 by Dhutch

[David]

I have been specifically talking about the Electrolux absorbtion type fridges when run from 12 volts. Models typ. 212.

 

Compressor type fridges are an entirely different matter.

 

John is right here, if I recall that Electrolux fridge when run on 12V runs constantly (just like the gas flame is "constantly on") so draws current 24 hours a day. They are notorious for being battery killers.

 

Compressor type do run more efficiently, the new ones draw about 4amps for approx 30 to 50% of the day, the advice to keep them full is correct, if the freezer box is empty fill it with freezer blocks once frozen they will help keep the fridge cool and the battery usage lower. Top loaders are also better as the cold air cannot "spill out" when the lid is opened

david

[NB Alnwick]

I think there is some confusion here.

 

Maverick seams to have an Electrolux ABSOBTION Fridge, Or '3-way' fridge (runs on gas/12v/240v).

- These are incredably ineffencnt when running of electricity (or gas, infact) compaired to normal COMPRESSOR fridges.

- And certainly the earlyer/cheeper vesions had/have little or no thermal regulation on the electrical modes, inparticualr the 12v mode, which was only really ment to be used when driving you caravan between sites. So they tend to draw a goodly amount of electricty, often continuasly non-stop all day.

Daniel

 

Our boat is fitted with an Electrolux Fridge - we always run it on gas unless we are hooked up to a mains electricity supply - which is extremely rare. Running on it gas works out to be extremely economical and has proved to be completely satisfactory.

 

There are as many ideas and preferences out there as there are boaters - what we have suits us and we wouldn't change it. Gas is an ideal medium for cooking, heating water and keeping our victuals cold.

 

The thought of having to start an engine to boil a kettle for a cup of tea in the morning has always put us off the idea of going 'all electric' . . .

[NB Alnwick]

With regard to BSS - properly installed gas fridges are acceptable. We had our boat surveyed and the marine surveyor checked the installation thoroughly and confirmed that it met with all necessary safety requirements.

Edited April 16, 2007 by NB Alnwick

[Big Steve]

My boat was BSSed last week and the gas fridge was passed OK. If you install one between BSSes don't you just tell the insurance company? Or tell them, and they might ask for a BSS man to inspect it and give his opinion, wouldn't cost much, I shouldn't think.

[Maverick]

Although I would prefer to bow to your greater experience that is not what my sister and her husband have found with Blake. They run a 12V fridge constantly when they are on the boat and when I have borrowed it, went on a 10 day cruise to London and up to Bishops Stortford and did not give the fridge a second thought. It was blooming hot too!

 

And we ran a 240 fan off the inverter for most of the night.

 

The hire boats that I have used did not have any problems either.

 

Nick

 

How many batteries and what size alternator???

 

I think there is some confusion here.

 

Maverick seams to have an Electrolux ABSOBTION Fridge, Or '3-way' fridge (runs on gas/12v/240v).

- These are incredably ineffencnt when running of electricity (or gas, infact) compaired to normal COMPRESSOR fridges.

- And certainly the earlyer/cheeper vesions had/have little or no thermal regulation on the electrical modes, inparticualr the 12v mode, which was only really ment to be used when driving you caravan between sites. So they tend to draw a goodly amount of electricty, often continuasly non-stop all day.

 

edit: post crossed with johns

Daniel

 

That is correct. It is an Electrolux 3 way fridge but not an old one. It is about 18 mths old.

[boatie]

The chandlers are wrong.

 

As long as you don't modify the exhaust on a gas fridge they are permissable. They can be vented into the cabin.

 

Personally I decided not to go down this route. I also have two 210 amp hours and run a 240v fridge bought from Makro for £80. I also run a tv and fan at night with no probs

 

Boatie

[bottle]

That is correct. It is an Electrolux 3 way fridge but not an old one. It is about 18 mths old.

 

Hi Maverick

 

Does not matter how old it is they are all exactly the same design.

 

The 240v/12v/gas Electrolux was designed for the caravan industry (not boats) it all started when the regulations for towing a caravan were changed and it became illegal to tow a caravan with the gas turned on.

 

The first models had 12v and gas but as more camp sites got electric points the 240v was added.

 

The Electrolux is an absorption type refrigerator, it requires a heat source at all times, when using gas this is supplied by the flame when on 12v or 240v it is from a little heater element that replaces the flame.

 

When on 12v or 240v they will not cool the fridge only just maintain the existing temperature. (the temperature control knob only controls the gas side the 12v/240v is not controllable.

 

Eletrolux used to advise starting the fridge on gas and only using 12v when actually towing. ( 12v coming from the towing vehicle via seven pin plug/socket)

 

To sum up the Electrolux is designed to run on gas. The others are just temporary ways that came about via the caravan industry.

 

edit :typo

Edited April 17, 2007 by bottle

[NB Alnwick]

How many batteries and what size alternator???

That is correct. It is an Electrolux 3 way fridge but not an old one. It is about 18 mths old.

 

This type of fridge is perfectly legal, safe and sensible to run on gas and, if reuired can be fitted with a purpose made vent that draws in fresh air and exhaust out side the boat - that's what we have.

 

Getting back to the original question - I note that just one battery in the bank was replaced by a new one. This may not be relevent and I am not an electrician but years ago when changing the batteries of my MGB (two x six volt) I was always advised that you must replace them as a pair - even if one of them seems to be OK because unless they are both evenly matched in terms of output and the extent of plate wear etc. the poorer battery will drag the better battery down very quickly . . .

[Workhorse]

I'm interested in this discussion.I have a 240 volt fridge that runs off the shore line, but am fitting a 2500w inverter for when we're travelling. How will the batteries stand up to this type of work, and what sort of load will be placed on the batteries through the inverter?

[warlock]

Well I'm not sure what type of fridge I've got but with 3 110Ah and a 105Ah batteries all connected together (no islators yet..it was like that when I bought it.) I get about a week on them. That includes running 12v lights, pumps and the fridge. I've gotta fit a charger but until then it's gonna have to be a case of lifting them out and charging one at a time..unless someone has a better idea.

[Sir Nibble]

Sorry, time for me to throw my own particular hobby horse into the mix. Battery power is a plus-minus sum. If your fridge takes on average say 2A thats 48Ah over a 24 hour day. If you cruise for 4 hours thats 12A (not allowing for losses) that the charging system has to generate for the whole 4 hours just to keep up with that load alone. Now that isn't much for a modern alternator, providing it is spinning fast enough throughout the whole time.

You need to identify whether your problem lies on the plus or minus side of the sum, ie, is your discharge excessive or your charge insufficient, then we can look at how to resolve the situation.

Don't like to go back to this without more figures to back it up, but. Diesel duck, he's gotta electric fridge and his batteries were always flat. He needed 2000rpm (speeding!) to get reasonable alternator output. I modified his alternator so it is no longer 65A but about 45, counter intuitive I know, but the point is he now gets 30A at idle, and his batteries do not now run flat. I am not suggesting the same for you, but do you have a voltmeter? What charge voltage do you get at what speeds? Let's look at both sides of the sum.