Batteries

[Mike]

What capacity batteries does everyone have, and what type are they? My tray is 40 inches x 11 inches, so I could fit:

1. five leisure batteries of 85AH giving 425AH total.

2. two 180AH semi-traction giving 360AH.

3. four 6 volt deep cycle of 225 each, which I assume gives 450AH total when wired in pairs to give 12 volts.

 

Option1 is cheapest.

Option 2 fits the present wiring, but is 360AH enough for a boat with 12 volt fridge and a fair demand for TV through the inverter?

Option 3 is dearest: is it wise to use 6 volts batteries like this? Are deep cycle ones a good idea?

 

The batteries will be charged from a 70 amp alternator or a Sterling 30 amp charger, and the engine is started from a separate battery and alternator.

 

All comments/experience & advice gratefully received.

 

Mike

[davidandheather]

What capacity batteries does everyone have, and what type are they? My tray is 40 inches x 11 inches, so I could fit:

1. five leisure batteries of 85AH giving 425AH total.

2. two 180AH semi-traction giving 360AH.

3. four 6 volt deep cycle of 225 each, which I assume gives 450AH total when wired in pairs to give 12 volts.

 

Option1 is cheapest.

Option 2 fits the present wiring, but is 360AH enough for a boat with 12 volt fridge and a fair demand for TV through the inverter?

Option 3 is dearest: is it wise to use 6 volts batteries like this? Are deep cycle ones a good idea?

 

The batteries will be charged from a 70 amp alternator or a Sterling 30 amp charger, and the engine is started from a separate battery and alternator.

 

All comments/experience & advice gratefully received.

 

Mike

Hi we have 720amp of fiamm full traction batteries made up of 2 volt cells

a 90amp alternator

a 100/2500 amp Mastervolt inverter/charger

and of course a seperate starter battery

we find in the winter this will give us about 2 days without a charge

Eg Hurricane heating system 7amphr

dishwasher

 

tv/digibox

fridge

heather hairdryer loads of amps

in the summer we get at least 3 days without a charge

the only drawback of our system is the cost but you pays the cash and takes youe choice the main thing to remember is with our 720 amp you only have a useable no more than 50% of it

David

[Guest]

We have 600a/hr of sealed lead acid batteries. I am not fond of them-they are lazy.

[Keeping Up]

We've got 330 Amp-hour (3x110) - also have a 12 volt fridge and quite a lot of TV usage. It seems to be enough as long as the engine is run at least every other day (or every day if we use a lot of power one day, such as using the hoover or microwave a lot), although with our old Batts fridge which was less efficient it was better to run it every day.

[Canal Shop Man]

All the information I have suggests the following:

 

The higher the Amp-hours the better. This means that for the same usage, the batteries are discharged less and this gives a much longer life.

 

The lower the voltage of each battery the better. Therefore 12v are OK, 6v are better, 2v are even better.

[GUMPY]

What capacity batteries does everyone have, and what type are they? My tray is 40 inches x 11 inches, so I could fit:

1. five leisure batteries of 85AH giving 425AH total.

2. two 180AH semi-traction giving 360AH.

3. four 6 volt deep cycle of 225 each, which I assume gives 450AH total when wired in pairs to give 12 volts.

 

Option1 is cheapest.

Option 2 fits the present wiring, but is 360AH enough for a boat with 12 volt fridge and a fair demand for TV through the inverter?

Option 3 is dearest: is it wise to use 6 volts batteries like this? Are deep cycle ones a good idea?

 

The batteries will be charged from a 70 amp alternator or a Sterling 30 amp charger, and the engine is started from a separate battery and alternator.

 

All comments/experience & advice gratefully received.

 

Mike

 

I would go for 6v every time.

For a given size of battery case the plates are thicker so will tolerate more abuse and a deeper discharge

I have 8 200ah 6v making up my battery bank.

 

Julian

[John Orentas]

A battery is the term for a group of individual accumulator cells invariably they each give two volts, it doesn't really matter whether they are individual cells or built up into units of 3, 6 or 12 units giving 6, 12 or 24 volts.

 

It is generally agreed that it is best to use 'traction' or 'leisure' batteries for domestic use but all this business of plate thickness and distortion is something of a misnomer it is the surface area of the metallic plates that makes one type different from another, in practise in a modern cell the plates and separators are bonded together in a solid lump.

 

I always take the view that we should be completely mercenary in out choice, the going rate for a cheap 110 a/h leisure battery is about £45 in a caravan or motor home dealer and in my experience they will last between 6 and 8 years. There are batteries that will last longer but they are perhaps double the price but do they last twice as long, if they don't are they worth buying I would suggest not.

 

How many batteries do you need, I would say the minimum you feel comfortable with, there is no point in having a massive bank that will keep you going for a week if you charge them every two days anyway and I am not sure that they don't like being cycled too often, some people take the opposite view.

Edited February 19, 2006 by John Orentas

[Canal Shop Man]

How many batteries do you need, I would say the minimum you feel comfortable with, there is no point in having a massive bank that will keep you going for a week if you charge them every two days anyway and I am not sure that they don't like being cycled too often, some people take the opposite view.

This is rubbish - the more you discharge a battery the more you shorten its life. This is supported by all battery manufacturers. Batteries are designed to store power, not to be run down. OK so domestic batteries cope better than starter batteries at being discharged, but you shouldn't wait till the batteries are flat before charging them or they won't last long.

 

Fit as many as you can make space for (or can afford) - it will be worth it in the long run. Similarly, it's better to get more cheap ones than fewer expensive ones if price is the limiting factor.

[anhar]

This is rubbish - the more you discharge a battery the more you shorten its life. This is supported by all battery manufacturers. Batteries are designed to store power, not to be run down. OK so domestic batteries cope better than starter batteries at being discharged, but you shouldn't wait till the batteries are flat before charging them or they won't last long.

 

Fit as many as you can make space for (or can afford) - it will be worth it in the long run. Similarly, it's better to get more cheap ones than fewer expensive ones if price is the limiting factor.

I would agree with second para. above up to a point but having said that, it makes little sense to have a total amp-hour capacity of batteries that is wildly in excess of your needs. That would probably be a waste of space and money. Also you have to observe the charging rate you have available which if we're talking gels/AGMs (which I assume we are, nobody fits dirty old LA topper up jobs any more do they?) must be at least 15% of capacity though 25% is the advisable rate. (though for the old style LAs this was typically only 10%). Thus ideally a 400ah bank of gels/AGMs would require charging at least at 60a and preferably 100a. And that assumes no consumption by devices whilst charging. If there is, which frequently will be the case, then this consumption must be added to the charge rate.

 

The best way to find the required battery capacity, rather than just guessing or vague statements about getting the most you can fit in, is to add up the consumption of all devices on the boat over a 24 hour period in amp-hours. This must include both 12v devices and 230v inverter powered devices if fitted. Add in a safety margin of 33-40% and that should be the optimum capacity needed. You won't need more, unless perhaps you anticipate fitting some seriously additional power consuming devices to the boat in future.

 

regards

Steve

Edited February 19, 2006 by anhar

[John Orentas]

Quote;

"This is rubbish - the more you discharge a battery the more you shorten its life. This is supported by all battery manufacturers".

 

I don't think so, the worst thing you can do to a battery is charge it up, put it on a shelf and ignore it.

 

I use liquid acid batteries, they are cheap and I get 8 years use out of them. As far as I am aware gel type batteries were developed in response to the difficulties of transporting and handling batteries containing liquid acid, that doesn't bother me I have never spilt a battery in my life.

[Guest]

Peukert's law anyone? "The faster a battery is discharged, the less total Amp-hours it will yield."

Hence a larger battery bank will reduce the discharge rate from each battery and seemingly "increase" the available A/H capacity of the bank. This knowledge is applied to EV's where a modest increase in A/H capacity sees large improvements in operating range.

Edited February 19, 2006 by Guest