Sealed or open wet cell battery's?

[Robbo]

The problem with traction batteries is that they don't give or out take the amps. So if you only need a small capacity battery bank they may not be the best solution if your charging via a fossil fuel source.

[Graham.m]

The problem with traction batteries is that they don't give or out take the amps. So if you only need a small capacity battery bank they may not be the best solution if your charging via a fossil fuel source.

 

Sorry Robbo, is what you are saying that traction deep cycle batteries will not release their charge at c5/C10 or better and not take in a charge at C5/C10 ?

[nicknorman]

Sorry Robbo, is what you are saying that traction deep cycle batteries will not release their charge at c5/C10 or better and not take in a charge at C5/C10 ?

I think Robbo is correct in saying that traction deep cycle batteries are worse at taking and giving high currents, compared to leisure types. After all, the whole point of leisure batteries, which of course are effectively starter batteries, is to supply the high CCA for starting. Thinner plates = higher currents.

 

Certainly when I replaced our leisure batteries with semi-traction types (Trojans) I expected to find they gave lower voltage when under heavy load from the inverter with the kettle on - 200A from 450AH - and this turned out to be noticeably correct.

[Graham.m]

I think Robbo is correct in saying that traction deep cycle batteries are worse at taking and giving high currents, compared to leisure types. After all, the whole point of leisure batteries, which of course are effectively starter batteries, is to supply the high CCA for starting. Thinner plates = higher currents.

 

Certainly when I replaced our leisure batteries with semi-traction types (Trojans) I expected to find they gave lower voltage when under heavy load from the inverter with the kettle on - 200A from 450AH - and this turned out to be noticeably correct.

 

The chart below is for a 6 volt trojan AGM 230AH it shows that at a discharge of 75A it will last about 115 minutes.

 

A starter battery is designed to give a high rate of discharge for seconds normally 30 or so seconds. They have very thin plates to allow them to do so.

 

A deep cycle battery is designed to give something like a a 20th of its capacity off over 20 hours. From what you posted I would suggest that your battery bank is not big enough to run the inverter that you are using.

 

See http://www.trojanbattery.com/reliantagm/the chart won't display on here

Edited November 9, 2015 by Graham.m

[nicknorman]

The chart below is for a 6 volt trojan AGM 230AH it shows that at a discharge of 75A it will last about 115 minutes.

 

A starter battery is designed to give a high rate of discharge for seconds normally 30 or so seconds. They have very thin plates to allow them to do so.

 

A deep cycle battery is designed to give something like a a 20th of its capacity off over 20 hours. From what you posted I would suggest that your battery bank is not big enough to run the inverter that you are using.

 

See http://www.trojanbattery.com/reliantagm/the chart won't display on here

Our battery bank is just about adequate. The point is not whether our bank is adequate though, the point is which type battery, assuming the same capacity, is best at supplying high currents, and the answer is not traction batteries.

[Graham.m]

Our battery bank is just about adequate. The point is not whether our bank is adequate though, the point is which type battery, assuming the same capacity, is best at supplying high currents, and the answer is not traction batteries.

 

If you want a battery that will supply a high current for a very short time, seconds then use a starter style battery. If you want a set of batteries that will give you a long life and supply the power required in a boat then use the correctly sized deep cycle battery. Remember the faster you discharge a battery the shorter its life and faster its discharge cycle.

 

But then as I wrote earlier perhaps you need a generator to run your electric kettle.

 

You need to use batteries for the purpose they are designed for to get the best life and value

Edited November 9, 2015 by Graham.m

[nicknorman]

If you want a battery that will supply a high current for a very short time, seconds then use a starter style battery. If you want a set of batteries that will give you a long life and supply the power required in a boat then use the correctly sized deep cycle battery. Remember the faster you discharge a battery the shorter its life and faster its discharge cycle.

 

But then as I wrote earlier perhaps you need a generator to run your electric kettle.

 

I think you just want an argument about this for the sake of it. Do you really think you need to tell me that the faster you discharge a battery the faster its discharge cycle is?

 

Deep cycle batteries are great for supplying power for boats. They have just one drawback, an inability to pass high currents, relative to other types. This is what Robbo said, he is correct and there is no point in arguing further about it.

 

Oh and by the way, in this thread and an earlier one, you are not seeing the big picture. Whilst it is true that batteries prefer a slow charge for longevity, battery longevity is not the be-all. You have to look at the big picture which includes the cost of running an engine / generator for long periods at light loads. There is a balance to be struck between the cost of charging and the cost of battery replacement. And that is before you start to consider the substantial nuisance to you and others from running generators.

[Robbo]

 

Sorry Robbo, is what you are saying that traction deep cycle batteries will not release their charge at c5/C10 or better and not take in a charge at C5/C10 ?

What I'm saying is that you can't charge them quickly like you can do with other types of batteries, if you don't need a large capacity bank and you have a big alternator or use a genny to charge with a high amp charger then traction may not be the best solution. It isn't just cycle counts that costs the money, it's how you charge them that as well.

[Graham.m]

I think you just want an argument about this for the sake of it. Do you really think you need to tell me that the faster you discharge a battery the faster its discharge cycle is?

 

Deep cycle batteries are great for supplying power for boats. They have just one drawback, an inability to pass high currents, relative to other types. This is what Robbo said, he is correct and there is no point in arguing further about it.

 

Oh and by the way, in this thread and an earlier one, you are not seeing the big picture. Whilst it is true that batteries prefer a slow charge for longevity, battery longevity is not the be-all. You have to look at the big picture which includes the cost of running an engine / generator for long periods at light loads. There is a balance to be struck between the cost of charging and the cost of battery replacement. And that is before you start to consider the substantial nuisance to you and others from running generators.

 

No I must admitt I am surprise that someone who declares an interest in Electronic seems not to appreciate that if the battery bank is correctly sized and designed it will supply the currents it is designed for. In your case if you wish to regularly draw 200A from the bank then maybe you should be looking at a bank far larger.

 

Badly installed generators are a noise nuisance, properly installed you should not be able to hear them less than half a boat length away.

What I'm saying is that you can't charge them quickly like you can do with other types of batteries, if you don't need a large capacity bank and you have a big alternator or use a genny to charge with a high amp charger then traction may not be the best solution. It isn't just cycle counts that costs the money, it's how you charge them that as well.

 

But only at the cost of shortened life and higher cost

[Robbo]

 

No I must admitt I am surprise that someone who declares an interest in Electronic seems not to appreciate that if the battery bank is correctly sized and designed it will supply the currents it is designed for. In your case if you wish to regularly draw 200A from the bank then maybe you should be looking at a bank far larger.

 

Badly installed generators are a noise nuisance, properly installed you should not be able to hear them less than half a boat length away.

 

 

But only at the cost of shortened life and higher cost

Even well installed generators with sound proofing to make it whisper quiet are still very inefficient at fully charging batteries. My point is that if you have a high current charger to match even a modest sized generator to make it run at its most efficient load the batteries need to be specced to do so, but if your power consumption is low so you don't need a large capacity bank then traction batteries arnt the best solution.

[nicknorman]

No I must admitt I am surprise that someone who declares an interest in Electronic seems not to appreciate that if the battery bank is correctly sized and designed it will supply the currents it is designed for. In your case if you wish to regularly draw 200A from the bank then maybe you should be looking at a bank far larger.

 

Badly installed generators are a noise nuisance, properly installed you should not be able to hear them less than half a boat length away.

 

But only at the cost of shortened life and higher cost

I don't need to be looking for a far larger bank since the present one adequately meets our needs. It is a good engineering compromise for the power needs vs space taken up. As an engineer you should know that the most important part of the job is listening to the customer's needs, not installing something that you want but they don't need.

 

It is certainly possible to have quiet generators, however nearly all generators one finds on the cut are noisy and intrusive. Engineers need to live in the real world, not an ideal one.

Edited November 9, 2015 by nicknorman

[Robbo]

But only at the cost of shortened life and higher cost

It's total cost per kW that counts and that has to include how you charge them. Not one battery type suits all.

Edited November 9, 2015 by Robbo

[Loafer]

(Mops brow, still reading)

[peterboat]

i have 1500 ahs of full traction batteries why because i am a high electric user also the kettle goes on dishwasher/washing machine, which with a smaller bank would cause the inverter to beep. i also like the fact that in the winter with poor sun for solar i have that reserve to run the fridge etc without worrying where the next amp will come from. it really is horses for courses

[Graham.m]

Even well installed generators with sound proofing to make it whisper quiet are still very inefficient at fully charging batteries. My point is that if you have a high current charger to match even a modest sized generator to make it run at its most efficient load the batteries need to be specced to do so, but if your power consumption is low so you don't need a large capacity bank then traction batteries arnt the best solution.

 

I think underneath we might agree, it is a question of speccing the system correctly, whether it is for cost/life or other considerations.

Boaters seem to forget that all they use from a battery has to be put back into the battery, it is a restricted resource. If boaters insist on having AC equipment aboard, washing machines etc then I suggest a decent generator, the cost of running those items using the generator is cheaper than using batteries and inverters by 10 or 20%. Everytime you convert from one type of power to another that is an inefficiency cost of order of 20%

[Robbo]

 

I think underneath we might agree, it is a question of speccing the system correctly, whether it is for cost/life or other considerations.

Boaters seem to forget that all they use from a battery has to be put back into the battery, it is a restricted resource. If boaters insist on having AC equipment aboard, washing machines etc then I suggest a decent generator, the cost of running those items using the generator is cheaper than using batteries and inverters by 10 or 20%. Everytime you convert from one type of power to another that is an inefficiency cost of order of 20%

I haven't done any sums yet, but I have a feeling a fuel cell genny like the Efoy may be more cost effective especially if you like to run from battery. If it's not cost effective now it's certainly one to keep an eye on.

 

The problem with a generator is that if you want easy of use then you need built in and silent so a desiel raw water cooled would be a good choice, unfortunately these tend to start at 4kw, so keeping it at its max efficiently would be around 3kw. For charging batteries alone that would be some serious sized charger and a very large battery bank to match. Even if you have a dish washer running which uses little when not heating the water and bulk charge with a modest size charger it would be rare to use around 3kw for long periods of time.

 

The benefit of the Efoy is that you have a constant but low power source so the majority of the time you will be running directly from the Efoy, when you need to extra the batteries will provide, but as soon as you don't they get charged so keeping them fully charged more often than you would with a genny.

 

My guess is that due to this been more efficient and reducing the need for a large battery bank it may be more cost effective than the diesel genny solution.

Edited November 9, 2015 by Robbo

[Graham.m]

I don't need to be looking for a far larger bank since the present one adequately meets our needs. It is a good engineering compromise for the power needs vs space taken up. As an engineer you should know that the most important part of the job is listening to the customer's needs, not installing something that you want but they don't need.

 

It is certainly possible to have quiet generators, however nearly all generators one finds on the cut are noisy and intrusive. Engineers need to live in the real world, not an ideal one.

 

Oh I live in the real world and am amazed what people expect batteries to do for them. As a consultant my job is to listen and then tailor to their needs. In the case of a marina moored private leisure boat it is totally different to a CC liveaboard. My remarks on here have being aimed at CC liveaboards. I advise and t is up to the owner to accept or not the advice.

 

It makes me sad when I see people on forums who have run into problems with batteries etc because of bad advice or just lack of knowledge.

[Graham.m]

I haven't done any sums yet, but I have a feeling a fuel cell genny like the Efoy may be more cost effective especially if you like to run from battery. If it's not cost effective now it's certainly one to keep an eye on.

 

Oh the fuel cell would be the answer to all the problems, assuming ease of refueling and availability. At present they are far too expensive and too small. Not sure what BSS would say about the fuels

[by'eck]

I think Robbo is correct in saying that traction deep cycle batteries are worse at taking and giving high currents, compared to leisure types. After all, the whole point of leisure batteries, which of course are effectively starter batteries, is to supply the high CCA for starting. Thinner plates = higher currents.

 

Certainly when I replaced our leisure batteries with semi-traction types (Trojans) I expected to find they gave lower voltage when under heavy load from the inverter with the kettle on - 200A from 450AH - and this turned out to be noticeably correct.

 

 

 

The chart below is for a 6 volt trojan AGM 230AH it shows that at a discharge of 75A it will last about 115 minutes.

 

A starter battery is designed to give a high rate of discharge for seconds normally 30 or so seconds. They have very thin plates to allow them to do so.

 

A deep cycle battery is designed to give something like a a 20th of its capacity off over 20 hours. From what you posted I would suggest that your battery bank is not big enough to run the inverter that you are using.

 

I always understood it was not thinner plates per se but the larger number of them that could be accomodated within a specific battery case that defined a starter battery and the higher current they could supply - this because of the greater plate surface area in contact with electrolyte.

[Robbo]

 

Oh the fuel cell would be the answer to all the problems, assuming ease of refueling and availability. At present they are far too expensive and too small. Not sure what BSS would say about the fuels

At the moment the Efoy has one that does 200amps per day, the cost of purchase is cheaper than a decent diesel genny. Need to do my sums on the overall running costs (over the lifetime of the device including purchase), but my guess is that it will be similar.

[nb Innisfree]

The problem with listening to advice is the need to arm yourself with enough knowledge to be able to judge who best to take advice from, otherwise it's just a stab in the dark. You may be lucky enough to know the track record of a particular advisor but if you're not prepared to make the effort and research the subject it's down to listening to the majority consensus which can be full of inaccuracies if that majority is basing their knowledge on the same method.

 

Often results in the blind leading the blind.

[Loafer]

At the moment the Efoy has one that does 200amps per day, the cost of purchase is cheaper than a decent diesel genny. Need to do my sums on the overall running costs (over the lifetime of the device including purchase), but my guess is that it will be similar.

 

Is that 200 Ah per day? It would indeed be interesting to see the result of a feasibility study.

[Graham.m]

 

 

 

I always understood it was not thinner plates per se but the larger number of them that could be accomodated within a specific battery case that defined a starter battery and the higher current they could supply - this because of the greater plate surface area in contact with electrolyte.

 

It is plate area, so a very physically large battery with huge (area) thick plates could theoretically give a large instant current. Of course there would be a problem of where to put the battery. Each cell has only two plates, pos & neg, whether they are made of one lump of lead etc or a lot of thin sheets separated by insulators and combine electrically into one plate.

[Graham.m]

The problem with listening to advice is the need to arm yourself with enough knowledge to be able to judge who best to take advice from, otherwise it's just a stab in the dark. You may be lucky enough to know the track record of a particular advisor but if you're not prepared to make the effort and research the subject it's down to listening to the majority consensus which can be full of inaccuracies if that majority is basing their knowledge on the same method.

 

Often results in the blind leading the blind.

 

In my opinion it is my job to give the lay person all the knowledge they need to be able to make an educated decision. That frequently means explaining how things work and why. I spend more time doing that than working out the advice.

 

Too often the advice on the cut is that is the way we have always done it. Basically take it or leave it, it should not be.

 

Is that 200 Ah per day? It would indeed be interesting to see the result of a feasibility study.

 

Yes http://www.efoy-comfort.com/which-model#overview

 

added http://www.fuelcellsystems.co.uk/shop/SFC_Fuel_Cells.htmlUK supplier

Edited November 9, 2015 by Graham.m

[nicknorman]

I always understood it was not thinner plates per se but the larger number of them that could be accomodated within a specific battery case that defined a starter battery and the higher current they could supply - this because of the greater plate surface area in contact with electrolyte.

You're right of course, but to get more plate area within a given size of battery, you have to make the plates thinner. So I guess it's chicken and egg as to whether it's more plate area = thinner plates, or thinner plates = more plate area.

Edited November 9, 2015 by nicknorman