Batteries (again...)

[Justme]

I remain to be convinced that solar panels are cheaper than diesel generation unless one is convinced he will live forever.

 

I save roughly half of the diesel that I would use by having solar power.

 

Just on fuel savings I will have paid for the PV kit in about 13 years (up dated stats as total consumption has fallen after a few changes & actual L per hour is lower than makers specs)

 

Add in a large value to not needing the genny all summer.

 

Plus the panels have fallen in price (£1.99 per watt on 800watts inc del & vat) & that would knock 4 years of the time.

 

10p on a L reduces it by 2 years.

 

At £1 per L its down to 7 years even on my more costly PV & 5.5 years with new prices.

[smileypete]

I think you are implying that before the absorption charge stage is reached the charging voltage will not be high enough for the "spare" battery bank. If my understanding is correct, then I had not considered that. At the moment the problem is that the absorbtion stage is reached too quickly. I have a good mains battery charger so I will try that, as you say, as the least cost option to start with.

Maybe worth comparing the inverter input current to charger output current.

 

If the batteries are 'open cell'/non sealed then it's also possible to do a trickle charge.

 

cheers,

Pete.

[Ermenilda]

Definitely an octopussian disaster. The batteries wouldn't get charged up properly, and the distribution system would get even less of what little was available

 

haha OK - I seem to have scared everyone off with the Octopus idea eh? is that a definate unanimous 'no chance this would work' then? no real explanation of why they wouldn't charge properly or why the distribution system would get less power - not sure what is the thing that is actually wrong with this idea... but agree if it worked then someone would probably already have been doing it

 

The batteries have now been charged off the mains for ~48hrs each and re-installed in the boat - will post the 'reality results' when I have them

 

oh and the following quote that I already replied to;

 

Because you never, ever, gave them a full charge from new - so they started sulfating from the first day you used them.

 

Tony

 

 

http://www.smartgauge.co.uk/products.html (But you knew that anyway)

 

I realised that although I don't remember the exact voltage when they were first put in the boat I do recall the analogue voltmeter installed in the distribution panel was reading very high around the 13v (something I hadn't seen in many years!)

 

the other thing is that when they were delivered the courier company couldn't find the delivery address and by the time I got in touch to work out what was going on they had been sitting at the depot for at least 3-4 days - which means whatever charge was put into them before they left the supplier had the 24hr period to settle down and 'show' the stable/actual voltage which indicates the condition of the battery - which therefore must have been 100%?

 

I dunno - I guess my science is what happens in reality so will see what happens from now on with them

[Naughty Cal]

If they do recover maybe you should have a rethink of your charging regime. You need to fully recharge them and not discharge them as much.

[Gibbo]

what do you reckon to this?

 

 

Pointless? Disaster waiting to happen?

 

Both.

 

no real explanation of why they wouldn't charge properly or why the distribution system would get less power - not sure what is the thing that is actually wrong with this idea...

 

Basically (and again this is going to sound rude) the idea is just so completely stupid that I wouldn't know where to start to even begin to get you to understand just how ridiclous it is.

 

How you can think it can do anything to improve matters completely evades me and therefore I don't know what to say to explain why it won't.

 

Please explain to me how you think it can improve anything

[Gibbo]

it seems to me that it is therefore 'tougher' to push the last 20% of Ah's into a big battery - but it won't be so hard to push the last 20% into lots of little batteries that are all being charged 'individually'...

 

This is one of your basic errors that is throwing your thinking all over the clouds.

 

If it is 'tough' to get the last 20% into a big battery (be that one big battery or 2463 smaller batteries making up one big battery) and you then split it down into 2463 smaller batteries you will find that the level of 'tough' to get the last 20% in to the small batteris is exactly the same.

 

The time will be exactly the same.

[Ermenilda]

thanks for the reply but that doesn't really help does it?

 

Reality Phylis.. reality...

 

I might be an average boater but I am not a halfwit that doesn't know when a battery is flat (Infact come to think of it that is probably about the ONLY thing any one average/expert alike CAN actually determine about a battery - when the buggers are flat!!!)

 

and in regards to 'if they recover' I am so frustrated at having allowed this thread to drift off into something that has ended up pointing the finger 100% at me, the charging regime and my average boater skills for letting them 'get into this mess in the first place'

 

how come nobody thinks the things could be duds from the off? or at the very least not performing to the stated specifications etc.?

 

something I have been holding off adding to this thread is that I finally got hold of 'Mr Elecsol' when I called him from a different phone number than usual (surprise surprise) and guess what he told me THIS time -

 

"we don't give invoices to customers"

 

"errr what - are you serious? you told me 2 months ago to contact your accounts department to get one sent before you abruptly/very rudely hung up on me"

 

"we don't give invoices to customers"

 

"but that is outrageous! You told me before that you do and I have been trying to contact your accounts department and yourself for months to get this sorted and have never had a call back and now you tell me you don't issues invoices?!?"

 

"we don't give invoices to customers - good bye"

 

"but wait! how rude! surely you MUST legally have to provide an invoice?"

 

"we're just going round in circles here - we don't give invoices to customers - good bye"

 

"NOOOO! this is so out of order what proof do I have for the warranty?"

 

"the payment on your bank statement is your proof" *click*

 

I was soooooo ****** off with him - I called back - needless to say the ***** didn't answer - left a voicemail and told him what a bad rep him and his batteries have out on the net and that I would be calling his resellers to tell him what a disgraceful experience I had been subjected to

 

I will stop short of telling you what I found out as I was specifically asked not to repeat what I was being told along with a lot of 'you didn't hear it from me' kind of chats (If you wanna know - go call them up - VERY enlighting)

 

Needless to say - what I was told has given me a VERY strong case to suspect these batteries were duds from the start or at the very least Elecsols do not do what they say on the tin (and I am not talking about all the hyped up sales cr*p that I fell for - I am talking about what is literally on the tin *hint*hint* they don't do it apparently)

 

I could happily get a couple of days out of the old forklift batteries on only a few hours charge - I am not saying what works for the forklifts works for the Elecsols and that this wasn't just knackering the forklifts but they worked consistently in this charging regime for just short of 2 years (so what's up there experts?)

 

most replies on here and the general consenus seems to have made up their mind to point the finger at me having knackered them - which is really annoying and frustrating

 

I think one thing might be certain - when it comes to choosing your bi-annual set of batteries (BTW - I think it is a joke/criminal/environmentally irresponsible to work on the basis of having a battery bank to only last a couple of years) I don't think you'll be buying Elecsols on the off chance that whatever mega setup/military/unrealistic charging regime you employ might work and it is not the battery at fault but the average boater to blame...

 

anyone willing to take the gamble?

[bottle]

Lets see if I have got this right:

 

the batteries were knackered when new.

 

the charging routine maybe suspect

 

it has cost some a lot money

 

you maybe have learnt something

 

my solution:

 

buy some new batteries, your choice of type, wet lead, AGM or Gell.

 

charge then correctly.

 

not only listen but hear what the true experts are saying.

 

stop trying to re invent the wheel.

 

simplessssss

[mayalld]

thanks for the reply but that doesn't really help does it?

 

Reality Phylis.. reality...

 

I might be an average boater but I am not a halfwit that doesn't know when a battery is flat (Infact come to think of it that is probably about the ONLY thing any one average/expert alike CAN actually determine about a battery - when the buggers are flat!!!)

 

and in regards to 'if they recover' I am so frustrated at having allowed this thread to drift off into something that has ended up pointing the finger 100% at me, the charging regime and my average boater skills for letting them 'get into this mess in the first place'

 

how come nobody thinks the things could be duds from the off? or at the very least not performing to the stated specifications etc.?

 

something I have been holding off adding to this thread is that I finally got hold of 'Mr Elecsol' when I called him from a different phone number than usual (surprise surprise) and guess what he told me THIS time -

 

"we don't give invoices to customers"

 

"errr what - are you serious? you told me 2 months ago to contact your accounts department to get one sent before you abruptly/very rudely hung up on me"

 

"we don't give invoices to customers"

 

"but that is outrageous! You told me before that you do and I have been trying to contact your accounts department and yourself for months to get this sorted and have never had a call back and now you tell me you don't issues invoices?!?"

 

"we don't give invoices to customers - good bye"

 

"but wait! how rude! surely you MUST legally have to provide an invoice?"

 

"we're just going round in circles here - we don't give invoices to customers - good bye"

 

"NOOOO! this is so out of order what proof do I have for the warranty?"

 

"the payment on your bank statement is your proof" *click*

 

I was soooooo ****** off with him - I called back - needless to say the ***** didn't answer - left a voicemail and told him what a bad rep him and his batteries have out on the net and that I would be calling his resellers to tell him what a disgraceful experience I had been subjected to

 

I will stop short of telling you what I found out as I was specifically asked not to repeat what I was being told along with a lot of 'you didn't hear it from me' kind of chats (If you wanna know - go call them up - VERY enlighting)

 

Needless to say - what I was told has given me a VERY strong case to suspect these batteries were duds from the start or at the very least Elecsols do not do what they say on the tin (and I am not talking about all the hyped up sales cr*p that I fell for - I am talking about what is literally on the tin *hint*hint* they don't do it apparently)

 

I could happily get a couple of days out of the old forklift batteries on only a few hours charge - I am not saying what works for the forklifts works for the Elecsols and that this wasn't just knackering the forklifts but they worked consistently in this charging regime for just short of 2 years (so what's up there experts?)

 

most replies on here and the general consenus seems to have made up their mind to point the finger at me having knackered them - which is really annoying and frustrating

 

I think one thing might be certain - when it comes to choosing your bi-annual set of batteries (BTW - I think it is a joke/criminal/environmentally irresponsible to work on the basis of having a battery bank to only last a couple of years) I don't think you'll be buying Elecsols on the off chance that whatever mega setup/military/unrealistic charging regime you employ might work and it is not the battery at fault but the average boater to blame...

 

anyone willing to take the gamble?

 

OK;

 

• It is, indeed possible that the batteries were duds from the off.
  
• It does, however, sound as if your charging regime would have made the situation worse.
  
• If they persist in refusing to issue an invoice, tell the VAT man.
  
• If they refuse to even discuss the problems, take them to the small claims court.
  

[Ermenilda]

Basically (and again this is going to sound rude) the idea is just so completely stupid that I wouldn't know where to start to even begin to get you to understand just how ridiclous it is.

 

How you can think it can do anything to improve matters completely evades me and therefore I don't know what to say to explain why it won't.

 

Please explain to me how you think it can improve anything

 

Believe me - I've come up with enough 'stupid ideas' in my time to know the difference between someone being bloody mindedly non-constructively rude and rude for the sake of telling me I am making a basic error. I take yours to be the latter and even if it were the other or a bit of both - don't worry I can take it and am not offended

 

some of the ideas have worked many haven't - but none would even have ever been attempted if I hadn't thought of them... (which reminds me [but I don't want to imply it is of the same nature or anything] I also wanted to say a special 'reeespect!' to smileypete which I didn't fit into my previous posts - the thing about the improvement on the wiring of the batteries on Gibbo's tech doc that was linked to earlier in this topic - nice one - I didn't realise you were also 'up there' with the best of 'em )

 

I very much appreciate your help Gibbo and I don't want to push my luck here - I know this is your free time and nothing holds you to having to reply to me and my foolish ideas. I still have some smoldering embers left that I won't go into as I don't want to take up yours/anyone's time airing out my stupid theories and no - I can't honestly tell you how it will work any better than what I have already tried to do - I just feel/felt that there was 'something in it' - obviously not and thanks for clearing that up (although if it is so basic what is wrong I don't understand why a long explanation is required...? I guess what you are saying is that if I am stoopid enough to sugest such a thing surely my electircal knowledge is suspect at best - and you're not prepared to 'start from the begining' and you're probably right...but I thought I knew a little beyond the basics)

 

I just wrote a load of stuff here from a few experiments I did on a couple of my old batteries on a mains charger - but ended up deleting it all basically each battery individually took about 5-6A but when wired together they only took about 7A in total. That started me off thinking that this strengthened the idea of seperating the batteries from one another but then I remembered the amps flowing into the batteries on the boat didn't seem to do this - they didn't change [much] when I switched from 1 to 2 or BOTH - each one took pretty much the same as what it was always taking - so this just threw my theory out the window...

 

at the end of the day a battery takes whatever it takes (although you can force higher charging currents into a battery with a mains charger high/low swtich which baffles me) they're rugged old school and going strong technology and they do what they do and you can't do a thing about it - end of story - I just honestly don't understand how the nirvana of running kW of power a day is achievable without sinking a boat with the weight of batteries and charging equipment required...

 

Lets see if I have got this right:

 

the batteries were knackered when new.

 

the charging routine maybe suspect

 

it has cost some a lot money

 

you maybe have learnt something

 

my solution:

 

buy some new batteries, your choice of type, wet lead, AGM or Gell.

 

charge then correctly.

 

not only listen but hear what the true experts are saying.

 

stop trying to re invent the wheel.

 

simplessssss

 

thanks - but how is this any different than what I just did? the Elecsols must have been charged 100% when delivered - when they went down I charged them - when I realised they were going down quickly I charged like mad and decreased usage dramatically

 

the charging routine is not suspect - you just all made up your minds that you consider it to be! it worked fine for the forklifts - I thought a couple of days running on batts was pretty cr*p but you all seem to think that is great! I should have just stuck with them...

 

you think I should just chuck yet more money at it?

 

I am hearing what the experts are saying - reality is what reality does - in other words the only way to use batteries is keep them on constant charge - if that's true, which I have no reason to doubt, then I must admit defeat and give up

 

I really wonder sometimes where I get the patience to persevere... where do I throw my money at next then? (Having a 'bad boat related day today' got ripped off by a welder few months back and he has basically told me to whistle if I think he is coming back to sort out his abomination of a job - is there a section on here to name and shame boat related rogues? I would guess it to be overflowing if the years of experience I have had with the various charlatans/marina people/'experts' I have met over the years is anything to go by...)

 

god I'm just fed up of it all now (throws toys out of pram...)

 

just seen your post mayalld - thanks for that... It has been suggested to request a charge back from my credit card company to shake him into action

 

yeh - I learnt something - don't ever buy an expensive/Elecsol battery ever ever ever ever ever ever again...

[nb Innisfree]

For what it's worth after 4 years daily charging I have decided it's either long charging times and long battery life, or, short charging and short batt life or any combination between. For me next time it will be cheap wet cells with minimum charging and regular batt renewal, might as well abuse cheap batts than dear ones and save a packet in diesel.

 

But that's my take on it

[blodger]

OK - but what is the point of all the K's if all you can push into a battery is a handful of amps - I would have thought you would be spending more on fuel than you are putting into the batteries but it sure seems like you've done your sums and it all looks good.

 

But this brings me onto what (most may shout out in unison) is completely obvious and there is no way of getting away from - 'you have to put back the amps you take out' so I guess it's great if it is a silent thing built in under the deck and all the bells and whistles (believe me I would LOVE something like that) but a good ol Lister SR2 running for 8-12 hours is gonna bring on some seriously p'd off neighbours knocking on your door!

 

but really though - dredging back all the 'knowledge' - it's not just about having a whacking great battery bank coz whilst it might mean that you can sit with your feet up gobbling all the kW for a few days - you're gonna have a helluva time getting all those amps back into the batts... OK so lets get a whacking great big generator/charging system and we'll have those suckers charged up in no time! NOPE! sorry but if you want to charge these batteries up you are going to have to be nice to them and drip feed them bit by bit because they won't take more than they want (but this also made me re-think - how come the mains battery charger I have plugged in now is able to push ~3A on 'slow' - ~5.5A on fast and ~20+A on boost? I thought a batt would only 'take what it wants/can...?!?')

 

whaddya reckon experts?

 

I sympathise regarding the failure of your elcosols whether it be inherent vice or you not reading the signs and responding appropriately or both. I am not clear what your 'charging regime' has been that was sufficient for your former batterries so can not conclude that it was faulty but from your postings it sounds that you have found putting back in what you have got out problematic.

 

If you have mains available the majority of the time any batteries are maintainable for a long life with the most basic of chargers. One really needs a decent 4 step charger for boat batts. Without mains (there's lots on other threads, etc) it is a balancing act trying not to discharge the batteries too far before charging them up as high as possible to the unattainable 100% so as to prolong their life. We have to adapt our lifestyles and boats to accomplish the latter as best we can.

 

As an example my boat had been used as a liveaboard for 7 years attached to the mains. On our first holiday cruise the three domestic batterries needed replacing and doing an energy audit did so with 4 110a and also replaced the 55a alternator with a 70a plus stirling regulator. Next the wife wanted a washing machine so to cope with that when the engine was running underway a second alternator and 2nd bank of 3x 100a batts were needed. Since two other triple banks of secondhand batteries have been added. When first in drydock solar panels and a wind charger were added to the ability to help the batterries. I do not often have to run my engine merely to charge the batts.

 

I have recently been helping a liveaboard with an SR2 with a starter problem; he manages quite well with a 36a alt and two truck batteries. He uses candles a lot; Each to their own.

 

I wish you luck in getting some satisfaction either from your ecosols or the firm

[mayalld]

For what it's worth after 4 years daily charging I have decided it's either long charging times and long battery life, or, short charging and short batt life or any combination between. For me next time it will be cheap wet cells with minimum charging and regular batt renewal, might as well abuse cheap batts than dear ones and save a packet in diesel.

 

But that's my take on it

 

It is a good philosophy.

 

Most boaters (myself included) lack the self-discipline to look after batteries as they should be looked after.

 

In consequence, their life will be less than it might be, and that means that cheap tat or expensive stuff is going to last about 3 years with luck.

 

Which means that it makes sense to buy cheap!

[Naughty Cal]

Reality Phylis.. reality...

 

Really.

 

It is not good to ever run your batteries down to flat. Beyond 50% discharged and they begin to really suffer and you lose performance/capacity. Now you obviously know best so thats where i will leave it.

[Gibbo]

............(although if it is so basic what is wrong I don't understand why a long explanation is required...? I guess what you are saying is that if I am stoopid enough to sugest such a thing surely my electircal knowledge is suspect at best - and you're not prepared to 'start from the begining' and you're probably right...but I thought I knew a little beyond the basics)

 

Something like that!

 

The idea is so daft that I cannot work out what you think it can achieve or, more importantly, why it can achieve it. If I don't know why you think it can achieve anything (and, as I said, the idea is just so silly that anyone who comes up with it clearly defies all logic), how do I know which bit to start with to explain why it is so daft?

 

Start with your diagram (with the diodes) and the basics. The batteries are flat so the alternator is throwing out its maximum current (bulk stage). The current will divide equally between all the batteries. Now, instead, connect all the batteries together in the normal manner. What do you think will be different? I guarantee you that the current will divide equally between all the batteries (assuming they are in the same condition and state of charge). If they are not in the same state of charge and condition then the current will not divide equally. But neither will it do so with all those diodes in there. And the difference will be exactly the same whether the diodes are there or not.

 

So it has achieved nothing in the bulk stage.

 

Now move to acceptance. The current is falling and the voltage remains the same. Each battery takes whatever charge current it is going to at that voltage. Again, assuming all batteries are at the same state of charge and in the same condition then the current into each battery will be identical. If they are in different states of charge and condition then the curent will be different in each battery. This applies whether or not the diodes are there. The difference between each battery will be identical in both cases.

 

So it has achieved nothing in the acceptance stage.

 

Now you need to consider that adding in the diodes introduces a volt drop. So during the acceptance stage the voltage across the batteries will be lower than without the diodes. The batteries will therefore draw less current.

 

So putting in the diodes will increase the acceptace time to achieve the same level of charge.

 

Further consider that you have a total of the alternator output current multiplied by the volt drop across the diodes (which will give the power in watts) wasted in the diodes. That power has to come from somewhere. Clearly it comes from the alternator. That is power that should have gone into the batteries. The power output from the alternator is limited and therefore stealing some to heat up some diodes can only reduce the power into the batteries. It cannot possibly ever do anything else.

 

Even if diodes were 100% efficient and had no voltage drop whatsoever (and therefore wasted no power) the scheme still would achieve precisely nothing.

 

And that is why I am so confused and don't know where to start. How on earth can you think it can ever do anything other than waste power?

 

I would have thought that even someone with no knowledge whatsoever of the subject would look at the idea and instantly burst out laughing knowing instinctively that it's plain stupid.

[mikevye]

I have read armenadilldos comments on elecsol batteries/delivered duff. To my awareness elecsol have battery charge indication (green eye fully charged) incorporated in the battery design. This would give even the worst battery numpty in the whole world an opportunity to reject the battery before installation.

[nb Innisfree]

Gibbo why do you have to be so arrogant? we're not all electronic geniuses like you but trying to learn and get to grips with things. Ok it must be frustrating and boring to go over the same things but that's what teaching's all about. I have found your information very helpful over the last year but you have a strong disregard for 'numpties' who ask 'daft' questions. Try to be more patient, though I expect you're too thick skinned to care.

[Justme]

I have read armenadilldos comments on elecsol batteries/delivered duff. To my awareness elecsol have battery charge indication (green eye fully charged) incorporated in the battery design. This would give even the worst battery numpty in the whole world an opportunity to reject the battery before installation.

 

 

If you mean the green, white, black ball thingy then your are falling for the marketing spiel.

 

a, it only shows the condition of ONE CELL

b, it changes from green to white at quite a low voltage (sub 12v I think) & by the time the white goes black the bat is already shot.

c, I am sure there are more reasons too.

[Robin2]

the charging routine is not suspect - you just all made up your minds that you consider it to be! it worked fine for the forklifts - I thought a couple of days running on batts was pretty cr*p but you all seem to think that is great! I should have just stuck with them...

.

.

.

you think I should just chuck yet more money at it?

.

.

.

god I'm just fed up of it all now (throws toys out of pram...)

 

Have you considered operating two separate battery banks as mentioned in one of my earlier posts on this subject? I think it is the only practical way to ensure that each bank is alternately charged to 100% without excessively long engine hours. However I am interested to hear everyone's view.

 

I guess you have, yourself, come to the conclusion that the diodes would not help. As far as I can see all they would do is prevent a charged cell from discharging into a less charged cell. But if the cells were all collected together to start with they should all have the same charge. And the diodes will waste power.

 

I think a hydrometer is the best tool to identify a dodgy cell - it should show a different specific gravity reading compared with the rest of the cells.

 

You do raise an interesting question which has not been addressed yet - how should you test a battery when it is delivered to prove that it is up to specification?

 

And, from the research (on the web) that I did there should be nothing wrong with discharging a deep cycle battery well below 50% as long as you are prepared to live with the reduction in the total number of discharge/charge cycles it will survive. Presumably discharging only to 75% would be even better than a 50% limit. But what the "never go below 50%" brigade do not acknowledge is that the battery will take a faster charge when it is more deeply discharged and that makes much better use of your generator fuel. After all, the whole thing is a balance between the cost of batteries and the cost of diesel.

 

My idea, with two battery banks, is to use one bank in the range 40% to 80% (or 30% to 70%) for (say) a week and then charge it up to 100% during the subsequent week when bank2 is being used for "house" duties.

 

I don't profess to be any more than a competent amateur, so all other comments ae welcome.

Edited October 29, 2009 by Robin2

[Guest]

I once thought of using two banks, with a suitable changeover switch so that they could be charged iand deployed ndividually, or together, depending on requirements. I was told, and thinking about it since it seems reasonable, tht it is better to simply connect the banks together and use them as one bank. IIRC the reason put forward was our old friend Peukert, who insists that when drawing a smallish load, the battery bank is effectively bigger, and vice versa.

Edited October 29, 2009 by Guest

[nb Innisfree]

Have you considered operating two separate battery banks as mentioned in one of my earlier posts on this subject? I think it is the only practical way to ensure that each bank is alternately charged to 100% without excessively long engine hours. However I am interested to hear everyone's view.

 

I guess you have, yourself, come to the conclusion that the diodes would not help. As far as I can see all they would do is prevent a charged cell from discharging into a less charged cell. But if the cells were all collected together to start with they should all have the same charge. And the diodes will waste power.

 

I think a hydrometer is the best tool to identify a dodgy cell - it should show a different specific gravity reading compared with the rest of the cells.

 

You do raise an interesting question which has not been addressed yet - how should you test a battery when it is delivered to prove that it is up to specification?

 

And, from the research (on the web) that I did there should be nothing wrong with discharging a deep cycle battery well below 50% as long as you are prepared to live with the reduction in the total number of discharge/charge cycles it will survive. Presumably discharging only to 75% would be even better than a 50% limit. But what the "never go below 50%" brigade do not acknowledge is that the battery will take a faster charge when it is more deeply discharged and that makes much better use of your generator fuel. After all, the whole thing is a balance between the cost of batteries and the cost of diesel.

 

My idea, with two battery banks, is to use one bank in the range 40% to 80% (or 30% to 70%) for (say) a week and then charge it up to 100% during the subsequent week when bank2 is being used for "house" duties.

 

I don't profess to be any more than a competent amateur, so all other comments ae welcome.

 

In my case case dividing bank leaves 2x480ah@24v, each bank would just about accept our 100A alternator to bulk charge from 60% to absorption at approx 75% SOC which will meet our daily power needs. (No point charging any higher as it would defeat the whole point of bulk charging on engine only) The other bank will then be charged from 60% to 100% via a 230V 3 stage charger powered from inverter on first bank and then the whole caboodle swapped round each day. This will ensure minimum engine running. The problem is the need to drop below 50% SOC on one bank to fully charge the other. We would need to double bank sizes which would require 16x120AH batts!

 

Even if it was economically viable we don't have the space for all those batts. and I'm sure I would disappear up my own wormhole.

 

It's been our experience that discharging to 50% results in voltage deterioration over a very short time

Edited October 29, 2009 by nb Innisfree

[blodger]

I think the smartguage site very well explains Peukert and that it is beneficial to operate battery banks together and that has been my experience

[bottle]

In my case case dividing bank leaves 2x480ah@24v, each bank would just about accept our 100A alternator to bulk charge from 60% to absorption at approx 75% SOC which will meet our daily power needs. (No point charging any higher as it would defeat the whole point of bulk charging on engine only) The other bank will then be charged from 60% to 100% via a 230V 3 stage charger powered from inverter on first bank and then the whole caboodle swapped round each day. This will ensure minimum engine running. The problem is the need to drop below 50% SOC on one bank to fully charge the other. We would need to double bank sizes which would require 16x120AH batts!

 

Even if it was economically viable we don't have the space for all those batts. and I'm sure I would disappear up my own wormhole.

 

It's been our experience that discharging to 50% results in voltage deterioration over a very short time

 

In the best possible way and I quote Manuel on this Que!!!!!

 

You suggest using a battery bank to run an inverter (losses/inefficiency) to run a charger (losses/inefficiency)to charge some batteries.

 

Basically you will use more energy from the first bank than you put into the second bank surely??.

[nb Innisfree]

In the best possible way and I quote Manuel on this Que!!!!!

 

You suggest using a battery bank to run an inverter (losses/inefficiency) to run a charger (losses/inefficiency)to charge some batteries.

 

Basically you will use more energy from the first bank than you put into the second bank surely??.

 

You're probably right, that's why I will stick to my one bank

[smileypete]

I once thought of using two banks, with a suitable changeover switch so that they could be charged iand deployed ndividually, or together, depending on requirements. I was told, and thinking about it since it seems reasonable, tht it is better to simply connect the banks together and use them as one bank. IIRC the reason put forward was our old friend Peukert, who insists that when drawing a smallish load, the battery bank is effectively bigger, and vice versa.

True, though once a bank starts getting sulphated it's discharge efficiency drops.

 

So a large partly sulphated bank may be less efficient than one half it's size in good condition.

 

 

In my case case dividing bank leaves 2x480ah@24v, each bank would just about accept our 100A alternator to bulk charge from 60% to absorption at approx 75% SOC which will meet our daily power needs. (No point charging any higher as it would defeat the whole point of bulk charging on engine only) The other bank will then be charged from 60% to 100% via a 230V 3 stage charger powered from inverter on first bank and then the whole caboodle swapped round each day. This will ensure minimum engine running. The problem is the need to drop below 50% SOC on one bank to fully charge the other. We would need to double bank sizes which would require 16x120AH batts!

A few points:

 

As mentioned it's also possible to split into 3 banks and use two out of three while charging the remaining one to 100%.

 

The bank being charged to 100% need only be charged from say 75% and not 60%.

 

The bank being charged to 100% can be charged from a solar panel, wind turbine etc, doesn't have to be an inverter/charger.

 

If charging from one bank to another, there's more efficient ways than using an inverter and charger.

 

Switching over need not be done every day(!), more like every 3 to 7 days.

 

cheers,

Pete.

Edited October 29, 2009 by smileypete