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New batteries with good batteries


Frankieboy

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I have just got 3 new batteries to replace the old ones but one of the old ones seems to be ok. Is it worth keeping it and linking it up with the new ones or should I just chuck it with the rest of the old ones?

If it isnt performing at 100% I dont want to wreck the other batteries because of it.

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If it seems OK, and you've got room to keep it as well as the new ones, then keep it. Whatever capacity it has left, will just add to the new ones.

 

The only way it can wreck the new ones, is if it's actually got a shorted cell so it's a 10v battery instead of a 12v battery. If it had that, it would be pretty obvious by - if nothing else - its output voltage.

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If it seems OK, and you've got room to keep it as well as the new ones, then keep it. Whatever capacity it has left, will just add to the new ones.

 

The only way it can wreck the new ones, is if it's actually got a shorted cell so it's a 10v battery instead of a 12v battery. If it had that, it would be pretty obvious by - if nothing else - its output voltage.

 

Thanks.

There should be room, but before I do I'll double check its voltage to make sure it has the right output.

Would it's output voltage be 12v no matter what the charge, i.e. if it is half flat?

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Thanks.

There should be room, but before I do I'll double check its voltage to make sure it has the right output.

Would it's output voltage be 12v no matter what the charge, i.e. if it is half flat?

If faulty its voltage will be 5/6th of the voltage of a good battery at the same state of charge.

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I have just got 3 new batteries to replace the old ones but one of the old ones seems to be ok. Is it worth keeping it and linking it up with the new ones or should I just chuck it with the rest of the old ones?

If it isnt performing at 100% I dont want to wreck the other batteries because of it.

Based on experience rather than any scientific proof, the capacity and open circuit voltage of batteries seems to fall with age, also the self discharge rate increases.

 

For these reasons I would suggest that it is not a good idea. It is doubtful that the capacity of the older battery is anywhere near what it was so even if you do use it the benefit is likely to be marginal. Also based on experience the boaters I know who have tried this have not seen any medium or long term benefit.

 

When a battery goes down and is tested for high discharge, what often happens is that one cell (usually the positive one) reverses polarity and starts to charge in the opposite way thus subtracting from the voltage available. It may be that if the older battery is on its way, at some lower state of charge this may happen and it could then be taking charge from the new batteries. Of course this is only a suspicion and I have never seen it happen.

 

I doubt that the older battery would damage the new ones as such but if it did tend to discharge them then it would accelerate the sulphation.

 

Regards

 

Arnot

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The capacity of a battery falls as it ages. This we all know. The self discharge does indeed increase slightly but as this is already very low it's not really an issue.

 

What many people are unaware of though is that the voltage, at any particular state of charge, does not change even one tiny little bit until a cell completely packs in.

 

If a particular battery measures 12.55 volts at 65% SoC when new, it will still measure 12.55 volts at 65% capacity when it is almost completely knackered. I think the confusion arises because when a battery starts to get old (and therefore sulfated) it becomes harder to charge (it just takes longer) so people think it is in a higher state of charge (going from how long it's been on charge) than it really is and thus the voltage is lower than they expect it to be leading to the (incorrect) conclusion that the voltage falls as the battery ages (Hi Arnot :lol:)

 

What this means in practical terms is that adding it in parallel with your new batteries is perfectly acceptable provided it is only old and not actually broken.

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The capacity of a battery falls as it ages. This we all know. The self discharge does indeed increase slightly but as this is already very low it's not really an issue.

 

What many people are unaware of though is that the voltage, at any particular state of charge, does not change even one tiny little bit until a cell completely packs in.

 

If a particular battery measures 12.55 volts at 65% SoC when new, it will still measure 12.55 volts at 65% capacity when it is almost completely knackered. I think the confusion arises because when a battery starts to get old (and therefore sulfated) it becomes harder to charge (it just takes longer) so people think it is in a higher state of charge (going from how long it's been on charge) than it really is and thus the voltage is lower than they expect it to be leading to the (incorrect) conclusion that the voltage falls as the battery ages (Hi Arnot :lol:)

 

When you say 65% capacity, are you including sulphation or not?

 

So if the battery is 35% sulphated, after a normal full charge what would you expect resting voltage to be? What would you expect a SmartGuage to read?

 

cheers,

Pete.

Edited by smileypete
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When you say 65% capacity, are you including sulphation or not?

 

So if the battery is 35% sulphated, after a normal full charge what would you expect resting voltage to be? What would you expect a SmartGuage to read?

 

cheers,

Pete.

 

I think he means that if it started as a 100Ah battery and had now sulfated down to being a 1Ah battery, when it is 65% charged it will still read the same voltage as it did when it was new.

 

Richard

 

It just has lots less ions stored in it, or something like that

Edited by RLWP
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I was about to ask this very question myself! I've just got two new batteries (long story) but I already had two which were only 18 months old. The two older ones both seem OK - they still read 12.55v more than a week after disconnecting them. I had worried that the two older ones would somehow 'drag down' the new ones, but now I think I'll hook them all up together to make an uber-battery-bank!

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I think he means that if it started as a 100Ah battery and had now sulfated down to being a 1Ah battery, when it is 65% charged it will still read the same voltage as it did when it was new.

 

So Gibbo is saying when a 99% sulphated 100Ah battery has it's remaining 1Ah charged fully charged, it will read the same voltage as it did when new and fully charged?

 

cheers,

Pete.

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So Gibbo is saying when a 99% sulphated 100Ah battery has it's remaining 1Ah charged fully charged, it will read the same voltage as it did when new and fully charged?

 

cheers,

Pete.

 

That is what I believe he is saying, but also that it may take bloody ages to be able to fully charge this miserable 1Ah battery due to sulfation.

 

Richard

 

I hope I got that right, else when Gibbo turns up I'll look a right idiot...

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More than usual? :lol:

 

It's a fair point. Really from here the only way is up.

 

Richard

 

As D H Lawrence would say “I can never decide whether my dreams are the result of my thoughts, or my thoughts the result of my dreams.”

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I think basically what he is saying is a battery, with age, becomes smaller in capacity. So if a 100Ah batt has lost half it's capacity then at 50% SOC voltage will be at the mid point as it would be with a new one, but 25Ah remains instead of 50Ah. So in effect mixing old and new is like mixing different capacity batts.

 

Waits with trepidation.

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:lol: soooo confused :lol:

 

all I've ever read/heard/discussed about adding a dud/older battery to a bank has been strongly advised against and that the bank will ultimately 'settle' to the state of the worst battery

 

I can kinda go along with all the replies in that this battery doesn't seem to be too bad (but there seems to be absolutely no way any mortal can determine this short of smashing the thing apart to find out and isn't it slightly suspicious that 'one' of the old batteries is still good?!? how'd that happen? surely they all 'run down' together over the 2 year servicable life boaters seem happy to expect from them?) so am now entirely convinced that absolutely nothing about batteries makes sense

 

From the experiments I did charging 2 batteries of dissimilar states (one had been charged for a day the other was dead flat) from a mains charger it was evident that more Amps flowed into each of the bateries when connected individually than when they were joined together in a bank (~5-6Amps individually against ~7A when joined) my conclusion was that the better battery was kind of partly flowing into the worse one (not really but 'compensating kind of thing') which once pondered upon for 30 seconds made obvious sense from what I had heard about putting a 'bad' battery into a bank - all the others 'help it out' and in the process get dragged down!

 

when I first read this post I thought "yeh - chuck it my way!" (I just can't believe the number of batteries I see chucked out from boats - surely they can't all be duds!)

 

but then of course I thought "what would I really do with it?!?"

 

which got me onto thinking - wouldn't my Stupid Diode Octopus - whilst being stupid in terms of not providing any benefit for a bank of equal batteries at equal states - might provide a whole shed load of benefit for batteries of disimilar states to be joined together to operate as one bank without affecting one another?

 

There was no mention that it would not work or that the circuit diagram was 'incorrect' or likely to blow anything up - only that it was stupid because it 'wouldn't do anything' and would cause power loss as heat through the diodes (not a big deal surely?)

 

So would it be possible to gather together the best batteries you can find that have been discarded (= £0 /battery) and link them up as in the Diode Octopus configuration and VOILA! ultra cheap/free battery bank that you can add and add and add to! (limited only by available space which may of course be a problem for many but not all - I'd find the space if this worked!)

 

OK - so it is obvious this will not be to everyones tastes nor will it equal a brand new battery bank in Ah's or aesthetics - but who cares about any of these facts if it works! Even if you purchased the new battery(s) every X months when finances allowed there would be no concerns of simply adding it to the existing bank using this setup

 

is it really that stupid?

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I admire your courage in the face of ridicule :lol:

 

bring it on! :lol:

 

Many a great scientist was ridiculed before his peers for outrageous ideas "the Earth is round not flat" PAH! ridiculous! it has been their conviction, determination and I believe ability to think out of the box/not follow the herd/listen to others/not to be confrontational/arrogant or blinkered in their approach that their theories have won through and helped change the very understanding we have of this world and how it works!

 

(end of slightly ridiculous speech - will get off my soap box now and nooooo - I am NOT for a second trying to imply I consider myself to be in this league or that this Diode Octopus thing is anything short of pure ridiculousness and will never work! But it gives me the courage not to be afraid of ridicule so any ridiculers who wish to ridicule, ridicule away! be good if could keep it constructive tho eh? :lol: ) *yikes - now I've done it!*

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:lol:

 

there's one of them now?

 

Keeping Up - I think you said it was an "Octopussian disaster waiting to happen" - which was definately funny if nothing else! :lol: but still I have not seen you or anyone else properly prove/explain why my theory will not work other than the fact that it will 'do nothing'?

 

I am guessing the reason is that you think if you do then it will encourage me to keep going on and on trying to improve it/think up an alternative and clog the forum with more of my silly ideas that you will have to avoid reading...

 

I guess you're right but it ain't gonna stop me unless creative thought is banned on this site or something and I get dragged off stage right by the moderators?

 

BTW - where'd you get that emoticon? not one of the standards - I feel privileged you feel the need to have used it on me! :lol: haha

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bring it on! :lol:

 

Many a great scientist was ridiculed before his peers for outrageous ideas "the Earth is round not flat" PAH! ridiculous! it has been their conviction, determination and I believe ability to think out of the box/not follow the herd/listen to others/not to be confrontational/arrogant or blinkered in their approach that their theories have won through and helped change the very understanding we have of this world and how it works!

 

(end of slightly ridiculous speech - will get off my soap box now and nooooo - I am NOT for a second trying to imply I consider myself to be in this league or that this Diode Octopus thing is anything short of pure ridiculousness and will never work! But it gives me the courage not to be afraid of ridicule so any ridiculers who wish to ridicule, ridicule away! be good if could keep it constructive tho eh? :lol: ) *yikes - now I've done it!*

 

You are Chris_w ....... I claim my tenner :lol:

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:lol: soooo confused :lol:

 

 

when I first read this post I thought "yeh - chuck it my way!" (I just can't believe the number of batteries I see chucked out from boats - surely they can't all be duds!)

 

but then of course I thought "what would I really do with it?!?"

 

OK - so it is obvious this will not be to everyones tastes nor will it equal a brand new battery bank in Ah's or aesthetics - but who cares about any of these facts if it works! Even if you purchased the new battery(s) every X months when finances allowed there would be no concerns of simply adding it to the existing bank using this setup

 

is it really that stupid?

 

Has it given you any thoughts regarding setting up your forklift batterries as a second bank to help prop up your elcosols?

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Erminelda

 

Let us look at your octopus:

 

Think of the batteries as water tanks and the cables as water pipes and your diodes as taps.

 

Water flows via the taps to the tanks.

 

But taps cause a restriction in the flow even when fully open

 

So the tanks take longer to fill

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You are Chris_w ....... I claim my tenner :lol:

 

kapow! another one! :lol: hahah

 

(I vaguely recall hearing mention of Chris W and 'how he is' etc whilst reading other posts - I didn't fully grasp just 'how he is' but if it is along these same lines that he dared to think out of the box and y'all shot him down for it then tsk tsk shame on you)

 

Has it given you any thoughts regarding setting up your forklift batterries as a second bank to help prop up your elcosols?

 

yes! most definately but not the forklifts - they are too tall and I never liked the way they were squeezed in etc. - at the moment I have 2 out of 3 of my original 8 year old DETA batts on charge off a mains charger trying out various experiments with equalizing off a DC charger and continous days on the mains charger - it's ONLY an experiment but is good real world experience! if I manage to get them into a healthier shape I might well try it - nothing to loose - they used to last at least a day off a 1-2 hour charge before being taken off the boat

 

FYI - I had 3 DETA 180Ah Batteries (the ones I am talking about charging off the mains now) in a bank and the ~700Ah (purely at a guess actually!) forklifts as the other bank - 1-2 hours charging a day gave upto 2 days off the forklifts and just short of a day on the DETA's - vast improvement over the 1 hour charge = 1 hour use Elecsols! (and good ballast too!)

 

I also just realised that I thought the DETA were a higher Ah but I just checked and that is what it says on the side - each one is VERY heavy - I mean VERY - but the 220Ah Elecsols I could carry half way up the tow path without breaking my back - despite being rated as 220Ah they are about a 1/3 of the weight of the 180Ah DETA's at a guess (more lead = better charge capacity eh! or the reverse as the case may be with Elecsols?)

 

Erminelda

 

Let us look at your octopus:

 

Think of the batteries as water tanks and the cables as water pipes and your diodes as taps.

 

Water flows via the taps to the tanks.

 

But taps cause a restriction in the flow even when fully open

 

So the tanks take longer to fill

 

no problemo! who cares? think about it...

 

The engine will rapidly charge the capacitor (which will also pass part of this charge via the voltage limiter to the batteries whilst the engine is running)-> turn off the engine and the capacitor continues to slowly discharge into/charges the batteries via the voltage limiter maintaining a 14.8v output running through these 'restricting taps'

 

who cares about the loss at the 'taps'? we are talking about a small but continous current flowing into the poor little delicate battery watteries that only like to be charged slowly, kept cycled between top 20%, kept at 100% 100% of the time then chucked away and replaced with a new set every 2 years etc etc etc... you name it - we KNOW the physical realities of batteries and like it or lump it that's how it is...

 

I guess the problem is something to do with the size of capacitor you would need to make this effective/don't have to keep running the engine for 5 minutes every hour or something but am sure that too could be 'thought out'

 

I keep thinking/coming across UPS's - from what I know they are basically a 12v battery with an inverter that can provide enough power for X minutes to computers/electrical equipment but I believe there is also a capacitor in there too! Doesn't that mean it is merely a matter of working out how to do the same thing with differented rated equipment that can run off an alternator output rather than the mains?

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I also just realised that I thought the DETA were a higher Ah but I just checked and that is what it says on the side - each one is VERY heavy - I mean VERY - but the 220Ah Elecsols I could carry half way up the tow path without breaking my back - despite being rated as 220Ah they are about a 1/3 of the weight of the 180Ah DETA's at a guess (more lead = better charge capacity eh! or the reverse as the case may be with Elecsols?)

 

Need to get the problems in charging and useage balance on the boat sorted. Humping batterries on and off the boat to charge them is no way to have to spend your time.

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