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Post by smileypete on Oct 30, 2016 14:34:01 GMT
Yeah but Peukert is all but irrelevant for the typical narrowboat owner. There was fundamental misunderstanding of it on CWDF in hindsight, which seemed to be reflected in what you wrote, Nick can fill you in on the details. Bullshit! Can speak for youself if you like but Nick explained it further up: Although it may be too complex for the scope of the original article, I'll just say a bit about CEF and peukert. Read or not as you please! CEF (Charge efficiency factor) is the ratio of amp hours that have to be put back, compared to amp hours taken out. The difference is the amount of amp hours that went to cause gassing of the electrolyte (breaking down the water into hydrogen and oxygen). Note that charge efficiency is not directly related to energy efficiency. This is because energy is amp hours times volts, and when discharging the volts are lower than when charging. So whilst the CEF might be 90%, the power or energy efficiency will be quite a bit less. CEF is not related to peukert. Summary: peukert relates to the speed of the chemical reaction in the battery that creates the current. Peukert is relevant to the way in which a battery's capacity in AH is specified. Typically a battery may be specified at 110AH if when discharged at 11A it is flat after 10 hours. "Flat" or zero state of charge is, for the purpose of the discharge test, defined as a specific end voltage, maybe 10.5v. But if you discharged the battery at 22A instead of 11A, you would get to the end voltage of 10.5v before 5 hours was up. Why? Just because the chemical reaction slows down as most of the chemicals get used up, and it gets harder for the different chemicals to "find" each other in order to react. So perhaps the same battery, when tested at 22A, would only have 95AH by the time it reached 10.5v. So what happened to the rest of the AH. Well, nothing really. They are still there, just a bit sleepy. Give them a rest for a while and then continue to discharge the battery slowly and they can all be recovered. So peukert is only relevant to AH remaining if you want to discharge a battery at a highish rate until it is flat. If you discharge a battery at a high rate for a short time, and then allow the battery to recover by stopping the discharge or discharging slowly - i.e. typical usage on a boat - the badged AH remains available and peukert is irrelevant.(Bold added) I think Nick explained it very well and I can go along with that.
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Post by Gibbo on Oct 30, 2016 14:38:11 GMT
Can speak for youself if you like but Nick explained it further up: Although it may be too complex for the scope of the original article, I'll just say a bit about CEF and peukert. Read or not as you please! CEF (Charge efficiency factor) is the ratio of amp hours that have to be put back, compared to amp hours taken out. The difference is the amount of amp hours that went to cause gassing of the electrolyte (breaking down the water into hydrogen and oxygen). Note that charge efficiency is not directly related to energy efficiency. This is because energy is amp hours times volts, and when discharging the volts are lower than when charging. So whilst the CEF might be 90%, the power or energy efficiency will be quite a bit less. CEF is not related to peukert. Summary: peukert relates to the speed of the chemical reaction in the battery that creates the current. Peukert is relevant to the way in which a battery's capacity in AH is specified. Typically a battery may be specified at 110AH if when discharged at 11A it is flat after 10 hours. "Flat" or zero state of charge is, for the purpose of the discharge test, defined as a specific end voltage, maybe 10.5v. But if you discharged the battery at 22A instead of 11A, you would get to the end voltage of 10.5v before 5 hours was up. Why? Just because the chemical reaction slows down as most of the chemicals get used up, and it gets harder for the different chemicals to "find" each other in order to react. So perhaps the same battery, when tested at 22A, would only have 95AH by the time it reached 10.5v. So what happened to the rest of the AH. Well, nothing really. They are still there, just a bit sleepy. Give them a rest for a while and then continue to discharge the battery slowly and they can all be recovered. So peukert is only relevant to AH remaining if you want to discharge a battery at a highish rate until it is flat. If you discharge a battery at a high rate for a short time, and then allow the battery to recover by stopping the discharge or discharging slowly - i.e. typical usage on a boat - the badged AH remains available and peukert is irrelevant.It is incorrect. Peukert is probably more relevant to narrow-boaters than most other uses (maybe with the possible exception of caravaners) because Narrow-boaters have a habit of trying to get away with the smallest bank possible and it is those people that get hit hardest by it.
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Post by smileypete on Oct 30, 2016 15:40:13 GMT
It is incorrect. Peukert is probably more relevant to narrow-boaters than most other uses (maybe with the possible exception of caravaners) because Narrow-boaters have a habit of trying to get away with the smallest bank possible and it is those people that get hit hardest by it. It's irrelevant until/unless you hit 10.5V under load. Almost always this is because the batts are well on the way to being knackered. Broadly I believe there's two notable groups of boaters: - A large proportion who wreck their batts due to lack of basic knowledge when it comes to proper charging. A transition to living aboard off-grid virtually guarantees this. - A much smaller proportion who worry if their batts drop below 49.999%. They may well still slowly wreck their batts though, o yes...! These days all I can do is offer some simple hints and tips on charging etc, hopeful that all of the above will truly get to grips with volts and amps and get decent life from their batts.
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Post by Gibbo on Oct 30, 2016 16:01:56 GMT
It is incorrect. Peukert is probably more relevant to narrow-boaters than most other uses (maybe with the possible exception of caravaners) because Narrow-boaters have a habit of trying to get away with the smallest bank possible and it is those people that get hit hardest by it. It's irrelevant until/unless you hit 10.5V under load. Almost always this is because the batts are well on the way to being knackered. Broadly I believe there's two notable groups of boaters: - A large proportion who wreck their batts due to lack of basic knowledge when it comes to proper charging. A transition to living aboard off-grid virtually guarantees this. - A much smaller proportion who worry if their batts drop below 49.999%. They may well still slowly wreck their batts though, o yes...! These days all I can do is offer some simple hints and tips on charging etc, hopeful that all of the above will truly get to grips with volts and amps and get decent life from their batts. I disagree entirely. Simpy using a microwave on a typical narrow-boat installation with inverter will bring Mr Peukert well into the doorway.
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Post by lampiniafloat on Oct 30, 2016 17:16:43 GMT
Hi, Numpty here!
We have 2 x 12v 110A gel leisure batteries, and a Victron 2 x 140w Polycrystalline solar system with a 15A - MPPT controller. The monitor is a NASA BM-1, which is excellent and which i have learned to stare at lovingly over the past 7 months - especially when it tells me my batteries are at %104 after a sunny day!
We are on a landline at the moment and are at the stage where the solar is't cutting it for charging the 12v, even though it's only used for LED lights and the water pumps.
I have a "Ring Automotive Workshop Charge20" battery charger here, says it's suitable for lead acid & gel. 3 charging modes - 1) 80A rms 55A dc 12v Engine Start. 2) 20A rms 12.8A dc 12v Fast Charging. 3) 3A rms 2A dc 12v Slow Charging.
Questions:
Is it true that my leisure batts can get "lazy" if not discharged and charged regularly? (i was running everything through the inverter when the solar was doing well i.e. recharging to %104 at least every other day.. We are not huge power users by any means..)
How do i use this charger properly? Should i isolate the 12v before connecting (the manual says +itive then -ative) the croc clips? Or is it enough to turn the inverter off?
Assuming the monitor is telling me the batts are, say, 80% charged, which charging mode should i use? Does this charger automatically go into "float" mode?
All help most gratefully recieved - have been told that the batteries are in very good nick for their age and would like to keep them that way!
:-)
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Post by tonyqj on Oct 30, 2016 17:29:37 GMT
May I suggest you copy/paste this post into a new thread in the Equipment section?
It's not really relevant to this thread and is likely to receive more replies over in Equipment.
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Post by lampiniafloat on Oct 30, 2016 17:40:57 GMT
Righty -ho, will do!
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Post by Telemachus on Oct 30, 2016 22:00:56 GMT
It's irrelevant until/unless you hit 10.5V under load. Almost always this is because the batts are well on the way to being knackered. Broadly I believe there's two notable groups of boaters: - A large proportion who wreck their batts due to lack of basic knowledge when it comes to proper charging. A transition to living aboard off-grid virtually guarantees this. - A much smaller proportion who worry if their batts drop below 49.999%. They may well still slowly wreck their batts though, o yes...! These days all I can do is offer some simple hints and tips on charging etc, hopeful that all of the above will truly get to grips with volts and amps and get decent life from their batts. I disagree entirely. Simpy using a microwave on a typical narrow-boat installation with inverter will bring Mr Peukert well into the doorway. Not really. Peukert is about the finite speed of chemical reaction within the battery. No AH are lost due to peukert as a result of a short term high current demand such as running a microwave, if the battery is then rested or run at a low discharge afterwards. However it is true to say that running a microwave off a smallish battery bank does lose some WH. More AH have to be extracted to run a ~constant power device such as a microwave, than if the same energy were to be extracted more slowly. Energynis lost as a result of the lower terminal voltage due to internal resistance and peukert. The important point is to distinguish between WH and AH. Peukert only concerns itself with current - voltage doesn't come into it and therefore it is not about power or energy. peukert's only use is in a "time to run" meter, which is pretty pointless for a narrowboat since power demand is rarely constant right up to the point that the batteries are totally flat. Peukert has no place in an AH-counting SoC meter, except in the silly "time to run" display. Just by way of clarifying my position, let's consider a 110AH @10 hour battery. So you could take 11A for 10 hours, then it would be flat. So let's say you took 50A for an hour. Then you let the battery rest for ~ 5 hours, and then resumed discharge at 11A until flat. What would the total AH taken out be? Answer 110AH. So no AH are lost as a result of a short term high current discharge if the battery is then allowed to recover a bit. Peukert only describes lost AH if the high current discharge is maintained until the battery is flat. Even then, if the battery is rested, the "lost" AH are recoverable.
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Post by smileypete on Oct 30, 2016 23:11:13 GMT
] I disagree entirely. Simpy using a microwave on a typical narrow-boat installation with inverter will bring Mr Peukert well into the doorway. In the real world though it's a rarity with healthy batts. Which makes it largely irrelevant to boaters.
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Post by Gibbo on Oct 31, 2016 11:45:39 GMT
I disagree entirely. Simpy using a microwave on a typical narrow-boat installation with inverter will bring Mr Peukert well into the doorway. Not really. Peukert is about the finite speed of chemical reaction within the battery. No AH are lost due to peukert as a result of a short term high current demand such as running a microwave, if the battery is then rested or run at a low discharge afterwards. That is where your error lies. The assumption is wrong. 1. Battery recovery applies after a heavy discharge. 2. But also, during a heavy discharge, energy is lost. It is wasted as heat, the generation of which is not proportional to the discharge current. It is proportional to the square of the discharge current. Peukert's effect is the combination of the two.
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Post by Telemachus on Oct 31, 2016 11:57:07 GMT
Not really. Peukert is about the finite speed of chemical reaction within the battery. No AH are lost due to peukert as a result of a short term high current demand such as running a microwave, if the battery is then rested or run at a low discharge afterwards. That is where your error lies. The assumption is wrong. 1. Battery recovery applies after a heavy discharge. 2. But also, during a heavy discharge, energy is lost. It is wasted as heat, the generation of which is not proportional to the discharge current. It is proportional to the square of the discharge current. Peukert's effect is the combination of the two. It's getting to be a habit on here but you are confusing electrical charge and current, with energy and power. Certainly (and as I said earlier) when a battery is discharged fast, energy is lost. As you say, it is related to the square of the current (power = I^2R). But peukert does not concern itself with energy, it is all about current and charge which has no dimension of energy. A consequence of battery internal resistance and the slowness of the chemical reaction, is lost energy (due to voltage drop). But peukert's equation doesn't describe lost energy and voltage doesn't come into the equation. Anyway the fundamental point is that peukert has no place in an AH counting gauge, since no AH are lost due to fast discharge over an above those recovered at the battery terminals (provided the battery is rested afterwards). Well not quite, peukert is relevant for the "time to run at the current rate of discharge" display, which is pretty useless in practice.
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Post by Gibbo on Oct 31, 2016 13:30:08 GMT
I'm confusing "electrical charge and current, with energy and power "? That's the funniest thing you've ever written.
You are wrong.
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Post by Telemachus on Oct 31, 2016 13:45:16 GMT
I'm confusing "electrical charge and current, with energy and power "? That's the funniest thing you've ever written. You are wrong. Needless to say I realise that you do understand the difference, however you are mixing it up in your post. Anyway in the absence of any counter argument I shall consider that you agree with my point.
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Post by Graham on Oct 31, 2016 13:53:56 GMT
It's getting to be a habit on here but you are confusing electrical charge and current, with energy and power. Certainly (and as I said earlier) when a battery is discharged fast, energy is lost. As you say, it is related to the square of the current (power = I^2R) I'm confusing "electrical charge and current, with energy and power "? That's the funniest thing you've ever written. You are wrong. It is over 50 years since I have done any of this but my brain is screaming Nick your wrong, does not mean I am right. An electron, Ion etc has a charge and thus some energy. That charge can cause the electron to move because of the associated charges around it. The attraction, if brain is even working, is related to the voltage of the charge that is rejecting or attracting. The current is related to the number of charged particles the attracting charge can move at the relevant speed. Thus an electron or Ion does not move without voltage so voltage has got to be involved in there somewhere else you cannot have current as there will be no flow of particles. Brain dead
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Post by Telemachus on Oct 31, 2016 14:06:33 GMT
It's getting to be a habit on here but you are confusing electrical charge and current, with energy and power. Certainly (and as I said earlier) when a battery is discharged fast, energy is lost. As you say, it is related to the square of the current (power = I^2R) I'm confusing "electrical charge and current, with energy and power "? That's the funniest thing you've ever written. You are wrong. It is over 50 years since I have done any of this but my brain is screaming Nick your wrong, does not mean I am right. An electron, Ion etc has a charge and thus some energy. That charge can cause the electron to move because of the associated charges around it. The attraction, if brain is even working, is related to the voltage of the charge that is rejecting or attracting. The current is related to the number of charged particles the attracting charge can move at the relevant speed. Thus an electron or Ion does not move without voltage so voltage has got to be involved in there somewhere else you cannot have current as there will be no flow of particles. Brain dead Ever heard of MeV in the sphere of particle physics? Mega electron volts. It is a measure of energy. Without the volts, there is no energy. An electron in isolation (not in an electric field) has no energy as a result of its charge. Charge is not energy! In your text above you mention a few things that relate to electric field gradient or voltage. It is these that give a charged particle energy.
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