Battery charge current vs voltage?

[mitiempo]

Here's an interesting link that describes what a battery monitor can tell you that you may not have known about your batteries before. Worth reading.
http://c34.org/bbs/index.php/topic,4787.0.html

 

[Plevier]

Willow and Allan
Trojan T105 is priced at about $169 CDN, but I guess that won't make much difference to you. But here, maybe a 20-30% increase over the cheap ones.

Willow
CEF will vary but is consistent with a given battery. Here's the pages on setup from the manual. I think that while not perfect, they're very close, and no other method is anywhere near as close for finding out battery soc in a real time way. So much nicer to push a button instead of pulling out a hydrometer (after resting the battery of course).

The manual that you've posted shows that the monitor takes 2% charge current as being fully charged (when it's actually quite a bit short of it), and it assumes 90% charge efficiency. That's only valid over a charge range up to something like 80% of full. Above that it drops markedly, to as little as 50% nearing full charge. (Floating at full charge, by definition the charge efficiency is 0, the float current is entirely losses).

I'm not knocking monitors, far from it, but don't expect unrealistic precision, and bear in mind that when the monitor says fully charged the battery isn't really. They have to take this approximation, the last bit of charge is too slow and low efficiency for them to cope with.

On a typical cycle between say 50% and 90% states of charge, this monitor will I'm sure be pretty much spot on. If you use very shallow cycles it will get well out of sync, and the instructions warn you that in some conditions you may have to re-sync it.

See http://photovoltaics.sandia.gov/docs/PDF/batpapsteve.pdf for more details and curves.

Batteries like Trojan are worth the cost if you are using them hard (i.e. regular cycling) but carefully (i.e. monitoring, not over-discharging, and with a good charger). Otherwise I don't think so, you won't get the benefits if they aren't cycling much or if you aren't careful with them. Just use cheapos!

 

[mitiempo]

Willow
I agree with what you say, but there is a way around that. I have, based on the forum I linked to above, changed the charge current to 1%, and the charged voltage to 15. This eliminates the issue you describe. All of these parameters are user adjustable. Whatever nitpicking is done about monitors, they're miles beyond anything else practical in a normal situation. Nothing else will give you any kind of accurate state of charge on a boat where the battery system is being used regularly. Amps in and amps out at any given time is also invaluable.
Batteries like the Trojan need a good charger, but the cheap batteries also need a good charger or they will last an even shorter time. You have to look at it as a system, just buying a good battery doesn't do it. Solar panel(s) are the same - they have to be matched with a good controller otherwise you won't get the most out of them. The same for an alternator. Virtually every internal regulated alternator is designed to taper current off very fast - in other words thay are designed for a start battery. Every diesel I have seen comes with this type of alternator. A proper 3 stage external regulator can get the most out of an alternator. A lot of people upgrade their alternator when a better regulator would be a better purchase. And no, this wouldn't benefit someone who uses the boat seldom and doesn't put a real strain on the system.
To go farther the 1/2/all/off switch on virtually all boats, at least in the past, with the charging routed through it, is there for one reason only - it was inexpensive for the builder. It doesn't benefit users - who would not want to charge both batteries? How many boats have had dead batteries because it was left on both? How many have fried alternator diodes because it was turned to "off" by mistake? How many find it confusing and don't understand it fully? This is a change all could benefit from, but it requires an ACR or similar. The manufacturers had this option but there are many things on a boat that are better selling features than charging circuits and a lot more visible.
But if you cruise a lot and don't like running the engine more than necessary,
and want a more reliable electrical system that lets you know where you stand at all times, instantly, a monitor is a good way to start. There is really no other option that I know of.

 

[Plevier]

Willow
I agree with what you say, but there is a way around that. I have, based on the forum I linked to above, changed the charge current to 1%, and the charged voltage to 15.

Does that result in it never saying "fully charged"? If you're taking some out of the batteries every day or every other day that would be true but it would upset a lot of people!

Batteries like the Trojan need a good charger, but the cheap batteries also need a good charger or they will last an even shorter time.

If you're trying to cycle them substantially yes, but then better batteries will pay off too. If you're using cheap batteries because they aren't cycled much - e.g. not away often and no battery fridge - then AFAICS the only benefit of a smart charger will be getting a good amount of charge in overnight. That's my position for now! I use car batteries and a simple charger. On the rare occasion when I'm away more than 2 nights, it can be a problem. If I start to do more when retired (SWMBO permitting) an upgrade will be needed. (Of the batteries and charger, I mean!)

You have to look at it as a system, just buying a good battery doesn't do it. Solar panel(s) are the same - they have to be matched with a good controller otherwise you won't get the most out of them. The same for an alternator. Virtually every internal regulated alternator is designed to taper current off very fast - in other words thay are designed for a start battery. Every diesel I have seen comes with this type of alternator. A proper 3 stage external regulator can get the most out of an alternator. A lot of people upgrade their alternator when a better regulator would be a better purchase. And no, this wouldn't benefit someone who uses the boat seldom and doesn't put a real strain on the system.

Yes - alternator output more than about 20% - maybe even 10% - of battery capacity is pretty pointless without smart regulator (unless you're making or selling them .

##

 

[mitiempo]

Willow
Most cheap chargers (automotive type) will just boil the batteries. Any un attended charger should be a proper 3 stage one.
As far as the monitor settings here's the link that explains in detail.http://c34.org/bbs/index.php/topic,4922.0.html
The monitor will not think the batteries are fully charged until it counts the amp hours down (up) to zero. In other words it will determine the battery is fully charged when all the amps used (+ loss for charging inefficiency) are returned to the battery, not from a set of parameters only.

 

[Plevier]

Willow
Most cheap chargers (automotive type) will just boil the batteries. Any un attended charger should be a proper 3 stage one.
As far as the monitor settings here's the link that explains in detail.http://c34.org/bbs/index.php/topic,4922.0.html
The monitor will not think the batteries are fully charged until it counts the amp hours down (up) to zero. In other words it will determine the battery is fully charged when all the amps used (+ loss for charging inefficiency) are returned to the battery, not from a set of parameters only.

OK, got it re the monitor. That makes sense. Defining <2% current at 13.2V as full charge is definitely optimistic. Your work around will be a lot nearer.

All your kit is obviously top class, as you need for live aboard/blue water cruising, and what you say makes perfect sense by those standards. However most boats aren't used that way and not all owners can afford/justify your standards (I bet you've got over £2k worth of batteries, charger, monitor, high output alternator and good regulator, and do you have solar and good regulator too? Maybe £3k!)

My point was that you can get away with less if your use isn't so demanding. My term "simple charger" was perhaps ill chosen, I didn't mean an unregulated one. You need a regulated charger, not a really nasty automotive one, but a single voltage one will do if there's plenty of recharge time between trips. Lots of people have such chargers from pre switched-mode days when multi stage chargers were more difficult to do, or many of the better car chargers are regulated now. An overnight charge won't put as much in as you'd like, but you live with it.

In my case, new genoa winches are a much more pressing need than a top class charger and batteries. Then instruments ... maybe fancier sails ... in fact really I'd like a bigger, newer boat!

So no disagreement at all with your recommendations and high standards where justified (and affordable) but it's horses for courses and lots of people with less demanding use patterns can get by happily with cheaper stuff. A friend of mine has a 5 year old Bavaria and over the last 4 years has gradually cruised it from UK round to Greece. Each year I do a couple of weeks with him. The boat has the standard charger which I'm pretty sure is single voltage, and a couple of truck batteries which are original. They do fine.

 

[Sybaris]

Hi,
I have also got the Freedom charger and Link 2000 monitor and am very happy with them. I read your messages about the 15V 1% settings (and the links you gave) and am trying to understand this correctly (I am not an expert at electrics at all).
With the changes the Link will only figure the betteries to be fully charged once the amp counter has counted up to 0. That means that the amp in and amp out calculation has to be assumed to be perfect. Is that always the case?
What happens if it is not correct and it thus charges too long (overcharges)?

And additional question is, how is the Link affected by other charge sources? I have two alternators and a solar panel regulator with 240W panels in addition to the Freedom charger.
Cheers,
Per

 

[mitiempo]

Willow
Definitely not needed for the average weekend sailor. But I'd bet your friend with the Bavaria has a 3 stage charger - they've been the standard on new boats over here for a long time. If one was to upgrade here's what I'd do. I would think If you don't have a 3 stage charger that should be the first add-on if you have mains power where you dock. After that I'd eliminate the charging going through the main battery switch and charge the start battery with an ACR or similar. Can't imagine why anyone would not want to charge both batteries and the start is seldom down much anyway. Next if you cruise much I'd go for a bigger house bank and then a monitor. If you plan a longer cruise to warmer climes I'd next add solar with a good MPPT controller to be as independent of the engine as possible. I'd add a 3 stage external regulator for the alternator last as if solar can work it's a lot quieter than the engine anyway.

 

[mitiempo]

sybaris
At standard setting the link considers the batteries to be fully charged when it goes to float. We know this is wrong as there is a lot of time to go before the batteries are totally charged. By changing the parameters to 15 volts and 1% there is no problem as the charger will say "full" only when BOTH of the TWO parameters (float voltage AND percentage of charge) are met for the specified time period at the SAME TIME and not simply when it goes to float on the charger.
The Link should not be affected by your solar panels and regulator as it is reading the batteries and will not charge when it knows the batteries are fully charged. This is no different really than starting the engine while the charger is on - same result, the batteries state of charge will determine whether or not the charger is turned on and what charge mode it is in.

 

[Sybaris]

Mitiempo,
The thing is that the two parameters will never be met, so the monitor will only consider full charge, i.e. go to float, when the amp counter has gone back up to 0. Hence my question, is that counter really always correct? especially when you have other charge sources.

 

[mitiempo]

sybaris
The monitor will count amps in or out and doesn't care or know where they come from. So the monitor will consider the battery fully charged when the count is back up to 0. As explained in the link the standard settings (2 amps and 13.2 volts) will cause the monitor to think that the batteries are fully charged when they are not. It should be very close.

 

[Sybaris]

The attached link to the thread do not explain my concern and I am still dubious about this. The suggested modification is akin to having Xantrax add a switch that disengages their way of calculating when the battery is full and only relying on the shunt, i.e. the amp in/out being under all condistions correct. If that is the case Xantrax installed a lot of logic for nothing.
If you are connected to shorepower for long, does your meter ever show that you have amp over zero? (mine does), and if so how can that be, if you rely only on the amp counter only then the battery is either full or not.

 

[mitiempo]

Sybaris
As the manual for any Link product explains (page 20 in your manual) they can get out of sync. They can be put back in sync either automatically or manually. As the links I posted showed, the Link thinks that the battery is fully charged when it goes to float as set originally. We know this is not true. So the link as set assumes a fully charged battery when it's not. Other reasons can be aging batteries or the wrong parameters during installation. If you charge any other way, eg alternator with 3 stage reg, shore power, or solar with a good controller, you will be overfull according to the link. Remember no matter how you put the charge in it has to go by the shunt and be measured so the monitor counts all amps in no matter how they got there. Xantrex didn't install a lot of logic for nothing, they installed a good logic system that can be tailored to your system or anybody else's by customizing it. They wouldn't have allowed you to change it if it worked for everybody. Whenever any link type product is insttalled it has to be programmed for your specific system. I assume you originally did this. This includes battery amp hours, Puekert factor for your batteries, and the voltage and amp settings we have been discussing. The link should not overcharge and once set accurately to bank size, Puekert factor, etc should be accurate on amps in/out. I don't remember if I posted the full link or a part of it earlier but it you go to this link http://c34.org/bbs/index.php/topic,4922.0.html and read just the first post entirely I think you'll understand it better. The alternative to not changing the parameters is to have the monitor say the battery is full when it's not and as the link I posted shows, over time you will lose a fair amount of capacity based on its readout.

 

[Sybaris]

Mitiempo,
Hi and sorry for having to be a pain but I cannot fully agree with the logic and the link you refer to (which in it's turn refers to another person). Yes of course Xantrax added the settings for a reason, but to set it to 15V 1% is not not to tailor it to your system, you are then basically disabling the "fully charged" logic and only relying on amp in/out (the shunt). If that was the way to go with all battery banks then I wonder why Xantrax did not say so in their manual, and why even include the logic.

 

[mitiempo]

Sybaris
When you set it to 15 volts and 1% you are disabling a fully charged logic that doesn't work, as explained in the link. You are setting it so it reads full when full, not when it goes to float, which is less and can be cumulative. It does work.

 

[Sybaris]

Mitiempo,
We are just going to have to disagee on this. I choose to trust that Xantrax put a lot of thought and engineering in their "fully charge logic" rather than going by the theory proposed by Stu Jackson who does not appear to be an electrical engineer. He does not indicate how he measured his batteries to prove that the float kicked in when the batteries were not fully charged. The only thing he does is to refer back to the amps not being 0 when it happens. This proves nothing and is basically leading the argument into a loop.
I don't think that you can simply go by the shunt and amp counter, and if you do then the value can never be above zero because it should be impossible to charge a battery more than full.
You say "it does work", but this does not seem to be based on any form of battery measurement other than using the Xantrax gauge either by you ot Stu.

 

[mitiempo]

Sybaris
The last approximately 15% of charging is float stage. The Link is factory set to consider the batteries full when the charge voltage is 13.2 and the current is less than 2% of the bank size, which you have entered when you originally programmed your Link. Lets assume the bank is 400 amp/hours. 2% of 400 is 8 amps. If you are tied up on shorepower and the ONLY item on is the invertor/charger there is no problem with this. The Link will not register full until the voltage drops to 13.2 volts AND the charging current drops below 8 amps (2% of bank size) for four minutes. Both parameters have to be met, not just one. This works as designed.
Now look at someone living aboard, cruising, using a refrigeration unit or whatever. In other words the charger/invertor is not the only draw on the batteries. Same 400 a/h bank size. Charger reaches the last 15% of charging and voltage drops to 13.2. Current is over 2% of bank size so charging continues. Then the fridge comes on and uses 5 amps and runs for more than 4 minutes. The fridge or other item fools the Link - by using 5 amps the Link sees a smaller amount going into the bank. If this exceeds 4 minutes and the 13.2 volt parameter is already met the Link will say "stop charging the battery is full". But it's not. That is the easiest way I know of explaining this problem. You end up with a bank that is not fully charged - it could be down by 20 or 30 amps at this point. It is cumulative and I'll explain why. You said that your link shows positive amps on shorepower. When the battery is fully charged the Link will synchronize automatically. I've included that section of your manual below. It will reset the amp hours to zero when the battery bank is fully charged (according to the Link). But as I've described above the battery bank might be down a ways. so it will leave room at the top for more charging. When you plug in the shorecharger will see the battery bank is down a bit and start charging. These are the amps over zero that the Link shows. It reset because it determined the bank was fully charged because BOTH parameters were met for over 4 minutes. The next time when charging is almost complete it can happen again. Resets to full again. Bank is down even farther. I hope I have made this easier to understand. In addition to the section describing synchronization from your manual I've included the summary from the posting as well.

ps If this is your situation (and I think it is as well as the reason for amps over zero on the meter) your batteries will undercharge and over time the amount of undercharging will increase. This will shorten the battery life considerably.

 

[Sybaris]

Mitiempo,

I have read the link, which you have referred to several times, and your explanation more or less repeats what Rich Stidger wrote.

Regarding the synchronisation think about this:

Option 1. Install on a fully charged battery. Ok this is obvious, the amp meter is at 0 right from the start, and the battery is full, but we are not dealing with this here since our battery is not yet fully charged.

Option 2. When installed on a partially charged battery you should charge until the charge parameters are met. While you are charging the amp meter will then be counting up (i.e. above zero), and when the battery is then full and you start to discharge (draw electricity) the counter is automatically reset to zero. Now if you use values 15V 1% which Rich admits "those parameters are never going to be met" and since the amp meter is counting positive how will you ever know when the batteries are fully loaded in this scenario?

Rich bases his whole argument on the following statement: "This can happen even if the used AH are not counted down to zero"

That means that he is assuming that the charge is not complete and he has been cheated only because the amp meter says so. He does not seem to have any other means of calculating that the battery is not fully charged (except for a low voltage reading in the morning). The amp meter (shunt) can’t possibly be 100% correct over time without being adjusted now and then.

Don’t you think it seems strange that the engineers at Xantrex went through all the trouble to introduce the two charged parameters when none of that is in fact needed?

I have now spent a good part of the evening going through my Freedom 10 and Link 1000 manuals as well as the Xantrex site. First of all I notice that there does not seem to be any connection between the 0 amp reset of the Link and the actual charge stages on the Freedom. The Charging is done as follows regardless of the Link's amp meter:

(1) Bulk Charge. Keeps a constant current (50A in my case) until the bulk voltage is reached (14.3 in my case)

(2) Acceptance. Keeps a constant voltage (the bulk voltage) and the current will gradually drop down to 6-7A. This stage will never run more than 1h.

(3) Float charge. Keeps the battery at a constant float voltage (13.4 in my case). The remaining charger amps are available for DC applications from the charger.

The 6-7A value is taken from my Freedom manual and I don’t know if charged current percentage is used if connected to the Link 1000. This is not clear in any text and it must be said that the manuals are not easy to interpret always.

Rich is never cheated of any charging because even if he is recharging a much depleted battery which would require an acceptance time of more than 1h the float charge will keep on charging, but it will take longer.

He also writes “Then to make matters worse, the recharge efficiency factor is recalculated to a higher value (ex. 0.97 vs 0.95) so the at the next charge cycle the Link 20 thinks that the batteries require fewer input AH for the used AH” and I don’t know where in the documentation he has found that the CEF value would affect the charging by thinking the battery requires fewer AH. Perhaps the Link 20 has a different manual, but that sounds way too weird to be true.

I have had my setup for 3 years now and am very pleased with it and we spend most time on anchor in the summer and much time with shore power in the winter so the charger/link gets to work in both scenarios.

 

[mitiempo]

Sybaris
If the adjustments (15v and1%) are done the meter should never count positive as it now does - and you ask about this as yours does this. The meter is counting positive because of the problems I explained. When it counts positive you will never know where you stand until it zeros again. The shunt should be accurate and is not adjustable. If it has any errors they will remain constant over its life. It is installed near your batteries and just passes along the accurate flow of amps to the meter. The meter on the other hand can be inaccurate in the circumstances described - the reason you have plus amp readings. The reason you have the meter is for accurate readings. If you are getting positive readings it is not accurate as it thinks the batteries are fully charged when they're not and this can be cumulative. If the meter is tricked into thinking the battery is fully charged in a cruising situation and electrical items are used at the top of the acceptance cycle further tricking the meter to change to float sooner it will add up. So the next time you plug in to shorepower you end up with even more positive amps and therefore greater inaccuracy before the meter auto-synchronizes (zeros).

"...and he has been cheated only because the amp meter says so. He does not seem to have any other means of calculating that the battery is not fully charged."
Do you? Isn't that what you bought the meter for - its accuracy? It makes sense to adjust the meter for the best accuracy as it's there to tell you battery status. If it isn't very accurate why bother.

" Don't you think it's strange that the engineers at Xantrex went through all the trouble to introduce the two charged parameters when none of that is in fact needed?"
The parameters are needed for accuracy, but don't work in all situations and should be adjusted. If you always charge at the dock after short trips the standard Xantrex parameters work. Every time the batteries are fully charged, regardless of meter readings, the meter resets when amps are drawn from the batteries again. I would think accuracy is nice to have, and more important to have before the batteries are charged fully, not just afterwards. You do have an issue as you describe plus readings, meaning that the meter thought the batteries were charged when they were not. By changing the parameters you are adjusting the meter for your situation. If you regularly get plus readings the issue does exist for you. If I were to fault Xantrex it would not be for settings but for not explaining it well enough in plain English. If you read and understand the manual thoroughly (most don't) they do explain it but it's in several places and requires a full understanding of how these monitors work. By the way every Xantrex monitor made has the same issues as the algorithms are identical in each monitor.

"Rich is never cheated of any charging because even if he is recharging a much depleted battery which would require an acceptance time of more than 1 hr the float charge would keep on charging, but it will take longer."
The acceptance time would not change. The bulk (called "charge" by Xantrex) cycle would be longer and would change to acceptance when the set voltage is reached (14.3 in your system). Acceptance would be normal with the exception that it would change to float too soon when the parameters are met earlier than they should be, and this is where the error occurs in some systems, not all. As I said, if you aren't using any 12 volt items the 13.2 and 2% works. But as I said and the links described it can be tricked. This is what we are changing the settings for - to avoid this error. Yes the battery will charge eventually, but it will take longer as more charge will have to go into the batteries in float mode than if the error did not occur. When that 12 volt appliance pulls from the battery and lets the monitor see a net amps in that is too low it declares the battery "full" before its time. This is avoided with the change to 15v and 1%.
One other important reason to know battery state of charge at a time other than full charge is "Time to Recharge". Batteries should not be taken below 50% level very often or their lifespan is impacted a great deal. If you are cruising and using to 50% and charging to 85% which is the most efficient plan, it is very important to know when the 50% level is reached. If your meter calls the battery "full" at say 90% instead of 100% it will not be accurate when it says 50% the next time the battery is drawn down. It will really be at 45%, and if the battery is again called "full" before its time it just gets worse. This is why it is very important to know state of charge with a reasonable accuracy. This is one of the main reasons to have the meter in the first place.

"...and I don't know where in the documentation he has found that the CEF value would affect the charging by thinking the battery requires fewer AH. Perhaps the Link 20 has a different manual, but that sounds way too wierd to be true."
It's on page 19 of your manual under the bold heading "Charge Efficiency Factor (CEF) and How It Is Used". It's not wierd but essential. When you use 1 amp from a battery you have to put more than 1 back. The less you have to put back the more efficient your battery is. The standard Xantrex setting is 87%. This means that for every amp used you have to put 1.15 amps back.
Every time you use more than 10% of your battery bank it recalculates this number when the battery is considered "full". If the meter thinks the battery is full before its time, it is obviously more efficient as far as the meter is concerned. Because the meter calculates that your battery is more efficient it thinks that next time your batteries need charging they will need less amps returned to be full. This is what Rich is referring to and it is true.
I hope this helps explain it better.
Brian

 

[Sybaris]

Hi Brian,

I hope this helps explain it better.
Brian

It Certainly doesn't.
Let us break this down into small statements and think outside the box. Please don't answer immediately but have a think about each statement. My answers are "True" to all statements.

Statement 1: Setting the values to 15V 1% effectively disables the Xantrex Charged Parameters (as described on page 25 in the Link 1000 manual). I think we agree on this and Rich says so as well, True or False?

Statement 2: With the Charged Parameters disabled, we are fully reliant on the amp counter, i.e. the shunt measuring the amps going in and out. I think we agree on this, True or False?

Statement 3: Rich advocates switching off the CEF calculation totally by setting it to a user defined fixed value of 94%. I think we agree that Rich said so in his text, True or False?

Statement 4: (this is taken from your reply and I definitely agree that you sometimes need to put more than 1 amp back for each amp going out but I have not found in my manual that the standard setting is 87% but that doesn't matter)
"When you use 1 amp from a battery you have to put more than 1 back. The less you have to put back the more efficient your battery is. The standard Xantrex setting is 87%.This means that for every amp used you have to put 1.15 amps back."
Remember that the amp meter registered 1 amp going out and 1.15 amps coming in. This means that the amp meter will eventually get increasingly out of sync and 0 will not indicate fully charged. Let us say for example that my battery now is 75% full and the fridge starts up and uses 15Ah, if I then switch on the charger I might have to add 18Ah to be back at 75%. So the amount going in is not always the same as the amount going out. True or False?

Statement 5: Following up on the previous two statements, Rich has set the CEF to a fixed value of 94% so the Xantrex thinks that the battery is 94% efficient, and it should therefore always put back very close to 1 amp for each amp going out, regardless of the state of your batteries. True or False?

Statement 6: (this is taken from the Xantrex manual)
"At a discharge rate above 5 amps [so if I am for example running the fridge, a couple of lights, the VHF and some more instruments I might be drawing say 14 amps] then the battery will supply less than the rated capacity."
I.e. if you draw 100amps from an 100Ah battery it will probably last for less than 1/2 hour, so it will only give around 45% = 45Ah. The amp meter will then have registered an outgoing current of -45Ah, but if you put 45 back with the charger your battery will not be full so when the counter gets back to 0 you are now undercharged. The example of drawing 100Ah is obviously extreme but it shows that the amount put back will need to be more than that taken out if you are drawing more than 5 amps. True or False?

In brief here is what I am trying to say.
By disabling the "Charged Parameters", which Xantrex engineered to estimate when a battery is fully charged, the device is now only using the amp counter (amp going in and out) to decide when the battery is full (amp counter at 0). Remember that the amp counter is just a shunt, it is only measuring what is sees going in and out.

Compare this to a barrel of water with a gauge measuring the water going in and out. We start by filling the barrel by adding 150 liters and since this is the first time we set the counter to 0 indicating fully loaded. We next leave the barrel overnight but there is a tiny crack in the bottom so we have lost 3 liters by next morning (this is to simulate a higher than 5 amp draw, or inefficiencies in the battery due to age or anything else). Next we decide to tap 25 liters and the meter will now show -25. For good measure we then decide to fill the barrel again, and since it is closed so we can't look in, we look at the meter and fill 25 liters until the meter again shows 0. The barrel is now full. Wrong, it only contains 147 liters although the meter says 0.

The fact is that it can easily be shown that the amps going out are not always the same as the amps going in, in order to reach the same charge (see statement 4 and 6), hence, you cannot rely on the amp counter only, and that is why Xantrex designed the "Charged Parameters".

Furthermore, by switching the CEF calculation off, you are giving even less information to the Xantrex algorithms, so that even if the amp calculation would be adjusted by the known efficiency of the battery it would not be of any use because it would not know the real efficiency of the battery.

I hope you might question Rich's reasoning if you analyze my statements, and if not then as I said before we will just have to agree to disagree. Since you have chosen to disable the Charged Parameters you might want to check what Xantrex says about this to be on the safe side. In any case I thank you for a nice argument, I have enjoyed digging deep in the manuals while thinking about this and now understand my Freedom/Xantrex setup even better than before.

Cheers,
Per