Charger and inverter settings

[booster]

I am in the process of doing the final testing and settings on our new power system, and thought it might be handy to have some of this information in one discussion. I am still vacillating on some of the settings, so it would be interesting to see what others have settled on. I don't think the system components make much difference if the operation and settings are similar, but I would expect that Magnum, Outback, Victron, Blue Sky, Morningstar, etc would be a big part of it. Mostly they just need to be settable.

If anyone has anything that they have found that is odd, obscure, or that took some tweaking to get right, it would be good for all of us to see, I think.

My current hangup is charge voltage and float transition (return, ending, tail) amps. I thought I was all set on using the Lifeline 14.3/13.2 settings for voltage, and my tested 1.0 amp return amp setting. My tests are making me rethink it for a couple of reasons. The charge cycle to full, from 220ah down, is very long, approaching 12 hours. Looking at where the time was going, it was getting to under 2.5 amps of charge in 6 hours. The last 2 amps of change took another 6 hours, with the last amp taking 4.5 hours of the six. That is a long time for little return, and way above the hold times we normally hear about for AGMs.

I reran the test at 14.6v absorption and it shortened the time by about 1 hour, but almost all the savings came in the early full voltage time, with the end still being dragged out.

If I had used the Lifeline general recommendation of .5% of capacity, or 2.2 amps (I can only set to 2 or 3amps, though) it would have been done in about 6.5 hours.

Other battery manufacturers, charger manufacturers, etc, recommend a wide range of return amp settings, from .1% for Odyssey to 3% for others. Some chargers are even at 5% recommended. Most that I talked to like Blue Sea and Magnum said actually testing the batteries to see what they take is best, which I did.

I did a new round of checking out battery manufacturer recommended profile charts, and came across this one on the Fullriver site.




It also had this as part of the description for the profile




This profile clearly shows that they expect the battery to continue to charge once it goes to float, and explicitly say they want at least 8 hours of float to do it. The graph highlights the dropping current on float. I couldn't find anyplace else that said anything like this, but many other brands want a equalization voltage level, low current, stage at the end of the charge cycle, which would also infer that they know they are not all the way full.

To me, the question is if they are saying that having the battery on full absorption voltage to the very, very end, is bad? It is also possible they want to allow for variations in the charging that might keep the charger locked in absorption forever, or way too long. Questions about this are way beyond the customer service techs at the manufacturers, who just recite the literature guidelines. Near impossible to get to the designers and researchers.

I think I am going to rerun the 14.6v test again, and use a return amp setting of 2 amps. I will then watch the amps at float to see how long it takes to get the .1-.2 amps at float that I see if I run it all the way on full voltage. If it would get there in an overnight campground charge, that would be great, I think, but I don't think it will. We will see.

This may be pointing to having two sets of settings, one for when you are traveling and doing the once a week get full charge at campgrounds, and a different one for at home where it has days to do it. Of course, if we drive for several hours, almost all the absorption time will already be done when we get to the campground.

[gregmchugh]

Are you using the temperature compensation option on the charger and is the absorption voltage matching the temperature compensated value shown in the Lifeline manual?

[booster]

Originally Posted by gregmchugh

Are you using the temperature compensation option on the charger and is the absorption voltage matching the temperature compensated value shown in the Lifeline manual?

The temperature compensation is on and functioning correctly, and the absorption voltages are basically the two, separately listed, specs put out be Lifeline.

14.3v+/- .1v is the old standard and is still in the tech manual. The 14.6v is from the 14.4v+/- .2v that is now listed in the cut sheets for most of the batteries, including the ones we have.

We only see 5*F increase in temp at 14.3v and 10*F at 14.6v, when we do a 220ah recharge cycle.

[booster]

Looking at the Victron charging profile that they show in their literature, it appears they are counting on a higher "float" voltage and then another float voltage they call "storage" which is more the typical float voltage for folks like Lifeline. It is interesting that they do it this way because they don't measure the return amps and do the absorption end based on a calculated algorithm based on bulk time. Since it is only timer based, it almost certainly won't be really accurate, so the must be counting on safely finishing the charging at the reduced voltage, and then going to true float charge. PD does something very similar, but with a fixed timer for absorption.

[markopolo]

I think I'd mostly stay with the Lifeline guidelines:

Bulk Charge 7.10 – 7.30 volts
Absorption/Acceptance Charge 7.10 – 7.30 volts
Float Charge 6.55 to 6.70 volts

They don't distinguish between Bulk, Absorbtion or Acceptance.

You could go with the max recommended:

14.6V until amps drop to 2A. Then float at 13.4V.

or, more gentle:

14.4V until amps drop to 2A. Then float at 13.2V.

or, right in the middle:

14.5V until amps drop to 2A. Then float at 13.3V.

Can you program in a weekly "Battery Refresh" to Bulk voltage then return to float?

[booster]

I think maybe some of this actually makes some sense. I have been revisiting some stuff that didn't make sense originally, but is blending in with some of the current stuff. Powerstream pushes high rate charging, but they stop before totally full and finish at a mid 13s voltage, with the claim that this limits the time that the batteries see higher than gassing voltage, especially at the end of the charge cycle. They don't appear to use amps, just time.

Looking at the Progressive Dynamics profile, it looks surprisingly along the same lines, Especially when you look at their example of charging.





It looks as it they, too, chose a relatively moderate absorption time and count on finishing at 13.6v and then to 13.2v later on. It makes sense, as if they overcharge by time at 13.6v, the battery is hurt much less than at absorption voltage that is above the gassing voltage. It is interesting to see the times to full charge in the options listed. They don't, however, say how they tell if the charge is really full.

[gregmchugh]

Originally Posted by booster

The temperature compensation is on and functioning correctly, and the absorption voltages are basically the two, separately listed, specs put out be Lifeline.

14.3v+/- .1v is the old standard and is still in the tech manual. The 14.6v is from the 14.4v+/- .2v that is now listed in the cut sheets for most of the batteries, including the ones we have.

We only see 5*F increase in temp at 14.3v and 10*F at 14.6v, when we do a 220ah recharge cycle.

Are the updated charging specs for Lifeline online somewhere?

[booster]

Originally Posted by gregmchugh

Are the updated charging specs for Lifeline online somewhere?

They are on, I think, all the cut sheets for the individual batteries. For ours this is it.

Lifeline Batteries - Marine & RV Deep Cycle Batteries

[booster]

Originally Posted by markopolo

I think I'd mostly stay with the Lifeline guidelines:

They don't distinguish between Bulk, Absorbtion or Acceptance.

You could go with the max recommended:

14.6V until amps drop to 2A. Then float at 13.4V.

or, more gentle:

14.4V until amps drop to 2A. Then float at 13.2V.

or, right in the middle:

14.5V until amps drop to 2A. Then float at 13.3V.

Can you program in a weekly "Battery Refresh" to Bulk voltage then return to float?

The Magnum won't do the timed refresh bulk like shown in some of the other profiles, but it can rebulk, or refloat, based on a voltage. If it was set high, like 12.7v, it would probably do it at least once every couple of weeks. I am considering that over just continuous floating.

What keeps coming back to me, without having the extra stage at the end for "storage" is that there is probably a preferred profile for camping, and a slightly different preferred profile for home, getting to shore power nearly full, or long term shore power. The camping one likely would fall a bit outside of the Lifeline specs.

I am going to put this into my test tomorrow to check times to full charge and things. What I would envision would be that when you are camping as we do, and plan to do, we will be off grid and maybe not totally full all the time, based on lots of things. In those cases, all the battery manufacturers like to have a totally full charge every 5-7 charge cycles. To us, that would be a stay at a full service campground, which we usually try to work into longer drives between destinations, so we might have as little as 10 hours of charging time, but usually more like 14-16 hours. If we could charge at 14.6v absorption to 2 amps, which is within 1.2 amps of absolutely full and takes about 6.5 hours at 50%, and then switch to 13.6v float to finish by morning, we could probably get the best of everything. Full charge with minimal time at gassing voltage, which Lifeline says it about 14.1 volts.

At home or on long time shore power, the recommended 14.3-13.2v would be fine, as it will get them full and hold them there with less stress on the batteries. If we were essentially full from driving and solar, which would be very common, this would also be the preferred profile, I think. The big thing is to not spend the last 3-4 hours at gassing voltage to get the last bit of charge.

Changing parameters on the Magnum is a 30 second job, so we will be able to do whatever we need to do easily. My guess is that we would rarely need to use the higher voltages because of the driving and solar, but it would be nice to know when it would be beneficial. The good thing is that all we have to do is go to float at 13.2 volts and if we have between 0 and .2 amps after settling, we know we are full.

For those with the PD chargers, this would also work well, once you knew how the batteries react to charging, based on amps from the Trimetric readings, and it is easy to use the Charge Wizard to go into bulk or float at will. It is likely that it is better for the batteries to be at 13.6v for the finishing than to put it back to 14.4v to finish the charging, unless you don't have enough time.

[gregmchugh]

Originally Posted by booster

They are on, I think, all the cut sheets for the individual batteries. For ours this is it.

Lifeline Batteries - Marine & RV Deep Cycle Batteries

Thanks, I find this new charging voltage recommendation to be interesting. On one hand you have the Lifeline Technical Manual showing very precise specs for charging voltages:

Absorption: 14.3v +/- 0.1v at 77 deg F
Float: 13.3v +/= 0.1v at 77 deg F

and looking at the data in the rest of this manual you see that all the info appears to be based on very controlled lab testing to define the optimum, in some sense, way to operate the battery.

In the battery sheet, we see recommended charge voltages given as:

Absorption: 14.2 - 14.6 volts
Float: 13.1-13.4 vollts

which in my mind are real world recommendations on charge voltages that will provide near optimum performance in normal use. This seems like very reasonable guidance given the real world variations in battery performance during its life and the fact that some chargers do not allow precise setting of charge voltages. For the typical user, the new recommendations will, I expect, give them performance and a battery life they are happy with.

Running testing as you are doing over the range of voltages to come up with an optimum setting for your batteries and charger seems to me like a fine experiment to see how the system performs today.

Once you have gotten things calibrated for the batteries at this point, are you planning to recalibrate at some regular basis in order to retain optimum performance?

Don't take any of this as any negative comment about taking a scientific approach to optimize your system and I also enjoy doing the same thing.

But, I am wondering if, in the end, you will be getting enough increase in performance in day to day usage to justify the effort to continue to do the testing to this level of detail at later points. How many more life cycles will you get? How much added battery capacity will you have that you really need? If you design the system using the 50% discharge limit to cover your typical usage and on occasion need to go to 80% to handle the loads won't you be getting a reasonable life out of the batteries, assuming of course you follow the other recommendations on getting to full charge regularly, etc. With a good battery monitor in place to keep an eye on system performance, I would be happy to optimize once and then proceed on not worrying too much about getting a little closer to optimum. But that is my practical side vs my engineering side that would be analyzing the crap out of the data every day

[markopolo]

Just quoting a bit:

Originally Posted by booster

...........................................

For those with the PD chargers, this would also work well, once you knew how the batteries react to charging, based on amps from the Trimetric readings, and it is easy to use the Charge Wizard to go into bulk or float at will. It is likely that it is better for the batteries to be at 13.6v for the finishing than to put it back to 14.4v to finish the charging, unless you don't have enough time.

Some PD chargers have a built in Charge Wizard profile but no way to force back to 14.4V. Mine is like that.

Last night, after running the 66 amp load while testing, I would have liked to force 14.4V to see the amps flow back in. The charger just went into 13.6V mode. They'll eventually get fully charged because of the boost to 14.4V every 21 hours.

[booster]

Originally Posted by markopolo

Just quoting a bit:



Some PD chargers have a built in Charge Wizard profile but no way to force back to 14.4V. Mine is like that.

Last night, after running the 66 amp load while testing, I would have liked to force 14.4V to see the amps flow back in. The charger just went into 13.6V mode. They'll eventually get fully charged because of the boost to 14.4V every 21 hours.

I didn't know they made different versions, I thought they all could be forced to both 14.4v and 13.6v whenever you wanted. That is a bummer because that is a very big feature to me.

I think, if I understand their literature right, you would get another 14.4v cycle if you unplugged and replugged the shore power, though. PITA to be sure, but for testing not to bad.

[markopolo]

The manual and battery sheet info is very similar if you assume the battery sheet numbers are at 77F.

+0.2V higher allowed on absorption.
-0.1V lower allowed on float.

14.3 bulk & 13.1 float both seem too low for modern robust AGM's.

-----------------------------------------------------

With my mixed bag of batteries I've set the Trimetric to indicate the batteries are charged when both 14.4V and 1 amp in conditions are met. I may have to adjust that but, from past observations, I think they'll get there.

[markopolo]

Originally Posted by booster

I didn't know they made different versions, I thought they all could be forced to both 14.4v and 13.6v whenever you wanted. That is a bummer because that is a very big feature to me.

I think, if I understand their literature right, you would get another 14.4v cycle if you unplugged and replugged the shore power, though. PITA to be sure, but for testing not to bad.

I'll try that today. Last night I had turned off both the 30amp main breaker and the 15amp breaker to the PD unit while testing. Maybe the PD unit still senses neutral or ground so it remembered where it was prior to the interruption.

[booster]

Originally Posted by gregmchugh

But, I am wondering if, in the end, you will be getting enough increase in performance in day to day usage to justify the effort to continue to do the testing to this level of detail at later points. How many more life cycles will you get? How much added battery capacity will you have that you really need? If you design the system using the 50% discharge limit to cover your typical usage and on occasion need to go to 80% to handle the loads won't you be getting a reasonable life out of the batteries, assuming of course you follow the other recommendations on getting to full charge regularly, etc. With a good battery monitor in place to keep an eye on system performance, I would be happy to optimize once and then proceed on not worrying too much about getting a little closer to optimum. But that is my practical side vs my engineering side that would be analyzing the crap out of the data every day

I have no real idea of how much improvement in cycle life any of this will actually give, and that part is virtually untestable in the real world. The largest part of it, for me, is trying to understand the entire dynamic of how it works and interacts, and make some sense of it. If I get a little more life, capacity, or convenience, that is a bonus. In our daily use, once done, we will certainly not be looking at fine details, but the knowledge of how it works will be there to recognize oddities much more easily if they occur, and to gain more insight.

That said, if you look at the level of test and change that come before the stuff I am doing now, there are some real benefits to be had, I think. The biggest of that category would be the use of return amps to terminate the absorption stage voltage on all of the charging sources, and the choice of the right equipment that won't interact badly with each other. A major part of figuring out that part of it was getting through all the claims and different styles of chargers and batteries in the market to learn how they had them setup. It turned out that most of the setups certainly aren't optimum, and they don't do a very good job.

I think the best thing that could happen would be if better knowledge of this kind of stuff gets more common and mainstream, so the manufacturers get pushed to start making better products to address the current shortcomings.

[gregmchugh]

Originally Posted by booster

I have no real idea of how much improvement in cycle life any of this will actually give, and that part is virtually untestable in the real world. The largest part of it, for me, is trying to understand the entire dynamic of how it works and interacts, and make some sense of it. If I get a little more life, capacity, or convenience, that is a bonus. In our daily use, once done, we will certainly not be looking at fine details, but the knowledge of how it works will be there to recognize oddities much more easily if they occur, and to gain more insight.

That said, if you look at the level of test and change that come before the stuff I am doing now, there are some real benefits to be had, I think. The biggest of that category would be the use of return amps to terminate the absorption stage voltage on all of the charging sources, and the choice of the right equipment that won't interact badly with each other. A major part of figuring out that part of it was getting through all the claims and different styles of chargers and batteries in the market to learn how they had them setup. It turned out that most of the setups certainly aren't optimum, and they don't do a very good job.

I think the best thing that could happen would be if better knowledge of this kind of stuff gets more common and mainstream, so the manufacturers get pushed to start making better products to address the current shortcomings.

Don't take my comments wrong, I think you are doing some very interesting and useful stuff. Just the kind of analysis needed to really understand how all this stuff works and I am just like any other geek always wanting to understand what is really happening in anything technical.

Keep sharing the testing results, they are very useful. It would be nice if the charger manufacturers at least allowed more configuration of the charger operation to let the technically inclined users set up the system to their likeing.

[markopolo]

Automatically terminating all charging based on return amps is just great.

Returns amps is an easy and ideal way to know if your particular batteries are charged.

Before, I could check return amps with the clamp on ammeter. Now I can just look at the Trimetric. But it still requires looking and manual intervention.

New RV's, particularly the higher priced units, need to start coming with (or the option to purchase) that level of automatic monitoring and control installed by the RV manufacturer. That would make it easy for folks who are not so technically inclined to keep the batteries in top condition.

[booster]

Originally Posted by markopolo

I'll try that today. Last night I had turned off both the 30amp main breaker and the 15amp breaker to the PD unit while testing. Maybe the PD unit still senses neutral or ground so it remembered where it was prior to the interruption.

That is interesting, and maybe PD has fallen into line with most of the other manufacturers (not a good thing in this case, maybe). Nearly all of the chargers look at the battery voltage when they are connected to shore power. First they make sure they have adequate battery to charge, but then most of them determine if they should go into absorption or float. Usually, it is just a just a voltage reference point, like 12.6-12.8 volts. If they see that voltage, they go to float. I think this came to be to try prevent overcharging of already full batteries on chargers that have fixed absorption times. While the certainly is a consideration, it can very often also lead to undercharging, if the battery isn't full, but the charger sees higher voltage from solar or surface charge from driving. Our Magnum also does this (lots of details in the Magnum issue thread), which would be OK if used in straight timer mode, but it also does it in return amp mode, which is just plain wrong to do. In return amp mode, you can't overcharge a full battery as it will quickly go to float based on amp, so no issue. It doesn't have the same problem in CC/CV mode and does a full cycle each time if in return amp mode, but then you don't ever get float. The Blue Sea charger we used to use did a full cycle each time it saw shore power and worked perfectly using return amps that way. The good thing, for us, is that you can still force it into bulk with a button push, and then it runs a return amp charge profile and will either shut off right away if full, or finish the charge and go to float. Have to remember to do it, though, which shouldn't be necessary. At that point solar or surface charge don't matter.

There are ways that might allow you to get it into absorption again. It is possible that if you drop the battery voltage artificially, you might be able to get the force button to work, or it might go in with a shore power cycle. If you have a 12v load big enough to pull down the batteries to 12.5v or so, that may just do it when you plug in. It will be harder to pull down the voltage when the charger is on, because you will have to use all it's capacity also. Maybe you can do it with the separate inverter in that case, and try the force button.

Now you have me wondering if the separate Charge Wizard stuff does the same thing? Bummer if they did, because the PD always appeared to be the economical, albeit manual, way to do return amp charging easily.

[booster]

Originally Posted by gregmchugh

Don't take my comments wrong, I think you are doing some very interesting and useful stuff. Just the kind of analysis needed to really understand how all this stuff works and I am just like any other geek always wanting to understand what is really happening in anything technical.

Keep sharing the testing results, they are very useful. It would be nice if the charger manufacturers at least allowed more configuration of the charger operation to let the technically inclined users set up the system to their likeing.

I have no problem with questions, suggestions, added information from folks. All if it adds to the mix and brings in different experiences and points of view. Many find the discussions to technical, but a few don't, and that is where it all gets to come together.

I find it really interesting to look back and see how far that charging and batteries discussion has progressed over the years here on the Forum. When all this started, AFAIK, return amp charging was never even a known entity here. It showed up as a small detail in the instructions for the Blue Sea charger I got to address a multibank issue and escalated from there. Now we are into the minute details, theory, specific equipment goods and bads, and seeing systems based on all of it being built. It would be much more difficult to be where we are now, if you are trying to do it all on your own, without input and "reality check". There is a reason all the good companies have "design review" meetings--they work, just like they do here.

[booster]

[QUOTE=markopolo;36935]The manual and battery sheet info is very similar if you assume the battery sheet numbers are at 77F.

+0.2V higher allowed on absorption.
-0.1V lower allowed on float.

14.3 bulk & 13.1 float both seem too low for modern robust AGM's./QUOTE]

From what I have been seeing in practice and trying to fish out of everybody's literature, that is the way I am leaning also, especially on the absorption. When I first found the higher voltage for absorption, my first thought was that they are carefully trying to address undercharge issues in some way. Many of the other brands have gone to 14.7v absorption. Trojan did similar with their wet cells when the put out the "daily charge" of higher voltage than normal charging. It was to be able to get a full charge overnight, as in golf course cart charging. We know the Lifelines will survive the voltage, as they allow "conditioning" at very high voltages for a long time period.

It may just be the low voltage, long time, charge cycles give the best results in the lab, but higher voltage, higher charge rates, work best in the real world. I would also put a disclaimer on it that if you want to do high rate, high voltage, charging it is essential to have temperature control and return amp termination to prevent overcharge and overheat issues.