"Smart" Battery Chargers

[sailorboy1]

I don't think my "smart" charger/inverter is very "smart" at all!! I will admit I haven't really paid a lot of attention to what my "smart" ProMariner unit does to acturally get the batteries to 100% SOC the 1.5 years I've had it. I mostly only use it for bulk charging when I need to supplement my solar and never have really expected it to fully recharge my batteries.

Since I've been in a slip a couple of months I have had the charger on, but I've also have the solar still on and during the day the solar was doing all the work and going through full charge cycles each day. Since I'm leaving soon I decided to turn off the charger so I could watch the batteries cycle for a couple of days to see if all was well with them .

Today it's overcast and rainy so I turned the charger back on and it ramped up to absorption, supplying max current in bulk just like it is supposed to do. But it decided the batteries were fully charged and dropped into float when they were still accepting 4% of 20C and the batteries were still -16AH. That's not fully charged!!!

Since the solar had shutdown because it sensed the charger was on I reset it and it was happy to take back over and charge back those -16AH. My solar controller is "stupid" and has no battery type programming etc. All it knows is to do bulk charging till it reaches absorption voltage I set in it and then to hold that till it reaches the programmed number of hours or low current and drop into float.

So much for charger manufacturers claims of smart "advanced charging algorithms". They are just stupid chargers with a fancy name.

[Stu Jackson]

You're right, of course. They're only "smart" compared to older one voltage level chargers. Unlike your solar controllers which may, just may, be able to know the current, these newer chargers don't, because they are not connected to any shunt. So they can't determine when to switch "stages" other than simple egg timers.


If you search on egg timers by Maine Sail you can read away. Indeed, Maine Sail's writeup about your very charger discusses this, too:

Wiring a new charger From Maine Sail:

http://forums.sailboatowners.com/ind...5/#post-880275
and
https://marinehowto.com/installing-a...ttery-charger/


john31ct has been calling it "end amps" or "trailing amps" for quite some time.

[john61ct]

I have yet to come across **any** charge source that will get a bank to 100% Full as per endAmps out of the box, even those costing thousands.

The best are user-custom adjustable, but the owner must **do so** to match their setup, verifying that point is reached "most cycles" if possible.

And adjust for changing conditions and usage patterns.

The ideal is a charge source integrated with a BM reading trailing acceptance via a shunt **at the bank**. Very few do.

ProMariner is a brand, which model?

> still accepting 4% of 20C

Do you mean, still accepting 0.04C or 4A per 100Ah capacity? Or something else?

> the batteries were still -16AH

According to which BM? What makes you think that is properly calibrated? They rarely are, and usually must be reset every few cycles, ideally every time you verify 100% via endAmps.

Originally Posted by sailorboy1

So much for charger manufacturers claims of smart "advanced charging algorithms". They are just stupid chargers with a fancy name.

Keep in mind, charge sources have been getting better, but the more sophisticated ones, getting closer to our fast rising expectations, do cost **a lot** more than the mainstream definition of "intelligent".

[sailorboy1]

All my settings for my BM etc. are correct and I’m not playing the “expert” questions games.

[Stu Jackson]

Originally Posted by john61ct

>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

According to which BM? What makes you think that is properly calibrated? They rarely are, and usually must be reset every few cycles, ideally every time you verify 100% via endAmps.

>>>>>>>>>>>>>>>>>>>>>>>>>>>

This one ^^^ is getting truly tiresome.


Why?


Because [some] [many] [everyone] of us who own these coulomb counters ACTUALLY know how to use them.


Maine Sail started this mantra a decade or so ago, and it seems to have woven itself into the repeatable but maybe false cliche. I wrote an article on it, The Gotcha Algorithm, and he did one as well.



Perhaps it would be more helpful to say "Figuring you know how to properly calibrate your coulomb counter..." instead of "They rarely are..." How do you know they're not?

[Wood]

I received this response from Promariner support regarding end amps.........


"
Craig,
Can you be a little more precise on absorption time? Voltage during absorption will be constant with declining current. Is absorption phase a set timed amount like 1 or two hours? Or is it based on trailing amp acceptance - and if so what is that amperage?


Good Morning,

The absorption time is determined by the current being called for by the batteries. There is not a specific timer to determine that time period. If the batteries are having a hard time taking a charge for some reason, the unit will time out after about 18 hours. Once the output gets to under an amp, it should switch to the auot-maintain.

Regards,

Craig Roy
ProMariner Support
1-800-824-0524
www.pmariner.com"

[john61ct]

Originally Posted by Stu Jackson

Because [some] [many] [everyone] of us who own these coulomb counters ACTUALLY know how to use them

Yes for the regulars here, no problem.

99.99% of owners would not be aware of the issues involved **at all** and thus that should be the default assumption.

If you get tired of repetition, please just ignore it.

[a64pilot]

You will have to turn it off and on at least once to get to full.
There is some charging in float voltage, but it’s slow. All chargers I am familiar with drop to float prematurely, it must be some kind of protection scheme to drop to float when close to full and let the batteries finish under float voltage.

Having said that Solar can really confuse any “automatic” charger, it can easily make a battery appear to be more charged than it is.

My Magnum can be set to drop to float at a set end amps, so can my outback 80 with additional parts.
However even the Magnum can be confused by Solar, if bank voltage is above a certain voltage it won’t go to absorption voltage, but float and Solar can of course raise the banks voltage above that certain point making the bank appear as if it’s almost fully charged when it’s not.
I can trick the Magnum by programming it make it drop to absorption voltage temporarily.

I’d like to have a simple switch that absorption voltage one way and float the other and let me control it, but as far as I know this simple thing doesn’t exist. I’d really particularly like it for the alternator.
Mark Grasser’s old regulators had a “force to float” switch that you could flip and of course force it to float, but so far as I can find no one else’s does.

[Stu Jackson]

Originally Posted by john61ct

Yes for the regulars here, no problem.

99.99% of owners would not be aware of the issues involved **at all** and thus that should be the default assumption.

If you get tired of repetition, please just ignore it.

john, that was not my point. Good pun, using default, though! Gotta hand it to ya!



Teaching moments should be used, rather than blanket statements like **at all**.


The repetition, if any, should be:


If you want to learn how to use your coulomb counter:


1. RFTM


2. Read this, which also includes a handy dandy link to MS's article, too:


For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

http://c34.org/bbs/index.php/topic,4922.0.html

DEFAULTS are factory settings that are made to be modified to suit your setup.

Also read this one:

Programming a Battery Monitor (by Maine Sail)

https://marinehowto.com/programming-a-battery-monitor/




********************************


See, not so hard (it's eight years old).

[john61ct]

post as I like I will

[noelex 77]

Originally Posted by a64pilot

All chargers I am familiar with drop to float prematurely, it must be some kind of protection scheme to drop to float when close to full and let the batteries finish under float voltage.

This is not universal by any means. It depends on the algorithm.

As a general trend using the default settings a small (relative to the size of the battery bank) smart battery charger will tend to drop to float too late and a large (relative to the size of the battery bank) smart battery charger will tend to drop to float too early. However, there are plenty of exceptions.

[kenbo]

Originally Posted by john61ct

Yes for the regulars here, no problem.

99.99% of owners would not be aware of the issues involved **at all** and thus that should be the default assumption.

If you get tired of repetition, please just ignore it.

But John, sailorboy1 is a regular on this site and not one of the 99.99% of owners...

I've always felt that while trailing amps is a good way to know when you're fully charged there are other just as good ways such as delta V/delta T. But when your not on the bench and your battery is online doing it's thing, micro measuring becomes more like a "how many angels can dance on the head of a pin" exercise.

[sailorboy1]

Originally Posted by Wood

I received this response from Promariner support regarding end amps.........


"
Craig,
Can you be a little more precise on absorption time? Voltage during absorption will be constant with declining current. Is absorption phase a set timed amount like 1 or two hours? Or is it based on trailing amp acceptance - and if so what is that amperage?


Good Morning,

The absorption time is determined by the current being called for by the batteries. There is not a specific timer to determine that time period. If the batteries are having a hard time taking a charge for some reason, the unit will time out after about 18 hours. Once the output gets to under an amp, it should switch to the auot-maintain.

Regards,

Craig Roy
ProMariner Support
1-800-824-0524
www.pmariner.com"

Yeah I asked them once when considering installing one in a friends boat and got a similar meaningless answer. I pushed back a few times and finally got an answer from a “senior” engineer that boiled down to it being a fancy timer.

I find it stupid that my Outback solar controller can measure amps and my fancy smart charger/inverter that cost more than twice as much can’t.

[a64pilot]

It is measuring amps, it will display them too. It’s measuring both amps, voltage and time.
But it can’t know what it’s connected to, a 1000 AH bank and a single starting battery will terminate at different points. Then you have gel, AGM, and flooded batteries too, and selecting each default program only sets charging voltages, which is close, but I used the custom mode to be dead on.
So it uses an algorithm that is a little conservative and gets you close without overcharging, cause perfect isn’t possible on something that is “automatic”.
Assumption that on average dropping to float a little early is better than hanging in at absorption for too long and overcharging. Remember most that have batteries that water can be added don’t often check, and AGM and Gel you can’t.
At least that is my belief.
But it works and works perfectly well for the average person that docks the boat, plugs in and goes back to work until the next weekend, which is the majority of boat owners.

The rest of us who know and understand, can simply turn it off and back on.

[john61ct]

Originally Posted by sailorboy1

I find it stupid that my Outback solar controller can measure amps and my fancy smart charger/inverter that cost more than twice as much can’t.

Outback makes great kit.

But measuring amps put out by the controller does not help with intelligent charge termination if there are variable concurrent loads.

Very very few charge sources can be configured to transition to Float based on endAmps **measured at the bank** where it's actually helpful.

As long as AHT is adjustable, the owner can ensure the right voltage is maintained until 100% Full is reached.

Even the fanciest most expensive kit requires adjustments to work properly, expecting great performance OOTB is just unrealistic.