How Does a Heart Interface Link 2000 Work?

[Stu Jackson]

Originally Posted by Delfin

And if I had a Link 2000, that sounds like a good idea. Since I have, as I said, a Link 20, that isn't an option.

True, the 20 doesn't, although the algorithm is identical. FWIW, this was covered in the Gotcha article where I discussed my friend's Link Pro which similarly doesn't have that CEF feature.

[john61ct]

Some BMs / charge controls can stop-charge (transition to Float) based on reading trailing amps acceptance directly, which is much more accurate than coulomb-counting.

Using the latter does require an accurate CEF setting.

I believe the LINK units should be able to actually auto-calculate CEF, measure it directly.

Older Victron BMVs did so, 500 series was also sold as "XBM" by Xantrex.

Newer Victron BMV 700 series rely on the owner adjusting CEF manually.

[Stu Jackson]

Originally Posted by john61ct

1. Some BMs / charge controls can stop-charge (transition to Float) based on reading trailing amps acceptance directly, which is much more accurate than coulomb-counting.

2. Using the latter does require an accurate CEF setting.

3. I believe the LINK units should be able to actually auto-calculate CEF, measure it directly.

4. Older Victron BMVs did so, 500 series was also sold as "XBM" by Xantrex.
Newer Victron BMV 700 series rely on the owner adjusting CEF manually.

1. Would you care to share specifically which ones? Coulomb counting has to be involved, doesn't it? Why? Because trailing or end amps IS counting coulombs, i.e., amps.

2. What do you mean by "accurate?" The shunt sends the signal to the monitor and "measures" amps. While of course accuracy is to be desired, how does this "strawman" (to use ramblinrod's favorite word) come into this at all, john?

3. Of course they do. However, if you'd bothered to read the Gotcha article I linked, AND Maine Sail's piece, you'd have LEARNED that the auto CEF recalc is one of the two functions that should be modified from the default values to avoid a too early switch to float. john, I OWN a Link 2000. I KNOW HOW IT WORKS. My Gotcha article explains why. You wrote: "I believe the LINK units should be able to..." If you're guessing, please stop. Also, as the Gotcha says, the Link 20s and Link Pros cannot change the CEF like the Link 2000 can.

4. I don't own a Victron, and refuse to guess. What we do know, from my Gotcha article and Maine Sail's, is that the algorithms for the Links and the Victrons are the same.

[john61ct]

Measuring amps (instantaneous) is all that's needed for endAmps based termination, no need at all for having an accurate CEF %,

as opposed to "totalizing Ah in vs out" charge cycle control, where an accurate CEF % is critical.

[Stu Jackson]

Originally Posted by john61ct

Measuring amps (instantaneous) is all that's needed for endAmps based termination, no need at all for having an accurate CEF %,

as opposed to "totalizing Ah in vs out" charge cycle control, where an accurate CEF % is critical.

john, one of the things I learned in my 50 year engineering career is that one has to work with the available tools. While your statements may be true, it doesn't begin to address the OP's question of how his Link 2000 works.


It counts coulombs. And "totalizing Ah in vs out" is absolutely worthless because of battery acceptance, which means that it takes much longer to put amps back in as the battery gets full.


But the Link(s) and other coulomb counters work just fine but they do not and cannot do anything other than switch from bulk & absorption voltage to float voltage for any charger that is hooked up to them, i.e., Freedom units. Otherwise, i.e., if it's NOT a Freedom inverter/charger, it's ALL manual control: read the end amps, turn off charger, NO control of the switch from abs to float which is all left up to the egg timer on ALL chargers that are NOT a Freedom I/C.

An "accurate" CEF is a fool's errand based on real world use of these tools.

I have reset my CEF to a fixed value to avoid "premature floatulation." It's one of the two functions that I changed. Both of them are included in the link I posted. When my end amps show as 1-2% of my house bank capacity at absorption voltage by resetting the charger off then back on on, I have a full bank.

It's really that simple. It's also Basic Battery Charging 101.


The Link 2000 allows you to use instantaneous amps or averaged over three or four different periods of time. I keep mine on instantaneous, easy to read end amps, of course taking into account any loads that are on, but those are usually pass throughs at that stage of charging.


john, do you have a Link unit?

[john61ct]

Originally Posted by Stu Jackson

It counts coulombs. And "totalizing Ah in vs out" is absolutely worthless because of battery acceptance, which means that it takes much longer to put amps back in as the battery gets full.

Exactly what CEF adjustment is designed to handle.

And yes no one cares about it as some abstract that needs to be objectively "accurate",

it is just an adjustment that needs to be tweaked - on any instrument that has that feature - until the 100% SoC guesstimate based on Ah counting (coulomb totalizing) is in alignment with

endAmps, the actually objective direct measure of 100% Full and proper stop-charge point.

Just clarifying my meaning for you, we are not in any disagreement here.

[Pizzazz]

My understanding is that the Link 2000 starts, say from battery full. When amps are drawn from the battery it calculates remaking capacity based on the peukert constant and the rate of draw. When charging it calculates energy put in based on the CEF (which is not constant during the charging cycle). Once it reaches battery fully charged, it calculates the average CEF based on some function. All of this involves a approximation but it averages out well. If you know the CEF for your battery chemistry, you can help the Link 2000.

[Stu Jackson]

Originally Posted by Pizzazz

My understanding is that the Link 2000 starts, say from battery full. When amps are drawn from the battery it calculates remaking capacity based on the peukert constant and the rate of draw. When charging it calculates energy put in based on the CEF (which is not constant during the charging cycle). Once it reaches battery fully charged, it calculates the average CEF based on some function. All of this involves a approximation but it averages out well. If you know the CEF for your battery chemistry, you can help the Link 2000.

No, because the CEF can either be allowed to adjust itself OR to be set at a fixed figure. This is covered in my Gotcha link. At least on the Link 2000, but not on the Pros or 20s.



I do not understand your last sentence. "Help" the Link? Do just what?

[Pizzazz]

I think we are saying the same thing, Stu. When the Link 2000 recalculated the CEF at every complete charging cycle, over time it comes with an average CEF. However the calculation is an approximation, based on the accuracy of the peukert constant, the state of the battery, etc. If one new the CEF for a particular battery and age, it can be entered into the Link 2000 to help it calculate amps in/out without this approximation. I am not sure which method is better. At the end of the day all of this is an approximation and it is probably good enough in both cases. I have left mine on auto recalculation and I am happy with the overall results.

[scfoster]

Thanks for the info. Purchased a one owner 2001 Beneteau 361 two weeks ago; it has a Freedom 20 with a Link 2000. Took about a week of fiddling with it to begin to understand it's functions.
The original owner did some odd things with the electrics.
There is a 200Ah 8A4D AGM battery (bank #1), a 200Ah Deka 904D wet cell battery (bank #2) and an Interstate SRM-27 engine start battery.

The Link 2000 is set up to monitor bank #1 & #2. When charging on shore power, there is a higher voltage supplied to the engine start battery.

The plan is to do a complete audit of the system. Would prefer to combine the 400Ah into a single bank, more than likely Firefly batteries and put the engine start as #2 on the Link 2000.

Have set up the Functions on the Link 2000. The information posted here has been helpful.
Couple things I've noticed. If the F02 battery type for #1 is set to 03 (AGM), #2 inherits that setting.
For some reason, the system will not switch from 'Accept' to 'Float'. Not sure why. Left the charger on for a long period of time and the AGM was gassing.

Was thinking of replacing the Freedom 20 with a Xantrex Freedom SW 2012 or 2013, with the more modern system control panel. Jury still out on that.

[Pizzazz]

I would not replace the Freedom with Link 2000 until it fails. Initially, you can combine your house batteries into a house bank and the starter battery into bank #2. Set the charging parameters to in between wet cell and AGM, they are close enough. The Freedom charges all batteries with the same parameters. There is a function F09 or F11, I think, that controls which battery current to use to transition to accept and float. Choose the smaller battery to ensure full charging but make sure your battery selector switch is set to both when charging so that it knows when to stop. This is the most common reason why the charger does not switch to float.

After your current batteries are run down, you can invest in better batteries.

[scfoster]

Originally Posted by Pizzazz

I would not replace the Freedom with Link 2000 until it fails. Initially, you can combine your house batteries into a house bank and the starter battery into bank #2. Set the charging parameters to in between wet cell and AGM, they are close enough. The Freedom charges all batteries with the same parameters. There is a function F09 or F11, I think, that controls which battery current to use to transition to accept and float. Choose the smaller battery to ensure full charging but make sure your battery selector switch is set to both when charging so that it knows when to stop. This is the most common reason why the charger does not switch to float.

After your current batteries are run down, you can invest in better batteries.

The problem with combining is one set is AGM and the other wet cell. Not planning on taking any long trips, so may do away with the wet cell and put the engine battery back in front of the engine where it belongs. Then document everything and clean up anything I find.