Hack Freedom 20/Link-2000R for LiFePo4?

[jviss]

Has anyone considered "hacking" their older charge/inverter system to work with a LFP bank? I was thinking, as a minimum, of modifying it so it just stops charging when it enters FLOAT. I'd also like it to ring a bell or something, so I'd know it was done and could shut down the engine if I was just charging batts.

Could be an interesting DIY project.

 

[Stu Jackson]

Good question.
I've had my Link 2000 for almost 20 years and have become somewhat of an "expert" on its use, with many thanks to Rich Stidger.
The Link 2000R is identical to my Link 2000 although it does not have the regulator controller built-in to it (for those who don't know what the R stands for).
From everything I know, the ONLY function the Link can actually control is when it signals the charger to go into float from acceptance.
This switch to float is based on only two things that the Link algorithm can measure: the charging voltage and the percent of bank capacity. Those two default parameters are able to be changed in the Link and are discussed in great detail in the links below.
I have a Freedom 15, and the manual states that the Link cannot change the charging voltages on a Freedom unit, at least on mine.
I don't know how one would get into the "guts" of the chip inside the Link because it is not designed to stop charging itself, but only to tell the Freedom when to switch to float from acceptance to float (the three stages or phases on the link are titled Charge (which is really bulk), acceptance and float), based on these parameters.

The "Gotcha" Algorithm Links: (mine and Maine Sail's which concludes that the algorithms are identical for Links and Victrons)
For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"
Link-series Charging Algorithms -- The "Gotcha" Factor!
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)
Making Your Battery Monitor More Accurate - Marine How To

 

[jviss]

This switch to float is based on only two things that the Link algorithm can measure: the charging voltage and the percent of bank capacity.

I don't think this is correct. I can set mine to terminate ACCEPT based on time or charging current. So, it must also measure current and time.

I have a Freedom 15, and the manual states that the Link cannot change the charging voltages on a Freedom unit, at least on mine.

Mine are programmable.

I don't know how one would get into the "guts" of the chip inside the Link because it is not designed to stop charging itself, but only to tell the Freedom when to switch to float from acceptance to float (the three stages or phases on the link are titled Charge (which is really bulk), acceptance and float), based on these parameters.

I can make a circuit that detects when it goes into FLOAT and shut off the alternator.

 

[Davidasailor26]

Depending on how DIY you want to go it should be possible to do this with a microcontroller like the hobby-friendly Arduino. You could have the Arduino read the DC voltage, and when it falls to Float open a relay to power down the charger. The Arduino could trigger an alarm too. If your boat is somewhere with wifi it’s possible to control it remotely too so you could top off the charge before you go to the boat.

 

[Stu Jackson]

I don't think this is correct. I can set mine to terminate ACCEPT based on time or charging current. So, it must also measure current and time.

........

Perhaps you misunderstood. The Link 2000R time sequence appears to be for charging with the alternator. You asked about using the charger for lifepo.

 

[jviss]

Perhaps you misunderstood. The Link 2000R time sequence appears to be for charging with the alternator. You asked about using the charger for lifepo.

Perhaps you misunderstood! I was talking about charging LFP with the alternator, using the Link 200R regulator.

 

[Stu Jackson]

Yes, you're right, my apologies. Might you not agree that it could be pretty much the same answer though in terms of getting "into it", i.e. the Link's chip, while a separate logic board like the Arduino noted might do so functionally?

 

[jviss]

Yes, you're right, my apologies. Might you not agree that it could be pretty much the same answer though in terms of getting "into it", i.e. the Link's chip, while a separate logic board like the Arduino noted might do so?

I was thinking an external circuit, like an Arduino project, as you suggest.

 

[Garbonzo]

The Victron Monitors have an internal relay switch that can be told to do anything you want... Would that not suffice? The LFP charging situation is so much simpler than LA that just ON and OFF is all you need to know.

 

[jviss]

The Victron Monitors have an internal relay switch that can be told to do anything you want... Would that not suffice? The LFP charging situation is so much simpler than LA that just ON and OFF is all you need to know.

How would that work?

I honestly don't want to invest another nickel in Victron, the first was such a big disappointment. I'd rather, it I was adding gear, change over directly to something designed specifically for LFPs on sailboats, 'though I haven't found anything like that yet.

 

[Garbonzo]

Victron Monitors have an on off relay that you can program for whatever you want... Like shut off the field wire to the alternator at predetermined voltage (14.4 volts) or SOC and then turn back on at a lower setting. Very simple. Since the LFP needs no absorption or even float, you are done.

 

[jviss]

Victron Monitors have an on off relay that you can program for whatever you want... Like shut off the field wire to the alternator at predetermined voltage (14.4 volts) or SOC and then turn back on at a lower setting. Very simple. Since the LFP needs no absorption or even float, you are done.

Thanks.

You know, I've done some thinking about this, about FLOAT for LFPs, and what that means on a boat.

I don't recall where I read it, but you are apparently not supposed to FLOAT an LFP. But then, if you are motoring and also using electricity, like electronics, fridge, autopilot, charing a laptop, etc., you would much rather use the generated power from the alternator for those loads than deplete the LFP house bank. So, how do you do that?

Well, I think FLOAT is a small charge, meaning, the charger is applying a voltage that's above the open circuit voltage of the bank to induce a small maintenance charge. But, if you regulate the alternator output for the terminal charge voltage of the bank, you. will stop charging when the bank is full, but the house loads will be taken up by the alternator instead of the house bank.

So, you really don't want to stop the field current, you want to "FLOAT" at a lower than usual voltage, as exactly equal to the banks terminal charge voltage as possible - maybe just a little lower, to be on the safe side.

What do you think?

 

[Stu Jackson]

What do you think?

I think you need to keep thinking.

you want to "FLOAT" at a lower than usual voltage, as exactly equal to the banks terminal charge voltage as possible - maybe just a little lower, to be on the safe side.
------ I assume you meant float at a lower than usual float voltage. If the charge voltage is less than the bank's resting voltage, nothing will get charged because charging only occurs when the charging voltage is larger than the bank's resting voltage.

I don't recall where I read it, but you are apparently not supposed to FLOAT an LFP.
------ That would be just about every single thing written about LFPs.

But then, if you are motoring and also using electricity, like electronics, fridge, autopilot, charging a laptop, etc., you would much rather use the generated power from the alternator for those loads than deplete the LFP house bank. So, how do you do that?
----- How you do that is you put the AO into the house bank, use it from the house bank and recharge the house bank. Much of the good news about LFP is that they have high acceptance, so recharging occurs pretty rapidly even when the cells are not depleted very much if at all.

So, you really don't want to stop the field current
----- It would seem to be a much easier thing to do than to change charging voltages of an alternator. Based on say a Balmar MC-612 or 614, one could reprogram the V for acceptance to the float V and the float V to your "lower float" V, but I don't see any advantage.

Let's say you have your fridge on, you're motoring so the alternator's outputting, and your batteries are fully charged, having just left the dock. In this case, any battery sensed regulator will get to float voltage very quickly (although the Balmar regulators do have minimum times for the first two stages which you wouldn't want to eliminate because it wouldn't be there when you actually needed it). If the load exceeds the alternator's output (which will be small), the bank will start to draw down. The reason for this is your electrical system is still being "run" by the bank, not the alternator. The alternator, at whatever stage/phase of charging it may be, is putting Amps into the battery bank and then the system. Always.

You wrote: you would much rather use the generated power from the alternator for those loads than deplete the LFP house bank. So, how do you do that?

----- You don't and you can't unless you completely rewire your electrical system to divert the AO to the loads, which is a dangerous thing to do if the load disappears and the AO has nowhere to go. That's the basic fallacy of your whole approach. It's like people who think their shorepower charger is actually running their system when they're plugged in. It's not, it is merely charging the house bank which in turn is running the system.

No idea why you're trying to complicate something so basic and simple.

 

[jviss]

No idea why you're trying to complicate something so basic and simple.

I'm not overcomplicating anything, I'm just starting a discussion about how to keep running loads off the alternator when the engine's running without overcharging the LFP bank. And, I'm drawing a distinction between the traditional float stage of charging regulators, designed for lead acid chemistries, and how you might want to operate your regulator with LFPs to not overcharge them, but run the loads from the alternator.

I assume you meant float at a lower than usual float voltage.

Yes, the 'usual' float voltage being higher than the resting voltage of LA chemistry batteries, and inappropriate for LFP.

If the charge voltage is less than the bank's resting voltage, nothing will get charged because charging only occurs when the charging voltage is larger than the bank's resting voltage.

Obviously so.

How you do that is you put the AO into the house bank, use it from the house bank and recharge the house bank.

It's not clear what you're saying here.

It would seem to be a much easier thing to do than to change charging voltages of an alternator.

There's no such thing as the "charging voltages of an alternator." The alternator output voltage is regulated by control of the field current. For example, the unregulated output of an automotive-type alternator can run to 90 to 120 VDC. Changing the charging voltage is something a smart regulator can do, easily. It's programmable for most, even for my ancient system.

and your batteries are fully charged, having just left the dock.

I'm at a mooring. The batteries are never fully charged.

If the load exceeds the alternator's output (which will be small), the bank will start to draw down.

Obviously so, but not likely with my 125A alternator.

The reason for this is your electrical system is still being "run" by the bank, not the alternator. The alternator, at whatever stage/phase of charging it may be, is putting Amps into the battery bank and then the system. Always.

The wires are not "smart," and don't know or control where the current should go. So, for a system with the AO on the house, and the loads connected to the same node [1], current will flow in the the legs of the node according to the load presented - the impedance, if you will. So, for a fully charged pack, at the terminal charge voltage, near zero current will flow into the house bank; as the house load increase the regulator will adjust the field current to maintain the selected voltage, and the additional current produced will flow to the loads, not into the battery first and then into the loads. There's no sequencing or memory in the wires.

"Run by the bank" is not a technical concept of any value in this discussion.

You wrote: you would much rather use the generated power from the alternator for those loads than deplete the LFP house bank. So, how do you do that?

----- You don't and you can't unless you completely rewire your electrical system to divert the AO to the loads, which is a dangerous thing to do if the load disappears and the AO has nowhere to go. That's the basic fallacy of your whole approach. It's like people who think their shorepower charger is actually running their system when they're plugged in. It's not, it is merely charging the house bank which in turn is running the system.

I'm not suggesting one separate the AO from the bank, For example, when plugged in to the dock, your batteries are acting like big capacitors that filter the output of the charger, and smooth out any temporary load impulses, but on average, the charger is "running" the loads.

Let me net this out: what do people think of running loads off the alternator once the LFP bank is fully charged? I think the answer is to choose a working voltage for the LFP bank that won't overcharge the bank, like, for example, picking the 90% SOC point, which might be 13.2 Volts for your bank, and then just adjusting, i.e., programming the regulator for that voltage as FLOAT. That's all.

Even better, for a smarter system designed for LFP, have a way of selecting what maximum SOC you want for the bank and have the regulator stop charing at that point while still running the loads - so different voltage set points for float. If you want to run at 80% max, then maybe it's 13.32V (based on your particular pack. A smart BMS that actually controls the regulator could do that, rather than just shutting down the regulator.

 

[Garbonzo]

Well, interesting discussion. I am only pointing out that LFP's are much simpler to manage than what we are used to and some folks have a hard time adjusting to it. IF you have a Victron, a Balmar regulator and alternator and an LFP bank, you can very easily tell it what to do, either by SOC or peak voltage, and even an full charge alarm. Concern over sulfation, which up to now has been the bane of all things battery and makes a 100% SOC the wholly grail is gone. Set your regulator to cut off the field at 80%, no issues, I already control the peak charging rate to 90 amps on the 125 amp Balmar at mainsails recommendation so the cutoff would be no issue.

 

[jviss]

Set your regulator to cut off the field at 80%,

How do you do that?

Do you presently have an LFP bank ant the setup you describe?

 

[Garbonzo]

How do you do that?

Do you presently have an LFP bank ant the setup you describe?

Yes and no. I have the balmar set up with the alternator charge limiting on the Oasis firefly's in my steel schooner, and the Victron set for 80% with Battleborn LFP's in my RV. Also, have a switch on the boat to cut of the field if desired, through the balmar. All very simple, BUT you must have an external programmable regulator like the Balmar setup. Got all the boat stuff from MaineSail.

In order, for this to work on my RV, I have to have the chassis batteries (eg starter) hooked up to the alternator so when you cut off the LFP charging, you don't crater the alternator, which you will be concerned with if you have a conventional alternator on the boat.

 

[jviss]

so when you cut off the LFP charging

How does this happen? The BMS disconnects the bank?

 

[Garbonzo]

How does this happen? The BMS disconnects the bank?

In my case the Victron relay switches a battery disconnect solenoid. Also can hook an alarm to let you know charging is complete and you can flip the switch.

 

[jviss]

So, @Garbonzo , if I understand this correctly, on the RV you use lead acid connected to the alternator always, and disconnect the house LFP when they reach 80% SOC. Is that correct? So, your house loads run off the LFP bank even when you're running the engine, and you draw them down to some point and then reconnect the bank to the alternator? Is that so?