External alternator regulator for Lithium banks ?

[Jd1]

Has anyone run across an external regulator that is built strictly for lithium battery banks ?
Although I currently run an MC-614, I would like to switch to something specifically geared for lithium batteries once the last lead acid batteries die a natural death and get replaced with lithiums.

[witzgall]

The mc-614 can be programmed and setup to work nicely with lifepo4 batteries.


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[Jd1]

Originally Posted by witzgall

The mc-614 can be programmed and setup to work nicely with lifepo4 batteries.

Ok, I bite, what you suggest for setup parameters ?

The reason I was thinking about a dedicated lithium regulator is because the charging is quite different. There is no float, there is no real absorption and even bulk charge is more along the line of 'cram it in as fast as possible and only reduce current towards the very last end stages'.
I would want bulk charge to be the highest alternator output current possible with a belt manager setting possibility and a alternator temperature cutback. I have not yet achieved this state with my settings (but then the lead acid battery causes problems with that so I have to wait until I am totally lithium)
So yes, some of the settings are similar to the mc-614 but there is enough difference to make a dedicated controller worthwhile IMHO....
Really looking forward to those parameters though !

[mbartosch]

Originally Posted by Jd1

Ok, I bite, what you suggest for setup parameters ?

The reason I was thinking about a dedicated lithium regulator is because the charging is quite different. There is no float, there is no real absorption and even bulk charge is more along the line of 'cram it in as fast as possible and only reduce current towards the very last end stages'.
I would want bulk charge to be the highest alternator output current possible with a belt manager setting possibility and a alternator temperature cutback. I have not yet achieved this state with my settings (but then the lead acid battery causes problems with that so I have to wait until I am totally lithium)
So yes, some of the settings are similar to the mc-614 but there is enough difference to make a dedicated controller worthwhile IMHO....
Really looking forward to those parameters though !

AFAIK there is no such thing as a dedicated Lithium alternator regulator, but the MC614 can do pretty well.

Charging LiFePO4 batteries is both easier and harder than lead acid.

Easier because Lithiums do not need a lot of the charging regime voodoo which has been developed to address lead acid behavior. As described in the long LiFePo4 thread, for LiFePO4 set the absorption voltage to 13.8 or 13.9 V and float to 13.3 or even 13.2 V and you are good to go.
For "charging speed" it really does not matter if you set it to 13.9 V or any higher value, the charging current will max out in both cases for a half empty battery. The only difference with different voltages is that you will reach much higher (unnecessarily high) in the "top charge knee". You want to avoid that, hence 13.8/13.9 V.
No need for special chargers, just set the thresholds to these values and you are good. On the MC614 you can reduce maximum field excitation (belt manager), and you should do that (read Maine Sails article). Using a temperature sensor on the alternator is a good idea as well.

Voltage difference between resting voltage and charging voltage in combination with the total resistance of wiring and batteries will determine the maximum current that will flow during charging. Typically the current will be limited by charge sources capacity, not by the batteries and wiring.

Effectively this means that a dedicated "bulk" stage is meaningless for Lithium. They are literally in bulk mode all the time. Bulk for lead acid means the charger ramps up charging voltage to overcome internal resistance in order to max out charging current (that's the constant current phase of the charger). It's not applicable for LiFePO4 because they are already accepting max current at absorption voltage without the need to raise it further (nor would it be possible, voltage simply collapses to pack voltage plus a few fractions of a volt, just enough according to Ohm's law to allow maximum charging current the charging source can deliver).

Because of the extremely low internal resistance the batteries pretty much short your charging source - which makes charging harder than lead acid. When designing your system you will have to make sure that all your charging sources can withstand delivering maximum current continuously.

Finally, connecting LiFePO4 and lead acid to the same charge regulator (even separated by the battery isolator) is not a good idea. You will either undercharge the lead acid battery or overcharge the Lithium bank. Both is not good.

I suggest rip out the battery isolator, attach the alternator regulator and alternator only to the Lithium bank and configure it for LiFePo4 values. Get a DC-DC charger (e. g. a Balmar Digital Duo) and charge the lead acid bank via the DC-DC charger from the Lithium bank.
Cleanest solution, and not that expensive.

[a64pilot]

This is one specifically for Life-Po batteries

Mark Grasser - DC Power Solutions

Although I think your issue will be with the alternator, not the regulator, but thats just a guess, I don't have LIfe-Po batteries

[Stemci]

Good Morning,
Medsail.com featured this guy on a podcast recently on this subject. While I am boat less at the present time and can't comment from personal experience , I love to learn about anything to do with sailing. I believe http://www.bruceschwab.com/ is worth a visit. Steve

[Jd1]

Originally Posted by mbartosch

For "charging speed" it really does not matter if you set it to 13.9 V or any higher value, the charging current will max out in both cases for a half empty battery.

This is exactly what I was thinking originally .... alas, this is not the behavior I am seeing. The regulator seems to have smarts in it that looks at set bulk voltage, currently sensed voltage and then adjusts current that is supplied - independent of capacity of the alternator.
I see sensed voltage at less than set voltage and current less than capacity even when the belt load manager is off (set to zero) and the alternator temperature is well below maximum. I do not have a battery temperature probe connected but don't believe that should be an issue.
If I artificially reduce sense voltage, with all other parameters unchanged, I can increase charge current up to the maximum the alternator can supply. This aspect of the regulator was unexpected and is the sole reason why I am monkeying around with things!

[Jd1]

Originally Posted by mbartosch

I suggest rip out the battery isolator, attach the alternator regulator and alternator only to the Lithium bank and configure it for LiFePo4 values. Get a DC-DC charger (e. g. a Balmar Digital Duo) and charge the lead acid bank via the DC-DC charger from the Lithium bank.
Cleanest solution, and not that expensive.

That was my very first thought until I found out that the Digital Duo (and indeed all DC-DC chargers I looked at) switches on at 13V. This would presumably put a continuous load on the lithium bank until it drops below 13V (and I do not know what the tolerance is - does it start at 12.9, 13 or 13.1) which is definitively not what I want.
Please correct me if I am wrong because I agree that this would be a much cleaner solution!

[Maine Sail]

Originally Posted by Jd1

That was my very first thought until I found out that the Digital Duo (and indeed all DC-DC chargers I looked at) switches on at 13V. This would presumably put a continuous load on the lithium bank until it drops below 13V (and I do not know what the tolerance is - does it start at 12.9, 13 or 13.1) which is definitively not what I want.
Please correct me if I am wrong because I agree that this would be a much cleaner solution!

You simply wire it to work as a key on device with ignition and only charge the start or reserve bank when the engine runs...

[Maine Sail]

Originally Posted by Jd1

This is exactly what I was thinking originally .... alas, this is not the behavior I am seeing. The regulator seems to have smarts in it that looks at set bulk voltage, currently sensed voltage and then adjusts current that is supplied - independent of capacity of the alternator.
I see sensed voltage at less than set voltage and current less than capacity even when the belt load manager is off (set to zero) and the alternator temperature is well below maximum. I do not have a battery temperature probe connected but don't believe that should be an issue.
If I artificially reduce sense voltage, with all other parameters unchanged, I can increase charge current up to the maximum the alternator can supply. This aspect of the regulator was unexpected and is the sole reason why I am monkeying around with things!

Your issue is likely being caused by improper sensing location and not feeding alt B+ directly to the LFP battery.

Also important, and even Balmar is incorrect on this in the manual (or just lacks the proper guidance), the regulator neg/black and red/v-sense wires make up the sensing circuit, not just the red v-sense wire. The red sense wire is only half of the voltage sense circuit.

Unless both the reg black and reg v-sense see the actual LFP terminal voltage your regulator will be voltage limiting before the bank is at the voltage limit. Correct voltage sensing for LFP is critical because we have a very narrow window of voltage to work within.

[Jd1]

Originally Posted by Maine Sail

You simply wire it to work as a key on device with ignition and only charge the start or reserve bank when the engine runs...

Ahhh .... so simple .... never occurred to me. Tanks!

[Jd1]

Originally Posted by Maine Sail

Your issue is likely being caused by improper sensing location and not feeding alt B+ directly to the LFP battery.

Also important, and even Balmar is incorrect on this in the manual (or just lacks the proper guidance), the regulator neg/black and red/v-sense wires make up the sensing circuit, not just the red v-sense wire. The red sense wire is only half of the voltage sense circuit.

Unless both the reg black and reg v-sense see the actual LFP terminal voltage your regulator will be voltage limiting before the bank is at the voltage limit. Correct voltage sensing for LFP is critical because we have a very narrow window of voltage to work within.

As mentioned before (I think) I am not sensing at the actual battery terminal and also do not have the ground sense wire going to the battery. I did however verify on the regulator that it's displayed sense voltage was below the set battery voltage while still current limiting. As an example, the sense voltage might be 13.9V, the set voltage is 14.6V and current was limited to something like 80 amps on a 200 amp alternator.
Having said that, I will verify this again. Unfortunately getting that single ground sense wire in is a MAJOR PITA.
Hmmm, come to think of it, there is nothing saying that the ground sense line has to go into the same path as the power cables - going a substantially longer route should be ok as there is minimum current flowing on that wire. I will have to check what kind of current is expected on that wire and to verify that it isn't the alternators field current because that would still cause an issue with voltage drop over a longish distance on an 18 or so gauge wire.
I really like the suggestion re wiring in the Duo Charge with an ignition interlock like you suggested. That would really be ideal! I will read up on what all is required to get that going. Thanks !

[Maine Sail]

Originally Posted by Jd1

As mentioned before (I think) I am not sensing at the actual battery terminal and also do not have the ground sense wire going to the battery. I did however verify on the regulator that it's displayed sense voltage was below the set battery voltage while still current limiting. As an example, the sense voltage might be 13.9V, the set voltage is 14.6V and current was limited to something like 80 amps on a 200 amp alternator.
Having said that, I will verify this again. Unfortunately getting that single ground sense wire in is a MAJOR PITA.
Hmmm, come to think of it, there is nothing saying that the ground sense line has to go into the same path as the power cables - going a substantially longer route should be ok as there is minimum current flowing on that wire. I will have to check what kind of current is expected on that wire and to verify that it isn't the alternators field current because that would still cause an issue with voltage drop over a longish distance on an 18 or so gauge wire.
I really like the suggestion re wiring in the Duo Charge with an ignition interlock like you suggested. That would really be ideal! I will read up on what all is required to get that going. Thanks !

#1 Run temporary test sense leads

#2 Disconnect alt temp sensor (I am assuming no batt sensor)

#3 Set Belt Manager back to 0

#4 Confirm your settings took and saved

#5 Neg reg wire will carry as much as 1.5A so for a long run you want a wire substantial enough to not incur much drop. Red sense wire carries no current.

Now repeat these tests

[Jd1]

Decided that half measures are 50% too short and I ran a 10 ga wire for the alternator sense negative. While I was at it I installed a couple extra wires for a field cutoff system for the future when I am 100% lithium. Nothing is hooked up yet but the grunt work is done.
I will report on the results when I get things hooked up.
I might just put a switch in to choose which battery I am sensing from ......

[Jd1]

WoooHoooo .... With the ground sense going to the split point between the two banks I have seen charge current go to 120A to the lithium bank and that is with the bank at about 85% state of charge. A bit more wiring to do but already soooo much of an improvement!