Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[CatNewBee]

If you research LFP, of course you'll watch them all the time. That is not the point.
As a liveaboard, they are cycled every day, sometimes even during the day according to your charge sources.

The LFP bank leaves somewhere between full and empty all the time. My 1000Ah has discharged over 600Ah sometimes when I use A/C, and everything else on board during the night, sometimes it never reaches the set point for days, some days it hits the full voltage twice. Its not a big deal, and my setpoints are safe, they are way below the full cell spec. 14.2V (3.55V) for float are way below 14.6V stated by the manufacturer (full charge 3.65V)

[CatNewBee]

btw. while tuning the setpoints, I rely on my Multimeter at the battery contacts, that is exactly the same reading than the REC battery BMS display (+/- 0.002V). The readings of the Victron MPPT is different to the reading of the inverter/charger is different to the BMV reading on the shunt. they are not tbat accurate due to wiring losses and voltage drops, even at 0 current there are variations of up to 0.2V. That said,my setpoints are empirically evaluated and adopted based on the true voltage at the battery and may seem to high, in fact they are just right.

[CatNewBee]

Also the float setting is ok, it is set to keep the battery at -60.. -80Ah (92..95% SOC), and suppliesall devices if possible with power without having any charge current going into the battery. When the solar does notprovide enough energy, the battery is further discharged. so this is for me the optimal setting.

[CatNewBee]

here some screenshots...

[john61ct]

Originally Posted by CatNewBee

14.2V (3.55V) for float are way below 14.6V stated by the manufacturer (full charge 3.65V)

But still lots higher than I would go, especially if holding Absorb time.

But your bank, your call, you may get 2700 cycles and be very happy with that.

[CatNewBee]

Originally Posted by john61ct

But still lots higher than I would go, especially if holding Absorb time.

But your bank, your call, you may get 2700 cycles and be very happy with that.

even then, this are 7..10 years. So I am ok. with that.

[john61ct]

Me, hoping to move the bank to many boats / homes / vehicles, and eventually pass it on to my grandkids.

Haha just kidding but…*

[FLYSolartech-GiocoSolutions]

Sorry CatNewBee, you've probably already written that but I haven't found it, your cat is 24V based. Am I right?


What about the 1000ah batteries, what voltage each one?


Thanks in advance

[CatNewBee]

it is a 12V system, 4 cells 1000Ah each.
they store 15kWh of Energy (measured) nominal cell voltage is 3.4V (2.8...3.65V is the spec, they are 98% full at 3.55V)

[arsenelupiga]

CNB, question for you:

alternator - in another blog, i have seen claim that hitachi 80 A alternator does not have temperature compensation. Meaning that if alternator is used to charge LFP, will burn out, as voltage does not increase fast enough and limit output. However, internet research and experience is telling me that my alternator x 2 has working temperature compensation, therefore limiting output when temperature increasing to protect alternator. What is your experience ?

I am trying to think of experiment to prove or disprove my alternator temperature compensation works. Turn on all consumers and see if output is falling & voltage not rising. Any better idea ?

I like to think of issues in advance and test every component before implementation.

[john61ct]

Temperature compensation is a separate feature from

**protecting** an alt from running too hot by reducing amps output (derating).

Both are functions of the voltage regulator, not the alt itself.

Nearly any alt can be converted to use a full-featured VR like Balmar's MC-612.

Which also has the rare feature of allowing for user-custom voltage setpoints, IMO required for use charging LFP.

The same is true for Sterling's BB line of DCDC chargers, an alternative solution to the frying-alt problem, and has the advantage of working from any DC charge source, or even traveling with the bank from one boat / vehicle / off-grid cabin to the next.

[arsenelupiga]

Originally Posted by john61ct

Temperature compensation is a separate feature from

**protecting** an alt from running too hot by reducing amps output (derating).

Both are functions of the voltage regulator, not the alt itself.

Nearly any alt can be converted to use a full-featured VR like Balmar's MC-612.

Which also has the rare feature of allowing for user-custom voltage setpoints, IMO required for use charging LFP.

The same is true for Sterling's BB line of DCDC chargers, an alternative solution to the frying-alt problem, and has the advantage of working from any DC charge source, or even traveling with the bank from one boat / vehicle / off-grid cabin to the next.

contrary to popular belief, we need to motor very little our L 400, hence alternator generated energy is last of my worries. so i want to get as cheap as possible on alternator.

[CatNewBee]

Well we motored a lot in the last weeks and the alternators are stil alive,
they yeld about 20..40A to the huge LFP bank, (another 20..30A go straight to the board electric for lights, navigation, radar, auto pilot, fridges and some current will charge the AGM starter battery for not very long) so I assume they are not overloaded.

My explanation for this is, there are the separation diodes from Lagoon and also the higher voltage of the battery with 13.4V, so there is simply not enough difference to push a higher current. My batteries drop to SOC of 70..80% usually over night with hgh usage of the galley, watermaker etc, also the solar contributes to keep them charged.

I do not think, they will hurt my alternators in normal operations. We have run the engine on a passage for 36 hours non stop, all good, we use to run at 4kn and 1500rpm consuming 1.4l/h, to the wind at 2000rpm to stay above 4kn on one engine at a time. Once per day we push the lever to 3000rpm for 10min to clean it.

At much lower SOC with Voltage below 13V there may be much higher Amp draws, but as ĺong as the battery is not too discharged - no issues at all.

[arsenelupiga]

Originally Posted by CatNewBee

Well we motored a lot in the last weeks and the alternators are stil alive,
they yeld about 20..40A to the huge LFP bank, (another 20..30A go straight to the board electric for lights, navigation, radar, auto pilot, fridges and some current will charge the AGM starter battery for not very long) so I assume they are not overloaded.

My explanation for this is, there are the separation diodes from Lagoon and also the higher voltage of the battery with 13.4V, so there is simply not enough difference to push a higher current. My batteries drop to SOC of 70..80% usually over night with hgh usage of the galley, watermaker etc, also the solar contributes to keep them charged.

I do not think, they will hurt my alternators in normal operations. We have run the engine on a passage for 36 hours non stop, all good, we use to run at 4kn and 1500rpm consuming 1.4l/h, to the wind at 2000rpm to stay above 4kn on one engine at a time. Once per day we push the lever to 3000rpm for 10min to clean it.

At much lower SOC with Voltage below 13V there may be much higher Amp draws, but as ĺong as the battery is not too discharged - no issues at all.

thanks, very helpful. It helps you run low revs, instead of say 2500 RPM.

Only problem i see is in situation where have to push the boat hard against wind/waves at say 2500+ RPM in some kind of gale/storm conditions pushing you towards shore.

Do you have ability to manually disable alternator to house batt charging or you confident enough not to cause any issues even in extreme situations when revs high for longer periods?

[CatNewBee]

Originally Posted by arsenelupiga

thanks, very helpful. It helps you run low revs, instead of say 2500 RPM.

Only problem i see is in situation where have to push the boat hard against wind/waves at say 2500+ RPM in some kind of gale/storm conditions pushing you towards shore.

Do you have ability to manually disable alternator to house batt charging or you confident enough not to cause any issues even in extreme situations when revs high for longer periods?

I have the automatic cut-off of my legacy chargers (shore, alternator) based on SOC (above 95%) they kick in again below 90% SOC, but I could manually switch the solenoid off in maintenance position, so it stays off all the time. Never felt this would be necessary yet.

The main reason for ths set up was to allow the AGM start batteries to run their full absorption with disconnected LFP and not to protect the alternators.