LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[Cotemar]

Originally Posted by rjtrane

I have a set of 1,000 AH Winston cells - 16 each in series for a 48v/1,000 AH bank. I'm on my second (boat is dormant half the year) - when I turned on the battery after sitting idle all summer - no charging - no discharging - no loads - it had barely lost any charge.

I have a BMS that monitors all cells and turns off loads/charging if any cell gets out of spec. I have yet to balance the cells since December 2012. Only when the battery is discharged do I notice a significant difference between highest and lowest cell - about 2.82v low and 3.20v high. When charged, all cells are typically 3.34v.

This season, I have ONLY charged with a 6kW solar array and a pair of Outback FX60 controllers.

I'll have a better handle on them once I upgrade my Steyr hybrid drives, which charge or load the battery and give them some serious loads. I typically only run a single 8kBTU A/C, 14 cu.ft. Hitachi fridge, DC/DC converters to ALL 12v and intermittently the induction cook tops and water maker. The drive motors can crank up to 140A/48v each - that should be interesting, but only .25C.

I have alway admired your boat and its design. You have the most solar panels that anyone has ever put on a 40 foot boat.

Will be interesting to see how she goes with the Steyr hybrid drives.

[folivier]

rjtrane did you get the monitor from Balqon? Looks nice.
I'm using 4 of the same cells for a 12 volt system in my motorhome.

[deckofficer]

Originally Posted by folivier

rjtrane did you get the monitor from Balqon? Looks nice.
I'm using 4 of the same cells for a 12 volt system in my motorhome.

How is that 1000 a-hr 12 volt bank working out for you? Was your alternator and wiring up to the task of that kind of charge acceptance?

[folivier]

Working good so far. Having a bit of trouble getting my Freedom 2500 with (older) Link 2000 to charge where I want it. Charging fine at 13.65v & 110 amps but can't figure out how to get it to a higher voltage. The Link is reading 0.4 volts higher than the Victron BMV-600 which matches the battery voltage.
Ran the engine today for 1/2 hour at 1100 rpms. SOC was at 85%, alternator put out 56 amps. Temperature on alternator got up to 94F, belts at 80F, battery isolator at 67F. So no problem so far. I'll try again when SOC is about 50%.
Turned off shore power for a few hours and was using 2% capacity/hour based on SOC readings of Victron. So I should get much better than 24 hours on batteries.
Question: will charging only up to 13.6 volts cause me a problem? I assume it will give me a bit less capacity?

[roetter]

Originally Posted by Joe Parklane

The alternators are Balmar 6 series (small frame) 100 amp. Your alternators (wow internal temp sensors) seems to be working very well...jealous and you have a well regulated system as my very limited knowledge understands. I assume the starting batteries remain in the circuit to protect the diodes when disconnected while charging(my set up also). My system has been set up very conservatively...charging sources stop charging at 13.8, however I have seen some over shoot on my setup (750 amp CALBs 4s4p integrated BMS((BMS set for HVC disconnect @ 14.2) and cell boards per 4s with balance resisters @ 3.525 volt pack 14.1) with voltage climbing to 13.9+ volts briefly. This is very conservative with double redundancy to protect the pack designed and installed by a very knowledgeable electrician.

The Hitachi and Mitsubishi alternators at least have a thermistor in the control circuit of the internal regulator. I assumed that pretty much all internal regulators have that feature. On the Mitsubishi on a Volvo engine the regulator goes as far as totally shutting down the alternator to recover from over temperature. I fixed that problem by cleaning out the dust and dirt from the alternator and the regulator cooling fins.

[rjtrane]

Balqon designed the BMS for me. It has few flaws that will need some reprogramming. Plus a few add-ons. I find them very cooperative and easy to deal with.

The first issue we discover was the Tyco solenoid kept welding shut on start up. Turned out the capacitors in the inverters were causing this, so we devised a "slow start" to charge the capacitors prior to closing the switch.

Once we have the motor/generators up and running again, we'll need to devise a method to have the BMS instruct the hybrids to either stop running or stop charging should a cell get out of spec. Previously, we had to monitor the BMS manually then shut off hybrid as necessary.

The electric motors ran well with the original 400 AH AGM battery bank. But I'm busy installing latest wiring upgrades which is not as easy as hoped.

The Sun Power PV array seems to just keep working. With good power management, Sunshine should be able to live on the hook here in the Floida Jeys or the Bahamas for extended periods of time w/o starting the diesels. Including modest speed cruising of about 25 NM per day from time to time.

I feel similar battery installations with or without the solar could make sense for "normal" cruising yachts.

[Maine Sail]

Originally Posted by folivier

Question: will charging only up to 13.6 volts cause me a problem? I assume it will give me a bit less capacity?

Yes you will get slightly less capacity, I don't know how much because I have not tested it, but if you let the current taper to about 5A of net accepted current at 13.6V you should be upwards of 85% +/- I would think..

[goboatingnow]

Originally Posted by Maine Sail

Yes you will get slightly less capacity, I don't know how much because I have not tested it, but if you let the current taper to about 5A of net accepted current at 13.6V you should be upwards of 85% +/- I would think..

Very cell dependant in my experience , the curve can be so flat that its hard to determine where you are stopping. Some simple amp counting would give an indication

Dave

[Maine Sail]

Originally Posted by goboatingnow

Very cell dependant in my experience , the curve can be so flat that its hard to determine where you are stopping. Some simple amp counting would give an indication

Dave

Exactly but he has Winston's so I would assume they are similar to my bank..

That said limiting voltage to 13.6V will create a longer current taper. Of course even with his inverter he only has 10% of "C" and with his alternator barely 5% of "C" so he may still have a short taper even it voltage limiting at 13.6V..

[Maine Sail]

Resting Voltage Observations:

A while back someone had asked about resting voltages etc.. Over the last week + I have run some observational tests on my bank...

Bank:

4 X 400Ah Winston

Charged:

To Full: 13.82V to 4.6A of net accepted current. (Fluke 179 DVM & Mastech 3050EX charger)

Charge & Loads Disconnected (except battery monitor): Bank allowed to rest for 4 days at 69F.

Open Circuit Voltage Measured: 13.362V

Discharge:

Load: 147A load applied to bank removing -41.4 Ah's

Rest: Battery allowed to rest for 28 hours at 69F

Open Circuit Voltage Measured: 13.358V


Net resting voltage difference after a 147A load applied that removed -41.4Ah's (approx 10% of capacity) is just 0.004V or not even really relevant for measurement purposes on a boat.


BTW I am learning why my Smart Gauge is not able to find SOC on Li. So far I have 8 cycles from 100% to 50%, one cycle from 100% to 0% plus a few 10-20% DOD cycles .....

It does however seem to wok pretty well on LA....

[goboatingnow]

Well snart gauge relies on interpreting the dynamic model of voltage versus Soc for an LA. it will never work properly on Li

Dave

[Maine Sail]

Originally Posted by goboatingnow

Well snart gauge relies on interpreting the dynamic model of voltage versus Soc for an LA. it will never work properly on Li

Dave

I pretty much knew that it would not work, but I wanted to try it anyway. All my emails and attempts to contact the manufacturer went 100% unanswered. I then put Rick at Balmar on the job and they won't even answer the US importer/distributor so I did not feel too bad.

The good news is that it appears to track LA pretty well provided you give it 10-20 cycles.... I can't make any claims as to how it works when you add in solar, wind, loads etc. but on the bench it appears to do what it claims, given some time for it to get to know the bank.........

[roetter]

Our new LiFePo system

I replaced the 6 new flooded LA Exide 130Ah batteries in our new boat with 8 Balqon specials 700Ah cells for 12V/1400Ah.

I use a LightObjects programmable voltmeter set to:
HVC 14.2 off/ 13.4 back on
LVC 12.0 off / 12.5 back on
With it I drive two BlueSea solenoids for LVC and HVC.
All loads are on the LVC busbar and all charges are on the HVC busbar.

I have a Junsi Celllog, just need to hook it up. Too many other things to do still. So far cell voltages are very close when measured (less than 10mV) with a multi meter.

We will rarely be in a marina. So all power comes from solar and alternators.

Solar:
6 – ET-Solar 300W panels – 1800W.
3 panels in parallel on one Outback FX60
3 panels in series on another Outback FX60

The first 3 weeks we lived on a dock in Ft. Lauderdale while installing all the systems. I used the factory Cristec charger every 3-4 days to get the voltage to about 13.8V then shut it off.
Then we had 2 weeks of travelling down the Bahamas islands with most days motoring as the winds were nearly always on the nose. No problems so far with the stock Hitachi 100A alternators (more in another post).

Now we have been on anchor for two weeks with no motor runtime. The first 10 days we had no problem getting the batteries to near full or full every day. However, the last 4 days we had 100% cloud cover and some rain. Really gray.

Usage:
We run two 12V Vitrifrigo fridges (poorly insulated) and a 110 quart Dometic portable fridge/freezer set to -15C. We also run a Spectra Newport 400 12V water maker. From the Victron Multi-Plus inverter we run a toaster, a cappuccino maker and a washing machine.

On Wednesday, the last decent day, we had friends leave, so we did some washing and water maker running that brought the batteries down. The next 4 gray days the solar produced only between 120 and 230 Ah. By Monday morning we were 900 Ah down – 35% SOC.

Today the solar produced 650Ah or 4.7kWh.Even though we did a 5-hour watermaker run we are up 400Ah (to -500Ah) on the batteries.

[roetter]

The new Yanmar 54hp engines come with a 100A alternator on serpentine pullies. I left them the way they are to see how they behave with LiFePo. The alternators have internal regulators with temperature control. They lower the target voltage with rising case temperature. At a later date I may change these out. So far I am doing well with them.

Today we were 900Ah down from full on 12V/1400Ah Winston batteries. A good time to do some checking on the alternator. In the table below you will find the time, voltage (measured at the input to the Cristec zero-voltage drop “diodes” , the drop was 0.02V at 50A). I used a Mastec clamp meter on the cable from the alternator to the diodes for the amp measurement.
The temperatures were measured with an infrared automotive thermometer.
The AltCase temperature was measure on the magnet laminates.

Alternator charge test port engine - 20 January
Engine cold – started running at 1600RPM
Batteries -900Ah SOC

Time Temp C Temp C
Min V A AltCase Belt
-1 12.79 0 23 23 before start of engine
1 14.30 72 32 30
5 14.10 51 60 46
10 14.06 56 60 56 water maker started
20 14.01 50 75 67
30 13.99 40 82 75

[deckofficer]

roetter,

My guess is with as many gray days that you have had, your pleased with the performance of your (8) 700 a-hr Balqon discount cells?