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Update 4 January 2016:  We have now used the new system for almost 4 months including a passage from Australia to Thailand.  All seems to perform as expected.  The batteries charge very quickly on either the genset, engine alternator or solar panels.  On average, at anchor, we use 155 amp hours per night that is re-charged easily in 1.5 hours with the genset/invert.  It is clear that our inverter-charger is too small to get the maximum charge rate that these new batteries will accept.  We max our a about 100 amps.  The good news is that the batteries accept 100 amps right up to 14.1 volts when they are nearly charged.  So they are rarely not fully charged each day.

In Thailand 2011 we replaced our house batteries with Victron Energy (VE) gel batteries using four 220 Amp/hour units.  In addition, the inverter/charger was replaced with a VE unit and VE solar panels and MPPT for their voltage regulation was installed.  Our new VE Lithium Iron Oxide (LiFeO) batteries and essential auxillary equipment was purchased from Wheelhouse Marine Electronics (The Yacht Shop NT) of Darwin, NT Australia.  The installation was done professionally by Wayne Bateman and David Omnes.

While in Darwin we decided to make the leap from lead acid (LA) battery technology to LiFeO.  There is a lot of discussion in the various forums about use of this newer technology and no real consensus.  After reviewing the opinions of others and the state of the technology, I deemed it time to update.  I believe the time is here as several companies offer "integrated" solutions including VE and MasterVolt which are both frequently used in marine applications.  Clearly individuals wishing to reduce the costs for implementing LiFeO technology can do so by assembling the bits necessary but I viewed this as simply beyond my level. 

LiFeO and LA technologies differ in some fundamental ways from  from each other that makes a "drop-in" from one to the other impractical.  One way they differ significantly is that LiFeO batteries have a very low internal resistance and hence can take a lot of charge without generating a lot of heat.  The implication of this is that they can be charged more quickly and by using a simple fixed charge curve. This is a big benefit for a cruising boat and should reduce the amount of time necessary to run our generator as well as getting more complete charge from all sources (engine alternator and solar panels included.  Related to this low internal resistance is that they keep a high consistent voltage at a wide range of charge i.e. the state of charge (SOC) is not easily monitored simply by looking at the open circuit voltage.  SOC is best determined by monitoring power used.  Fortunately we already have a VE battery monitoring system in place.

The second big way that these two technologies differ is that each cell of each LiFeO battery requires electronic monitoring and controlling to assure that each cell is balanced relative to the all the others.  Thus, this is where an "integrated" system comes into play.  For some people this is also the basis of their fear of using LiFeO.  When using more than one battery, there must be an external battery monitoring system (BMS) connected to each battery to control input and output of charge to the batteries.  The BMS used in our newly installed system can control the VE MultiPlus inverter/charger (limiting charging if needed and limiting the invert's use of the DC power if necessary).  Furthermore, it can open a switch (Ct-Li-ct) from the solar/alternator/wind generator input to stop excess charging of the Lithium batteries.  The BMS also controls one other switch (Ct-Li-Load) that can open to stop current from the Lithium batteries to the house DC power circuits.  The information sheet on these switches is seen in this linked document. A typical VE LiFeO battery installation schema is shown in Figure 1.  The one for sV Villa G is a bit different and the actual schema of our new installation is illustrated in this linked documentFigure 1
While replacing our house batteries and making necessary changes, we used this as a chance to improve the layout of the cabling and tidy things up.  Now we have bus bars to replace the previous stacks of cables used in a number of places and as a result, we have no more than 3 cables bolted to any one point.  

VE's technical team advised us to replace the four LA 220 Amp/hour batteries with two 190 Amp/hour LiFeO batteries. I was a bit uncomfortable with this, so chose to add one 90 Amp/hour LiFeO battery as well.  In theory and according to VE, in practice, we should routinely be able to use 90-95% of the overall capacity of these new batteries for over 2000 cycles.  This is possible as LiFeO batteries are not damaged if taken to a low state of charge (10-50%) as LA batteries are; however, full discharge must be prevented by the BMS.  Also, because of the low internal resistance and use of simple fixed charging curves, the LiFeO batteries get closer to full charge in actual use compared to LA batteries.  

The old batteries are shown, in place, in Figure 2.  They had a lot of cables and were tightly packed in the compartment. 






















 

The new batteries are show in Figure 3.  They were small enough that we had a lot of place for installing the BMS (seen in the middle below the fuse to the house DC out).  Note the black daisy chain cable that connect all the batteries and the BMS.  There are two blue covered cables that go to the MultiPlus and the battery monitoring system.  The BMS also has two small (+) cables that go to the two switches that it can control.  These switches are seen in Figures 3 and 4.  Figure 5 shows the blue solar MPPT regulator, the emergency combiner which can combine the engine battery to the house battery circuit and one of the (+) bus bars that is newly installed. 






















 

Some early observations are 1) with partially discharged batteries my engine Balmar 130 Amp/hour alternator charges at 13.7v and 80 Amp/hour running at 1200 rpms; 2) The MultiPlus charges at 110 Amp/hour which has been set as its limit reaching 14.1 volts maximum.  The new batteries are only slightly warm to touch after charging. 

Some illustrations of the new cabling, automatic swtiches and the manual switches are shown below along with a photo of the new VE 130 Amp/Hour AGM engine start battery.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

New Engine Battery

Travels of the crew of Villa G