Techie – Batteries LiFePo4 – The three little pigs

Lithium IRON Phosphate battery technology – LiFePo4 – looks to be in production world wide and seems to be a safer electrical storage technology than the previous Lithium Ion battery chemistry was for use on a cruising sail boat. We looked at sources and costs and shipping charges and and and…   We got a note from friends who said they were driving down from San Diego CA USA to Guaymas Sonora MX and and and we jumped at the opportunity to have batteries shipped to them in San Diego and we will figure out how to get them from Guaymas to where ever we are…  Our 4 year old 6 volt GC2 220 Amp hour batteries (4 in the house bank) are showing their age …

There are many cost comparisons on the web for lead acid vs. AGM vo Gel vs LiFePo4 vs vs vs, sufuce it to say we picked the LiFePo4’s …

The LiFePo4 batteries are interesting in that they seem to have conquered the Lithium Ion battery problems of overheating.toxicity, hazardous waste, fire and etc.

The ones we ordered are advertised as “drop-in replacement” for lead acid batteries.  Having studied the web info, bot all of it I am sure, we hope our installation wcan be relatively clean fairly low impact to the boat systems in place.

I’ll go over our planned changes, which we hope to keep to a minimum.   Thinking that if you have to spend a fortune to implement the lithium batteries that them become way less attractive!  And I’ve just put interesting links found investigating making our house bank a lithium iron phosphate battery bank…

  1.  LiFePo4 batteries – 4 each 100 Ah  12v LiFePo4 “drop in: batteries $870 ea,
  2. Battery Monitor – replace the NASA BM-1 Compact with a Victron BM-702 $218
  3. Add Diode Battery Isolator – A battery isolator should reduce the charge voltages passing through it bu 0.4 to  volts effectively reducing out charge voltages from 14.4 max to 13.4/14.0 max – Sure Power 1202-D Marine Battery Isolator 120 Amp max.  We will run both the alternator output and the shore power charger through this… $65
  4. Solar Charge controller – Replace our e20 from eMarine Inc with a 4215BN EP Tracer 40A 12V 24V MPPT Solar charger Controller regulator with MT50. It has user programmable charge voltage settings $210
  5. We are also getting some temperature monitor equipment to keep an eye on the alternator temp while charging and the battery bank temperature.
  6. I also saw some Amp/Volt/Watt hour meters with shunt for $17 each and had to see how they work!  Toy time for this one…  We will put one in system somewhere to access their value!
  7. We may add a solar panel.  We think we are a little under served by the two 135 watt kyocera panels in the current syste,  Thinking of adding a 100 or 150 watt panel…



“Three little pigs”  – you say! 

Ya, “the three little pigs”,  what do I mean?    Our major problems in our conversion from Lead Acid batteries to Lithium batteries looked to be the three charging systems we use on-board s/v Hajime:  1) solar panels,  2) the diesel motor alternator, and 3) the shore power battery charger…   We hope to slaughter the pigs as follows:

Some new equipment needs for s/v  Hajime:

As an overall control tool, we have ordered a Victron MC-702S.  It is a gauge for being able to count Amp Hours in and out…  The 702 also gives us info on an aux. or starter battery and programmability to control relays based on state of charge limits (SOC) if we feel it necessary in the future…

Victron Energy Precision Battery Monitor BMV-702S Retail $243.00

Seems our “NASA BM-1 Compact” is a bit crude for using with a LiFePo4 bank, it has no programmable features and no re-set-able functions :

Image result for nasa bm-1 image

We are changing our solar controller for the photo voltaic panels which we can program voltages for the charge phases.  We found this 4215BN on ebay which is user programmable on all three phases between  9 and 16 volts…

4215BN EP Tracer 40A 12V 24V MPPT Solar charger Controller regulator with MT50

We are thinking of adding a third PV panel to our two panel system:

Kyocera 140 Watt 12 Volt Solar Panel Fixed Frame KD140SX-UPU, Kyocera, 140 Watt Solar Panel

Size 26.25 x 1.88 x 59″  of our existing two Kyocera 135 W panels came with the Hybrid Wind/Solar kit from eMarine Inc. purchased in 2010…  and we are looking at adding a third panel when we can…:  more later

We need to manage/track the alternator  charge cycle so we don’t overheat our 120 AMP Beta 30 OEM 120 Amp internally regulated alternator…  We do need to get the output voltage limited to <=14.0 volts … Our studies conclude that a diode based charge splitter will reduce the voltage output of an alternator by  0.4 to 0.9 volts. Using this we hope to reduce the output voltage of both the alternator and the shore power charger…

Sure Power 1202-D Marine Auto RV Battery Isolator 2 Batteries 120 amp


Our alternator a 120 Amp OEM from Beta Marine supplied on our Beta 30 Marine diesel engine looks to top out at 14.4 volts output, so maybe the splitter/diode  (old tech) is just the ticket to reduce our alternator output voltage to around 14.0 volts max. without trying to use an external voltage regulator… TWT  (time will tell)

Rebuilding A Westerbeke Alternator

We plan to monitor the temperature of the system components ie. alternator and batteries so we found a temperature gauge and type K thermocouples to put in-place to help us monitor, we had a infrared gun  type and have added thermocouple type…


Engine Temp Monitoring & Over Heating Baseline Assessment  Digital-Thermometer-Dual-Channel-Input-Thermocouple-K-J-T-E-R-S-N-C-F-Type-TQ22 New-Omega-120-0-01-Fine-Wire-Glass-Type-K-Thermocouple-SA1XL-K-120-SRTC


We may need to add similar process controls for our shore charging and get a procedure in place prior to replacing charger with better suited equipment but to begin with we will run our existing charger through the diode based battery splitter and see if it reduces voltage to acceptable levels!

Installing A Marine Battery Charger Image result for marine battery charger


New Equipment :   Bayite DC 100 AMP meter and Victron BMV-702s and 100Ah LiFePo4’s.  The “Bayite DC100 meter”  is a toy for us to see how a well a $17 gauge will work in this environment …  A remote temperature gauge and thermocouples,  A programmable solar charge controller and a cahge splitter 120 Amp for alternator and battery charger output voltage reduction…

100A DC Digital Watt KWH Current Power Energy Meter Ammeter Voltmeter 7-100V US Victron Energy Precision Battery Monitor BMV-702S Retail $243.00  LIFEPO4-12V-100AH-LITHIUM-PHOSPHATE-DEEP-CYCLE-BATTERY-FOR-SOLAR-WIND-SLA-Repl NEW-Sealed-Sure-Power-1202-D-Marine-Auto-RV-Battery-Isolator-2-Batteries-120-amp  Digital-Thermometer-Dual-Channel-Input-Thermocouple-K-J-T-E-R-S-N-C-F-Type-TQ22  New-Omega-120-0-01-Fine-Wire-Glass-Type-K-Thermocouple-SA1XL-K-120-SRTC 4215BN EP Tracer 40A 12V 24V MPPT Solar charger Controller regulator with MT50

Summary (for now):

I have looked and looked to see if anyone has been dumb enough to to try to put the “drop in” 100 amp hour into a 400 amp hour house bank by building a parallel connected battery bank.  No one has been brave enough to stand up and say “I tried”.

Well, we are going to try and in order to only risk half of out battery investment in the beginning, we are looking to try two of the 100 Ah batteries in parallel and if all goes well we may add the other two we purchased to the house bank if needed!

General Info, parts info etc…

Thanks Alan, a post link:

There is a blog/web page by Compass Marine takes issue with the idea of “drop in replacements” and we are taking his concerns and warnings to heart while we implement the energy storage system into s/v Hajime:  Here is an ir-reverent rant from Compass Marine ( on, it is really rather comprehensive and in my opinion well done, Thanks Compass Marine!   Could title an entire blog, “Oh my, what have we gotten into?”  or maybe “Ha Jim e! it’s your LiFePo4!”  …:

Liked this info from above blog, hope my quoting the below text is taken as a compliment and not a copyright infringement:

“LiFePO4 Pro’s:

2000+ “claimed” cycles to 80% DOD (depth of discharge). If we compare the best AGM batteries to LFP we find that reputable manufactures such as Enersys/Odyssey claim just 400 *lab ratedcycles to 80% DOD.

I suspect, (wild ass guess), that LFP prismatic cells, from reputable manufacturers such as Winston, CALB, Sinopoly, Hi Power, GBS and others, can last approx 1600-2400 cycles even when pushed regularly to 80% DOD, in the real world of the marine environment. The manufacturers claim more, but so do the lead acid makers, and these are always ideal “lab” conditions. Of course at this point in time this is a WAG (wild ass guess) on my part. I can assure you even 1600+ cycles is a very long time. I have been busting my hump for approx 28 months and have only managed to put 550 cycles on this bank and that is with accelerated cycle testing..

Of course the average lead acid battery on boats is often dead well before 150 cycles and they rarely if ever even come close to the “lab rated” cycles. Do the math on your own bank, be honest about it, and see how many cycles you had, to 50% SOC, before your bank needed replacement. Most boat owners are shocked when they do this math.

*I have never seen a single lead acid battery bank hit its lab rating in the marine environment, especially not on cruising boats. These lab numbers are fairy-tale ratings when translated into the real world. I also don’t entirely trust the lab ratings of the LFP cells, though some have done the testing and have seen this.


Alex MeVay the CEO of Genasun firmly believes in 2000+ cycles to 70% DOD. This is utterly amazing cycle life if it can really happen. Based on what I am seeing at 550+/- cycles I am trending towards believing it..

Approx 80% of an LFP banks capacity is fully usable. With lead acid you often have just 30-35% usable capacity (50% SOC to 80-85% SOC) due to charge acceptance current limiting. With LFP current limiting or acceptance taper is very, very short in duration, even at relatively low charging voltages of 13.8V – 14.0V.
Very, very short current taper even with large current sources. Charge to nearly full before even attaining absorption voltage. This of course is entirely dependent on your charging voltage and your current source. We charge at 120A steady (160A alt set up to run at 120A continuously) and our current taper lasts only 30-35 minutes. Compare that to HOURS and HOURS of current limiting using a 120A charge source on 400Ah lead acid batteries. With a small charge source, like solar or wind, you will hit 99%+ SOC before any current limiting occurs. Our bank literally has to be chock full before our solar array can even get to 13.8V…. These batteries can take immense current, and charge extremely fast, but really tend to do extremely well with .3C to .5C in charge current…..
Less than half the weight of lead Ah to Ah and almost always more compact. The 400Ah bank in this article weighs 134 pounds less than a 400Ah lead acid bank. However, to equal the usable capacity of a 400Ah LFP bank you would need approx 900Ah’s of lead. This makes the 400Ah LFP bank approx 400 pounds lighter than the equivalent usable capacity in lead acid!
The term “dead lead” is s term I coined in my electrical seminars. The typical lead acid bank consists of 65-70% of the weight being comprised of “dead lead” or the excess lead you carry around but that you can not use. If you have a usable capacity of just 30-35% of the bank, when out cruising, this means that you are carrying around 65-70% of that weight in unusable “dead lead” capacity. This 400Ah LFP bank weighs 130 pounds & 80% of it is easily usable. This means just 20% of it not easily usable or you simply don’t want to use it for best longevity. As a result, we carry around a measly 26 pounds of unusable battery on our 36 footer..

Lets go back to usable capacity for a moment. If we want to equal the usable capacity of this 400Ah LFP bank in lead, we would need 8 GC2 6V golf cart batteries or approx 900Ah’s. 35% of 900Ah is a usable capacity of 315Ah’s. 80% of the 400Ah LFP bank is a usable capacity or 320 Ah’s. The 900Ah lead bank weighs 520 pounds. If you use just 35% of that bank then you are hauling around 338 pounds of “dead lead” or 338 pounds of unusable capacity.. Twenty six pounds of unused LFP or 338 pounds of “dead lead”..?? Points to ponder…

LFP banks have a very strong & flat charge & discharge curve with a very steep & fast rise or drop at either end. These ends are called the “knee’s”. LFP’s will maintain voltages well above that of any fully charged lead acid bank, and remain very close to their 3.3VPC / 13.2V nominal voltage level, and hold quite steady voltages with little change almost all the way to 80% DOD. They will maintain a very tight voltage range even under “normal” house loads. Espar heaters, refrigeration, watermakers etc. will all perform better. Equipment likes higher voltages. Even bilge pumps will pump more water. Voltage sag that can drop out electronics during bow thruster or windlass use is almost entirely eliminated.
Charge efficiency is also referred to as the Coulombic efficiency. These batteries are as near 100% efficient as I have ever seen on my test bench. Take 200Ah’s out and put 200 Ah’s back in and you hit the voltage and net accepted current at almost the exact same Ah’s out to Ah’s in. Until LFP I had never witnessed anything like this, even with the best AGM’s. Lead acid ranges from 70% to as high as 90% +/- efficient but you still need to put back in 10-30% more than you took out, and this is with “healthy” lead acid batteries. As they sulfate the charge efficiency or Coulombic efficiency gets even worse.
We know the Achilles heel of lead is sulfation and in order to fight off sulfation we need to charge them to 100% SOC as often as possible. This proves very difficult for many boaters and cruisers unless your boat resides at a dock after each sail or sits on a mooring with an adequate solar system. LFP batteries do not need to get back to 100% SOC so, FOGEDABOUTIT…….! This is a major win for LFP. When we come back from a weekend on the water, and our battery is at 50% SOC, I DON’T CARE!!!! I shut down the boat, and the solar and go home. LFP batteries actually prefer to sit at 50-60% SOC rather than at 90-100%.. As I said earlier this is a mental paradigm shift we need to overcome in our human behavior/thinking around our batteries…
Sulfation is by far and away the cancer and #1 killer of lead acid batteries. These batteries do not sulfate, no cancer, so there is no need or worry to constantly get back to 100% SOC before you leave your boat. LFP batteries actually prefer to be left at mid range SOC rather than full. Enjoy that sail home, WITHOUT THE MOTOR!!!
Without question LFP is the safest of the Li battery formats. Many argue, and these arguments have certainly been well made, LiFePO4 is as safe or safer than lead acid. ALL BATTERIES ARE DANGEROUS, let us not forget that. As Li goes LiFePO4 is currently the safest. Remember we are surrounded every day by far more volatile Li technologies in computers, iPads, iPods, tablets, video games, cell phones and even cordless tools. LFP is less energy dense than other more volatile Li formats, but when compared to lead acid everything looks energy dense. We have no need on boats for “Dreamliner” level energy density, thus we use the considerably safer LiFePO4/LFP technology not LiCoO2 like Boeing chose.. If you believe LiCoO2 & LiFePO4 batteries are the same PLEASE STOP READING HERE and go back & hug your lead acid batteries…..(grin)”


Cruisers forum topic, at this writing 326 pages and growing, a topic on using LiFePo4’s as a house bank.  Kinda WOW for using the web as a crowd sourced wealth of information… taking it as every web thing with a grain of salt …

Here is a fellow who has pondered the problem some, maybe too much “some”:

A links for charging recommendations for the LiFePo4’s:

Here is link to the alibaba site for the EWT manufacturer and the info (what there is) on the 12v 100Ah LiFePo4 battery module we are getting:

Here is link to site selling the BMS (Battery Management System) shown in the photo on the above site, Model Number is  PCM-L04S50-674, looks like the is the BMS in our EWT 100 Ah batteries:

And a link to purchasing the BMS via alibaba  at $0.6 USD per unit???:

BMS Specifications from above site:

Model: PCM-L04S50-674
No  Test   item Lifepo4 Li-ion/Li-polymer
1 Voltage Charging voltage DC 14.6VCC/CV
DC:16.8V CC/CV
Balance voltage for single cell 3.65V±0.025V 4.20V±0.025V
2 Current Balance current for single cell 36/72±10mA 42/84±10mA
Current consumption for single cell ≤20μA ≤20μA
Max. continuous charging current 50A 50A
Max. cont. discharging current 50A 50A
3 Over charge
(single cell)
Over charge detection voltage 3.9V±0.025V (optional) 4.35±0.025V (optional)
Over charge detection delay time 0.5-2.0S 0.5-2.0S
Over charge release voltage 3.8±0.025V 4.15 ±0.05V
4 Over discharge
(single cell)
Over discharge detection voltage 2.0±0.05V




Over discharge detection delay time 100~300mS 100~300mS
Over discharge release voltage 1.9±0.1V 3.1±0.1V
5 Over current
Over current detection voltage 0.06~0.6V 0.06~0.6V
Over current detection current 80~500A (can adjust) 80~500A (can adjust)
Detection delay time 5-20ms 5-20ms
Release condition Cut load, Cut load,
6 Short
Detection condition Exterior short circuit
Detection delay time 200~500us
Release condition charge up
7 Resistance Protection  circuitry ≤50mΩ
8 Temperature Operating Temperature Range -40~+85℃
Storage Temperature Range -40~+125℃
9 Dimension L130*W70*T13mm
 So it looks like the batteries are covered for abuse, we are looking into temperature monitoring for our alternator and for the battery compartment too…
Misc info:
The Yanmar 3.15″ mount is found (of course) on Yanmar as well as Mercruiser, Lehman, Perkins-Sabre and Hitachi equipped engines.  3.15″ is the internal dimension between the two mounting feet.
Here is our existing Iskre Letrika AAK4855 120 Amp 12v internally regulated alternator:
Image result for alternator AAK4855  


Description:-  Alternators Iskra Letrika

Product Alternator
Aftermarket P/N IA1196
Voltage 14 V
Current 175 A
OEM P/N 11.204.252  Letrika
Description AAN8164
Notes Dust-proof

Cross References

Manufacturer Manufacturer P/N
BETA MARINE 200-05261


Product Alternator
Aftermarket P/N IA1542
Voltage 14 V
Current 120 A
OEM P/N 11.204.479
Description AAK4855
Notes Dust-proof   woohoo techie’s

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3 Responses to Techie – Batteries LiFePo4 – The three little pigs

  1. Allen Gordon says:

    This is a great post about batteries. Thanks Jim.

  2. svhajime says:

    Ed, I looked at the pages you posted and I think these are similar products to the batteries I ended up using in the blog post. Both have on-board or kit supplied for battery management. Still a novice at this. Our batteries are only going into their third season, but seem to be acting same as when installed… Thanks, Jim

    Try this link if you are in USA for ebay sellers…

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