If you are considering this, the following post should be very informative. It is a long read because there is a lot involved but should be worth the time, hope you agree.
Background
As I had noted in the blog entry for the watermaker installation, we had been planning a trip to Glacier Bay, Alaska for some time. Leading up to the trip, I had concerns that the house batteries in our boat were getting tired and started to investigate installing lithium batteries. I knew that they had much greater power density but wasn’t sure how much. I found that in the same physical 4D battery dimensions that our 200 Ah AGM’s fit into, I could put 300 Ah lithium batteries. AGM (Absorbed Glass Mat) batteries are a type of lead acid battery. That pair of AGM’s gave us a total usable 200 Ah of power, because lead acid batteries shouldn’t be drawn down below 50% of their capacity to avoid shortening their lifespan of, at best, 1,000 cycles. A pair of 300 Ah lithium batteries that can repeatedly be drawn down 80% with no additional degradation from their 4,000-5,000 cycle lifespan would provide 480 Ah of usable power. This would be a huge improvement of nearly 2 1/2 times the capacity. On top of that, the price to replace the top of the line AGM’s that were in the boat would be almost $1,400 apiece and the LiFePo4 batteries that were very, very expensive only a few years ago could be purchased for less now. There are a bunch of other costs that come into play but if the batteries need to be changed anyway, this would be a good time to absorb these other costs.
As it turned out, when testing the AGM’s that were in the boat, I discovered a battery post that was not loose but not fully tight. The batteries each tested at 96% of original capacity, in spite of their age (approximately 7 years) so the degradation in performance I was seeing could be attributable to the post that needed tightening. After cleaning and tightening the connections, and using the batteries, I had some faith that the existing system would be able to make the trip to Alaska and back. This was good because I was having trouble finding an installer, a marine electrician, that would respond to my inquiries.
Marine trades of all sorts were very busy, including electricians. When I did find one that took the time to discuss my project, I learned that, in addition to installing, they expect to acquire all the equipment needed (at their wholesale pricing) and charge you full retail pricing. I hadn’t considered this. I had been acquiring numerous parts of the system over a few months when I found something online at an attractive price. I had also been south of the border a couple of times that allowed me to capture those attractive prices along with free shipping and minimal if any duty or taxes when returning.
All part of the advance planning!
Not including the batteries, there was approximately $4,000 worth of equipment purchased for the project that would have cost between $5,000 and $6,000 at local, retail prices. Locally sourced equivalent batteries would add another $1,000 over what I had paid, making my advanced planning and extended shopping worth about $2,500 in savings. After all the time needed to find an installer and subsequently learn that they weren’t too keen on a project where they didn’t get to supply all the equipment, there wasn’t enough time left before my departure date for Alaska. The project would get delayed. The marine electrician I met with had quoted a six to eight day timeframe required for installation, equating to $7,500 to $10,000 in labour. I needed time to stew on that for a while as well.
I would have to rely on the existing AGM’s to get through the trip but, as noted, they did test and perform quite well. Our trip lasted 11 weeks and during the 8th week the batteries began to falter, not lasting through the night on a full charge. We resorted to turning off one of the refrigerators overnight to help but by the end of week ten, that wasn’t enough. Luckily the last week of the trip, week 11, was spent entirely in marinas, with shorepower eliminating the inconvenience. I tested the batteries after our return and they were down to roughly 2/3’s of their capacity. It was definitely time for a change.
After taking the remaining months of summer to think things over without a deadline/departure date looming, and considering all the research I had done on the specific requirements for this type of installation, I decided to tackle the installation myself.
I am not recommending this approach for anyone that doesn’t have certain skills and training. My background, experience and education give me a significantly greater understanding of the requirements than most other people.
In addition to being a Professional Engineer and a Qualified Marine Surveyor, my dad sent me to night school when I was in grade eleven to be an apprentice electrician, so I could wire our cabin at the lake!
The uninitiated might be asking at this point, ‘what is so complicated about changing the batteries to a different type and why is it so expensive?’ Because the batteries are so different, you can’t just take out the old ones and put in the new ones. There several other considerations that need to be accommodated. The following further elaborates on these considerations and costs.
Equipment Selection
There are numerous batteries on a boat for numerous different purposes. I wanted to make changes to the house battery system only. There are two sets of engine starting batteries, a starting battery for the generator and a battery to support the windlass, six other batteries in total, not including the house batteries. There are a couple of places where these systems interconnect, so that also needed to be considered but, for the most part the house battery system is separate.
Lithium batteries, in this example Lithium Iron Phosphate or LiFePo4 batteries (there are several different chemistry variations of ‘lithium’ batteries) have a much lower internal resistance than lead acid batteries, meaning they can charge and discharge much faster. This can be advantageous in numerous ways but also requires certain safety measures to be in place. Rapid, uncontrolled discharge from these batteries releases so much energy so quickly that fire is the usual result. Fire is almost always bad but, on boats it is terrible. Charging very quickly can be, as noted, advantageous, but if a normal alternator is left to charge these batteries in the same manner as lead acid batteries, the alternator will be continuously at its maximum output, likely overheating and possibly starting a fire. How the energy goes into and comes out of this type of battery needs a greater degree of management than lead acid batteries.
Unlike lead acid batteries, LiFePo4 batteries require a BMS or Battery Management System connected between the battery and anything else. The BMS will impose specified maximum allowable charge and discharge currents as well as provide over/under charge protection, over temperature protection and cell balancing. The larger the battery, typically the higher charge and discharge rates the BMS allows. The combined discharge rate of the battery bank needs to be high enough to supply the vessel’s needs when all of the DC loads are on.
Research lead me to understand that there are two manufacturers of the needed equipment that stand out, Victron Energy and Mastervolt. They both also supply lithium batteries. Mastervolt batteries have a built in BMS while Victron’s utilize a separate, external BMS. Most other battery suppliers utilize a built in BMS. Both these manufacturers batteries are very expensive. There may be some nameplate pricing involved here and, prior to a few years ago there was limited competition. Not so any more.
Now there are a multitude of battery suppliers to choose from. Because there are lots of options, lots of research is needed when choosing. If installing on a boat, look for ABYC (American Boat & Yacht Council) recognition on the manufacturer’s website. This will provide comfort that the manufacturer has designed the battery for the use you are considering. Lots of suppliers have very competitive pricing. Some are clearly on the bad side of ‘You get what you pay for’ but there are several that defy that rule. Also, the more high tech, the higher the cost. Batteries that have a BMS that can communicate with the rest of the system (networked) are more expensive than ones that can’t. Some are built for cold weather applications that include automatic internal heating. Some have Bluetooth connectivity. I felt that this system would work well with a fairly basic battery so I looked for a decent quality, large capacity battery without the options I didn’t need.
I chose LiTime 300 Ah batteries. They are ABYC compliant, are the physical size of a 4D battery (what I was replacing) and have EV Grade Automotive cells. This model doesn’t have a heater (we don’t need that here), nor does it have Bluetooth or networking capability. LiTime reviews seem to put them at the upper end of the mainstream market but not into the highest quality, high end and high cost bracket. I thought this was a good place to start. An equivalent size battery from Mastervolt or Victron costs about three times the price so there’s lots of room for my decision to be good! Your battery decision is up to you.
Because an alternator lighting on fire should be avoided, a system is needed to manage the alternator as well. There are also two leaders in this field, Wakespeed and ARCO. ARCO is the latest arrival with their Zeus Programable Alternator Regulator. The Zeus is a bit pricier, but comparable when all the dusts settles because it includes more of the necessary additional pieces. These need to be purchased separately if a Wakespeed is used. Most importantly though is the ease of programming with the Zeus. It’s all done through an intuitive app on your phone or pad. The Wakespeed requires you to log into it with a laptop and be comfortable with some basic programming skills. Not insurmountable but the Zeus is infinitely easier. I chose to install a Zeus regulator. This was the single most expensive piece of equipment, at about $1,100.
Most boats will have an auxiliary alternator that charges the house batteries. This alternator likely has an internal regulator. To use either of the programable regulators mentioned above, the alternator’s internal regulator needs to be removed or bypassed allowing the new fancy and expensive addition to do the work. Most auto-electric shops can do this for under $100.
Both Mastervolt and Victron build combined inverter/charger systems that, next to the batteries, would be the anchor of the system’s operation, if starting from scratch. This project wasn’t starting from scratch. Our boat already had an inverter, a small 6 Amp charger and a large 100 Amp, three bank charger. The three banks were used to charge the port starting batteries, the starboard starting batteries and the house batteries. The small charger was dedicated to the generator starting battery. Of importance, the charge profile for an AGM battery is different than what a Lithium battery needs. Unfortunately the large charger is old enough that it doesn’t have a lithium profile built into it. We therefore needed a new charger for the lithium house batteries. Because we already had an inverter that worked flawlessly and was integrated into our electrical system for automatic operation, a combo inverter/charger was ruled out. The small charger for the generator battery was removed, allowing the charging bank formerly assigned to the house batteries to charge the generator battery, keeping the existing, large charger fully utilized.
Most lithium battery manufacturers state a recommend charge current for their batteries. The recommended charge current is not a ‘must’, it is an optimal, usually meaning, the fastest repeated charge rate the battery can use without any detriment to its lifespan. The recommended charge current for the 300 Ah LiTime batteries is 60 Amps (each). I was therefore looking for a 120 Amp (or close) charger. The Victron Phoenix IP43 50 Amp chargers can be ‘daisy chained’ and networked together so one works as a master with others following to provide the optimal output as needed. They are also Bluetooth capable and can be networked using Victron’s VE Network cables not only to each other but into Victron’s communication hub called a Cerbo GX. The Cerbo GX can be connected to a touchscreen display (at the helm, in this case) and can also display the same information on a phone or a tablet. With the help of a Smart Shunt networked in, the display can also show what energy is going into and out of the batteries at all times. This all seemed like the right equipment for the job, so I didn’t just install a different charger, I installed a monitoring system as well. I can see what’s happening in the system and most importantly (to me) how much time is left before charging is needed. More monitoring meant more money – going back to the question near the start!
Another variant I needed to consider is the bow battery. On our boat this battery helps run the windlass. It is a large AGM battery that is tied into the house battery charging system and receives charge once the house batteries are fully charged via an ACR (Automatic Charging Relay). Because the charge profile on this system would soon be for lithium batteries, the bow battery would suffer from overcharging if the system wasn’t changed. The solution to this was to replace the ACR with a DC-DC charger that uses the lithium profile power but outputs an AGM charge profile. Another blue box (Victron products are blue) for a few hundred dollars – back to the earlier question!
The current flowing into and out of the batteries (or anything for that matter) can be measured using a ‘shunt’. The Zeus alternator requires one on the alternator output, the +ve cable, and one on the battery -ve cable. The Victron system uses the battery negative shunt to monitor flow out of and to adjust charge into the batteries. The smart shunt referred to earlier (equipped with Bluetooth and can be VE Networked) can do double duty, also working with the alternator.
That defined the big parts and pieces needed or wanted for a conversion to lithium house batteries with monitoring;
1) Batteries $2,100 ($1,050 ea)
2) IP43 Chargers $1,300 ($650 ea)
3) DC-DC Charger $300
4) Alternator Regulator $1,100
5) Shunts $200
6) Cerbo GX Mk2 $400
7) GX 70 display $400
Costs shown above are approximate and rounded.
Because there are numerous heavy cables that need to be built or altered, a ratcheting cable cutter and a hydraulic cable crimping tool were purchased along with an assortment of cable, cable ends and heat shrink, large and small. There was also a shroud, 3D printed to fit between the chargers to mount two cooling fans with thermostatic controls. This part sounds expensive but, in total, was less than $100. The cost for all of this was, rounded up, about $1,100, coming to an approximate total of $6,900. Again more of the answer to the original question.
Note:
1) Marine wiring should only use tinned copper wire and fittings. Anything else doesn’t meet standards because it will corrode, causing premature failure, and
2) All heat shrink should have internal heat activated sealant.
I am not recommending this approach for anyone that doesn’t have certain skills and training. My background, experience and education give me a significantly greater understanding of the requirements than most other people.
Safety Considerations and Regulations
Before going further, let’s touch on some of the safety requirements. All of the regular requirements such as batteries being firmly fastened and having the positive posts covered are still required. Making sure the cable size used is properly protected by fuses or breakers of an appropriate rating and having a switch to disconnect the battery(s) from the system is still needed but there are some additions. ABYC E-13 is the new section that applies to installation of LiFePo4 batteries. There are five parts that address, 1) Installation Requirements, 2) Charging Systems, 3) BMS, 4) Over-current Protection and 5) Temperature Management.
The Installation Requirements specific to LiFePo4 batteries, in addition to the points above, require the batteries to have ventilation, avoiding the typical battery box enclosers, to allow for cooling. The Charging Systems have to use charging profiles suitable to the batteries, There must be a BMS employed for each battery. Over-current Protection must be installed. Temperature Management involves monitoring battery temperature and if necessary, providing a means to reduce their temperature, either by reducing the current flow or, if needed, added cooling.
The new house batteries purchased have internal BMS’ that will disconnect the battery if a continuous discharge rate of 200 Amps is exceeded or a surge rate of 400 Amps is exceeded for more than 5 seconds. The cables connecting these two batteries to each other and to the system are 4/0 AWG Marine 600V 105C cables. This circuit, one way, is approximately 8 feet long, not bundled and has a 250 Amp fuse about halfway between the ends. A 8 ft run means there is a 16 ft circuit length, because the current not only flows out but also has to complete the flow back. These cables are rated for 378 amps when inside an engine space, as these are. This cable is protected from current above its rated capacity in the original setup by a 250 Amp ANL fuse. At the end of the cable there is a large relay that can disconnect the batteries from the rest of the system. This relay is activated remotely by a switch in the cockpit, alleviating the need to get into the engine compartment but it is not automated in any way.
Because we are the original owners, I know the existing 250 Amp ANL fuse has never blown, inferring that there has never been a serious electrical system short nor has total demand ever exceeded 250 Amps. The new DC-DC charger has the potential to add 30 Amps of new draw to the system. Even though the batteries are capable of delivering very large currents, the total demand should never exceed 300 Amps. A 350 Amp fuse should maximize the power availability, allow all of the DC requirements to be met and provide some surge capacity, while still remaining below the cable rating of 378 Amps.
Fortunately, from an installation perspective, most of this hardware was pre-existing as part of the standard factory equipment. The only modifications considered would be; 1) replacing the ANL fuse block and 250 Amp fuse with a T fuse block and a 350 Amp T fuse, and 2) the addition of MRBF (battery mounted) fuses on each house battery.
Why the different types of fuses? The important difference in these applications is about how much current the fuse can safely interrupt. The T fuse has a very high AIC (Ampere Interruption Current) rating of 20,000 Amps and is considered the ‘Gold’ standard. MRBF’s (Marine Rated Battery Fuse), with an AIC of 10,000 Amps, could be referred to as the ‘Silver’ standard. My research indicates that ANL fuses like the one installed for the original AGM battery setup can be rated anywhere from 600 Amps to 6,000 Amps. All figures are quoted at 12V. The AIC rating is important because, if a current larger than the AIC rating is encountered the fuse will still blow but instead of leaving an open, safe circuit, there is a risk of welding itself back together, closing the circuit it was supposed to open. Therefore, the fuse employed must have an AIC rating higher than the maximum potential current it is meant to disconnect. While the ANL fuse was presumed to be sufficient for use with the AGM batteries, it does not meet that requirement when used with Lithium batteries.
Individual 12V LiFePO4 batteries can deliver approximately 8,000 Amps on a short circuit, exceeding the AIC rating of an ANL fuse, making the original fuse protection inadequate. The new fuse setup uses two MRBF’s to isolate the batteries from the system and from each other, if need be. Each MRBF 250 Amp fuse is dedicated to its own battery therefore the 10,000 Amp AIC rating is sufficient. Because each battery is rated to deliver up to 200 Amps continuously and is fused at 250 Amps, the MRBF’s will only provide protection if there is an unprecidented surge from its associated battery above 250 Amps, or a short circuit. The batteries are not fused lower than 250 Amps so one battery can still sufficiently power the system should the other internally disconnect for any reason. The 350 Amp T fuse, replacing the ANL fuse, is downstream of the batteries and their respective MRBF’s. The 400 Amp combined maximum continuous output capability of the batteries exceeds the 4/0 cable rating, as discussed above so the T fuse purpose is twofold. It will guard against an abnormally large continuous demand but still within the BMS limits and, if a short circuit in the system caused the extremely unlikely combination of the MRBF and the BMS catastrophically failing on one, or both of the batteries, it also provides a failsafe, with its 20,000 Amp AIC rating being large enough to safely disconnect what could be a 16,000 Amp short circuit current.
Both batteries are fixed into a custom built retainer with a fixed base that surrounds the bottom of the battery cases and a two piece top where the first piece fastens over the top of the cases but not the posts with the second fastened over everything, covering the posts and their connections. The tops and bases are fixed, with the remainder of the body of the batteries exposed to the surroundings, allowing for cooling. There is a temperature sensor on the batteries that will reduce the charge rate if the batteries get too hot and there is a circuit in the regulator that could activate a cooling fan (if installed) at a set temperature if needed. A photo of the battery installation with top of case installed is included further down.
All of these features and protections; 1) temperature monitoring, 2) charge control (BMS in each battery, programable alternator regulator, smart chargers), 3) fuse protection and 4) mounting methods, ensure the system is safe and fulfill all of the ABYC E-13 requirements.
Now that the equipment was selected and sourced, planning for installation could be finished. Part of the planning took place as equipment was selected. I measured the size of all the parts and pieces needed and measured the places where I wanted to install them, just to be sure everything would fit. Everything had enough space although the two 50 Amp chargers were a bit snug. Victron’s literature recommends having four inches of free space on all sides, which there wasn’t. This is required for heat dissipation. They use natural convection through cooling fins. Their mounting space is immediately adjacent to the large 100 Amp charger. The large charger will also generate heat but has built in cooling fans.
If the new chargers get too hot, they will automatically derate their output. Derating starts at 40C with total shut down at 60C, so the goal was to prevent them from reaching 40C. The solution was to provide forced air cooling. My daughter’s boyfriend (also an engineer) owns a 3D printer so I drew up some plans and he graciously printed a shroud to hold the two cooling fans. I built a fan control using programable thermostats with sensors placed between the charger’s cooling fins. One fan turns on at 28c with the second at 35c. So far the chargers have not reached 40C.
Installation, finally!
The installation effort was started with the DC-DC charger. Mostly because it is not networked into the rest of the system and its in a place with easy access. It is Bluetooth capable and can be monitored on a phone or tablet using the Victron Connect app but it is not equipped for networking. The ACR was removed and the DC-DC charger was installed in its place, see bottom of photo below.
Next in the installation was the auxiliary alternator, after taking it in to have the internal regulator bypassed. This sounds pretty simple but a shunt needed to be mounted on the output cable. Because this is the +ve cable, I wanted to mount it inside a protective, insulating box, preventing any accidental shorts. The best place in my engine room for this is right beside the alternator. The +ve cable from the alternator is sizeable enough that it doesn’t bend much in a short length and measuring the exact length needed was difficult and awkward while hanging over and reaching under an engine. My second attempt at building the proper cable was a success! See the photo below showing the alternator with temperature probe (left side) and alternator shunt, bottom right.
There were numerous wires between the alternator and the external regulator that needed to be properly connected. ARCO’s wiring diagram for the alternator side of the harness is shown below.
The next logical step was to complete the battery/control side connections to the regulator harness. The power supply and switch plus a couple of optional connections not needed at the time (but may be used in the future) were installed in a switch box near the regulator. The Zeus regulator and the switch box can be seen in the first photo above with a wiring diagram from ARCO shown below to describe the external regulator connections to the battery/control side.
As stated earlier, another shunt is used on the -ve side of the house battery bank to monitor voltage and current flow in and out. Installing this required fabrication of new main battery cable sections. These were the largest diameter cables in the installation, 0000 AWG, also termed 4/0. Building these really illustrated the value of a ratcheting cable cutter and the hydraulic crimper. The IP65 Smart Shunt from Victron that was installed has the option of allowing the system to monitor an additional signal, in this case the voltage of the genset starting battery. The batteries and the smart shunt are shown in the photo below.
The entire regulator wiring integration into the house battery system is diagramed below, courtesy of ARCO.
Installing the two stacked chargers with the cooling shroud, fans and thermostats also required some cable fabrication. Victron equipment is built to accept 6 AWG cables. Large enough for each piece separately, but not large enough for two combined so the individual cables come to a junction where they were connected to 2 AWG cables, which then carried the combined charge current (up to 100 Amps) through a 120 Amp breaker and then to the house batteries. A 2 AWG cable with 105C insulation under these circumstances is derated to 127.5 Amps. The AC power supply, via a 20 Amp breaker and 12/3 AC wiring from the main panel, was fed into a new junction box where both new charger supply lines were connected.
The Cerbo GX was mounted on the same bulkhead as the chargers but in an area with more space. The power supply and the networking cables from the chargers, the smart shunt and the alternator regulator were all easily accessed and connected.
The most difficult part of this segment was fishing a line back from the helm to the engine room so I could connect the display.
Once everything was installed, the equipment needed to be programmed. Most of this was pretty straight forward. The chargers all needed to be set to the proper profiles for the batteries they were to be charging. The polarity of the shunts needed to be checked to make sure they were installed correctly. The Zeus regulator needed the most information but, again, quite straight forward. The specifics about the battery bank, including size and chemistry were entered, resulting in population of an appropriate charge profile. A custom profile can be inputted manually if desired. Specifics about the size and type of alternator were entered as were temperature and current limits so the alternator never gets overloaded. I may have left a few things out but the concept should be fairly clear.
Finally, turn on the system, one part at a time. I checked that batteries were charging properly on shorepower first and then shut off the shorepower before starting the port engine (with the auxiliary alternator) to see if the alternator and regulator were working correctly. I watched it all using Bluetooth on my phone and then checked the display at the helm. Sadly the nice new touch screen was not working properly. Reading a couple threads on the internet suggested powering it off, disconnecting, reconnecting and powering up again. “Did you turn it off and turn it on again”. The answer every IT person has! It worked and the whole system was running properly. The last step was to connect the Cerbo GX to the local wifi network and log into the Victron Remote Management (VRM) portal allowing me to view my system from afar, which also worked.
Summary and Conclusion
I spent approximately 5 days working on the installation. Most of those days were pretty full days, after I had my morning latte, but probably not a complete 8 hours so let’s estimate between 35 and 40 hours of work. This does not include any of the prep work or any of the time spent researching or shopping, most of which was online.
Oceanic charges $150/hr for consulting so, for 40 hours that would be $6,000. I’d rather pay myself than someone else but, not everyone has that luxury. This is not your typical DIY project, as noted above. Working with electricity demands attention to detail and understanding requirements but if you are up to the task (very big if) it can be very rewarding not to mention very cost effective. I spent approximately $6,900 plus my own time and effort, saving approximately $10,000. Three quarters of that was on installation costs and one quarter through diligent shopping.
If you are not sure you’re up to it but really want to be, maybe Oceanic can help get you over the ‘hump’. If you are contemplating doing an installation like this on your own vessel but need a some outside input or even some hands on help, contact me at murray@oceanicyachtsurveys.com or (403) 815-1415 to discuss. The first call is free!