LiFePo4 selection and placement

[bgruenthal]

We are excited new owners of a 2018 R23 and are contemplating upgrading to LiFePo4 batteries. We have heard that the factory option now being offered is 6 Dakota 100Ah batteries. Two questions: (1) why 6 100Ah instead of fewer larger batteries (e.g., 2 x 200 Ah); and (2) are they all in the port lazarette or are some in the starboard lazarette to help blanace the weight? Fewer larger batteries seem more space and cost efficient, so that is the reason for the first question--we figure there must be a reason you selected 6 100 Ah. The second question is driven, in part, by the fact that we have a kicker motor which already adds weight to the port side. Thanks!

 

[Bruce Moore]

Bumping post delayed in moderation queue.

 

[trailertrawlerkismet]

I’ll answer battery location on our R25OB, as it relates to the Lithium Iron we have, thinking it might be the same for the R23OB. There are 4 of the 100’s located in the center locker and 2 in the port locker in addition to the start battery and thruster battery. I don’t have answers to your other questions.

Jim

 

[Submariner]

We are excited new owners of a 2018 R23 and are contemplating upgrading to LiFePo4 batteries. We have heard that the factory option now being offered is 6 Dakota 100Ah batteries. Two questions: (1) why 6 100Ah instead of fewer larger batteries (e.g., 2 x 200 Ah); and (2) are they all in the port lazarette or are some in the starboard lazarette to help blanace the weight? Fewer larger batteries seem more space and cost efficient, so that is the reason for the first question--we figure there must be a reason you selected 6 100 Ah. The second question is driven, in part, by the fact that we have a kicker motor which already adds weight to the port side. Thanks!

I just upgraded my RT27-OB from AGM (NW Edition) to LiFePo4. It's a lot of work and was expensive.

Ranger tug uses the same LiFEpo4 electrical schematic for all their LiFEPo4 installs. This applies to the RT23, 25-OB, 27-OB, as well as the Cutwater boats. (All outboard models).

I know of at least one RT27-OB owner that the factory installed the 200ah Dakota's instead of the 100ah batteries. I would assume this to be an early implementation for RT.

Today, I see the factory deploying the 100ah (quantity 6). If I had to guess why, I'd say "Tetris". The first problem with adding anything to the boat is where to fit it. I've seen pic's of an RT27-OB with 6 100ah Dakota batteries in the port lazarette. It's full. But that leaves the center cockpit storage completely empty and available for storage space.

I've seen the Cutwater 248 with LiFEPO4, that has the six 100ah Dakota split between the port and starboard lazarettes.

Six 100ah batteries as a G31 size are going to provide more options for a physical configuration across all their boats. A second reason I might think could be supply chain issues. It's probably easier to get a guarantee from Dakota for a lot of the same size of battery than dealing with multiple sizes of the batteries.

If you want to get rid of the port list you'd need to relocate the batteries to the center cockpit lazarette. I eliminated my two AGM batteries from the port lazarette and now have a single 320ah LiFEPO4 battery in the center cockpit lazarette. It sits about 1 foot to the starboard side of center. We have the T9.9 kicker and the cock pit refrigerator. We no longer have a port list on our boat.

I initially looked at going with Dakota's. I drew out my center cockpit lazarette to scale, I was looking at putting in a pair of 200ah Dakota's, how I would fit them, run the cables to them, secure them. Tetris. I ended up going with Lithionics largely in part due to their form factor. The shape and size and weight of their 320Ah battery, being only 1 battery was extremely attractive to me as it meant less cabling. I got all my port lazarette space back, I still have 2/3rd of my center cockpit available for storage, the boat lost some weight, and I increased my house battery bank usable capacity by 2.5 times.

Factory LiFePo4 schematic and write-up.
https://www.letsgochannelsurfing.com/luxury-edition-lithium

How I upgraded to LiFePo4 on an RT27-OB NW Edition with a tech write-up.
https://www.letsgochannelsurfing.com/lithium

 

[CruisingElvinRay]

I’m on a journey that will eventually end with lithium batteries for my house bank. I say journey, because there are a LOT of changes that I’ve made in preparation for the conversion. (I’ve learned a lot from Channel Surfing - pay attention when he offers advice)

We ordered my R-23 with one of the versions of “Air Conditioning Underway”, which included a slow-start A/C system and an extra (3rd) FLA House battery. The oddity is that the 3rd battery was located in the starboard locker next to the thruster battery. The other two house batteries are in the port locker next to the starting battery. It took a full day to carefully go through the process of doing a side-to-side swap of the starting battery and the 3rd house battery. The 3rd house battery being so far away was causing balance issues in the bank of 3.

Another difference from the manual schematic is that I only have one ARC, connecting the Start and Thruster batteries. My house bank gets engine charging via the Yamaha accessory battery charge isolator. When running, the engine charges the start battery and then the house bank.

Other things I’ve done in preparation (no particular order):
-upgraded the ABSO 20A charger to ABSO 60A
-Replaced the standard solar controller with a Victron SmartSolar controller
-installed a Victron 712 Smart Battery Monitor on the house bank with voltage monitor on the starter battery.
-installed a smart battery voltage monitor on the thruster bank.

As for battery placement, whichever battery solution I choose will be at least 270Ah and will fit where my existing house bank is in the port locker. This will also require a DC-DC charger, as well as Cabling and fuse changes. Then, I’ll remove the ACR and move the Yamaha accessory charging cable to the thruster battery. I’ll keep the center locker clear for storing my Takacat 260LX that we used for the first time last week while on a mooring. It takes the full space.

Up next:
Solar and Batteries. Neither will be cheap. Will have >400W of solar to help put energy back into the batteries. I’d love to have 600Ah of battery storage, but I just don’t have room for it. The Battle Born Game Changer 3 battery would be the best use of the space, because it’s height fully utilizes the vertical space in my locker, giving me space back on the other two dimensions. Decisions…. Decisions…


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[Submariner]

I’m on a journey that will eventually end with lithium batteries for my house bank. I say journey, because there are a LOT of changes that I’ve made in preparation for the conversion.

You are so right on this. They advertise some LiFePo4 batteries as "drop-in". This is misleading. Drop-in does not mean one can simply pull out their old AGM or FLA batteries and "drop-in" LiFePo4 batteries. "Drop-in" LFP batteries means the battery is self contained with it's own internal BMS. There are internal and external BMS's. The purpose of the BMS for LFP batteries is to act as a safety switch. High voltage, low voltage, high temp, for example, all would cause the BMS to disconnect the battery such as to protect it (and ultimately, to protect you and the boat!).

The LFP battery must be isolated such that every charge source supports LFP. The voltage, absorption time, tail current, all must match what your specific LFP battery wants. There are so many nuances and fine details to be met with LFP.

As an example, the 20amp ABSO battery charger that came with my RT27-OB I still have on the boat. It charges the thruster and engine battery only. It does support LFP on channel1, but I can't use it for LFP. The 20amp ABSO only supports a tail current of 1, 2 or 4amps. The 60amp ABSO charger I installed as a 2nd battery charger is dedicated to the LFP battery bank only. It supports 3, 6 or 12amps of tail current. The Lithionics 320ah battery I installed requires that charging stop when the tail current drops to 10amps. The 20amp ABSO would most likely over-charge my Lithionics battery.

Some LFP batteries with internal BMS's can not be installed in series or parallel with others and only work stand-alone. The 320ah Lithionics battery I bought is one of them. External BMS's require a lot of extra components that look complicated. Some less expensive LFP batteries can't handle an inverter due to the in-rush current requirement. If LFP isn't done right on your boat, you run the risk of your insurance company dropping your coverage.

For the Lithionics (Li3) battery I installed, I had to create a drawing. Lithionics had to approve the drawing. The drawing had to illustrate all charging sources and all loads. Installation had to meet ABYC standards. I had to replace my Skylla 70 amp battery charger with the 60amp ABSO charger because Lithionics hadn't tested it and thus, didn't know if it'd work or not. Unsupportable they said.

The key take-away with LiFePo4 (LFP) batteries... think of it as a system, because that's what it is. The system needs to work together.

When done right, LFP is awesome. When I leave my home-port (covered slip), my 400 watt solar array provides the power we need, paired with the engine and a 30amp DC to DC charger. I run the hot water heater off the inverter powered by LFP without issues now and shore-power hookups at a guest marina are optional.

 

[bgruenthal]

Thanks for all of your input. We understand that this is not a simple project! We expexct to do a lot more research. And, we are lucky to have an adult son with quite a lot of mechanical and electrical experience who is willing to help. But, LiFePo4 is new to him too, so we will all be learning.

 

[Submariner]

Up next:
Solar and Batteries. Neither will be cheap. Will have >400W of solar to help put energy back into the batteries. I’d love to have 600Ah of battery storage, but I just don’t have room for it. The Battle Born Game Changer 3 battery would be the best use of the space, because it’s height fully utilizes the vertical space in my locker, giving me space back on the other two dimensions. Decisions…. Decisions…

To run your air conditioner, I'd go with the Victron 100/50 solar controller.

MC4 connections used for solar panels can not exceed 30amps. This is the controller to solar panel side. It's also 10AWG wire from the solar panel through the boat to the controller. With a pair of 24 volt solar panels, it shouldn't be a problem to stay under 30amps whether you hook them up in series or parallel.

For the solar controller to the house bank I'd run 6AWG wire with a 70 amp fuse. The fuse would go closest to the battery. (The factory wire is only 10AWG with a 30 amp fuse).

Then I'd look at a pair of 225 watt CustomMarineProducts panels. With 450 watts of solar in North Carolina, looking at the Solar Isolation chart (sun hours per day) for North Carolina, expect about 4.5 hours a day of direct sunlight. Cape Hatteras has an average of 5.31 hours. That'd yield about 2,400 watt-hours a day (about 3 hours of air conditioning).

If you could fit a pair of the 270 watt panels, that'd be even better. (They may fit, but it'd be close). At 540 watts total, you'd probably see about 2,900 watt-hours daily and get almost 4 hours of runtime on the air conditioner.

LFP won't suffer from the voltage drop of AGM/FLA. The inverter will love that. With the sun beating down on your panels it'll help offset the load on the battery bank. If you're up on plane, the engine will help out also since you've got the aux charging cable (or upgrade to a DC to DC charger for the house bank, like an Orion-TR 30amp). For LFP, they recommend that the DC to DC charger be 1/2 the size of your alternator to keep your alternator from overheating/burning up.

LFP + solar, they say is the ultimate combination. There is no minimum charge rate for LFP. LFP operates great in a partial state of charge. Generally you get 75% usable capacity with LFP. The max charge rate is usually substantially higher than AGM/FLA. So if you have the amps for charging, you can replace them quicker. MPPT controllers work even better with LFP because the absorption phase of LFP is so short.

https://www.bigfrogmountain.com/SunHoursPerDay.html

 

[CruisingElvinRay]

Thanks Martin. I’ve been talking with CMP. I’m debating using two separate 100-30 solar controllers (one for each panel). I don’t mind running additional cables. I’d love to have the 270s up there, but need to spend more time measuring and planning. I want to get the solar worked out before I decide on a battery bank configuration.


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[FlyMeAway]

I went deep down the rabbit hole on LiFePo4. I spoke to a number of installers and system designers and also considered DIY the install (briefly).

The best advice I got was from a marine electrician with a fair bit of experience with lithium conversions. He said a good rule of thumb is to take what you are spending on "drop-in" batteries + install of the batteries, and figure the other elements of the system conversion (parts and labor) will be 1-1.5X that. That will be changes to charging system, controllers, alternator / alternator regulators, etc. to support both the lithium batteries and the "mixed" lithium/AGM system (thruster and starter stay AGM). His advice proved sage: on a roughly $4.5k+tax Battle Born "drop-in" install on our R-31, several quotes for the rest of the system typically came in around $3-5k+tax (parts and labor, depending on exactly which options we went with). That makes the total system ~4X+ what new, high-quality AGMs would cost. I think for some the benefits of running aircon or ultrafast charging for weeks on the hook justify the cost, but we said no thanks.