Any special procedure for switching from AGM to Lithium batteries

[jimbeam]

Boat R27 has AGM batteries but wish to switch to Lithium. Anything special should be done to the electronics to switch?
jimbeam

 

[DDean]

You’ll want to speak with @Submariner as he did it. You have a rewire the boat. I’d consider carrying lithium battery packs like Ecoflow or Bluetti that just plug into shore power and run the boat off of those or recharge your AGMs from those instead. It’s very difficult to convert. It’s goes way beyond simply changing the batteries.

 

[scross]

As DDean implied, it’s also very expensive to convert. I remember costs of $8,000 to $12,000 to do the conversion.
Much cheaper to go to 400+ watts of solar, a portable power bank and or adding one or more AGMs to the house bank.

 

[dbsea]

I just converted my C30CB to LifePo4 and the cost was pushing $20k... welcome to 2025 inflation. 🙂

 

[freedomvango]

there's a few ways to do it

The actual singular conversion isn't hard

Battery
Class t fuse
Battery monitor with audible alarm (thanks for the note channelsurfing)
Confirm if your existing converter/battery charger will charge lithium
Confirm if your solar controller will charge lithium
Add a multi bank charger for your thruster and starter battery if you are reusing original one for your house battery
Dc to dc charger replacing the ACR
That's honestly all you NEED to do

However you aren't at all taking advantage of the cool parts of lithium. Fast charging and discharging make it even better
I do lithium systems weekly on vans and redid my r23 with lithium and full Victron running gear and 1200w of solar.
You can go as simple or as crazy as you want. It's really use case and budget driven. Be more than happy to grab a call with you to go through stuff if it helps!

The real move is the inverter upgrade which gets rid of the smaller battery charger and charges significantly faster, solar upgrade, as well as the capacity

 

[Rebel112r]

It is a job, but it is not terribly difficult. My conversion cost about 2500 dollars. Not much additional wiring needs to be done. I needed new house batts anyway so decided to replace with Lithium. This will be 3rd season, no problems so far. I ended up, with 300 amp capacity, got rid of old solar controller, put dc-dc charger in its place, replaced original controller. Factory charger was capable of charging the lithium. Bought about 10 ft each of 4/0 cable, pos and neg. Got rid of both charge controllers. Paralleled the thruster and engine start, and they reside on stud side, lithium in middle where Channel Surfing put his. I had already added a 330 watt panel and got rid of factory panel. The wiring that needs to be done is mostly making use of what is there, there is some shortening and moving and adding terminals and buss bars. The solar keeps up on the dock, very seldom plug in, fridge runs all season. Engine starts, thruster works, I am happy with conversion.

 

[Submariner]

Boat R27 has AGM batteries but wish to switch to Lithium. Anything special should be done to the electronics to switch?
jimbeam

Here's how I did mine. I've published everything, including electrical schematics.

Website

House Battery-Lithium | LetsGoChannelSurfing

www.letsgochannelsurfing.com

I have several video's published on the subject, but this is probably the one that describes it the best.

 

[Submariner]

Boat R27 has AGM batteries but wish to switch to Lithium. Anything special should be done to the electronics to switch?
jimbeam

It's a game of tetris. I don't know if you have the R27 classic or the R27-OB. I have the R27-OB, and due to space constraints, I had to re-wire the cockpit for the entire charging system, and add a second battery charger. I converted a NW edition to LFP. You have to isolate the house bank from AGM, and ensure that all charging sources to the LFP bank, support LFP. It all starts with a drawing. I have the schematic published on our website. Then it's a game of Tetris to fit the components into the boat. Bigger boats are easier in my opinion as they have more space. The R27-OB is pretty compact. It also matters on what type of LFP battery you go with. My install was $7k, and I did all the work myself. (about 45 hours of labor). I also paid to have my design and implementation reviewed by Ocean Planet Energy, who specialize in marine electrical to make sure I didn't overlook anything.

 

[Submariner]

Battery
Class t fuse
Confirm if your converter will charge lithium
Confirm if your solar controller will charge lithium
Add a multi bank charger for your thruster and starter battery
Dc to dc charger replacing the ACR
That's honestly all you NEED to do

ABYC also requires a battery monitor with a physical gauge be installed so there's an audible alarm that can be sounded. The physical gauge can offer Bluetooth for convenience, but there's no way to get an audible alarm from a bluetooth only battery monitor.

It's also important to verify the battery charger will charge the LFP battery that is being installed.

I had a Skyla 70amp Victron battery charger that supported LFP, however, it wouldn't work for my LFP battery. The Skylla required a communication connection to an external BMS (Victron's) to tell it when to stop charging. The Lithionics battery I installed had an internal BMS and thus, couldn't communicate to the Skyla.

The ABSO 20amp multi-bank battery charger that came with my R27-OB also supported LFP. However, the tail current settings were 1, 2, and 4amps. The 320 ah Lithionics battery I installed required that charging stop when the tail current dropped to 10amps. I had to install an ABSO 60 amp battery charger as it had tail current settings of 3, 6 and 12 amps (so I set it to 12 amps, so as to not overcharge my LFP battery). I kept the 20amp charger for the engine/thruster and added the 60 amp charger for the house bank.

I looked at converting an RT29 inboard as well. The inverter/charger that came with the NW edition stated that it supported LFP. But there wasn't any configuration in the inverter/charger to actually support LFP. It needed to be replaced to function with LFP.

 

[freedomvango]

there's a few ways to do it

The actual singular conversion isn't hard

Battery
Class t fuse
Confirm if your converter will charge lithium
Confirm if your solar controller will charge lithium
Add a multi bank charger for your thruster and starter battery
Dc to dc charger replacing the ACR
That's honestly all you NEED to do

However you aren't at all taking advantage of the cool parts of lithium. Fast charging and discharging make it even better
I do lithium systems weekly on vans and redid my r23 with lithium and full Victron running gear and 1200w of solar.
You can go as simple or as crazy as you want. It's really use case and budget driven. Be more than happy to grab a call with you to go through stuff if it helps!

ABYC also requires a battery monitor with a physical gauge be installed so there's an audible alarm that can be sounded. The physical gauge can offer Bluetooth for convenience, but there's no way to get an audible alarm from a bluetooth only battery monitor.

It's also important to verify the battery charger will charge the LFP battery that is being installed.

I had a Skyla 70amp Victron battery charger that supported LFP, however, it wouldn't work for my LFP battery. The Skylla required a communication connection to an external BMS (Victron's) to tell it when to stop charging. The Lithionics battery I installed had an internal BMS and thus, couldn't communicate to the Skyla.

The ABSO 20amp multi-bank battery charger that came with my R27-OB also supported LFP. However, the tail current settings were 1, 2, and 4amps. The 320 ah Lithionics battery I installed required that charging stop when the tail current dropped to 10amps. I had to install an ABSO 60 amp battery charger as it had tail current settings of 3, 6 and 12 amps (so I set it to 12 amps, so as to not overcharge my LFP battery). I kept the 20amp charger for the engine/thruster and added the 60 amp charger for the house bank.

I looked at converting an RT29 inboard as well. The inverter/charger that came with the NW edition stated that it supported LFP. But there wasn't any configuration in the inverter/charger to actually support LFP. It needed to be replaced to function with LFP.

true true on the audible alarm. i take it for granted with the cerbos we install on that

 

[Submariner]

As DDean implied, it’s also very expensive to convert. I remember costs of $8,000 to $12,000 to do the conversion.
Much cheaper to go to 400+ watts of solar, a portable power bank and or adding one or more AGMs to the house bank.

100% agree. I wouldn't recommend converting a boat to LFP unless solar was upgraded to something between 320 and 420 watts on boats our size. Odd's are, upgrading solar will satisfy most boaters electrical needs which leaves the house bank to just get you through the night. The return on investment is huge with solar. It's also a much easier and less expensive upgrade.

I converted Channel Surfing to LFP for hot water, and other 120volt loads which we run a lot of. We run our inverter daily when on the boat, and ours is a NW edition without air conditioning.

 

[kurtwitte]

You’ll want to speak with @Submariner as he did it. You have a rewire the boat. I’d consider carrying lithium battery packs like Ecoflow or Bluetti that just plug into shore power and run the boat off of those or recharge your AGMs from those instead. It’s very difficult to convert. It’s goes way beyond simply changing the batteries.

Have converted a M.H. from lead acid to lithium. Not too bad there but really different on the tugs. There is another Youtube video that describes the process to convert Just the cabin to lithium. I have a Ecoflow in my M.H.. It makes my coffee, powers my 3.2 cu ft freezer for 24 hours. I then run my onboard generator(2K) for one hour a day to fully recharge the ecoflow(1260W) and do that on a daily basis while boondocking. I have a R27 with lead acid batteries and am deciding to 1. buy a ecoflow, or 2. buy a small 1000 w gas generator to carry. Lots of pro's and con's on this subject. I like the idea of carrying the generator for fail safe measures.