Considering Electric Yacht conversion....Lithium Question (simple one)

[Anonymous7500]

We are considering removing our Atomic 4 in favor of an Electric Yacht electric propulsion conversion. While most of our questions have been answered by using previously posted questions as well as the FAQ on Electric Yacht, we still have on glaring question.

All of the battery bank requirements referenced are based on lead acid or AGM batteries. It is our understanding that a 50% DoD is used for these batteries whereas an 80% DoD is used for Lithium Ion batteries. Therefore, a 260 amp hour lithium ion bank would provide equivalent power as a 400 amp hour AGM bank, correct?

Thanks in advance.

[DeepFrz]

There are a number of threads on LifePo4 batteries. They should answer your questions.

[simonpickard]

Hi there,

You're right pretty much, check out the thread I started a few months back asking about E.P. Some amazing advice in there (I do love this forum).


Just wondering though, what size boat do you have? And what are your plans? Do you cruise, etc? After summing up the thread I started I had to conclude that currently it's not very realistic to switch over to EP at the moment for anything more than using the motor to get in and out of the harbour.


Would be great to get some insight on your plans / goals with this project.


Regards,
Simon

[deckofficer]

Balqon has the 260 a-hr cells on a clearance sale of $190.

[Anonymous7500]

Originally Posted by deckofficer

Balqon has the 260 a-hr cells on a clearance sale of $190.

I have been looking at those with a lot of interest. I was originally looking at the 100 Ah batteries to use to get our feet wet with Lithium Ion batteries. But, I am quickly running out of reasons to not jump right in with a 260 Ah set up. It would exceed our house demands for the foreseeable future.

Originally Posted by simonpickard

Just wondering though, what size boat do you have? And what are your plans? Do you cruise, etc? After summing up the thread I started I had to conclude that currently it's not very realistic to switch over to EP at the moment for anything more than using the motor to get in and out of the harbour.


Would be great to get some insight on your plans / goals with this project.

The boat is a 30' Pearson. Our plans are to get from the Great Lakes to the Caribbean in the next 5 years. The major hurdle to that move is the Erie Canal or the St. Lawrence seaway. Both routes have extensive periods of motoring. The other, less attractive, option is to transport over land.

Electric Yacht claims that we can get 4 knots at 30 amps per hour. The 260 Ah Balqon bank will provide us with 6-7 hours of motoring at this rate. Unfortunately, that is only about 25 Nm and the St. Lawrence route is nearly 400 Nm.

I am currently replacing the old Monel fuel tank. The new fuel tank will require a new cradle to be built for mounting. I am attempting to make the cradle the appropriate size to be a future battery box. With the current design footprint, (16) Balqon 260 Ah batteries will fit quite nicely.

Thanks, Simon. I will check out the EP thread that you started.

[mbianka]

Originally Posted by Anonymous7500

We are considering removing our Atomic 4 in favor of an Electric Yacht electric propulsion conversion. While most of our questions have been answered by using previously posted questions as well as the FAQ on Electric Yacht, we still have on glaring question.

All of the battery bank requirements referenced are based on lead acid or AGM batteries. It is our understanding that a 50% DoD is used for these batteries whereas an 80% DoD is used for Lithium Ion batteries. Therefore, a 260 amp hour lithium ion bank would provide equivalent power as a 400 amp hour AGM bank, correct?

Thanks in advance.

Anon:

My 210 AMP 48 volt AGM battery bank has worked well for me for five years now. So I have not explored Lith Ion's which were fairly new and $$$ when I made my conversion to electric propulsion back in 2008. Yes, Lith Ions can be drained much further than lead acid types but, at greater cost and require a more complicated BMS (battery management system). My reason for going with AGM's when I converted was to keep it simple. I thought of the the scenario of motoring down the ICW and having a battery fail. I could then call up a local battery distributor and have an off the shelf AGM delivered the next day and be on my way again. Replacement times for lith ion batteries were much longer in 2008 I recall a month or more back then. Don't know what they might be now. I think I might still make the same decision today. But, what I know now that I did not know then is that the EP system would be much more reliable, cheaper and easier to maintain the the ole diesel was. So for me right now if it ain't broke don't fix it!

[mbianka]

Originally Posted by Anonymous7500

I have been looking at those with a lot of interest. I was originally looking at the 100 Ah batteries to use to get our feet wet with Lithium Ion batteries. But, I am quickly running out of reasons to not jump right in with a 260 Ah set up. It would exceed our house demands for the foreseeable future.



The boat is a 30' Pearson. Our plans are to get from the Great Lakes to the Caribbean in the next 5 years. The major hurdle to that move is the Erie Canal or the St. Lawrence seaway. Both routes have extensive periods of motoring. The other, less attractive, option is to transport over land.

Electric Yacht claims that we can get 4 knots at 30 amps per hour. The 260 Ah Balqon bank will provide us with 6-7 hours of motoring at this rate. Unfortunately, that is only about 25 Nm and the St. Lawrence route is nearly 400 Nm.

I am currently replacing the old Monel fuel tank. The new fuel tank will require a new cradle to be built for mounting. I am attempting to make the cradle the appropriate size to be a future battery box. With the current design footprint, (16) Balqon 260 Ah batteries will fit quite nicely.

Thanks, Simon. I will check out the EP thread that you started.

Anon:

FYI I recently just did an electro (motor) sail down the Hudson River from north of the Tappen Zee Bridge to Port Washington Long Island. A distance of 40 nautical miles. I operated under battery alone for the first few hours then fired up the small Honda 2000 generator when no winds showed up and went into hybrid mode. Electro sailed most of the way using just 900 watts of power from the generator (limitation of my battery charger) and a little over a gallon of gas for the entire trip. I may post a video of the trip in the near future on my blog.

[SoItGoes]

Just a quick note on the practical side of cruising with an elecric propulsion system...

We have a CAL 34 with the Electric Yacht system (which replaced the old Atomic 4) and lead acid battery bank and it works just fine for cruising. We've been electric for over seven years now of full time cruising and have not had a single day where we wished we had an internal combustion engine.

I'm still in the wait and see place on the Lithium chemistry batteries... Our current battery bank has been going strong for five years so, I expect, I have a couple of years to watch prices fall and better charging solutions to come into the picture before I need to jump to Lithium but for the moment your basic Sam's Club golf cart batteries are the way to go.