T-Pain Is On A Boat: Re: [Electric Boats] Cost for Lithium vs Lead Acid

Saturday, May 21, 2016

Re: [Electric Boats] Cost for Lithium vs Lead Acid

Hi Myles,

Nice letter of info for all.

I am heading to Seattle area tomorrow in my RV. I am going to help my briother do a conversion from diesel to electric motor.

I am interested in the lithium batteries you are talking about.

Please advise as to where I may see them. Maybe on my way.

Thanks, John Brophy

On Saturday, May 21, 2016 6:32 PM, "'Myles Twete' matwete@comcast.net [electricboats]" <electricboats@yahoogroups.com> wrote:

I'd like to hear an updated discussion of the cost differences between Lead Acid vs Lithium.
It seems the last time I purchased flooded 6v batteries, they cost me about $120 for 1.2kwh of rated energy storage---i.e. about 10c/kwh.
Lithium costs are high if you buy new. But some good and even excellent quality Lithium cells, modules and packs can be picked up on the surplus market these days at tremendously reduced costs.
About 2 ½ years ago I bought my first 2 modules (3kwh, 42v nom (48 – 31v) each) for about $1200 each --- i.e. 40c/kwh ( or 4x PbA cost)
Then 2 years ago I bought an additional 8 modules (24kwh pack) for $6k --- i.e. 25c/kwh (or 2.5x PbA cost)
Now, these same packs can be had for as little as $4.2k --- i.e. about 18c/kwh (less than 2x PbA cost!)
And this is for probably the best lithium batteries out there---U.S. made Enerdel modules.
And that pack includes connectors, some contactors, some cabling and even Enerdel RLEC's (CAN-bus BMS boards for each half-module)…

Land-based EV folks traditionally justify going to lithium based on "cycle life". But that doesn't have a lot of value for us E-mariners.
Probably even the most active E-boater with a significant size pack will still only see 100 or less charge cycles annually.
Even PbA batteries can last several years or more.
We hear 1000- or 2000- or even 3000-cycles (e.g. Enerdel ) for lithium. For a daily driver, that's a good thing. For my boat? At less than 30 charge cycles per year, it'll take me over 100 years to reach the 3000-cycle life of these cells on my boat!

Still, while the huge count of cycle life for lithium is unrealizable for most of us, the fact that a well treated lithium pack will essentially outlive your boat is useful to know. How many times would you have to replace PbA batteries if you used those during the life of the boat? Twice? Three times? Some of you out there are on your 2^nd or 3^rd pack already. Given that, it's easily arguable that a Lithium pack that costs just 2x the PbA equivalent is a bargain. And as mentioned above, they aren't just "in the future"---you can get these now.

If any of you are in the Pacific NW and would be interested in the batteries I mentioned, send me a note offline and I'll point you in the right direction---they're stored in Portland, Oregon. NOTE: I have no interest whatsoever in these, just know that there are some available.

Anyway, I'm sure there are lots of other options out there also.

In case this helps-

-Myles Twete, Portland