SailNet Community

SailNet Community (
-   Sailboat Design and Construction (
-   -   Weight saving battery technology experiences (

Blanes 03-02-2008 03:12 PM

Weight saving battery technology experiences
Lithium Iron Phosphate LiFePO4 or variants thereof. Not some of the other Li Ion technology like Lithium Cobolt LiCoO2 or exploding laptop battery version. Anyone heard of the technology? Anyone applying it for marine uses? What manufacturer/s? Advantage is it claims to be half the weight of an equivalent 800Ah AGM/Lead acid configuration? Looking at this for a cruising cat in S pacific/Australia area. Charging via Solar, Wind and Honda portable Gen set. Not much alternator charging from dual outboards.

Lithium iron phosphate battery - Wikipedia, the free encyclopedia
Developed at U Texas, and improved with MIT technology.
LiFePO4 cells have higher discharge current and do not explode under extreme conditions, but have lower voltage and energy density than normal Li-ion cells. Used on the One Laptop per Child project and also on some hybrid vehicles.

sailingdog 03-02-2008 03:59 PM

I don't know if they have this battery technology in large scale commercial production yet, especially in the larger sizes that marine use would require. Even if they did, it probably wouldn't be used in a marine environment initially, primarily due to costs.

falconev 03-03-2008 08:01 AM

costs are not a factor in using LiFePO4 packs.
1/2 the weight, 5+ X's the life cycles, higher output per smaller volume, flatter discharge curve, no negative impact on environment like lead, any voltage, Ah, ....what else you need to know ?
more Q & A offline at 9zulu9 at nyms dot net

sailingdog 03-03-2008 08:56 AM

Yes, but what are the initial costs of the batteries. Many people aren't willing to shell out the bucks, especially on an unproven, in the marine environment, technology. Also, is the infrastructure to support the batteries available. Can you get chargers and inverters that will work with them. I don't think so.

falconev 03-03-2008 10:10 AM

yes, and yes.
but you can't afford them anyway, so why piss on them.

sailingdog 03-03-2008 10:17 AM

Just curious, who said I was pissing on them.. Can you point to the chargers and inverters that are marine grade and made or support the LiFePO4 battery technology. If not, STFU. I'm stating the facts , and you don't seem to like it... what is your relationship to LiFePO4 batteries anyways... and why do you need to go through an e-mail anonymizer??? That's what NYMS.NET is.

Originally Posted by falconev (Post 275498)
yes, and yes.
but you can't afford them anyway, so why piss on them.

camaraderie 03-03-2008 10:22 AM

falconev...please point me to someplace I can buy one of these batteries in a 12V size with enough amp hours to be used on a boat (20 hour rate/100+a/h's).

camaraderie 03-03-2008 10:57 AM

All I can find on this technology is a 12V pack which supplies 10ah's for around $400!!! That would make the price of a group31 battery around $4000 bucks. :(

The Odyssey batteries seem like the best bang for the buck currently in available technology for full time cruisers looking for quick charging and high cycle life.

Zanshin 03-03-2008 11:00 AM


Originally Posted by falconev (Post 275443)
costs are not a factor in using LiFePO4 packs.

Can you explain how costs are not a factor in the boating market, where every penny is turned over twice (there are threads here about using an inkjet and other homegrown methods to print courtesy flags instead of buying them for $10 apiece!)?

Does that mean that the cost for a nominal 300Ah capacity with this new technology will be the same as or lower than Lead-Acid?

Gramp34 03-03-2008 11:12 AM


Originally Posted by falconev (Post 275443)
costs are not a factor in using LiFePO4 packs.

Well, I guess when it comes to boat ownership, costs obviously aren't a factor or no one would ever buy one. ;)

The biggest LiFePO4 battery I could find with a price attached is this one from eBay:

That's a 48V, 20Ah pack that sells for $429 FOB China (plus $95 shipping).

I can't vouch for the quality though -- as Red Green says "Nothing says 'poor craftsmanship' like lumpy duct tape."

Rewired this would be 12V @ 80 Ah. Similar to a Group 24 lead acid battery. Quoted weight is 20 lbs vs. 45 for a Group 24 lead acid. So you could save 25 pounds per battery.

A cheap lead acid is maybe $75 at your local big box store.

These things have a nominal cell voltage of 3.60 V, so four cells in series will give 13.4 V, a little bit above regular lead acid. Charging voltage is 4.20 V per cell, so a 12V pack would need a charging voltage of 16.8 V. Standard alternators are regulated at about 14.1 V, so it appears they couldn't charge one of these LiFePO4 batteries.

When mass production brings the prices down and provides the charging technology, LiFePO4 will probably give lead acid a run for its money. At current prices, installing them on a boat would just be another expensive hobby.



All times are GMT -4. The time now is 12:06 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
(c) LLC 2000-2012

For the best viewing experience please update your browser to Google Chrome