Lithium batteries? (LiFePO4, Lithium Ion Cobalt, etc)

Hi WWers,

It's been quite a while since I have posted, not much going on with boat upgrades for me these days. Last summer I sold my slalom boat (2nd boat) and I am back to being a 1 boat man). With that in mind I would like to put my Nautique SV211 on a diet to help improve the slalom wake. In addition to building a lightweight swim platform I am thinking about replacing my aging AGM stereo batteries with a new technology Lithium Ion Cobalt battery.

My current stereo battery bank consists of two 75lb Kinetik HC2400's (actually now replaced by some generic slightly higher capacity batteries). This is about 240 amp hours of energy at 12 volts. I am considering replacing these with this battery: http://www.ebay.com/itm/181972989679...da57ab9f6&cp=1

In case the link does not work, this is a Chevy Volt battery rewired to produce 200ah at 12v. The technology is:
CELL SPECIFICATIONS

Cell type Laminate type
Cathode material LiMn2O4 with LiNiO2
Anode material Graphite
Rated capacity (0.3C) 17 Ah
Average voltage 3.8 VDC
Maximum Voltage 4.2VDC
Minimum Voltage 3.0VDC

Unfortunately this battery only produces 11.4 volts (3x average voltage) so it seems to be too low for what I really want to do.

I have all wetsounds amplifiers and I have also sent a question over to them to see if this is too low but I think I know the answer...

Anybody else considering using some of the newer battery technologies in their boats?

Mike
mikeskiw@gmail.com

For a strictly regulated amplifier 11.4 volts would mean running it into the ground. It might operate at 11.4 volts but wasn't intended to do so over a protracted term.

For an unregulated amplifier it would mean half of rated power, poor sound quality, thin bass, and a few other issues that are all bad.

Hi David,

Good to hear from you!

I just found this on youtube: https://www.youtube.com/watch?v=Lg434K0gHeQ

In the analysis he found the similarly rated LiFePO4 ran almost twice as long before it hit a floor voltage of 12V so maybe it's not as bad as I think. The LiFePO4 is slightly different battery tech so that could also make a difference?

The Lithium Batterys are so bad A$$ check out this Gem car battery. This 1 battery 85 lbs and the size of 1 group 31. Replaces 6 flooded lead acid batterys at a total weight of 477 for 6 batterys

With a 90% total usable energy it's a power light weight battery.

Hard to believe this battery has as much power as 6 flooded lead acid batterys

You guys do know why meth labs explode right? Lithium and water don't play well together...

Do you know Gasoline & Sparks can create a explosion?

No they won't actually. But gasoline vapor and sparks may, if they're concentrated enough. I'm just saying if you submerge that battery inadvertently the results would be crazy. One little lithium strip from a AA and a 20oz bottle of water can create a ridiculous fireball.

I agree they are not meant for marine use yet but let these guys be the statistics if they want...

Ask yourself this. How often do your current batterys interact with water. Many lithium batterys are sealed just like traditional batterys. I do agree if you were to puncture the battery casing on a lithium ion and have water intrusion you could have a problem. I think it's a reasonable and fairly easy problem protect against.
To overcome

11.4V sounds like the nominal voltage. I assume it is a 3 cell pack. Normal lithium batteries have a 3.7V nominal voltage so it seems this may be higher. As you pointed out, 4.2V is a fully charged cell. This is a 3 cell pack so full charge is 12.6V which should be ok to run equipment. You don't want to run this type of battery down below about 3.7V per cell or you cause damage to the cell. You also don't want to overcharge so you need the alternator (or whatever charging system) to shut off at 4.2V per cell or you risk fire. Also note, as loads increase, voltage does drop. I use these type of batteries with real time telemetry (RC planes) and I can see the voltage drop as the load increases. In other words, a fully charged pack at 12.6V will not provide 12.6V depending on the load.