Saturday, January 28, 2012

Re: [Electric Boats] Re: Marine Li-Po Batteries 51.8Vdc 100-200 Ah

 

On Jan 26, 2012, at 09:44, martin demers wrote:
I would like to know what is the advantage with Li -po batteries in boats

A very good question Martin. [and I'm not sure I am qualified to answer ;)]


I chose AGM (lead acid) batteries for my boat for pragmatic reasons:

I'm not a battery expert, and where I hope to travel, I don't suppose I will find a whole lot.  AGM's were a smaller initial investment, it is easier to charge, and [I think] I understand the chemistry of it enough to charge them properly and keep them sufficiently maintained.  If I travel and need a replacement, I can quickly get a replacement. Until my wallet starts to get too heavy I will probably stick with lead acid.


On oversimplified comparison . . .

Lead Acid: (includes flooded, SLA, VRLA, AGM, and GEL)

Advantages:  cheaper, proven technology, easy to replace, chargers are readily available, a large bank of batteries can be charged all in series, no memory, high over-charge tolerance
Limitations:  heavy (30-50 wh/kg), cannot be left in a low-discharged condition, a deep cell battery has perhaps 300 cycles, high internal resistance, takes a while to charge (8-16 hrs), contains Lead

Li-Polymer: (LiCoO2LiMn2O4LiFePO4LiNiMnCoO2LiNiCoAlO2, and Li4Ti5O12 to name a few see Notes below)

Advantages:  lighter (100-130 wh/kg), can be made environmentally friendly (no Pb, Cd, or Hg), 1,000+ cycles, no memory, lowest internal resistance of rechargeable batteries, faster charge (2-4 hrs)
Limitations:  expensive, charging properly is critical, chargers are expensive,  (each cell needs to be monitored and charged individually when  charging), low over-charge tolerance, hard to find a dealer that will sell you one suitable for a DIY-EV boat (24-48vdc boats are either too big or too small)




In the Title Post, the battery chemistry refers to Lithium Nickel Manganese Cobalt  LiNiMnCoO(NMC)


Notes on Lithium Ion (Li-ion) and and Lithium Polymer (Li-po)†:

• Scientists and the media give Li-ion batteries unique names but unless you are a scientist, this might cause confusion.

• The polymer hype of the early 2000s is still going strong, however most users cannot distinguish between a regular Li-ion and one with polymer architecture.

•  All Li-ion polymer cells today incorporate a micro porous separator with moisture. The correct term is "Lithium-ion Polymer" (Li-ion polymer or Li-polymer for short.)

• Li-polymer can be build on many systems, such as Li-cobalt, NMC, Li-phosphate and Li-manganese.

• As far the consumer is concerned, the lithium polymer is essentially the sam as the lithium ion battery.


† - Batteries in a Portable World - Isidor Bunchmann - pp. 59-60.   See also "Battery Types" on www.BatteryUniversity.com, an up-to-date reference for comparing different battery chemistries.


Types of Li-ion batteries:  Table 2-10†

Chemical name
Material
Abbreviation
Short form
                  Notes
Lithium Cobalt Oxide1
Also Lithium Cobalate or lithium-ion-cobalt)
LiCoO2
(60% Co)
LCO
Li-cobalt
 
High capacity; for cell phone laptop, camera
Lithium
Manganese Oxide
1
Also Lithium Manganate
or lithium-ion-manganese
LiMn2O4
LMO
Li-manganese, or spinel
 
Most safe; lower capacity than Li-cobalt but high specific power and long life.
Power tools,
e-bikes, EV, medical, hobbyist.
Lithium
Iron Phosphate
1
LiFePO4
LFP
Li-phosphate
Lithium Nickel Manganese Cobalt Oxide1,also lithium-manganese-cobalt-oxide
LiNiMnCoO2
(10–20% Co)
NMC
NMC
 
Lithium Nickel Cobalt Aluminum Oxide1
LiNiCoAlO2
9% Co)
NCA
NCA
Gaining importance
in electric powertrain and grid storage
Lithium Titanate2
Li4Ti5O12
LTO
Li-titanate
Table 1: Reference names for Li-ion batteries. We will use the short form when appropriate.
 Cathode material         Anode material



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