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: (LiCoO2, LiMn2O4, LiFePO4, LiNiMnCoO2, LiNiCoAlO2, 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 LiNiMnCoO2 (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 Oxide1
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 Phosphate1 | 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.
1 Cathode material 2 Anode material
