Hi Kirk,
I'm sorry to hear that you have had such bad personal experience with lithium batteries. My prismatic LiFePO4 cells in my boat have proven to be the most trouble free battery that I have ever owned.
One problem is that Lithium-Ion is a very generic term that covers a number of different chemistries and construction methods. The high performance "pouch" cells are known to be more fragile and succeptable to mishandling. But I've never heard of an airline that doesn't let laptops or cell phones onboard, even in the cabin, so I don't see that the FAA is concerned about ALL Lithium batteries.
Prismatic cells like the ones in my boat are even more stable than the one in your phone, I've seen a cell ruptured (with a hammmer) and another pierced (with a huge metal spike) and nothing happens, no fire, no cloud, not even a spill. The cells no longer held a charge, but everyone involved expected that.
My lithium cells have sat for more than 6 months, while losing less than 15% of their charge. In fact, my batteries maintain their capacity better if stored at 60-70% charged, the manufacturer says that consistantly storing them fully charged might knock the cell's lifespan down to about 2000 cycles. That would not be a problem for me. I never run any sort of maintenance charger on this battery bank.
I don't watch my voltage at all, that what my $250 of BMS are for. If a cell approaches an overvoltage situation while charging, my charger automatically shuts off. If a cell approaches an under voltage situation while motoring, the throttle circuit is reduce by a factor of 5, reducing the load, allowing the cell to bounce back. That said, I've never run my boat's battery below 50% charged (except for performance testing), so the undercharge situation is largely theoretical.
So I take my Lithium battery pack for granted and can forget about it for more than a year with no adverse results. That is much better than my personal experience with FLA, AGM or NiMH batteries. My system is properly engineeered and well matched for my usage. YMMV. It sounds like Ned's personal experience with these batteries is similar to mine.
Fair winds,
Eric
1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh Lithium batteries
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Kirk McLoren <kirkmcloren@...> wrote:
>
> you have all the stuff for it to work and you manage your load so that you stay away from limits. Should work great under those conditions.
> But lithium has its problems. FAA has restrictions on lithium batteries (including lithium-ion batteries) in both carry-on and checked baggage on US flights.
>  The FAA is simply addressing the issue of lithium batteries spontaneously combusting, which has gotten plenty of press in the last few years. You don't need to crush one, you don't need to charge one, you don't need to use one. Just put it on the shelf, and some of them will spontaneously combust. Apparently there are some problems in the manufacturing processes and some defective batteries can just start to burn. Most likely during charging--but given the temperature and pressure changes (even in the airplane cabin) that might be enough "squeezing" to set one off.Â
>
> Mechanical sensitivity is not an endearing quality. The $45,000 dollar complaint some Tesla owners have experienced also is not endearing. If you are not familiar with that story it is about parking your Tesla for a couple of weeks and coming back to a failed battery pack which they (Tesla) don't warranty. I believe the moral of this story is parasitic loads and BMS leaks have to be anticipated and you MUST have power available if shore power is interrupted for appreciable time.
>
> Â A friend of mine used to race bikes and is still active in the wrenching end of the sport. Read this post and tell me what you think -
> Chiming in with real world experience on Shorai. I've not been successful starting my KTM990 when left out overnight below 45 degrees despite following several "warm up" procedures. I went back to the stock lead acid battery. Shorai sent me a replacement but I have not been able to test it yet. Â
>
> May save a few pounds but only starts when it is nice. Again, not endearing.
>
> I am glad you are having a positive experience with your installation. May you have many more positive experiences. But I would motor voltage like a hawk and have an alarm for low voltage. The Tesla experience can be duplicated elsewhere.
>
> Is there a perfect chemistry? No. Is there a chemistry you can take for granted and forget about when you leave on holiday? That would be prudent.
> If you are gone and the cord gets pulled out of the power socket or the circuit breaker trips you can get in deep kim chee with lithium. Probably not in 2 weeks like the Tesla owners but unsettling non the less.
>
> All the best
> Kirk
>
>
> Love is so short, forgetting is so long.
>
>
> ________________________________
> From: Ned Farinholt <nedfarinholt@...>
> To: electricboats@yahoogroups.com
> Sent: Tuesday, June 12, 2012 9:19 AM
> Subject: Re: [Electric Boats] NiMH Batteries Suppressed
>
>
> Â
> There are those of us who rather like lithium. I have had a 16 cell 160 ah bank for over a year with very fine performance. I have a bms but the charger and a total battery monitor, i.e., fuel gauge, have managed the bank to the point that neither the bms alarm nor shut-down have ever gone on. I am operating with a 0.5C load. There is no need for a blanket condemnation when they may be the best solution for some applications. My app is to go fairly fast (10-15 knots) for a long way (25+ nm). It works.
> Ned
> P.S. Â Love is giving of oneself for the good of the beloved. It can last forever.
>
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