Carter, glad to hear you endorse the overall cost as a major qualifier for your decision. You had me worried there. Yes, specialized use or availability often controls what we end up favoring. It is rarely simply the battery technology. And to my way of thinking the whole package needs to be considered. Overall cost rather than cost/energy is certainly valid.
My experience is that FLA will get there cheaply for higher maintenance, but AGM is hard to beat for a long life of low maintenance. I think right now on our land we have 16 vehicles (including tractors) that use batteries and was surprised to see that even though they are tended by a variety of mechanics, in every case they have gone over to AGM. (Usually one of the Optima types, but occasionally West Marine!)
Our trimaran uses a set of AGMs as a house battery system.
However, the electric canoe uses Lithium-Manganese driving a one HP outboard and these are new to us.... but so far are a very impressive technology. They only have about a dozen cycles on them, but I'll write more when I know more.
Luck to all, Roger L.
----- Original Message -----From: Carter QuillenSent: Wednesday, February 20, 2013 11:48 PMSubject: Re: [Electric Boats] Re: Comparing FLA to LiFePO4.Robert,Please don't interpret my argument for flooded lead acid as an enthusiastic endorsement of the technology, my experience has been that it really does kind of suck on many levels and has been a big disappointment from a performance standpoint. But if you don't have 8k for your battery pack, a million golf carts is a testament to the fact that a $1000 bucks will get you there. Also, with the high cost of Lithium, the overall life cycle cost is really too close to call definatively at this point with a too many variables.If you have the cash, who wouldn't rather drive the Testerosa? (Even if it does cost more). But the technology is still a bit fluid with lots of "claims" of superior performance that don't always pan out. Note that Boeing just switched from Lithium to NiCad after a very expensive failure of the Lithium technology in thier Dreamliner.It's good to hear that your experience with LeFePO4 was very positive and that's definitely the kind of feedback the industry needs.Lithium chemistry is probably the future but in the mean time, some of us are still stuck with what we can afford and my argument is that lead is not quite dead, yet!CarterFrom: Robert Lemke <robert-lemke@att.net>
To: electricboats@yahoogroups.com
Sent: Wednesday, February 20, 2013 10:49 PM
Subject: Re: [Electric Boats] Re: Comparing FLA to LiFePO4.
Since this is being kicked around I'll throw in my $0.02 and isn't worth that. I recently went the LiFePO4 route and from my tests I'll never go back to lead. The first thing I discovered was how conservative the a-hr rating is in real world usage. Over the years I grew accustomed to the 20 hour rate of lead acid. I purchased (8) 100 a-hr LiFePO4 cells and found that at that easy 20 hour rate they should have been rated 150 a-hr. Pulling 100 amps for a 1 hour rate they still managed 125 a-hr. That just doesn't happen with lead. A 60 lb group 27 battery gives my electric kayak a 16~18 nm range. The same weight of LiFePO4 gives me 80 nm. Fast charge acceptance is another perk, as I can pull into a marina bar/restaurant and my 8 lb, 50 amp charger will refuel the battery in the time it takes to have lunch and drinks. BTW, the charger has a lithium profile and was less than $200. Another positive is very small voltage sag under heavy draw and not much voltage swing during discharge. Combine all this with 2000+ cycles and electron energy storage doesn't get cheaper than this. Lead is Dead.--- On Wed, 2/20/13, Eric <ewdysar@yahoo.com> wrote:
From: Eric <ewdysar@yahoo.com>
Subject: [Electric Boats] Re: Comparing FLA to LiFePO4.
To: electricboats@yahoogroups.com
Date: Wednesday, February 20, 2013, 6:09 PM
Hi Carter,I know that your plan is largely solar and you've got generator and a full diesel driveline as backups, but here's some battery only performance data. So your eight T-125 (530 lbs) have a 20hr rating of 12kWh, but at a 25A load, the total capacity drops to 10kWh (that's the Peukert Effect kicking in). Put the load up to 50A and the total capacity is 8.4kWh. And at 80A (you said earlier that 80A = 3.8kts or 4.4mph), the total rated capacity falls to 7.5kWh, a loss of 37% to Peukert's effect. Limit your discharge to 60% of total capacity and you batteries will last 1.12 hours at 80A draw. At 3.8kts that works out to 4.25nm range on a full charge of your batteries. The Balqon pack with a 20hr rated capacity that is 67% higher than your FLA pack seems like a luxury, but let's check the same loads. Balqon doesn't list the weight, but it should be right around 500 lbs like your current pack. Starting with a total rated capacity of 20kWh, at 25A the rated capacity drops to 19.86kWh, very close to the 20 hour rated capacity. At 50A, the rated capacity is still 19.45kWh. Finally at 80A, the Balqon pack rates to 19.2kWh, losing only 4% to Peukert's Effect. Since LiFePO4 batteries can be consistently discharged to 80%, you could run the motor at 80A for 3.83 hours for a range of 14.5nm. That's 3.4 times the FLA range at 3.8kts under batteries alone. So at the cash register, the Balqon battery looks 8 times more expensive than the T-125s. But if you consider the increased range without any weight, the Balqon pack is only 2.3 times the cost of the T-125s. Trojan says that the T-125 is good for 650 cycles. At 2000 cycles for the Balqon, you would have to buy 3 sets of Trojans for the same number of cycles. If you factor in the full life span in cycles, the Balqon works out to 12% cheaper per mile than 3 sets of T-125s. I know that this doesn't change the fact that the original investment takes a bigger wallet, but that could ultimately save you money in the long run. I know that you didn't ask for this, but I like running the numbers, and it's been a while since anyone has done the math in front of the group. I figure that this exercise might be helpful for new mebers here. Fair winds, Eric Marina del Rey, CA --- In electricboats@yahoogroups.com, Carter Quillen <twowheelinguy@...> wrote: > > Followed the link to check it out. Nice battery and made in America, (mostly), to boot. >  > Wish I had an extra $8 grande, I'd buy one tomorrow. Puts my 8 pack of Trojan T-125s to shame but since I only paid about a thousands bucks for an 8 kW pack I don't feel that bad. Looking forward to the day when you'll be able to buy Lithium for the cost of lead and it's coming. In mean time, I'll have to be content with my horse and buggy and wait for the model 'T's of batteries to hit the market. >  > Carter > www.archemedesproject.blogspot.com > > From: James Sizemore <james@...> > To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com> > Cc: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com> > Sent: Wednesday, February 20, 2013 7:24 PM > Subject: Re: [Electric Boats] Re: Converting a small trimaran to electric drive > > > > Here is a 20kw lithium pack with bms and case for the below 8000, total package. > http://www.balqon.com/store.php#!/~/product/category=2897128&id=12658249 > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/electricboats/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/electricboats/join (Yahoo! ID required) <*> To change settings via email: electricboats-digest@yahoogroups.com electricboats-fullfeatured@yahoogroups.com <*> To unsubscribe from this group, send an email to: electricboats-unsubscribe@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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