T-Pain Is On A Boat: Re: [Electric Boats] Re: RESULTS ..... VERY GOOD

Friday, June 24, 2011

Re: [Electric Boats] Re: RESULTS ..... VERY GOOD

Pat:

I'm just starting my fourth season with my AGM batteries and they seem to be holding up quite well so far. too I did occassionaly charge them via my Dual Pro or Zivan chargers over the winters but, they are usually kept charged more likely from my solar panels and wind generator. This winter I used the Dual Pro charger on occassion to keep them balanced. I think AGM's were the right choice for my boat from a cost, life and maintenace stand point. I consider my boat primarily a sailboat with an electric propulsion auxilary. So I try to minimize my battery use and operate them very much like you do. As Eric points out I try to charge the bank as soon as possible after drawing them down. I was not keen on the Lithium battery cost and battery managment circuits adding more complexity to my system. I also did not want to continue to deal with the maintenance of flooded batteries. I think Lithium might be a good choice for all electric boats that are all electric like an electric launches where batteries are drawn down to a greater degree than on sailboats like mine. Of course if the price of Lithiums were to come down (or if some other new low cost battery technology comes along) by the time my battery bank needs to be replaced. I certainly would consider a change to them.

Capt. Mike

http://biankablog.blogspot.com

--- On Fri, 6/24/11, greenpjs04 <greenpjs@neo.rr.com> wrote:

From: greenpjs04 <greenpjs@neo.rr.com>
Subject: [Electric Boats] Re: RESULTS ..... VERY GOOD
To: electricboats@yahoogroups.com
Date: Friday, June 24, 2011, 8:40 PM

Eric,
You are hoping your Lithiums will last 10 years and you know from experience that deep cycle FLA's lasted 3 years. (I understand your point that careful management would have extended that, but I don't want my batteries to be the top thing on my mind). Do you have any feel for where AGM fits between the other two? Mine are still going strong after one year (as expected). I always recharge them after use and usually only use 20% to 40% of the rated capacity during any one outing. I hope they last a long time, but how many years is that likely to be? 5? Maybe I will get Lithiums when the time comes. Weight is not important in my case. (Except when carrying the batteries from the dock to my garage at the end of the season ;-)

Pat

--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Hi Pat,
>
> I agree. I know that my Lithium cells will die of old age before I get close to 1000 cycles. I'm hoping that they last 10 years. Considering that I typically had to replace my deep cycle batteries every 3 years, I'm ok with the tradeoff. I know that I killed my old house batteries through non-use, sulfation would reduce their capacity too much. I know that it was my fault, and that I could have gotten more life from them if I had been more diligent in my charging regimen when I wasn't using my boat, but it just didn't happen. One advantage to LiFePO4 is a very low self-discharge. After storing my cells unattended for a year while my boat was being worked on, they were still above 80% charged. Try that with lead acid batteries (actually don't, because it's not good for the batteries).
>
> That's why for boats, I never try to factor in the rated cycle life into my justifications. I've never had a boat battery die from too many cycles.
>
> On the other hand, for EVs that do deep daily discharges, cycle life is more applicable. You can actually run batteries through their entire cycle life. That's where Trojan T-105s ended up being a better deal than cheaper deep cycle alternatives. I experienced this personally when I was converting cars to electric back in the early 1990's.
>
> Fair winds,
> Eric
>
> --- In electricboats@yahoogroups.com, "greenpjs04" <greenpjs@> wrote:
> >
> > Both Eric and Charlie have provided valid useful numbers. However, other data must be considered as well. I use my boat about once per week during the roughly 25 week season. So, even at 2000 cycles for the LFP batteries, I will be 140 years old when the batteries have used up their cycles. Does anyone know a typical life for these battery chemistries in years? Do they really last for their rated cycles even if it takes 80 years to do that many cycles?
> >
> > I am currently using AGM, so I will only be 92 when 800 cycles are complete. (For those not good at math, I am currently 60.)
> >
> > Pat
> >
>