John,
Let's do that. We'll even double the number of T-105s to get the weight closer to the 200Ah 12V NiFe array.
2400Wh NiFe = 13.2" x 32" x 13.6" = $1760 FOB
5745 cu. inches, 280 pounds, 1920Wh usable @ 80% DoD
5400Wh T-105 = 10.4" x 28.6" x 10.7" = $600 delivered
3182 cu. inches, 248 pounds, 2700Wh usable @ 50% DoD
The four T-105s have 40% more usable capacity, are 44% smaller, are 11% lighter and and are 1/3 the cost of the 200Ah 12V NiFe bank. Even running the NiFe batteies to 100% DoD gives less capacity than the T-105s at 50% DoD. Using a 50% DoD on the FLA batteries also gives you a bigger reserve in case of an emergency.
But as I've said before, everyone needs to figure out what is most important for themselves, every choice comes with tradeoffs. The cool part is that we each get to build our boats any way we like. I'm looking forward to hearing how the first NiFe boat in this group turns out.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, john briese <goodguyforsure@...> wrote:
>
> All this "Math" forgets using 50% of charge on T105s and using 80 to 100% on Nife.
>
> Lets complete the math.
>
> To: electricboats@yahoogroups.com
> From: ewdysar@...
> Date: Tue, 16 Nov 2010 08:47:47 +0000
> Subject: Re: [Electric Boats] Picking batteries - NiFe
>
> Kevin,
>
> I did the math with the data on the link that you provided.... Looking at the 200Ah cells, they are 26.4 pounds dry or 264 pounds for a dry 200Ah 12V (2400kWh) battery. Add water and you're probably past 280 pounds or 8.5Wh/lb.
>
> Alternatively, a T-105 weighs 62 pounds (according to Trojan) and is rated for 225Ah @ 6V or 1350Wh. That works out to 21.8 Wh/lb. Take two in series and you've got a 225Ah 12V battery that weighs 124 pounds.
>
> Are you really sure that size doesn't matter? Lets compare the 200Ah 12V NiFe to the 225Ah 12V T-105s
>
> 2400Wh NiFe = 13.2" x 32" x 13.6" = 5745 cu. inches, 280 pounds
> 2700Wh T-105 = 10.4" x 14.3" x 10.7" = 1591 cu. inches, 124 pounds
>
> The NiFe battery is more than 3 times the volume of the two T-105s for 10% less rated capacity.
>
> I'm not passing any judgement, just doing the math so that people can decide for themselves.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, Kevin Pemberton <pembertonkevin@> wrote:
> >
> > Eric,
> >
> > According to this page batteries supplied by Ironcorebatteries
> > http://www.ironcorebatteries.com.au/page8.php 100Ah weigh almost 100lbs
> > for 12v pack...
> >
> > Kevin Pemberton
> >
>
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