NiFe batteries are available at
and
Steve Spence
Renewable energy and self sufficiency
http://www.green-trust.org
http://arduinotronics.blogspot.com/
On 11/13/2010 03:25 PM, Kevin Pemberton wrote:
>
>
> One cell that seems to get neglected on this list is Nickel-Iron. I
> believe they are likely the best of all batteries even though they are
> an old tech. Some battery banks still in use are over 50 years old.
> They don't care much how they are charged or discharged. They don't
> care if they are left to discharge and over charge or complete discharge
> fails to bother their life. Most of the time when they don't supply as
> rated a simple replacement of the electrolyte will put them back in
> original condition.
>
> It is true that they self discharge but this looks to me to be of little
> importance and this is why:
> A lead acid battery must be kept maintained with a trickle charge. This
> process plates the plates with the antimony that strengthens the
> plates. Nickel Iron can be left unattended and charged before you need
> to use your boat. Constant current charger is all that is needed to
> charge the nickel-iron battery because it can be overcharged without
> worry. This leads to lower charger expenditures. Nickel Iron is not
> cheep! But what is? Subtract High dollar equalizers and 3 stage
> chargers and the price seems more manageable. Take the maintenance
> chargers out of the picture and thinks may even look better. The fact
> that alkaline solution is used as an electrolyte and factor that the
> batteries will not be replaced in your lifetime and maybe your
> children's, and the two times you do need to be replaced and nickel iron
> looks very good. I bring this up because some are now looking at
> lithium batteries as an option. The thought scares me because they are
> so easily destroyed, and the price is out of this world. Edison
> developed the battery with an eye to electric vehicles, what are we
> thinking?
>
> Kevin Pemberton
>
> On 11/13/2010 11:47 AM, Myles Twete wrote:
>
>>
>>
>> Thanks Eric. That should inform folks who don't understand the
>> tradeoffs. My point is just that having more than a 500-1000 cycle
>> battery charge life is great advertising, but is pretty useless for a
>> seldom used boat. And given this infrequent usage, I personally
>> cannot justify even buying new flooded PbA batteries, let alone AGM,
>> let alone Lithium of any chemistry. My 6 used T105's cost me $120
>> total…even though the really only deliver less than 100ah at this
>> point, I expect they will last another 3 years at least and for me,
>> this scenario cannot be beat.
>>
>> Indeed everyone will weigh the tradeoffs differently…and should I
>> personally get into a more financially stable situation, I might be
>> tempted to add a string of Lithium to the boat.
>>
>>
>>
>> It's really great seeing so much more activity on this list these days
>> with very very constructive and informative dialog. It truly helps to
>> share your experiences out there so that new folks coming here realize
>> that they're not crazy after all in wanting to go electric.
>>
>> Thank you all!
>>
>>
>>
>> -Myles Twete, Moderator, Electric Boats
>>
>>
>>
>> *From:* electricboats@yahoogroups.com
>> [mailto:electricboats@yahoogroups.com] *On Behalf Of *Eric
>> *Sent:* Saturday, November 13, 2010 10:17 AM
>> *To:* electricboats@yahoogroups.com
>> *Subject:* Re: [Electric Boats] Picking batteries
>>
>>
>>
>>
>>
>> Myles,
>>
>> You make a good point. Once cycle life gets to be about 500 cycles,
>> the chances of having the batteries expire from cycle age are pretty
>> low for pleasure boaters like most of the people here. That said, I
>> know that for many boaters (me included) FLA batteries often die with
>> low cycle counts from mis-management. With their higher self-discharge
>> rates, FLA batteries will sulfate if not kept on a consistant charging
>> routine.
>>
>> AGM batteries seem to survive inattention for longer periods without
>> significant degradation.
>>
>> Lithium batteries, LiFePO4 batteries specifically, have a much longer
>> shelf life, and should be able to survive 6 months of sitting without
>> any noticible loss of capacity.
>>
>> Of course, with the considerable investment for any battery bank,
>> having an automated charging system, either plugged in or renewable,
>> will help any battery live closer to its potential.
>>
>> So my takeaway from this is that cycle life is not as critical for
>> most of our applications. Attributes like size, form, energy density,
>> the ability to deliver more of the stored energy, and cost could be
>> more important factors in choosing your battery bank.
>>
>> ======================================
>>
>> Even though FLA are obviously cheaper than our other major battery
>> types, I believe that they are least efficient for their size and
>> weight. I find AGM to be a good compromise between cost and delivered
>> energy. And finally, Lithium are half the volume and weight as either
>> lead acid type and usually deliver more Wh per charge for the same Ah
>> ratings, for a consdierably higher cost.
>>
>> I have found that a rough rule of thumb is that AGM cost about twice
>> as much as FLA for the same size, weight, and Ah rating. They will
>> deliver more range in our typical use cases. Lithium batteries cost
>> about 50% more than AGM for batteries that will deliver the same
>> range, but are rated 20% lower in Ah, and are 60% smaller and lighter
>> than AGM or FLA. This rough estimate includes BMS modules that will
>> prevent any high or low voltage event and help keep the individual
>> cells balanced with each other.
>>
>> Everyone here gets to decide what is most important to them. I picked
>> LiFePO4 batteries for many of the reasons listed above, but mostly
>> size and weight. Cycle life was not a consideration.
>>
>> Fair winds,
>> Eric
>> Marina del Rey, CA
>>
>> --- In electricboats@yahoogroups.com
>> <mailto:electricboats%40yahoogroups.com>, "Myles Twete" <matwete@...>
>> wrote:
>> >
>> > Interesting note on cycle life.
>> >
>> > It would take me 150years to go thru 6000 charge/discharge cycles
>> with my
>> > boat.
>> >
>> > Even if you were to use your boat every single day, it'd take over
>> 15yrs to
>> > reach that cycle count.
>> >
>> > Not even the manufacturers of these batteries advertise them to last
>> 15yrs,
>> > let alone 150yrs.
>> >
>> > Cycle life is meaningless to me and my boat except that if I were using
>> > Lithium cells, one overcharge or one over-discharge and the cycle
>> life goes
>> > from awesome to pitiful.
>> >
>> > -Myles
>> >
>>
>
> --
> Ubuntu10.04, Acer AspireOne, Virgin Mobile 3G Broadband2go.
> Doesn't get any better than this!
>
>
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