A minor nit The self-discharge rate is pretty high (20 to 40% per month) and the charging is not as efficient.
Power density is pretty bad too. For forklift operation this is not a problem as weight is a good thing, they are topped off every night and the power used to run a forklift is minimal given the overall consumption of an average factory. Wikipedia has a nice comparison http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery http://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery Here is a vendor: http://ironedison.com/ Dave > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Alex Pummer > Sent: Sunday, July 27, 2014 15:48 > To: [email protected] > Subject: Re: [time-nuts] OT Gel Cell question > > it is not a high performance battery but extremely robust, see there > http://www.nickel-iron-battery.com/ > it is no polluting, it could be shorted out overcharged > if you are lucky and find one old forklift with Edison > Battery -- which > was built some fifty years ego....it will out last you too > you could charge in current mode, C/10, 2C nothing will happen just > replace evaporated water in the elctrtrolyt which is KOH > 73 > Alex > > > On 7/27/2014 2:41 PM, Chuck Harris wrote: > > I too have spent a lot of time charging batteries using different > > methods on > > various chemistries. Once upon a time, I build a number of > suitcase > > battery > > chargers for the US Army that allowed them to charge every portable > > secondary > > battery type that they had in inventory... SLA, AgO, NiCD, NIMH, > > LiIon... I proved a concept, and someone else got to make > all of the > > money > > off of it when the ARMY shopped my prototypes around... but > I digress. > > > > When you try to charge a sulfated lead acid cell, you can > think of the > > cell > > as being a bunch of little parallel lead acid microcells > (uCell). Each > > is in > > some state of charge/discharge. > > > > So imagine this: > > > > +--+--+--+--+--+--+.....+--+---Plus terminal > > S..S..S.[B].S..S..S.....S..S > > +--+--+--+--+--+--+.....+--+---Minus terminal > > > > In this case, all of the "S"s represent a microcell (uCell) that is > > highly > > sulfated, and the "[B]" represents a microcell that is in perfect > > condition, > > and is taking a charge normally. > > > > If you try to put current into this lead acid cell, the sulfated > > uCells will > > appear as open circuits (due to the sulfate's insulating > properties), > > and the > > good uCell will take all of the current, and will keep the voltage > > down to a > > low enough value that the sulfated uCells will not see any > significant > > electrolysis action. > > > > So you say, "Pooh, I want the sulfated uCells to charge > too!" and up the > > voltage across the lead acid cell, and poof! The good > uCell dies from > > over > > heating, revealing a new uCell that wants to charge, and > poof, it dies, > > revealing another uCell that wants to take a charge, and poof... > > > > You get into a situation where your success causes your failure. > > > > If, instead, you apply high voltage pulses to the lead acid > cell, you can > > sometimes beat the system. The good uCells will take a > hit, but it is > > short > > enough that they don't have time to burn up, and the > sulfated uCells will > > get to draw enough current during the pulse that a little > electrolysis > > will > > happen, and convert some of their sulfate back into oxide > and acid... > > > > Sometimes you can win by using a pulse charge system. > > > > However, there is a little physical problem that has to be > > understood. Part > > of the way the lead acid batteries get their high current handling > > densities > > is because the lead plates are made to have high surface area. They > > are kind > > of like sponges on the surface. And, lead sulfate takes up > > significantly more > > room than lead oxide. Sorry, that is the way it just is. > > > > So, when a cell gets all sulfated up, the lead sulfate that > forms in > > the deep > > nooks in the mossy lead electrodes fills the nook up so > full that it > > breaks > > it apart, and damages the cell plate. This happens, albeit slowly, > > even when > > you treat the battery nicely. > > > > You can't win. Long term everything heads towards entropy. > > > > -Chuck Harris > > > > > > Brooke Clarke wrote: > >> Hi Robert: > >> > >> I've spent a lot of time charging batteries using > different methods > >> and on various > >> chemistries. > >> > >> When the charge is in the form of a pulse, ideally including a > >> reverse polarity > >> pulse, the charge is more effective. > >> This is also a way to sometimes, but not always, will recover a > >> battery that > >> otherwise will not take a charge from a DC source. > >> > >> I think this works because it takes some time for chemical > reactions > >> to work and by > >> using a pulse you can force the reaction to a higher level > that you > >> can't do using DC > >> without causing problems such as boiling the electrolyte. > For more > >> info see Burp > >> Charging: > >> http://www.prc68.com/I/BatChg.shtml#Burp > >> > >> Have Fun, > >> > >> Brooke Clarke > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
