When we talk Peukert effect we fail to remember one thing. As our lead acid batteries age the Peukert factor changes. This is not true with Nickel Iron. When new the two compare favorably but in time the polish of an old tech appears to shine. The catch 22 of lead is to keep the battery maintained we must limit it's ability to deliver over time. Any charging continues to plate the plates reducing their ability to release the charge stored in the plates.
This is expressed in many ways. We can start with the statement that we must not mix different age batteries. We can further show the implied limits of lead acid by looking up how many times on this list alone, an age factor with impaired distance traveled, can be cited.
I can see the cost thing, but I was thinking the reliable operation due to simplicity in design. Not the battery, but the entire support thing. No battery I can think of other than NiFe can be abused the way they can and survive. One mistake or failure of a charger can eliminate a complete battery pack while you are getting a nights sleep with all the other high priced batteries. One shorted cell in lead acid can bring down many batteries in your pack. The Iron battery company down under has smaller Ah batteries that seem a better fit for some systems. Don't know what importing them would cost. I have been looking more at hybrid than all electric anyhow so don't know how they fit for most here. I can bypass the controller with a knife switch to get in with a NiFe system because I would not need to worry about abuse and battery failure.
I have started my savings earmarked for NiFe pack. I have found large capacity banks just cost more to replace and as was stated, for house use may be a good option, and that is what I am doing first. In the future I can add to the bank without concern over battery age so it will be a win win for me. I am sorry to have brought up the NiFe, I did not intend for it to turn into a debate. My intent was to re-introduce a battery type as I wished someone had done here earlier. The house bank in my motor-home lasts just about 2 years (over 700 cycles), this bank needs replacement often in my book. My brother reports maintenance on his house battery claims it in 3 years. For him I recommended optima batteries because they are pure lead plates and will be what he needs, but still at close to 200 big ones for the optima, NiFe may still be a good bet.
Kevin Pemberton
On 11/14/2010 01:36 PM, Myles Twete wrote:
>A Peukert exponent of 1.00 means that there is no Peukerts effect at all and that the battery will deliver the same amount of energy at any discharge rate. I would guess that the Peukert's exponent for Nickel Iron batteries is higher than 1.00
>Eric
No doubt. References online claim virtually no Peukert effect for any of the Nickel chemistries including NiCd, NiZn, NiMH.
I’m sure he just was parroting these. Worse, the weblink he offered drawing folks to his personal Peukert calculator page does not provide any support for the 1.0 Peukert exponent claim.
From the brief looking I’ve done, I’d guess that the effective Peukert exponent for NiFe is below 1.05, and once you’re down that low, unless you’re drawing high-C loads, I don’t think you have to worry much about it.
I think the major beefs against NiFe batteries are:
· Cost
· Relatively high self-discharge rates
And those weigh enough against them that we don’t appreciate the uber-long life of them. Charge/discharge inefficiency isn’t much of an issue for many of us, but high initial cost and self-discharge rates are.
-Myles Twete
-- Ubuntu10.04, Acer AspireOne, Virgin Mobile 3G Broadband2go. Doesn't get any better than this!
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