Three Letters Re: Some Real Life Battery Data

Dear Jim,
I have some comments on the comments regarding batteries:

Nickel Iron (Ni-Fe) batteries do indeed have very long shelf and operating lives. But they also have some significant downsides. Similar to NiMH cells (they are not the same) they have a very high self-discharge rate. In some cases approaching 40% per month. If you have a large solar array that is always making excess power, you are all set. But if you are charging with a generator, and have a large bank to keep power available for extended periods, you will waste a lot of the generator’s output on self-discharge.

Ni-Fe batteries also do not like high charge/discharge rates, which means you may need a larger bank of them for the same type of service. This effect gets worse as the temperature drops. If you have a big bank, you will also need to waste more energy keeping them charged. Basically, there is a penalty for having your battery bank too big for the application. You would want to make the bank last you no longer than a week or so of typical service, thus limiting the amount of energy wasted to keep it charged.

On the plus side, you can leave the battery discharged for long periods without any problems and they will not freeze (in any sane temperatures). That’s good for a little used location. There is only currently one importer in the US that I know of.

There’s no conspiracy to keep them out of the market, it’s just that most applications work better, smaller or cheaper with lead acid. As the cost of electricity goes up, no one wants to use them for standby applications anymore due to the energy cost with keeping them charged. But as photovoltaic solar power becomes more common, perhaps there will be a revival of the technology.

Regarding lead acid cells with no acid, there are several issues with drying out a new battery for storage. If any acid is left it will cause undesirable changes to the plates. If you attempt to air dry the battery, the air pumped through the battery to dry it out will lead to oxide forming on the plates, ruining the battery in the drying process. There’s at least a few patents out there to address some of these issues, but none of them are ideal. Realistically, you would need to discharge the battery, then partially re-charge it, dump and flush the acid and then use inert gas to dry out the plates. Probably not worth the effort, and the required discharge/charge levels would vary based on
interior construction. Not likely to be economical or produce reliable results.

It’s too bad that none of the manufactures sell “green” batteries that have not yet been converted, but the required acid mixture and charge cycles to form the plates are most likely a proprietary process that they have no interest in sharing.

You can make your own batteries, but they won’t have anywhere near the capacity of a commercial product. Consider that the standard car battery has dozens of square feet of surface area and has been optimized over years of experience. Home made batteries, especially large ones, can lead to seriously unpleasant accidents. Having seen smaller batteries explode due to internal shorts, I would want nothing to do with a 5 gallon bucket of H2SO4 and rolled up sheets of lead.

I’m surprised that no one has mentioned simply not using batteries at all. If you live in a sunny location, one can simply use electricity when the sun is shining or the wind is blowing. Not perfect, but virtually guaranteed to work even after sitting idle for 10 years. Regards, – Cactus

James Wesley;
I found an interesting short video linked at Silver Bear Cafe about Nickel-Iron Edison Cells–a design battery I hadn’t about previously. I thought you might enjoy it. Thanks for the web site and all of the information. Regards, – Joe

Monday’s post mentioned the Nickel-Iron Edison battery. During its evening broadcast on 1-29-10 The Intelligence Report described a method to build your own Ni-Fe battery was discussed in the second half hour of the 8 PM broadcast. It was also mentioned where one could get Nickel without having to resort to melting nickels. At The Intelligence Report’s web page, click on “archives” in the left hand part of the screen. Scroll down to 1-29-10 then click on the “8PM” to download the mp3 file.

Great job with the blog! Thank you for the work you are doing. – Mr. C.