Towards a better tinyhouse

Inventing to freedom?

NiFe batteries

with 3 comments

Nickel-iron batteries

They don’t have any toxic heavy metals, they last a lifetime, and they could be cheaper than lead acid. Potentially you could even make your own.

It says they can have charge/discharge efficiencies of 85% there. Where are the batteries that can do that, is what I want to know. Who sells them or how do you make them?

If they can only achieve 60-65% that is not as good, but do not write them off altogether. Lead acid batteries are only something like 80% efficiency. So you lose ~40-35% vs. 20% of the energy that went into the battery, but if only half of the energy from the solar panels goes into the battery, with the other half being used as soon as it is produced, using nife instead of LA will increase the size of the solar collector array by only 15 to 20%, which might be altogether manageable.

If the cost of the solar collector is only 50% they system cost that is only 7.5% to 10% increase in cost. Then, remember, these batteries last much much longer than lead acid, which wear out fast enough that they have a substantial “running cost”, of roughly 8% the cost of the battery, per year, whereas NiFe do not.

So all things considered, the capital cost of the system as a whole might be more expensive, might be cheaper, depends on if you can get the better batteries, but by eyeballing it, I think they have a lot of potential to actually be cheaper over the long run.

Plus, no environmentally harmful lead, which is nice, and yet they are I think probably cheaper than lithium ion.

Also, there are sources like this one that indicate that in photovoltaic systems, lead acid batteries have other issues too, and depending on their usage patterns, they may have even lower effective charge/discharge efficiencies.

Some more links: says charge efficiency is actually quite high at room temp, but is not the same as round trip efficiency, but maybe the loss during discharge is pretty low and determined mainly by resistance. I wonder how much these batteries cost and if they are actually for sale.

BTW just a bonus, I discovered that if you search ebay for “thundersky lithium” there are some relatively cheap lithium iron phosphate batteries going on there.


Written by gregor

April 19, 2011 at 05:08

Posted in Uncategorized

3 Responses

Subscribe to comments with RSS.

  1. sorry to hear the conferences are not as well attended, for me it’s because of the busy season…i’m sure the ol gang, and maybe then some, will crawl out of the wood work when the snow flies….

    i’m always keeping an eye to power storage technologies…super capacitors have advanced quite rapidly and are now showing up in my electronic component supply catalogs, really quite an advance in power densities….

    all your posts stringing out make me feel bad that the blog seems the only way to apply yourself…your i great guy Greagor, but i have to say it’s been too much for me to keep up with lately, and worry others feel the same…maybe poll your followers?…again, i don’t mean to cause bad feelings, but i will be super busy til winter..



    April 19, 2011 at 06:51

  2. Posts stringing out? What do you mean?

    It would be nice though if I had access to a workshop to apply some of these ideas or otherwise work on this sort of thing, maybe open sourcing the photovoltaic collector or water recycler MBR for instance.

    At the same time I used to do that sort of thing, I had a place in a basement, and I think it is good to just think and read and learn from paper without building sometimes. In retrospect I think I spent too much time building and tinkering and not enough planning and designing and reading.

    When you can build stuff it’s tempting to stop refining the idea and just go try it. But if you were to use the time to think about how to do it even better instead I think that can lead to more interesting stuff sometimes.

    At this point I’m basically just sharing what I learn as I go along, if I happen to read something, that helps solve a problem I had sort of been wondering about – cheaper batteries that are not as toxic, in this case – then I post it so someone else such as yourself interested in building a tinyhouse or something might find it usefull.


    April 19, 2011 at 14:24

    • yeah i get what your saying about planning first..too many people likely jump into projects with out the knowledge to properly execute…i’ve been at this for many years and am quite adequately educated, though i still enjoy your angles on different topics….

      but i am working in a fabric structure with a mud floor that is just a bit to tight to be much more than storage, see, i just need a shop….



      April 21, 2011 at 05:59

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: