Announcement

Collapse
No announcement yet.

Nickel Iron vs. Lead Acid - Off Grid battery debate

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Mike90250
    replied
    Just worn out electrolyte.

    Leave a comment:


  • inetdog
    replied
    Originally posted by Mike90250 View Post
    I turned it into fertilizer to both neutralize our acid rain and add potassium to the soils.
    Sounds like really expensive Chinese fertilizer....

    Leave a comment:


  • Mike90250
    replied
    I turned it into fertilizer to both neutralize our acid rain and add potassium to the soils.

    Leave a comment:


  • inetdog
    replied
    Thanks, Mike. Just curious how you dumped the old electrolyte, which was not particularly toxic except for its pH.

    Leave a comment:


  • Mike90250
    replied
    Originally posted by inetdog View Post
    Mike, is it about time for another update on your system?
    After installing the auto watering system, which is more efficient in that i can overfill 6 cells at a time when the stupid floats stick, there's not much else to report. 2 years ago, I replaced the fluid (electrolyte) in the cells ( a week long process with mixing, cooling, dumping old, refilling and bolting the bank into place )

    I've purchased and am configuring new Schneider PC charge controller 150-60 and a new XW6848pro inverter, to replace old (still working, 10 year old gear), hopefully installing in the next 2 weeks. Keeping the old gear as "hot" spares. I figure better to replace when I can plan, instead of in a panic when something fails.

    Leave a comment:


  • inetdog
    replied
    Mike, is it about time for another update on your system?

    Leave a comment:


  • johnpearcey
    replied
    Originally posted by inetdog View Post
    Are you filtering the humidifier water? Straight from the coil there may be significant amounts of dust and organic contaminants.
    No. The dehumidifier has a set of air filters before the coils. And after 2 years of constant use, there is almost no perceivable residue in the container. So I really don't think I'd be able to filter it any better. I'm a little concerned about carbonic acid though. But the pH is 7 so it can't be too bad. I'll be checking the SG as I go.

    Leave a comment:


  • inetdog
    replied
    Are you filtering the humidifier water? Straight from the coil there may be significant amounts of dust and organic contaminants.

    Leave a comment:


  • johnpearcey
    replied
    So, time for an update. I've been using my NiFe cells since Feb and they're performing very well. I did not bother with the initial forming charge. I decided to let the daily usage take care of that. You can tell I'm a bit of a maverick I've attached a graph for the past few days. You can see I use about 30% of their capacity each day and not all days top them up. See my previous post for graph colours. (Ignore orange). We've had great sunshine this year in Ireland and the panels are giving us plenty of energy. The only downside I can see with NiFe is that the charge/discharge efficiency is around 60% (grey line). But a couple of extra panels sorts this out. And to be honest, I haven't noticed it at all. Compared with lead-acid, these babies are a game changer. And if they last as many years as the manufacturer says, then the total cost of ownership is going to be orders of magnitude less than lead-acid. NiFe do gas slightly. I've had to top them up once since Feb (10ltr). I'm using deionised water for half of them and condensed water from a dehumidifier for the other half. We'll see how things compare in a year or so.
    Attached Files

    Leave a comment:


  • johnpearcey
    replied
    Hey Mike90250, very much appreciate your help.

    I bought my cells from China and the 'manual' was a little sparse on details. There was mention of a forming charge (I think it was 12 hrs) but I thought I might be able to do that on the fly so to speak. I was under pressure to remove some really dead lead-acid batteries so I was taking shortcuts. Maybe I should hit the generator now for 12hrs and give them a good blast?

    And I'd very much appreciate a copy of that manual, thank you.

    Leave a comment:


  • Mike90250
    replied
    The cells, when new, need a conditioning or forming charge, which is similar to an activation charge for FLA batteries.

    Here's an excerpt from my manual:
    Chapter 3: First Charging and Storage
    3-1 Pre-charge Preparation
    3-2 Charging Procedures
    3-3 After-care of First Charging
    3-4 Storage of Charged Cells

    Installed and connected properly the battery should be fully charged as soon as possible. Before
    proceeding to charge, check the AC or DC battery charging power source and the battery charger

    1) For the first charge, the charging should be continued for 8 hours with the indicated constant current.
    The first charge is a 200% of the C/5 rating Appendix D. For example, if your battery bank is a 500 AH
    (at C/5 rating), divide the 500 by .25 which is 125, then charge for 8 hours. If you cannot charge your battery bank at the Ah called for then you can charge at less amp hour but you will still have to put in the correct amount of Ah into the battery bank, but will have to cycle your battery bank 2-3 times to have battery bank reach full capacity.
    2) This first charge should be done (but does not have to be) with a controlled charge source such as
    a inverter battery charger, a DC charging source or a battery charger plugged into an AC generator.
    If you use a solar array it could take days or even weeks! So we suggest a CONTROLLED charging
    source and not a PV array. If you are changing out an old battery bank we suggest that you cycle the new cells before removing the old battery bank.


    If you did not get a manual, I could email a copy of mine to you. There is useful info in the manual, it's more complicated than just hooking up.



    Leave a comment:


  • johnpearcey
    replied
    Originally posted by Mike90250 View Post
    First, I have to mention someone else was undercharging their NiFe and may have ruined some of their cells.

    But the question is why are you unable to charge the cells properly ?
    Unlike lead-acid, I can't see any reason why undercharging might be particularly harmful to NiFe. Is there some chemistry at work here that I'm not aware of?? I must admit that chemistry was never my strongest subject!

    So, sunshine is not very abundant here in Ireland. I'm figuring on running along with 50% charge using diesel only if I really need to. Then if a sunny day comes along, there'll be plenty of storage room available. Solar charging here is starting around 9am and finished at 4pm and I get about 30Ah in that time (37% full). So it might be worth me running at 50Ah at this time of year (I have total of 80Ah capacity)

    Leave a comment:


  • Mike90250
    replied
    First, I have to mention someone else was undercharging their NiFe and may have ruined some of their cells.

    But the question is why are you unable to charge the cells properly ?

    Leave a comment:


  • johnpearcey
    replied
    OK, so my previous comment about 77% for the batteries was actually the charge efficiency, not the energy efficiency. My mistake. So I have done a bit of work this morning and come up with an energy efficiency. This is very early days (in fact only 6 days worth of data at this point) and I will post an update in a few weeks time. The energy efficiency curve is heading towards 50% very roughly. My batteries started empty and I'm accumulating charge as I go so I expect the curve to be heading upwards and to level out in a few weeks time. I'll try and upload an image - not sure how this will work out. Black is voltage, blue is amps, green is charge estimate (Ah) and grey is efficiency (ignor Orange)
    Screenshot from 2020-02-27 10:14:22.png

    Leave a comment:


  • Mike90250
    replied
    I have no way to separate the battery consumption from the load consumption, so I don't have a efficiency #. I do log my inverter usage and solar consumption, and factor about 50% end-end efficiency, here's my #'s from a while ago. (screenshot includes a day with smoke from fires.)

    example, oct 1st, I harvested 16.1kwh, and consumed 9.088kwh, leaving 7kwh of system losses, most of which (5kwh?) is likely the NiFe batteries, the rest being heat in the inverter and 2 charge controllers.

    RedwoodFire_SmokeProductionLoss_10-2017.jpg

    Leave a comment:

Working...
X