Any micro-hydro experts around?

**rreidnauer** · 10-13-2007, 08:09 AM

Well, it depends on the situation. Like I said, they tend to self discharge a sizable portion of their power, (discharging as much as 10% in the first day, and roughly 5% every 10 days thereafter) making them significantly less efficient than a typical lead-acid battery. But, for certain cases, the nearly indestructible nature of the battery would make it a perfect candidate for places like an unattended cabin where the possibility of complete discharge could occur. (something that would kill a lead-acid battery in short order) The main advantage would be, it would likely be the last battery bank you'd ever have to buy, as they usually last a lifetime. (or longer) About the only thing you have to do is keep the electrolyte topped up and change the electrolyte ever 12~15 years. Being that they accept deep discharging far superiorly than a lead-acid, you can get away with a smaller bank of batteries. Lead-acid shouldn't be discharged below 75~80% capacity, as it will shorten it's life significantly if you do. A nickel-iron battery can be safely pulled down to 50% (and even lower) without harmful effects.

Comparison:
1000 amp/hour lead-acid bank, 75% discharge = 250Ahr or 25 amps for 10 hours.
500 amp/hour nickel-iron bank, 50% discharged = 250Ahr or 25 amps for 10 hours.
Half the capacity, same amount of available power. (technically more)

OK, another factor. Nickel-iron batteries have a lower cell voltage than lead-acid, (1.2v vs. 2.1v per cell) so more batteries will be required in a string to achieve the voltage needed. With their relatively higher price, it can make for a pricey battery bank, but when you consider that a lead-acid bank will get changed out several time in your lifetime, in the end, it's cheaper. (if you can absorb the high upfront cost)

So, if you can live with the upfront cost, (unless you're lucky enough to come across an old set for free) the lower efficiency, and a slightly different maintenance schedule, (more regular watering, but less equalizing charges) they are far superior to lead-acid. It's something each individual has to weigh for themselves.

**erisso** · 10-26-2007, 09:56 PM

Hi All ,
Well Rod Im one of the lucky that got a bank of 7, NIFE BATTERIES-REDDITCH metal cell. having 8 cell each + one of 4 cell?? total of 60 cell.
Thing is i cant find any info for them on the web as for the site posted in preveous message i cant find data sheet (http://www.changhongbattery.com/english/cp/view.asp?id=129) and im not quite shore what i really have as storage and power
Originally there was: 92 cell for a total of 120 Amp/Hours, Normal charge 24 amp for 7 hours, (battery #M2743, Type LR12 )

I have set up a 24V, 1200W turbine with a control unit switches.
according to what you said preveously, dont think the ratio is good,
but if not do you know what do i need to add
+ do these Bat. need special care as for charging (can they over heat)
+ can they safely be used and stored in my home
or could they produce harmful gas and therefor should not be in the house

Thanks for reading and any help or information would be appreciated

**rreidnauer** · 10-27-2007, 07:16 AM

Congratulations on your find. There's a good chance that the electrolyte hasn't been changed in a long time, and should be your first thing to do, but you can do some testing first and what they're worth. (actually, a before and after test would be interesting)

I didn't know there were NiFe batteries out there in combined cell cases, but so be it. Always something new for me to learn. :-) Ideally, for your 24v arrangement, you'd want 20 cells in a string. I don't know if you can break up individual cells, but if so, you could make up three strings of 20 cells. If you can, it'd look a bit like this:

Note, the 7th eight cell battery is electrically split into two four cell units. Care must be taken to get the positive and negatives in the right order when splitting up the cells, because if you get one (or more) wrong, your overall string voltage will be lower.

Alright, if you gotten this far, you'll need to determine what your Amp-hour capacity is. To do this, you need to charge the battery bank up. They are considered fully charged when cell voltage is 1.4V (28V per string) at rest after 30 minutes from removing from charge. Keep an eye on electrolyte levels when charging, as air is the enemy of NiFe batteries. It's possible they may not come up to full voltage, so you just have to do what you can. Once you got the bank charged as best as you can, you need to do a timed discharge at a known amperage rate. You'll need to know the amperage of your (preferably resistive) test load, (series up two car headlights perhaps) and you'll need to watch the voltage. NiFes are considered discharged at 1.2V per cell, (24V per string) and will drop off rapidly after reaching that value. I prefer a small load, say 5 perhaps 10 amps. It's a much longer test, but the results will be more accurate. Car headlights are about 5 amps. (two in series will still be 5 amps, and two sets paralleled to two in series will give about 10 amps at 24V)

OK, so the test loads are hooked up, and you note beginning time and the amperage being drained from the bank. Also note the voltage and write it down. When you initially connect the load, there will probably be a slight drop in voltage, but it should stabilize. Check back ever 30~60 minutes and record the voltage. If you start to see a voltage drop, check back more often. When you start to see voltage dropping off rapidly, you've reached the discharge limit of the batteries. Note the time. So, now you have a know amperage at a known number of hours, you multiply hours by the amperage and you get the battery bank Amp-hours.

Depending on what you come up with, you'll know how well it will work with your turbine. One thing to note, it's likely the wind turbine won't be putting out a full 1200 watts very often, so it will probably be fine. You must have dump loads on a turbine, so they will absorb the extra power when you are at full power production. Some other things to take into consideration. Most charge controllers are designed for lead acid batteries, so you may have to work through some teething issues to get it working right. More expensive controllers should be more flexible in controlling charge rates and voltages. NiFes do like to be charged slower than Lead acid, so you will need to watch temperatures and electrolyte levels closely while you figure out what works, but the good news is they are much more tolerant to damage than lead acid, so that should ease some worries while you experiment. I believe they vent off a combination of hydrogen and oxygen, so they should be treated in the same fashion as lead acid. (preferably not in the house, or at very least, an airtight container vented outdoors) Nifes also have a wider voltage range than lead acid, so it might drive some inverters nuts on low/high voltage shutdowns.

**erisso** · 10-27-2007, 02:41 PM

Thanks for your reply Rod,
I can break up to individual cells so think i can manage building this as 24 Volt
But i was thinking of 12V installation as it would be easier for me to work with and keeping the 4 cell as spare
now you got me worried about fast charging!! as it will be charging with lower wattage input
What do you think about the 12V installation?
If eventually needed can i put other type of battery with these or i need to keep same type?
http://i242.photobucket.com/albums/ff283/erisso/Battery1.jpg
http://i242.photobucket.com/albums/ff283/erisso/Bat1.jpg

Eric

**rreidnauer** · 10-28-2007, 11:00 AM

OK, that's more like it. Eight single cells packed together. That tag is a great example of the lower efficiency of NiFe batteries. It says 120 Ahrs., but also says 24 amps for 7 hours, which is 168 Ahrs. That's 71.4% efficient. 48 Ahrs will disappear without ever getting to be used.
Since the tag doesn't give a bank voltage, there's no way to determine the original wiring configuration, and therefore the amp-hours of the existing cells you now have. In any case, it looks like your turbine will be too big for the bank, but you can use the excess power to heat water or something.

You can do a 12 volt system, and it will double your amp-hours, but it still requires all your cells. (six strings of ten in series) Since you said your wind turbine is 24 volts, you'd have to deal with that. Stepping down the voltage will induce some additional losses. Also, 12 volt in general is going to be less efficient, and requires larger cables. (exponentially as amperage increases) But, it's easier to find affordable 12 volt inverters, appliances, and charging equipment, so it's a balance you'll have to find for yourself.

In either case, 12 or 24 volt arrangement, your wattage input/output is the same. Cut volts in half and you double your amps. If you were to step down your wind turbiine, you'd only increase the amperage coming from it, and the same concern you have of over rate charging still exists. There's no way to determine what your total amp-hours will be without a test, but the battery tag does suggest a good charge rate, (20% of capacity) though, being what they are, they should tolerate a higher rate. (I still think 30% is plenty safe) You just got to do like I mentioned before, and watch your temps and fluid levels if you much higher. You really need to make up those batteries in the configuration you plan to use, and find your amp-hours so you can better plan your charging profile.

You can not mix lead acid batteries with Nife batteries. Also, mixing cells of different Ahr capacities will lead to uneven charging. The bank should consist of all the same size and type cells.

On a side note, I originally planned on a 24V system, but I since decided to bump up to a 48V system. It allows me to get more watts though my charge controller, and keep my wire sizes down to manageable costs. Had I stuck with 24V, I'd been forced to get a second charge controller ($$$) and much larger cabling ($$$) The battery bank size doesn't change for the same wattage, just the battery wiring configuration, so there's no additional cost there. 48V inverters are pricier, but I believe it's worth the efficiency gains.

**erisso** · 10-29-2007, 02:21 AM

THANKS AGAIN,
Well to bad i call little late and the guy sold the 4 other battery's for 50$ peace
ok now i will do the testing as soon as find electrolyte and battery pack is mounted
ill be starting 12v as i have a 3000w/6000w 110v converter sitting here
as for wires i have 10 feet from bank to converter
Turbine is already 40 feet up in the air ( it cant turn I locked it)
and wired with 60 feet of #6 to were ill be placing my battery bank

Idd appreciate if you could take a look at my idea of battery configuration in fallowing link

http://i242.photobucket.com/albums/ff283/erisso/configuration2.jpg http://i242.photobucket.com/albums/ff283/erisso/CONfiguration.jpg

as i cant add battery to my bank
i thot of adding a bank that would help in 2 ways,
absorbing extra watt that my bank cant take from turbine and giving me extra storage without changing all batterys
both are showing 12v but as said any of them could be converted to 24v easily as both banks are independent.

im maybe off route so any comment is appreciated

In your "On a side note" you mention "I'd been forced to get a second charge controller "
I know from an other post that you intend to install a 3 phase turbine,
is this "charge controller" the same as "battery dump regulator" or an other thing thats required for
your installation or for all installations,
(please understand that im French speaking and some times same thing with 2 names gets me confused)

Eric

**erisso** · 10-29-2007, 03:30 AM

an addition
if my batterys are 12v for 8 cells this is 1.5V each
if im putting 2 extra cell to the line adding 3V to it for total of 15V per line
will not that drive my inverter crazy as it has hi/low protection
Eric

**rreidnauer** · 10-29-2007, 09:58 AM

Originally Posted by erisso

THANKS AGAIN,
Well to bad i call little late and the guy sold the 4 other battery's for 50$ peace
ok now i will do the testing as soon as find electrolyte and battery pack is mounted
ill be starting 12v as i have a 3000w/6000w 110v converter sitting here
as for wires i have 10 feet from bank to converter
Turbine is already 40 feet up in the air ( it cant turn I locked it)
and wired with 60 feet of #6 to were ill be placing my battery bank

Idd appreciate if you could take a look at my idea of battery configuration in fallowing link

http://i242.photobucket.com/albums/ff283/erisso/configuration2.jpg http://i242.photobucket.com/albums/ff283/erisso/CONfiguration.jpg

as i cant add battery to my bank
i thot of adding a bank that would help in 2 ways,
absorbing extra watt that my bank cant take from turbine and giving me extra storage without changing all batterys
both are showing 12v but as said any of them could be converted to 24v easily as both banks are independent.

im maybe off route so any comment is appreciated

In your "On a side note" you mention "I'd been forced to get a second charge controller "
I know from an other post that you intend to install a 3 phase turbine,
is this "charge controller" the same as "battery dump regulator" or an other thing thats required for
your installation or for all installations,
(please understand that im French speaking and some times same thing with 2 names gets me confused)

an addition
if my batterys are 12v for 8 cells this is 1.5V each
if im putting 2 extra cell to the line adding 3V to it for total of 15V per line
will not that drive my inverter crazy as it has hi/low protection

Eric

Too bad those cells got away from you, but I guess you'll have to get by with what you have.

Your mutli battery bank arrangement has me a little concerned. It might work, but it's a little more tricky than it appears. Think of electric like water. The battery bank is like a lake. A battery dump regulator works like an overflow gate on a dam. When the lake is full from incoming water from the river dumping into it, the overflow gate allows what water is coming in to just spill out the other side. Now if you got another lake on the other side of the dam, especially if it's a little higher elevation, (higher bank voltage) the overflow gate won't perform it's job of shedding the extra water, and the first lake overflows.

The problem is, you need a certain amount of over-voltage to drive the amperage into the batteries. While the first bank should charge just fine, I don't think the second bank will. (at least not very well) The voltage will be held at the dump value by the first battery bank, and will probably spill through the second dump regulator, unless you increase the value on the second one. But then, that overcharges the first bank. The only solution is you'd have to set the first regulator at a slightly lower value than the second, basically undercharging the first bank, until the second bank is charged and dumping too. It's not a good way, but it crudely works. You'd want to assure that the voltages of either bank don't exceed the other's full charge state, so one of them is never going to be fully charged.

I think a better solution might be to get something like a 90 amp battery isolator and separate both bank's chargings independently from each other. There are some losses through the isolator, and I still wonder if both banks would receive their full charges.

Yea, especially for wind and hydro turbine applications, "charge controller" and "battery dump regulator" are the same thing, and I tend to use both terms for the same thing. There are differences when applied to solar applications. Actually, for my turbine, I plan on three dump regulators. Each coming on as wind (and current) increase, and to act as a redundant safety should one of the controllers or dump loads burn out.

Yea, as for voltages of the bank. You may need to add or subtract a cell to get the balance required to work with your inverter(s). On larger NiFe systems like 48 volt banks, I've even heard of people having knife switches inline to drop cells in and out depending on state of charge, to control voltage to the inverters. You shouldn't have to worry about that, but you want to shoot for a battery string that doesn't exceed the inverter's high voltage cutoff when the bank is fully charged. And you want to have enough voltage that doesn't trigger the low voltage cutoff before the battery bank is depleted. If you're getting 1.5 volts per cell, I'd be surprised, but even then, I'd want at least 9 cells in a string (13.5 volts) to prevent a low voltage cuttoff when you begin discharging the batteries. (also 9 cells would put a depleted NiFe at 10.8 volts. I think most inverters shut off close to that) But again, I doubt you got 1.5 volts per cell. (might look like that way after immediately removing it from charge though) Eight cells simply won't be enough, because as soon as you apply a load, they'll drop to about 1.3 volts per cell (10.4 volts) and will cause the inverter to drop out on low volts right away.

Oh, one last thing, you can make you own electrolyte by combining 30% potassium hydroxide by weight to distilled water. Supposedly, there is some lithium that can be added too, but I'm unable to find out exactly how much. Also, a small amount of mineral oil is added to the cells to form a "surface film" to block carbon dioxide from getting to the electrolyte and plates. But a web search will turn up manufactures of ready made solutions. If you do see voltages of 1.4 or higher, I wouldn't bother changing the electrolyte. (just yet anyhow)
EDIT: Be careful making up your own eletrolyte if you attempt this. From what I understand, there's quite a thermal reaction when the two ingredients are combined. Do you're homework!

**erisso** · 10-29-2007, 04:01 PM

Well i did not receive my regulator yet
i thot the battery dump regulator was a ON/OFF relay sending or not to batterys

using first bank as primelary and dumping load to other bank wen first was full

ill be setting 10 cell per line and see what i get

ill have to rethink this with your 90 amp battery isolator and also like the idea of multiple battery dump regulator
ill be setting 10 cell per line and see what i get
what do you think of fork lift battery bank (other than high price LOL)

Rod, dont know you but im keeping you as friend you are strong in knowledge
this email was receive today from alkaline.co.za ,
witch i dont know were in the world there from as i email manufacturer but they replied

Eric

=====================================
Hello again,

* These batteries are normally used in railway (vibration) environment.
* They are pocket plate high performance cells
* The blocks are at least 30 years old
* Typically the battery will give in the region of 70% of original capacity (84AH)
* Apply this regime

Old battery that has been previously filled
1. The battery should be free of internal rusting (check if you are able)
2. filled with E22 electrolyte special mix with KOH and LiOH
3. Initial charged at 24A for 16 hours constant current
4. Discharge at 24A for 5 hrs
5. Recharge at 24A for 7hrs

* The cells then shall be at the best capacity that they are able to give

Tony Gordon
Project manager
Multi Power Systems
A division of Alstom Electrical SA (Pty) Ltd
Tel:- (+2711) 397-4861
Fax:-(+2711) 397-6094
(+27)(0) 82 373 6166

--
(???.? Eric Rivard ?.???)
(???.? Visit / Visitez ?.???)
http://www.preservation.ca

**rreidnauer** · 10-30-2007, 06:44 PM

Well, the dump regulator is an electronic relay. But, you are mistaken on the way the regulator is wired to the battery bank. The batteries are directly wired to the turbine. (well, actually though the rectifier) The regulator is wired in between the battery bank and the dump load. It is wired in this fashion to protect the turbine from a disconnect from load, which would result in overspeeding and damage to it. So you see, the dump load(s) must be at least or larger than the turbine's maximum output to use up it's power when the batteries are full. The cheapest regulators pretty much do just close on a preset high voltage, but the more sophisticated ones actually open and close many cycles per second, as the voltage approaches the set limit, it cycles open more than closed, but increasing voltage alters the ratio so it's closed more than open until the limit is reached, at which time the regulator is fully closed. The really fancy models even control the voltages at different levels to "condition" the batteries. I doubt they are really needed for Nife cells, since they are so tolerant.

As for a forklift battery pack, that's what I was hoping to do. (though, they are lead-acid) I was actually hoping to find a used pack that is still intact, but maybe a bit sulfated from discharge abuse. Using a combination of chemical and electrical desulfation, I'd try to restore the battery. Problem is, if it don't work, I got to dispose of the battery, and that can be pricey.

Looks like Tony's email reply has got a lot of good information in it. I wouldn't take his word on the amp-hours. That may be the rating of each 8 cell pack. (I kind of suspect it is) and if you have several paralleled together, you'll be multiplying that value with each set added to the bank. Again, I recommend doing the capacity test so you can definitively know the true value.