48 VDC NiFE Cells

[Herman]

Just a quick refresh when we purchased our property it was currently on small 24 VDC Lead Acid (LA)full solar with no grid feed this was fine to run a 400 lt fridge and a lap top at night with no TV this led us to install another system that also ran parallel being a 48 VDC system Nickel Iron (NiFE), During the Day the LA are use to run house hold appliances and at night NiFe switches in. this is achieved with a grid switching system that is controlled by one of the MPPT that activates between to two banks at 25.0 VDC is activated and when the LA drop to 24.3 VDC (these usually jump back up to 24.7 VDC after the switch) the Nife are activated. meaning we rely on LA during Daylight Hours and NiFe at night.

During minimal sunlight due to rain or heavy cloud cover on the LA I am Using an outbak charger invert (came with the property) and the NiFE I DC power Supply to charge the NiFe cells with a 6.5 KVA Honda generator, the reason for doing this was to save money keeping what was in place and building on it with minimal cost and it has been working quiet well except for those days when the weather has turned pear shaped or night during day then it is Hondas turn.

The ? I have what is the best normal Voltage to charge the NiFe Bank is it 66.6 VDC for Equalize Charge and 58 VDC up to 62 VDC for float

Your knowledge is appreciated

[mike90045]

Yes, those voltages sound reasonable.  How do you manage changing the charge controller settings from lead-acid to the NiFe settings ?  Do you use 2 different charge controllers ?

In the summertime, I dial back my float & absorb voltage some, to save water, and I still water the bank every other week.

[Herman]

Hello Mike thanks for the response

I use 2 MPPTS a Power Master for the LA Batteries this also controls the Grid switch between to 2 banks and an Midnite 150 on the NiFe cells both these systems are performing exceptionally well and cannot fault them.

I have taken note of your recommendations and have acted on it thanks for that

[russ_drinkwater]

Hello Herman,
How are things going with your Edison batteries?
You have everything sorted out?
Russ

[Herman]

Hello Herman,
How are things going with your Edison batteries?
You have everything sorted out?
Russ

Hello Russ sorry about the late response it is all working well as the Ni-Fe is receiving a good charge from the TSIG panels I have put in the next step will be either Selectronic SP-PRO Interactive Inverter/Charger 5kW 48V or the VFXR Series 3000VA 48 volt Inverter Charger - Outback Power VFXR3048E. I am tending to go for the SP-PRO even though it is slightly more expensive as it has every thing contained in the one box were as the Outback you have to add the mate and a few other parts to it which would bring it up to the same value as the SP-Pro.

[Westbranch]

Herman have you read post # 241 bt Robin , here?

http://kb1uas.com/mnsforum/index.php?topic=602.msg29761#new

[russ_drinkwater]

Hi, Herman
Yeah, I have often looked at those inverters on ebay, but they are way serious money. And a long way out of what I can afford.
$6,000 for the 24 volt 4500 watt unit I have on my watch list.
If I get my super I will get one.
What are cases on your edisons made of ?  Plastic or stainless steel?
On another note they are starting to try and stop people buying H2 SO4 here as well. Have been keeping all I can get my hands on and storing away in a sealed poly drum. Will worry about the purity and concentration later.

[Herman]

Thanks for that Westbranch

and hello Russ my batteries are made out of white plastic so i have a 12vdc strip led  behind them so i can check the water levels


PS Sorry about the late response

[Herman]

I have just heard from a friend of mine saying he is having troubles with his Sp- Pro Interactive Inverter/Charger 5kW 48V who have recommended that he drop 2 cells from his 48 VDC NiFe  bank to allow the SP- Pro to get a good charge into to the Batteries, so I am waiting for further info about it, I am also interested in  the VFXR Series 3000VA 48 volt Inverter Charger - Outback Power VFXR3048E which may be a cheaper option

[mike90045]

Yes, many inverters cannot get a full charge into the batteries, but the solar charge controllers CAN, just be sure you don't overvoltage the inverter and kill it, charging with the solar.

A trade is to increase the absorb time, at a lower voltage, will put more energy into the cells, but not as effective as the higher voltage.

[russ_drinkwater]

Hello Herman, that is a good idea using the strip led's to keep an eye on the fluid levels!
I bought a small 12 volt iron edison cell (only 10amps) to play with and the cell boxes are made of the same translucent plastic.
Often wonder what the life of that plastic is?
What is the max voltage you put into your 48 volt bank?
Some of the reading I have done states that will tolerate 18volts into a 12 volt bank!
My small panel does not have that ability as it is low output 40 watts at 0.5 amps.
Amazing thing is that little panel can gas the cells easily.
Do you have much bulging of the cell walls under charge?
The vent holes on these smaller cells do not seem to allow enough gas escape under charge.

[Herman]

Good day Russ

from reading Thomas Edisons manual

Charging Parameters
The proper float voltage is 1.45 volts per cell.    If 10 cells were used, the proper charge voltage would be 14.5 volts. 

The charge voltage can vary from 1.46 to 1.55 volts per cell.   Unlike other battery designs, the exact charge voltage is unimportant.   A higher voltage will result in quicker charges but more water loss that will necessitate more frequent topping up with distilled water.    Since the cells can withstand overcharge there is debate over what constitutes a proper charge voltage.     The higher you go the quicker water will disappear from the batteries.   At voltages greater than 1.5 volts/cell the batteries will store approximately 15% more power than they are rated for.   If 10 cells were used, the charge voltage could range from 14.6 volts to 15.5 volts.   It is probably better to use the 1.46 volts / cell level of charge in order to minimize water loss if the battery will be unattended for months at a time.   Regenerative catalytic caps are available to combine the h2 and o2 back into water if unattended maintenance is required.   There are also auto watering systems that are available.

The proper equalization voltage is 1.65 volts per cell.   If 10 cells were used, the proper equalization voltage would be 16.5 volts.  This equalization charge is applied for 8 hours using at least C/10 current.   According to Edison's original manual from 1914, it is best to completely discharge the batteries from time to time before applying the equalization charge.   Edison also recommends a 1.7 volt equalization charge and he recommends  changing the electrolyte every 5-10 years.

This will all come as a surprise for lead acid battery users.   In contrast to lead acid, the NiFe battery can be overcharged for decades at a time without damage and can be left discharged for years at a time and will still work perfectly when needed.

That last quote a lot off people do not believe and dispute

Due to my invertor I use 63.5 VDC for manual charge i would love to use 66.6 VDC that why i have been hinting for a good invetor Charger that can handle at least 68 VDC

I hope this helps a bit for you

[russ_drinkwater]

Thanks Herman.
Yes I concur that the edison cells will vent a lot or rather a lot more than the standard FLA cells.
The other thing I noticed on the small 12 volt setup I have is the cells bulge when gassing.
And you can hear the noise of the venting, sounds a bit like a 10 cylinder car that runs on compressed air at an idle!
I will try and change the plasmatronics 20 amp reg I have on the battery to a programmable regime and lift the charge voltage up a tad.
The cells/battery is at 14.5 volts most nights. Just a toy really and runs a string of LED 3 gang strip lights I setup inside an old gas lamp!
Looks really cool and runs for hours as well as lighting 2 rooms at once.

[Herman]

Hi Russ

I use a QPX600D PowerFlex+Dual DC Power Supply

Voltage  Range 0 v to 80 v
Current Range 0.01A to 50A
Power Range Up to 600W

This I use to charge my NiFe Cells when I am required to manually charge them and it does a fabulous job but i would prefer a invertor / Charger that is why i have been looking at the Out Back VFXR3048E which then allows full equalize charging and full charging with out tripping out which currently happens at the moment.

Remembering the full equalize charge is about 67 volt for a 48 volt Nife system what i have trips out at 64 Volt.

[BioPower]

Might be worth asking boB or Robin if the Midnite Inverter will do the job for you when they are released.