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Manual Recharging of Ni-Fe Batteries

Q24:Manual Overcharging System

Hooking up irrigation pump for a bigger load.

Here is a better trickle of water.

Even uphill slightly.

Very good so far. Enough to run entire system? 35 trees so far? Hmm? no

The 370 W motor draws 14 Amps, looks OK.

Bit of stretch to make both run on a 930W inverter. The inverter is handling 1000W OK, almost 32Amps. That is 100% of it's ability.

Even with water pump on as well. And washing machine. So it's quite a load on the batteries. Over 60 Amps.

The MPPT boxes are all on absorb at 9:00am.

Each MPPT amps coming in : Trina 19 A

Each MPPT amps coming in : Zeus 20 A

Each MPPT amps coming in : Canada 22 A

Each MPPT amps coming in : Sola 21 A

This is exciting indeed, and the bank reached FLOAT by 10:00 AM.

For manual overcharging, this solar Solar Trina voltage is 1 volt too high (34.2V).

By comparison the Jinko solar panels is 34.3 V (also 1 volt too high).

I have used both types as two strings successfully for manual charging.

For manual overcharging, this solar voltage is too high.

I had to upgrade the irrigation pump to submersible, as the one way valve, leaked, allowing water to siphon out.

The lead pipe in the tank has a 2mm blead hole to break air suction when the pump is off.

The big Inverter, 3000W for the bigger loads coming.

  • Water distiller 1500W
  • Water irrigation pump 1100W.

    The big inverter died, after 3 months of use, so back to smaller loads, and cheaper inverters are cheaper to replace and repair.

    The eight 34V Jinko solars panels on the right.

    The solar trina (second manual string) in the middle left of picture.

    Underneath pair the lines into parallel array.

    Place coloured tape (red and black) for each wire.

    Cover with blankets to kill the AMPS.

    Do not risk electrocuting yourself!

    Some tools for the job of joining all eight in parallel.

    I call this a BUS join, the central 80 amp line is not broken, and the crimp with the two +ve leads are fitted into the crimp. The anderson plugs that come with the solar panels are cut off, too expensive to use.

    Like so, crimped four times, and taped up.

    Do the next the same.

    Repeat for the -VE black BUS line, until like so. We have a manual charing system, coming in at 34V maxiumum and between 80 to 90 AMPS maximum. No solar controlling in this system.


    The system working at late afternoon, showing nearly 4 AMPS from the manual system,(the other 6.5 amps is showing the kitchen use, a slow cooker is ON).

    On top is a 100 AMP, resettable fuse to break the circuit when the manual charge system is to be turned OFF.

    The manual charing system will be used to manually charge the batteries,with all loads OFF, and all solar controllers and their solar panels OFF.

    This will overcharge the batteries for 6 to 8 hours, and restore them hopefully.

    We let you know how it turns out!!

    I received a hopeful email from David Bartlett, the seller of Nickel Iron Batteries in Victoria

    Fri, 17 June at 5:54 pm

    Hi Rob, if you can get 80+ amps in for 6-8 hrs you will see a big improvement in their performance. You will want to do this a few times. I have been direct charging my batteries for over a year and a half. I am buying a charge controller but they have been working fine

    Keep me posted

    Cheers David

    So far on my first day of manual charging...,

    Time: 9am

    57 Amps 34 Volts

    .... the batteries are bubbling away like mad!!

    Do NOT try this on lead acid batteries, they will blow up. Not so with Nickel Iron, they love being over charged, and running them down to 20% battery storage.

    After all day of manual charging I will test the capacity of the batteries, with a low discharge (fridge only) of 3 amps per hour, that's 150 Amp/hr/day and see how low to run the batteries dead flat and use the BMV monitor to measure the discharge.

    Than I will manually recharge them again, Hopefully restore the nominal battery capacity.

    Time: 2pm

    50 Amps 34 Volts

    Cell voltages are around 1.65 Volts per cell, battery temperature is 17 Degrees C.

    Things look great, the voltage is fine, and current OK for winter sunshine, and hopefully things will work out just great.

    Late in afternoon the winter sunshine is giving all it can. The 0.00 Volts on the right is correct, as the voltage on the negative lead to a battery should read zero.

    The red arrow shows the fuse breaker and ammeter for this new manual charing system.

    Things look complex now with all the meters and associated wiring.

    So far the 240VAC fridge is drawing 4 amps per hour roughly. Battery voltage, fully charged, is 28+ Volts.

    Will see the results in the morning.

    After 10pm, the voltage only dropped to 27.9 volts !!

    So far at 27.5 V, 39 Amp/hr removed.

    The battery capacity did not increase. Bother. David reckons a few more times, and I reckon my current was too low, needs to be 80+ Amps. So I plan to rewire Trina ( which is 34.2 Volts) into a 4 panel parallel array, also for manual charge, this will give me another 40 Amps. Stay tuned....

    What the manual charging swiching system looks like for the two charging strings.

    I can switch them both on and get a practical maximum of 98 Amps, even in winter.


    On 7 July 2022, I tried again, this time I have two strings of manual charging to 75+ Amps.

    Time: 10 am

    75.6 Amps 34.5 Volts

    Cell voltages are around 1.65 Volts per cell, battery temperature is 16 Degrees C.

    When I switched the manual charging off at 5pm, the battery stayed on 31 volts.

    During the night I loaded up the fridge, fan and water pump, even a bore pump for 4 hours, watering at 11 pm.

    Finally the Inverters had trouble at 142 Amp/hr discharge, on 21 Volts.

    Switched off all things except fridge, still running OK on 3 Amps, at 21 Volts.

    So I have reached 142 Amp/hr. Hmm? not much more than I have always had.

    Try again today on manual charge.

    Time: 10 am

    98 Amps 32 Volts

    On 8th July 2022, I got between 98 Amps down to 65 Amps, as the winter day progressed from 7:30 am until 4pm, the voltages rised slowly as the battery changes rapidly by 10:30, being 140 Amp / hr you expect it fully charging at this charging rate. The cell voltages rises from 1.3 V to 1.6 V. Again I switched off all the panels at noon and run heavy loads (bore pump and water pump, plus house) , a total of 50+ amps, and the batteries yielded only 125 Amp/hr .

    I switched on the manual charging system for the second time in the same day, for another 80+ Amps until 4 pm. On 19 Volts the cell volt never goes lower than 1.3 V and this is a worry, as I assume the cell voltage should drop to 1.0, but has never achieved this, so I must be draining the batteries down to 30% rather than 20 % SOC??

    Again over night, the battery capacity is 125 Amp/hr. No change than before. One gets less SOC depending upon how quickly you remove the amps, today I switched on the water pump, rather than allowing the fridge to drain the batteries.

    I am beginning to think that manually charging my batteries is NOT going to change anything about my batteries ...

    I will try again today.

    I have to switch off all Inverters as they do not like running at above 33 Volts. The manual charging system peaks at 34.5 Volts, which is one volt too high for the Inverters. One will have to think up a way to reduce the incoming voltage by 1 volt at 80+ Amps? Hmm?

    Another day of manual charging, over 75+ Amps for a full day . This time all loads switched off, except 24Volt loads (small pump, computer extractor fan and LED lights), so on the end of a full 24 hours, the batteries have 28 V and a discharge of 10 Amp/hrs.

    On the night fall, I measure 1.45 on the cells.

    On the morning, I measure all cell voltages, to ascertain internal battery losses:-

    1.39 1.40 1.40 1.381.39 1.391.39 1.39 1.39 1.39
    1.39 1.39 1.39 1.38 1.391.39 1.39 1.39 1.39 1.39

    So the voltages are more or less, the same. So no real internal battery losses overnight.

    The voltage is 28V showing fully charged.

    I will test the bank today, draining it with 20 Amps per hour.

    With 200 amps of storage, I should be able to run the water pump for at least 4 to 5 hours. I doubt this idea, but we will see.

    It did more or less, but I got tired of waiting to drain the batteries dead flat, and switched all the loads on, and the system coped with 60+ Amps for quite a while.

    Finally the system ran out of power, at 80Amp/hr discharge capacity 22V and running 60+ Amps.

    I suspect this is fairly normal, so overall I have not changed my battary amp hour storage capacity at all.

    There is no internal short draining my batteries either, as today's test proved.

    I suspect currently the battery bank is around 125 Amp hours on a 5 amp draw, and 90 Amp hours on a 40 to 60+ amp draw. No where near the 500 Amp/hr the manufacturing promise.

    Hence the objective of the manual charging is to improve the chemistry behaviour and increase state of charge capacity.

    I decide to do another manual charge (no loads connected).

    Time: Amps Voltage Cell V.
    6:30 am 6 A 32 V 1.60 V
    9:30 am 68 A 33.7 V 1.64 V
    10:30 am 73 A 34.4 V 1.68 V
    11:00 am 74 A 34.5 V 1.70 V
    12:00 am 73 A 34.4 V 1.70 V
    12:30 pm 72 A 34.4 V 1.70 V

    I decide the 3 hours at 70+ Amps is enough and switch off all solar panels.

    I than switch on a moderate load, water pump, fridge and bore pump, a total of 40 Amps.

    Time: Amps Voltage Cell V.
    1:00 pm 40 A 27.4 V 1.35 V
    1:15 pm 42 A 26.9 V 1.32 V
    1:45 pm 44 A 26.2 V 1.29 V
    2:00 pm 45 A 25.0 V 1.24 V
    2:30 pm 50 A 22.1 V 0.70 V

    The water pump and bore pump are switched off, while I measure the cell voltages

    1.30 1.30 1.00 0.951.21 0.871.24 1.30 1.30 1.28
    1.30 0.85 1.29 1.28 1.281.28 1.30 0.89 0.87 1.30

    According to the BMV monitor, the discharge from the batteries totalled 105 Amp/hrs . This is a 10% improvement for this kind of moderate discharging.

    So things seem hopeful

    I got three new things today:

  • Battery storage increased 10%
  • Got low V readings first time
  • Different readings across cells
  • Patience might be the key, keep at it.

    More charging current and more time manual charging. This means manual charging with no loads on the batteries.

    More flogging the batteries after fully charged. This means disch arging the batteries without any incoming power from solar panels.

    Overcast day, but tried again, manual charge. Switch off all loads.

    Amps ranged from 40 to 90 depending on clouds. At noon, fully charged I begin flogging the batteries. (Moderate load, both pumps 40 Amps) no solar panels.

    Time: Amps Voltage Cell V.
    12:00 pm 40 A 29.7 V 1.65 V
    12:30 pm 40 A 27.6 V 1.37 V
    1:00 pm 40 A 26.8 V 1.32 V
    1:30 pm 43 A 26.2 V 1.30 V
    2:00 pm 45 A 24.9 V 1.28 V
    2:30 pm 45 A 20.6 V 0.73 V

    From 2.30 pm I switched on manual again to charge for night use. 45 Amps @ 29 V.

    The total discharge from the moderate flogging of the batteries was 106 Amp/hr . This is about the same as yesterday. But better than previous floggings. Different cell voltage readings, and low ones too. Things seem to be changing.

    It's raining, bother.

    Last night on a miserable 40+ Amps manual charge since 2:30 pm, with fading light and little chance to recharge, the batteries are still 25V with fridge only removing 3 amps/hour, the total discharge has been over night 124 Amp/hr, or 150 Amp/hr cumulative.

    This is a big 20 % improvement. Still have voltage drops to go. wow !

    I got some more wonderful encouraging advice from my supplier, David Bartlett, from Iron Core Batteries:-

    Wed July 20 at 9:00 am

    "Loads during the day are generally carried by the solar with some exceptions on cloudy days. I would start finding out what you can run overnight on without the inverter turning off and repeat that for at least 5 nights so you can confirm that capacity is definitely in the battery.

    I would then add another small load and repeat the same process. Each time the battery is able to carry that load for at least 5 nights add another load and repeat the process. What normally happens is you slowly build the capacity into the battery.

    If you add too large a load the voltage will drop off quickly and you need to go back a step and consolidate the capacity you knew you had.

    It is a balance of slowly building capacity into the battery without putting too much load on it.

    When the capacity starts rising, you maybe able to add a larger load but need to turn off a smaller load to ensure you are not placing too much load on the battery. Once the larger load is able to make it through 5 nights, add the smaller load.

    There will be times you will not make it through the night depending on the charge you get into the battery during the day so you need to take this into consideration and not expect it to be.

    This winter we have had many cloudy days and so we are just not getting the charge into our battery and need to be conserative if we want thing running through the night.

    Once the capacity starts to rise it should speed up but do not add too large a load as you can start going backwards.

    Consolidate the load and ensure they are making it through a number of nights before adding more.

    Once you are getting what you need out of the battery, KEEP using it, do not turn things off as the capacity of a NiFe battery depends on how you use it.

    If you turn stuff to conserve the battery regularly, the capacity will slowly drop off as well and you will need to repeat the above".

    So I plan to do a LOW load through the night.

    Another manual charging by 3:00pm (cells got 45 to 70+ Amps) - overcast with clouds.

    Switch on LOW load, cooker and fridge (10 Amps per hour).

    no other loads (except 24 V DC loads)

    Time: Amps Voltage Cell V.
    4:30 pm 12 A 28.6 V 1.38 V
    5:30 pm 11 A 27.6 V 1.37 V
    6:00 pm 10 A 27.3 V 1.35 V
    7:30 pm 10 A 27.1 V 1.33 V
    8:30 pm 11 A 26.9 V 1.32 V
    10:30 pm 10 A 26.5 V 1.31 V
    12:30 am 9 A 24.9 V 1.27 V
    2:30 am 10* A 22.4 V 1.27 V
    3:30 am 8 A 22.1 V 1.27 V
    4:00 am 4 A 21.8 V 1.27 V

    * From here switched off slow cooker, fridge only.

    Than I measured all cells to ascertain bad cell voltages:-

    1.27 1.27 0.82 0.830.83 0.810.83 1.28 1.27 1.23
    1.27 0.89 1.27 1.25 0.800.80 1.27 0.80 0.80 1.28

    As you see I have quite a few "bad cells" , ie 0.80 instead of 1.27 Volts. Ten "bad cells" ??

    It's approaching sunrise, as I write this, I am so excited. Battery voltage is 20.6V, discharging 3 amps (fridge only) and the total discharge over night from 3 pm was over 150 Amp/hr.

    That is a 155-125/155= around 19% increase in battery capacity, on a low amp draining.

    So I need to continue this for 5 nights, adding slightly more loading after that.

    Things are looking hopeful.

    Many thanks to David Bartlett for his advice.

    Stay tuned....

    Friday 22 July 2022:

    Major run Manual charge
    75+ amps 7 am till noon
    First run moderate Flogging
    40+ amps total discharge 100 Ah
    Minor run Second Manual Charge
    60+ amps 2:30 pm until dark
    Second run low Flogging
    5 amps total discharge 150 Ah

    Been thinking of David's advice, and flogging the batteries moderately hard until they are near flat, is not helping with capacity, might make things go "backward" in his words.

    So I plan for manual charging all day, but in the middle for an hour, to do a moderately hard flogging for a while.

    During this; all solar panels are switched OFF, to work hard the batteries for one hour every day.

    I will do the low to moderate discharging over the night time, little by little increasing the load, until the capacity is improved.

    Saturday 23 July 2022:

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    90+ amps from 10 am
    40+ flogging no solar for 1 hour
    80+ amps on average
    60+ amps solar OFF from 4pm
    Overnight run low /mod Flogging
    10 -> 5 amps total discharge 127 Ah

    Monday 25 July 2022:

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    90+ amps from 10 am
    40+ flogging no solar for 2.5 hours
    40 + amps total discharge 157 Ah

    Too late in afternoon, so no use of batteries overnight.

    Tuesday 26 July 2022:

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    70+ amps from 10 am
    50+ amps solar OFF from 4pm
    40+ Amp flogging 2 hours low /mod Flogging
    10 -> 5 amps total discharge 150 Ah

    Wednesday 27 July 2022:

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    77+ amps from 10 am
    60+ amps solar OFF from 4pm
    40+ Amp flogging 2 hours low /mod Flogging
    10 -> 5 amps total discharge 160Ah

    160 is a 20% improvement since 125 days. Getting there slowly.

    Thursday 28 July 2022:

    Manual Charge Amperage
    65+ amps from 7 am (no loads)
    87+ amps from 10 am
    80+ amps solar OFF from 4pm
    40+ Amp flogging 1.5 hours low /mod Flogging
    15 -> 5 amps total discharge 142 Ah

    Friday 29 July 2022:

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    70+ amps from 10 am
    60+ amps solar OFF from 4pm
    50 Amp flogging 1.0 hours low /mod Flogging
    30 -> 5 amps total discharge 150 Ah

    Wired up a eight 1 ohm resistors in parallel to make a 1 volt drop, carrying up to 80Amps into the battery, so now I can run the Inverters at the same as as a Manual Charge. The charging voltage will stay under 33 Volts and allow the In verters to still function normally.

    The halls affect ammeter at the battery end shows 15.7 Amps and 29.3 Volts.

    The parallel resistors are left in the picture.

    Coming into the system from two strings, theere is only 16.6 Amps, an overcast day, and the voltage is 30.8 V

    The manual charging system is switched ON for both strings.

    A picture showing both ammeters at the same time, resistors shown in red circle. And a diagram shows the electric layout. There is a slight loss of amps? which is hard to answer why? I suspect the ammerters are not precise to each other. The voltage drop is 1.5V perfect for my needs.

    The shop had only seven 10Watt resistors, so I used seven 10Watt resistors in parallel and two 5 Watt 1 ohm resistors in parallel (to the parallel) to make the eight 1 ohm resistors in parallel at 10 Watts.

    Electrically a bit rough, but the theory meets the practical. On just 30 Amps, one resisor got hot enoough to melt the connector, so all the resistors were too hot ? Not sure why? So abandoned the idea, and went back to manual charging with Invertors switched off.

    Thursday 4 August 2022..

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    70+ amps from 10 am
    60+ amps solar OFF from 4pm
    40 Amp flogging 1.0 hours low /mod Flogging
    30 > 10 > 8 > 5 amps total discharge 170 Ah

    I ran a second fridge and fan until 3 am, and than fridge only after that, the voltage is still 20V.

    This is an improvement of 170-125/170 = 26% improvement since Manual Charging began.

    Been a slow tedious process.

    Thursday 8 August 2022..

    Manual Charge Amperage
    60+ amps from 7 am (no loads)
    80+ amps from 10 am
    60+ amps solar OFF from 4pm
    40 Amp flogging 1.0 hours low /mod Flogging
    20 > 10 > 5 amps total discharge 170 Ah

    Another 170 Amp/hr achieved !!

    Dear readers of OFF GRID Nickel Iron ..

    I am frustrated restoring these batteries.

    Maybe they suffered from Voltage Depression?

    Maybe I have a dead cell? Who knows?

    Beyond my abilities to fix right now?

    My batteries are still 125 to 170 Amp/hr of storage.

    Not much has changed due to Manual Charging.

    Just wasting precious distilled water.

    Would cost 2000 dollars to return these batteries.

    Just not worth the extra cost, so I have wasted over 10,000 on batteries that do not promise.

    Might have been better buying AGM Lead Acid and replacing them every 2 years.

    In total, last 14 years with 80% State of Charge?

    $1,400 for four 200Amp/hr 12V batteries in parallel.

    I could get 14 yrs of money spent for the same?

    A 14 year risk it works out?

    My 170Amp/hr Ni-Iron will be still working than.

    I still believe in Nickel Iron batteries.

    I think I just got some dud ones.

    So beware of Chinese manufacture

    Or of voltage depression issues.

    Also known as battery memory.

    One way to fix this is to individually charge each cell and test them individually.

    This is a difficult thing to do for a backyard person.

    For now I will stick with what I have.

    Will keep readers informed. Still hopeful.


    Next we look at a final overview on things.

    Ni-Fe battery technology

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