Alexkor Air Core Coil Radiant Charger

[SkyWatcher]

Hi nick, thanks for the informative reply.
Yes, so with those other AA's i was testing, 5 extra charge cycles at half capacity is not too bad and with no leakage.
Will see what happens to these other two.
I did not know that these alkalines have mercury and cadmium in them.
Well that changes things a bit, meaning to me, that unless I have these already on hand or used, I am only buying nimh in future.
Even though i think i read that already, thanks for reminding me that these are poison.
peace love light
tyson

[holtage]

How is your air core coil made? (The Alexkor Air Core Coil Radiant Charger)

Hi, Skywatcher. I want to ask you a question.
In this thread, you make a Alexkor circuit. I don't know How to wind the coil onto the air core, can you tell me how to wind the coil onto the air core, and if you can, give a photo of your air core to let me see how it looks like? Thanks!

[SkyWatcher]

Hi holtage, a picture is in the first post of this thread.
Used heavier duty cardboard tube (6" length X 1-3/8" diameter) from used up plastic wrap roll.
Used 24awg. bifilar (2 strands) magnet wire and taped the ends.
Still use this charger almost everyday, as it charges the smaller size cells very well, as well as 7AH size and rejuvenates them at the same time.
Have a couple different wall transformers for different voltages, depending on cell type to be charged.
Hope that helps, any other questions, just ask.
peace love light
tyson

[SkyWatcher]

Hi luno, thank you very much for that web forum link, translating all the russian text to English right now, to gather more information.
One thing for sure, almost any cell type seems to love the high frequency, high voltage, low current spikes of this air coil radiant charger.
AA nicads and AA nimh that should have been thrown out years ago, i kept for some reason, this charger is bringing back to life dozens of AA rechargeable cells, that most other radiant pulse chargers would not rejuvenate like this one can.
Of course it also works on pretty much any other type of cell also, even alkaline, etc.
This air coil charger is the main charger in use here, since it rejuvenates so well.
Will be trying to improve the output for faster charging of larger batteries and hope to gain some insights from that Russian forum, thanks again luno.
peace love light
tyson

[harctan]

Hello all. I've been experimenting with this type of pulse charger for the past few days and I thought I'd share my results. I used only what I had in hand at the moment. I drive the transistor using a 555 timer IC at 687Hz and 52% duty cycle. I attach the schematic and a picture of my setup. The coil is from leftover 0.45mm(AWG #25) magnet wire about 10 Ohms resistance, single-filar, air-core, sloppily wound. I use two relatively new SLA 12V 1.3Ah batteries, witch are conditioned from a bedini fan for about 10 charge-discharge cycles. Before the test one battery was charged to 14.5V and the other was driven down to 11.2V. Resting voltages were 12.79V for drive battery and 11.96V for charge battery. After 2h17min drive battery droped to 11.20V and charging voltage on the second battery was 12.69V. Resting voltages (after a few hours) were 12.10V for drive battery and 12.29V for charge battery. Amp draw from the drive battery registered at ~70mA which is obviously not accurate. During the charging the batteries and the transistor remained cool while the coil got just a little warm. Next day I swapped the batteries and repeated the experiment. Resting voltages were now 12.27V for drive battery and 12.14V for charge battery. After 47min they went to 11.20V and 12.59V charging voltage respectively. Resting voltage settled at 11.98V and 12.26V.

[Guruji]

Skywatcher did you try that charge on big 12v batteries?
Thanks

[SkyWatcher]

Hi folks, Hi guruji, only have 12volt-7ah on hand and it does charge those very well also and is NOT a fluff charge, it is solid.
Next step might be to try a multistrand coil with transistor for each strand, though not sure if that will affect frequency and performance.
Maybe just separate air coils with all flyback diode outputs merged into one output might work.
Even still, this works fine as is, just takes longer to charge the bigger batteries.
peace love light
tyson

[harctan]

Hello all. I've been experimenting with this type of pulse charger for the past few days and I thought I'd share my results. I used only what I had in hand at the moment. I drive the transistor using a 555 timer IC at 687Hz and 52% duty cycle. I attach the schematic and a picture of my setup. The coil is from leftover 0.45mm(AWG #25) magnet wire about 10 Ohms resistance, single-filar, air-core, sloppily wound. I use two relatively new SLA 12V 1.3Ah batteries, witch are conditioned from a bedini fan for about 10 charge-discharge cycles. Before the test one battery was charged to 14.5V and the other was driven down to 11.2V. Resting voltages were 12.79V for drive battery and 11.96V for charge battery. After 2h17min drive battery droped to 11.20V and charging voltage on the second battery was 12.69V. Resting voltages (after a few hours) were 12.10V for drive battery and 12.29V for charge battery. Amp draw from the drive battery registered at ~70mA which is obviously not accurate. During the charging the batteries and the transistor remained cool while the coil got just a little warm. Next day I swapped the batteries and repeated the experiment. Resting voltages were now 12.27V for drive battery and 12.14V for charge battery. After 47min they went to 11.20V and 12.59V charging voltage respectively. Resting voltage settled at 11.98V and 12.26V.

I repeated the same experiment but now I increased the frequency from 680Hz to 3.5kHz which gave me better results. Starting voltages for drive and charge battery where 12.90V and 11.84V respectively. After about 10 hours they reached 11.20V and 12.82V and they settled at resting voltages of 11.82V and 12.40V. I swapped the batteries and now it took 5:30 hours for the primary battery to drop to 11.20V while the charge battery reached 12.52V. Final resting voltages were 11.79V and 12.20V. During this test the batteries, transistor and coil remained cool.

[SeanK]

Which coil yielded better results

Hi Tyson,
In you initial posts you mentioned you made the Alexkor circuit coil with more turns than shown in his original circuit. Did your coil yield better results ?

[SkyWatcher]

Hi sean, thanks for the reply.
From memory, think the larger turn 24awg. coil did not have the same charge rate, though not sure if it was more efficient or not.
Still using the same air coil charger for months now, to recharge all AA's used here and the AA rechargeables are doing very well under this type of charging.
Though would like to make a larger air coil, with something like 18 gauge and just keep wrapping turns until the same 1.5 or so ohms is reached.
Would be interesting to see if all that added copper mass would add any benefits to charging the cells.
peace love light

[SeanK]

I am particularly interested in replicating this. I have a 48v battery bank (~350AH) and would be cool to charge from 12 V. I also have a 280v 100AH NiMh bank. Wondering if I could scale such a charger up to that voltage.
I'll start with AA size . PK's book, suggested scaling up with more drive circuits and coils. IS more copper expected to yield more A/Pulse or more V/Pulse ?
Its awesome you're so open to sharing. Thanks alot.

[SeanK]

Hi Tyson, many thanks for your continued encouragement and inspiration throughout this forum. I see so many wonderful post from you, its really exciting.

I made the coil using a 1/2 inch pvc conduit (~1.9omhs) and am using IN5006 as the diode with a BU2508A which I ripped from an old monitor. Results are not so great -- horrible actually.
You placed two HER303s in series in your setup (initial version) and I was wondering why you did that ?
Is that across the collector and the secondary battery +?
Sean

[SkyWatcher]

Hi sean, thanks for the reply.
The coil used here, is on a 1-1/4" diameter cardboard tube, 5 inch long coil and is using 24 awg. bifilar.
The base resistor also has a 100 nanofarad capacitor in parallel with it, because it would not oscillate without it.
So, check to see if your coil is even oscillating.
Maybe charge a small capacitor to see if the voltage is rising above the input voltage, that should tell you if it is oscillating, since you probably can't hear the high frequency.
Found your transistor online, that seems like it will work good, though could not find information about that 1n5006 diode.
You'll need a fast (reverse recovery time) diode for good charging, 50 nanoseconds or less, as even if your coil is oscillating, if it is a slow diode, you will see poor performance or charging.
Hope that helps for now.
peace love light

edit: the diode is off the collector to positive of charge battery and the other end of coil is to negative of charge battery, using this NPN transistor

[SeanK]

Many thanks for your reply Tyson.
Got my oscilloscope today( OWON PDS6062 ) Hoping it will help with my experiments.
Just to clarify:
The 100nF is in place of the 2700pF in the diagram at the start of this thread ?
Is the "test" charge cap to be placed where the charge battery would go ? (sorry if these are silly questions, I'll get it eventually).

[SkyWatcher]

Hi sean, thanks for the reply.
The 100 nanofarad replaces the 2700pf, at least in this setup, yours may need a different value capacitor, have a bunch around here to try, from all sorts of gutted devices, like cfl's, etc..
Yes, the test charge capacitor would be placed where the charge battery would be, though maybe the oscilliscope will also tell you if it is oscillating, if it's fast enough to see the spikes.
The only silly question, is one that is not asked.
peace love light