4 "F" cells in a 6D Mag w/Volt and Amp readings.

[BigusLightus]

Just assembled the first of my "Naukatoothunderphuk" lights.

This is a 6D Mag, AW three speed soft start switch and socket, Osram 64625 lamp, Boro lens, and 4 "F" size LiFePO4 batts. The batts required the top of the paper wrapper to be trimmed to allow them to make contact with each other. As soon as my Kapton tape arrives I wrap the top of each batt.

I'm just charging the batts for the first time. Thus the beamshots will have to wait a bit.

 

[Helmut.G]

Re: Just assembled the first of my lights

nice light, fits your username as well:thumbsup:

 

[donn_]

Re: Just assembled the first of my lights

What setup are you using to charge the cells?

From what I've read, you'll be seriously under-driving the lamp. You'll probably come in well under it's 12V default rating.

 

[BigusLightus]

Re: Just assembled the first of my lights

Underdriven? I was concerned about flashing on start up with fresh cells. Here is the description from the cells: Li-Fe-PO4 Rechargeable: 32900P ( F size) Cell 3.2V 4.5Ah, 90A Rate.

I'm guessing there will be very little sag with these. 3.2V nominal x 4 equals 12.8V. The safe zone is what I was hoping for. As soon as these charge up I'll measure and test everything. I might even try to check the Voltage at the pins of the bulb.

For charging I'll be using a Hyperion 1210 in A123 mode.

The four F cells fit perfect in the 6D tube. I'm excited.

 

[donn_]

Re: Just assembled the first of my lights

You'll lose somewhere between 2 and 3V to switch and spring resistance.

 

[BigusLightus]

Re: 4 "F" cells in a 6D Mag

Even with the AW switch?

 

[donn_]

Re: 4 "F" cells in a 6D Mag

From what I understand, the switch is most of it. 3-4 times normal spring resistance, IIRC.

 

[lctorana]

Re: 4 "F" cells in a 6D Mag

Easily checked.

With the large bi-pin bulbs, it is possible to attach test leads to the pins and test the actual bulb voltage under load.

I think you've done a great mod. The soft starter should take care of the overvoltage nicely.

 

[BSBG]

Re: 4 "F" cells in a 6D Mag

Even with the AW switch?

The AW D Switch is about 200 mOhm - similar to a stock Mag switch.

 

[BigusLightus]

Re: 4 "F" cells in a 6D Mag

Just measured each batt separately and together, just to make sure. Total open Voltage is 13.29. Voltage at the pins of the bulb is 11.94 on high, 7.24 on medium, and 4.08 on low. 13.29 - 11.94 = 1.35. So, I'm only loosing 1.35 Volts to losses. This is on brand new batteries that have not been charged by me yet. I'll post the post charge Voltages tomorrow.

During the test this thing was sooooo bright that it scared me. I could feel the heat during the few seconds of on time.

Tail cap current test are: 3.83A on low, 6.04A on medium, and 8.84A on high. Please note, I was holding the test leads by hand and might not have had the best of connections. I test for current twice and got the same readings except for high was down 3 100ths of an Amp.

 

[VegasF6]

Neat! Make sure you wear your safety glasses when working in the head of this thing, and be carefull with those probes! Man, those cells are no joke.

 

[BigusLightus]

It never occurred to me to take safety precautions. Really. This is only a flashlight, right?

I will take your advise VegasF6. After all, I use protective safety equipment for most of my other hobby projects. I wonder why it never occured to me?

Thank you for the enlightenment.

 

[Bimmerboy]

It never occurred to me to take safety precautions. Really. This is only a flashlight, right?

I will take your advise VegasF6. After all, I use protective safety equipment for most of my other hobby projects. I wonder why it never occured to me?

Thank you for the enlightenment.

VF6 is a good guy.

Sarcasm is an excellent tool when used properly.

 

[lctorana]

Re: 4 "F" cells in a 6D Mag

Voltage at the pins of the bulb is 11.94 on high...

So it's only just underdriven. By 0.06V.

Doing resistance fixes (e.g. tailcap spring braid, DeOxit & ProGold etc) will give you a few extra lumens yet.

At the moment, giving the bulb exactly its design centre voltage makes it what I call a "rightwire" rather than a "hotwire". It's a kind of torch I'm just getting into now - using super-hot bulbs at design voltage.

That way, you get mega lumens, with full bulb life.

 

[2xTrinity]

Re: 4 "F" cells in a 6D Mag

The AW D Switch is about 200 mOhm - similar to a stock Mag switch.

Can't be that high...

...Total open Voltage is 13.29. Voltage at the pins of the bulb is 11.94 on high, 7.24 on medium, and 4.08 on low. 13.29 - 11.94 = 1.35. So, I'm only loosing 1.35 Volts to losses. ...
Tail cap current test are: 3.83A on low, 6.04A on medium, and 8.84A on high. Please note, I was holding the test leads by hand and might not have had the best of connections. I test for current twice and got the same readings except for high was down 3 100ths of an Amp.

FYI a simple multimeter will NOT be able to accurately measure RMS voltage at medium and low, as the AW switch is PWM modulated, not a DC or simple sinusoidal AC voltage.

Anyway, back to the results from the "High" settings:

R = V / I
R = 1.35 / 8.84 = 152 mOhm

That's the resistance of EVERYTHING in the system -- including the cells, the spring, the switch, the bulb contacts, and a multimeter and leads.

Keep in mind this is for the maximum setting, where the mosfet switch is on with 100% duty cycle. Good MOSFETs are on the order of ~10mOhm when on. The switch will be lossier at lower settings, where the switch is being pulse-width modulated, but this can't really be quantified with a simple resistance value.

 

[BigusLightus]

I'm sincere in thanking Vegas for his advice. I honestly don't know why I didn't think of it before. I hope I didn't offend or mislead anyone.

The multimeter I used was a Fluke 87 III. A true RMS meter which is quite expensive. I've not calibrated it for use with PWM but I'm confident it is close. Is there a known PWM source that I can test it on?

Thank you

 

[Bimmerboy]

Eeek!... my mistake, BL. Darned internet communication.

BTW, cool mod, and I must repeat VF6... those cells are truly no joke! Wow... 90A. On paper, it looks like four of those could power an 1100W mod!

 

[BigusLightus]

Four more of these cells would probably start my car.

 

[donn_]

I'll be curious to follow your impressions of the F cells as you use them. I'm a convert to A123s, but so far, in the smaller sizes, 18650 and 26650. I intend to try some M cells soon.

I'm also interested in charging procedure and times. Are you doing them individually, or in series? If in series, are they staying balanced?

 

[BigusLightus]

Hi Donn,

I'm charging as we speak. Using Hyperion 1210 in a123 mode. Charging at 1C (4.5A). Doing each one separately so its taking longer but I feel safer that way.

One of my Christmas presents was a CBA II. I'll be cranking that up soon and will go nuts with all my batteries. I'll post the outcomes here when finished.

I also have some A123's and Emoli's. But those are for other light projects that I've not started yet. I just picked up a brake hone to slightly bore a few C Mags.

Thanks for asking.

Update: Voltages fresh off the charger. Only one minute or less of resting time.
batt #1 3.460
batt #2 3.495
batt #3 3.631
batt #4 3.464