Rechargeable A2?

Most rechargeable Li-ions don't fit in the A2 body, but I was thinking of using 2 RCR2 with a restistor so I don't fry the LEDs. I suppose I could make a spacer to house the resistor and make up for the shorter length of the RCR2s. The problem is I don't know the amp draw of the MA02 and don't know what size resistor. I think I'll need something like 1.5 ohms and 3.5 watt if anything like that exists. Anyone have any advice? Thanks. /ubbthreads/images/graemlins/icon23.gif

Look at the LED board, there are resistors for each LED on it.
These can be exchanged and nothing else is needed,
as the xenon beam is already regulated and will
work with the higher voltage.
(Willie Hunt LVR)
I look for an extra LED ring some time now, to swap out the LEds wit newer ones...

I was hoping to use a 1xRCR123(MP brand) with a CR123 spacer to fill the tube. However, the CR123 spacer that I have(DSpeck) is a little to big to fit in the A2's battery tube. Anyone know where I might to find a smaller diameter CR123 spacer?

seattlite,
The SF Z20 fits perfectly in the A2 (made of aluminum though instead of brass). I couldn't fit AW's MP in my A2. Also, 3.7v doesn't seem enough to power the circuitry in the A2. I hope that wasn't your only light you want to use those on. /ubbthreads/images/graemlins/icon23.gif

Pyro,
Changing the resistors on the LED ring makes a lot of sense, maybe I'll send Chop a PM. The reason I was thinking of having an extra resistor though is so that the A2 would have the same performance if I put primary cells in it.

I think that the voltage of the A2 lamp is 3.6 or 3.7 volts, and draw would be something like 1.5 amps, maybe less. The regulated circuit needs 6+ startup volts for good run time, and would handle the 8.4 volts of the RCR123's. If you could remove the leds or resistor them, you would be in business with 2 RCR123's.

Bill

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leukos said:
seattlite,
The SF Z20 fits perfectly in the A2 (made of aluminum though instead of brass). I couldn't fit AW's MP in my A2. Also, 3.7v doesn't seem enough to power the circuitry in the A2. I hope that wasn't your only light you want to use those on. /ubbthreads/images/graemlins/icon23.gif


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Nope. I have other LED lights that need the RCR123's. The MP's also work quite nicely in a Vital Gear F2 with a P91 /ubbthreads/images/graemlins/grin.gif.

Just for the heck of it I tested the current draw of my A2 a couple weeks ago. It was 1.500 amps from fresh Battery Station 123 cells.

If you put the resistor in line with the rechargeable cells in the body, a couple things to think about; 1.5 amps is a lot of current, the resistor is going to get "warm" and you will be dropping the voltage to the LVR and lamp as well as to the LEDs. A bunch of resistors in parallel should be able to handle the load if you can't find just the right value in a high wattage resistor. But any extra capacity you would get from the higher voltage of the Li-ion cells will be dissipated in the resistor. This may not be an issue since the cells are cheap to recharge, but you'd get longer runtime by just adding the extra resistance to the LED circuit.

One issue that may come up though, will the existing resistance in the switch be sufficient to keep the LVR from powering the lamp in low mode given the 8.4 volts of the li-ion cells vs the 6 volts the light is designed for. If not, you would need the resistor in the body, or you'll have to increase the resistance in the switch too. Remember that the switch resistance is no longer in the circuit when the LVR/lamp is on, only the SMD resistors on the LED ring are protecting the LEDs at that point.

Hope your experiment turns out well.

@mahoney:

I think what Pyro meant was that we wants to add a resistor only to the LEDs, not to the main regulation circuit.

Bullzeyebill said:The regulated circuit needs 6+ startup volts for good run time.

Click to expand...

Why is that? I think the purpose of the regulation is to keep a constant output, especially below 6V, when you batterys are already drained!

The LVR in the A2 reduces the battery voltage going to the lamp. If, as suggested, the lamp is 3.7 volts, the LVR will meter out the power coming from the 6 volts of batteries so the lamp only gets 3.7 volts. When the batteries are depleted to slightly above 3.7 volts the LVR shuts off, both to protect the bulb, and allow the "LEDs only" operation mode. The LVR can probably handle a higher input voltage than 6 volts, and you can change the SMT resistors to protect the LEDs, but...

The 2-stage switch has a resistor in it for the "LED only" mode that drops the battery voltage to a level that is below the "on" threshold for the LVR. That resistor may not be sufficient to drop the higher voltage from the Li-ion rechargables below the "on" threshold of the LVR and then the incandescent lamp would operate in both the modes. Hence the possible need for a resistor change in the switch too or a resistor spacer in the body of the light.

Good point, Mahoney. I noticed the resistors on the LED ring are marked 33RO, does that mean .33 ohms? I'm not too familiar with the small ones.

It's more likely to be 33 ohms, I think the R takes the place of the decimal point, but I would suggest testing with a meter to be sure of the value. If they are 33 ohm, that means the LEDs are getting about 50-60 ma through each of them when the incandescent lamp is on, depending on how much the battery voltage drops under load.

I think the resistor in the tailcap is 10 ohms, so I guess I'm at 43 ohms when I'm using the low mode. However, I don't think the resistor in the tailcap is engaged in the high mode (similar to McGizmo's two-stage switch), but the LEDs remain on. So I'm not sure at this point what resistor value should go in the tailcap and on the LED ring. Wouldn't my original idea of making a spacer with a resistor in it be less of a headache and more versatile?

Yes it might be simpler to just make the spacer, especially if you want to be able to easily go back to regular 123 cells for any reason. But at this point someone with more electrical engineering experience than I will have to step in. It occurs to me that a resistor value that will keep the LVR happy at it's fairly high current draw may not be sufficient to protect the LEDs at their more modest current draw. You still might end up needing to adjust the LED ring resistors even with a resistor in line with the battery. The A2 really was well engineered for a 6 volt power supply.

Well, I've been using two batteryspace.com's Powerizer RCR123a 650mAh in my A2, they're the only R123s that seem to fit. They last about 30 minutes in incandescent mode before the regulation kicks out. Usually the cells are between 3-3.1v when the lamp dims. I've ran them through my A2 about 5 times now with probably about 15 hours in LED only mode. I think I'll keep testing for long term effects and update periodically. /ubbthreads/images/graemlins/cool.gif

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leukos said:
Well, I've been using two batteryspace.com's Powerizer RCR123a 650mAh in my A2, they're the only R123s that seem to fit. They last about 30 minutes in incandescent mode before the regulation kicks out. Usually the cells are between 3-3.1v when the lamp dims. I've ran them through my A2 about 5 times now with probably about 15 hours in LED only mode. I think I'll keep testing for long term effects and update periodically. /ubbthreads/images/graemlins/cool.gif

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Are the Powerizer cells 4.2V fully charged? Did you blow out the LED's running at around 8.4V?

Well, charged to maybe 4.12. No LED failures (yet).

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leukos said:
Well, charged to maybe 4.12. No LED failures (yet).

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Hmmm....the MP's fit fine in my A2. Maybe, I'll muster up enough courage to run my A2 with 2 MP RCR123's.

Are the Powerizer cells unprotected (bare) cells?

How about those 3v R123's? I've read they charge to 3.7v, and under load they drop to 3.1 or 3.2v.

Here's the link to the "3.0v" 123 rechargeables:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1641

I am likewise curious whether they could be an answer for the A2, the L4, and a lot of the other CR123 lights that can't take 3.6V R123s....?

Would appreciate any thoughts. Thanks.