ROP HI - Max Safe Starting Battery Pack Voltage?

So, I bought a 6AA -> 2D ROP from a fellow CPF member, and I cycled all 6 eneloops in my La Cross BC-900 (discharge, then charge). 3 of the batteries sat for over 12 hours and the other 3 cells sat for over 1 hour. All together in the battery holder they read 8.64V.

What is the safe voltage for dropping this thing in the light and firing it up?

I know the bulb will pop >8.5V according to Lux's testing. The batteries are in a FiveMega adapter, and the low resistance mod has been done to the rear tailcap / spring. I know the batteries will sag under load + there are internal resistances in the maglite, but is that enough to keep the bulb from popping when the pack is at 8.64V (open circuit)?

If the battery "pack" is at too high of a voltage, about how long will the batteries need to rest for the voltage to drop? :thinking:

I'm wondering about this too...My 2D ROP is newly made and my eneloops are being recharged for the first time.

Should the next lamp blow.... :shrug:

EDIT: I'm good, my Tenergy charger haven't came in so I spent 4.5 hours today charging depleted cells two at once

it rounded out a little over 9V and it ran fine:twothumbs
Some unfortunate kid was skateboarding down across the street by the house and I almost knocked him over with the light. I apologized out loud, he replied with some profanity and rolled off:shakehead.

which reminds me...I was going to pick up a POB HID from Sam's....oh well, I'll stick with mag85 for the next mod

I've never heard of any consistent instaflash problems on a 6 cell ROP with eneloops, regardless of resistance modifications. Some people even run 7 cell ROP configurations. I personally wouldn't worry about it unless you had super low resistance hobby cells (like elite 1700s).

I run 6 eneloops in mine with no problem. Ive even gone as far as to get 7 cells in there without it blowing.

If you want, you can run the rop low for a couple minutes because that is capable of a higher load. After you run the low for a couple minutes, that should ease your mind with firing the thing up on high.

allburger said:

If you want, you can run the rop low for a couple minutes because that is capable of a higher load. After you run the low for a couple minutes, that should ease your mind with firing the thing up on high.

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I don't want to have to mess with swapping the bulbs and risking getting finger oils on them and having them go poof that way either. :mecry:

I guess I will just go for it.

Edit: Went for it when the pack measured 8.62, and it fired right up without any going poof.

There's no risk in running the ROP with 6 freshly charged AA batteries. I do it often with Eneloop and Duracell Pre-Charged, in fivemega's adapter. After charge, they will come at around 8.8V but under the load this bulb draw, the voltage will drop quickly under 8V.

I run my ROP with 7 eneloops and a dummy. i haven't had any problems yet but my rop has fairly high resistance but not an extra cell worth. i think with 6 cells you'll be fine. 8 eneloops will absolutely both the low bulb instantly(forgot to put the dummy back in and poof).

With so many different combinations of batteries and holders , modified switches and tail caps ( resistance mod ) I believe the best solution is to be prepared to sacrifice a bulb in testing each of your configurations.

In my case I gradually increased the voltage in my pack and waited till it flashed the bulb. In my combination, 7.9 volts is the limit of each six pack of batteries. The Ohm's resistance in all our lights / batteries will all be different, and resistance effects voltage directly.

What's the story on a two AW C Li-Ion ROP and the bulb going poof? :thinking:

I'd assume it's less of an issue than the AA's since the two Li-Ion's are only 8.4V and the NiMH's can go above 8.4V hot off the charger. Right now my 2C Mag host is stock but I plan to do all the resistance lowering mods to it.

According to LuxLuthor's testing thread, the max voltage should be 8.5v. If 2 C sized Li-ion batteries is popping the bulb, then either the bulb is a bit bad or the batteries were overcharged somehow.

Gunner12 said:

According to LuxLuthor's testing thread, the max voltage should be 8.5v. If 2 C sized Li-ion batteries is popping the bulb, then either the bulb is a bit bad or the batteries were overcharged somehow.

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I haven't popped any bulbs with my 2 AW C Li-Ion ROP yet, but I don't have my charger, so I don't have it up to 8.4V yet. I was just wondering what other people's experiences were with 2 "C" ROPs. :candle:

I seem to remember a post or thread that suggested that resistance fixes can cause bulb failure using the ROP HI.

Bill

Gunner12 said:

According to LuxLuthor's testing thread, the max voltage should be 8.5v. If 2 C sized Li-ion batteries is popping the bulb, then either the bulb is a bit bad or the batteries were overcharged somehow.

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If I remember correctly, someone asked Lux if he was turning off and on the voltage or if he was stepping it up. He said he was stepping it up, therefore, results may differ when clicking on with overcharged batteries.

uluapoundr said:

If I remember correctly, someone asked Lux if he was turning off and on the voltage or if he was stepping it up. He said he was stepping it up, therefore, results may differ when clicking on with overcharged batteries.

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You're right. He said that in post #3. He is not cold starting the bulb at each voltage.

Good point. That might be why I've head of ROP high bulbs popping with 2 Li-ion C or D batteries.

I have a 2C ROP running 2 C li-ion, in a FM body, with modded switch by JimmyM. It was initially designed for 2 18650. Jimmy said the switch has a mosfet, sorry, can't explain it. Maybe someone here can talk about mosfet modded switches for the ROP or other incan. All I know is that this ROP is nice and bright and these are on generic C li-ion. I need to order a set of AW, any body got a couple extra for sale?

uluapoundr said:

I have a 2C ROP running 2 C li-ion, in a FM body, with modded switch by JimmyM. It was initially designed for 2 18650. Jimmy said the switch has a mosfet, sorry, can't explain it. Maybe someone here can talk about mosfet modded switches for the ROP or other incan. All I know is that this ROP is nice and bright and these are on generic C li-ion. I need to order a set of AW, any body got a couple extra for sale?

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The Lighthound website shows them as currently being in stock.
You should have a look at the AW C body adapter ring also.

LumenHound said:

The Lighthound website shows them as currently being in stock.
You should have a look at the AW C body adapter ring also.

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Just a side note........if you are going to install the AW soft-start / three-level switch, then you do not need the AW 10mm extender/adaptor ring because the switch is shorter and allows more space for the longer cells. (my own experience with a 2x C Maglite)

The FM host has a deep tailcap with recessed spring and was running on AW cells without ring extender. I will order AW C cells soon, just didn't want to wait a few weeks for it to arrive in Hawaii .

cernobila said:

Just a side note........if you are going to install the AW soft-start / three-level switch, then you do not need the AW 10mm extender/adaptor ring because the switch is shorter and allows more space for the longer cells. (my own experience with a 2x C Maglite)

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Unless I missed something you can't use the AW soft-start / three-level switch with a ROP because it has a bi-pin socket. :thinking: