ROP Battery Config Question

[Brozneo]

Hey,

Im currently building my first ROP and just have a question about the battery set up - I've looked on the various ROP threads but haven't found the answer!

Originally I was going to build an ROP in a 2D Mag using FM's 6AA-2D adpater but after reading the ROP threads, I want to try a 7 cell ROP. Instead of using a 8AA-2D adpater with one dummy, the question I have is: If I use a 3D Mag, is it alright/safe to have 7 cells with a 6AA-2D plus one D config?

Also, with 7 cells is it safe to run the low lamp off it?

 

[flashburn72]

7 cells with rop low is bad bad bad.thats how I blew mine.7 rested cells with the high will work.as for using the one D battery with the 2d to 6aa.hmmmm I don't c y it wouldn't work,but I would use 1.2 volt nimh not 1.5 volt alkeline. sombody else will pipe in shortly with more I am sure.also the 8aa adapter will not fit in a 3d mag unless you use certain cells. local machine shop will bore it for bout 20 bucks I'm sure.

 

[DonShock]

The major potential drawback I can see happening when using 6aa and 1d would be the difference in capacities. The AAs would deplete quicker than the D so you might reach a point where the D cell was reverse powering one or more AAs. That can damage the cells. Also, you would not expect as much of a voltage drop on the D cell when under load. As mentioned, 7AA is right at the limit of what the ROP bulbs will handle. If the D cell holds a higher voltage, it might be enough to pop the bulb. If you are going to step up to 3D size instead of boring a 2D for the 8AA holder, you would probably be better off sticking with a 9 cell holder using two dummy cells.

 

[Brozneo]

The D cell that I will use is basically an AA cell in a D sized body - It has the same capacity as the AA's I will be using. So in terms of capacity this should be fine right? But under load will it still be like AA's? (In terms of the "Also, you would not expect as much of a voltage drop on the D cell when under load")

 

[the servents of twilight]

I use the ROP low bulb with 7 rested batteries in a few lights and have not blown a bulb yet. I don't use mag lights. I think the idea of using a D NIMH with 6AA NIMHs is possibly a bad idea. With that set up you may blow bulbs.

 

[RickyT]

The D cell that I will use is basically an AA cell in a D sized body - It has the same capacity as the AA's I will be using. So in terms of capacity this should be fine right? But under load will it still be like AA's? (In terms of the "Also, you would not expect as much of a voltage drop on the D cell when under load")

This will probably work ok in this setup.

I would put all the cells in your holder though, and make up the space with another dummy cell on the bottom.

I would be cautious about using seven good cells that hold their voltage under load on the high bulb, maybe even the low. A few spares would be good for testing.

 

[Brozneo]

Yeah it will be interesting! I have ordered 3 sets of bulbs - so thats plently to play with - I'm gonna try the 6AA plus 1D (same capacity as the AAs) setup and will get back to you guys about how it went! Should be interesting - haven't had any bulbs blow on me yet! Haha

 

[andyr354]

the 8AA-2D holder fits in my unbored mag fine with eneloop cells. I am only running 6 right now, haven't felt like trying 7 yet.

Andy

 

[mdocod]

That's an interesting idea (the fake D cell "cans" with AAs inside)... best thing would be to stick to the same brand/capacity for all the cells... such that the cell within the "D" can is the same as the rest of the cells...

Was just thinking.. I think they sell little adapters designed for turning a single AA into a D... they often come with "AA rechargable-kits" so all you have to have is AA cells/charger, but can run all the sizes of equipment.


On the other hand.. if you are stepping up to a 3D size, why not just do 9AAs and run a potted 1185? make the step up in size worth it.

 

[Brozneo]

Yeah Ive got 2 Mag85's - so now im just making some ROPs to see what they are like. Im in NZ and we have some pretty cheap NiMHs here, the place that I got my 'cr@p' NiMHs at cells AA, C and D cells all in the same capacity - they just use the AA cell and put bigger casings around for the C and D size, so for a 7 cell ROP I will be using 6AA's and 1D of the same "type" I do have better batteries but will give the 7 cell set up a try first.

 

[FILIPPO]

what about using modamag 1D>4AA + 1D>3AA in a mag 2D host?

I think that in this way you will have less resistance so you'd better to use a 12V 50W reflectorized bulb with the 7AA to take down the over voltage and than run the ROP ( 7,9V or 8,0V may be good....I think....)

 

[Lichtschalter]

I'm running my 2D ROP with 7 eneloops and 1 dummy in the 8AA>2D holder.

No problemss here. The eneloops are thin enough to fit the Mag body without boring.