Better run time: 8 AA's vs 4 D cells?

This is something I've been mulling over in my head. I've got a 4d Mag with an LED drop in. But what would offer the best run times?


Using some converters to run 8 AA's (either Lithium primaries or eneloops). As I understand it, you can buy plastic D sized adapters that run 2 AA's in parallel, so that'd be 4000-5000 mAH per pair of AA's. I know this is a lot lower than the 12000 mAH of an alkaline D cell, but wouldn't the AA option offer a more stable voltage?

How do you think run times would compared to just sticking with D cell Duracell alkalines?

depends on the amp draw of your drop in rechargeable battery's do better under high loads
there are rechargeable D cell's something like 10000 Mah, IMO the way to go
there are runtime/amp charts that will answer your question

A general rule of thumb that I use when comparing different common cell sizes is,

3 AAA = 1 AA

2 AA = 1 C

4 AA = 1 D

This assumes that the cell chemistry is the same. It's fairly accurate, but not exact. So regardless of the type of cells you use in your 4D M@g, provided you are comparing alkaline to alkaline, NiMh to NiMh, the 8 AA cells will only have about half the capacity/power/runtime of 4 D cells.

Dave

I'd go for the D cells. Without even looking at potential resistance losses in many AA to D adapters the Ds are going to win. While in some comparisons high end AAs may look pretty good, high end Ds in the same light will run even longer.

I'm also a little bit leery of a setup where if just one of the adapters develops a problem in the field the light becomes inoperable. IMO in this case AA to D converters are an overly complex solution to a problem that doesn't really exist.

The 4 D cells is best, but only if you get full capacity D cells! There are some D cells that has a capacity just a little bit above a single AA cell, stay away from them.

Ah, good point, HKJ. I was referring to "real" D cells, as well as the other sizes.

Dave

I have adapters that allow me to run 12 (3P4S) AA batteries in my Maglites. I have found that even using Eneloops in the adapters they tend to sag under load more than quality rechargable D cells. I still like them because they provide me with options.

As an example using a 3D format light, in this case the Lambda Vari Power SST-50. Eneloops (3 in place of each D cell for a total of 9) that have a resting voltage of just over 1.36v measured 3.8amps of tailcap current. Three Tenergy Premium D cells with a resting voltage of just under 1.36V measured over 4.5amps of tailcap current.

With the Lambda SST-50 the higher the voltage the more current it will draw so that tells us the D cells are maintaining their voltage better under a load.

I also tested 3 Tenergy C cells that had a resting voltage of 1.355 and they managed almost 4amps of current. So the Eneloops with three taking the place of each C cell still provided a lower voltage to the light.

Keep in mind the Eneloops were in a quality AA adapter that is designed for minimum resistance not some cheap mass produced plastic adapter.

Hope that answers your question.

My battery solution in my 3D Mag with Malkoff drop-in is to run 4 Maha Imedion NiMH C cells in a battery holder made of 1" PVC pipe. The Maha C cells offer good run time, are low self-discharge, and are far cheaper than the Imedion D size LSD cells. I reverse the tail cap spring to give a little more room in the battery tube since 4 Cs are a bit longer than 3 Ds. I've never tried it, but I'm pretty sure that 5 C cells will fit in a 4D Mag.

After re-reading my first post I'd like to add that throughout this thread I've seen nothing that was a 'Deal Killer' for using AAs for Ds. I can certainly see situations where this could give the user otherwise unattainable utility in cases where because of logistics or other restraints Ds were out of the question. It is a big world.

Sub_Umbra said:

After re-reading my first post I'd like to add that throughout this thread I've seen nothing that was a 'Deal Killer' for using AAs for Ds. I can certainly see situations where this could give the user otherwise unattainable utility in cases where because of logistics or other restraints Ds were out of the question. It is a big world.

Click to expand...

Other than reduced runtime you are correct.
If you already have rechargeable AAs and don't want to get into Ds it is definitely a viable solution. One of the reasons I have the adapters, I love having options.

These are the adapters I use:
http://www.candlepowerforums.com/vb...M6-rechargeable-solutions-Dummy-cells-Customs!

Not cheap but worth the money. You would have to contact mdocod and have him build you a 4D adapter that only totaled 4.8volts with Nimh batteries. This link contains series adapters that would have too high a voltage for your use.

WoodMan said:

My battery solution in my 3D Mag with Malkoff drop-in is to run 4 Maha Imedion NiMH C cells in a battery holder made of 1" PVC pipe. The Maha C cells offer good run time, are low self-discharge, and are far cheaper than the D size LSD cells. I reverse the tail cap spring to give a little more room in the battery tube since 4 Cs are a bit longer than 3 Ds. I've never tried it, but I'm pretty sure that 5 C cells will fit in a 4D Mag.

Click to expand...

I'm not sure what you are paying for Imedion C batteries but I doubt they are cheaper than the Tenergy D cells that you can get for just under $8 each for LSD or standard. I've never tested the Imedion C cells but have thoroughly tested their D and AA cells and have been less than impressed.

In fact I rate their D cells only slightly better than the "New" AccuEvolution D cells which are the worst on the market that I have tested. The Imedions are overpriced and perform less well than the reasonably priced Tenergy cells.

357mag1 said:

As an example using a 3D format light, in this case the Lambda Vari Power SST-50. Eneloops (3 in place of each D cell for a total of 9) that have a resting voltage of just over 3.6v...... Three Tenergy Premium D cells with a resting voltage of just under 3.6V......I also tested 3 Tenergy C cells that had a resting voltage of 3.55

Click to expand...

Hi 357. Where are you measuring these voltages at? I ask because it would appear that you have a high resistance in the "battery" circuit somewhere. The xAA to D adapters do add resistance, as in your case, there are six additional contact (not welded, or soldered) surfaces per D cell equivalent, compared to a single cell.

I have some cheapo DX 2AA to D adapters. I just put 2 eneloop AA cells in one that were charged a week or so ago, and have been used somewhat. The voltage reads 1.34 V for the single D adapter. This would suggest, although I didn't try it, that three of these in series would be about 4 Volts. Fresh of the charger, I would imagine the voltage would be well over 4 Volts.

Even if the resistance were lower in your "packs", the comparative results may still turn out to be similar. I just wondered why your voltage readings are so low, even with the C and D cells. Regardless, if you could figure out what the problem is, all of your cell combinations would fare better. Just curious.:thinking:

Dave

45/70 said:

Hi 357. Where are you measuring these voltages at? I ask because it would appear that you have a high resistance in the "battery" circuit somewhere. The xAA to D adapters do add resistance, as in your case, there are six additional contact (not welded, or soldered) surfaces per D cell equivalent, compared to a single cell.

I have some cheapo DX 2AA to D adapters. I just put 2 eneloop AA cells in one that were charged a week or so ago, and have been used somewhat. The voltage reads 1.34 V for the single D adapter. This would suggest, although I didn't try it, that three of these in series would be about 4 Volts. Fresh of the charger, I would imagine the voltage would be well over 4 Volts.

Even if the resistance were lower in your "packs", the comparative results may still turn out to be similar. I just wondered why your voltage readings are so low, even with the C and D cells. Regardless, if you could figure out what the problem is, all of your cell combinations would fare better. Just curious.:thinking:

Dave

Click to expand...

Dave,

I actually typed the voltage readings incorrectly. I will go back and edit my post. Each reading should have a 1 in front of it with the decimal moved to the left (1.36v, 1.355v, ect...). I read each battery individually and not as a pack.

Ah, that explains it. You're good to go then.

Dave

357mag1 said:

I'm not sure what you are paying for Imedion C batteries but I doubt they are cheaper than the Tenergy D cells that you can get for just under $8 each for LSD or standard. I've never tested the Imedion C cells but have thoroughly tested their D and AA cells and have been less than impressed.

In fact I rate their D cells only slightly better than the "New" AccuEvolution D cells which are the worst on the market that I have tested. The Imedions are overpriced and perform less well than the reasonably priced Tenergy cells.

Click to expand...

My point was not that the Imedion cells are the only ones to go with, but rather that C NiMH LSDs are a better alternative than AAs (if you have the charger) in a 3D or 4D Mag since they offer better runtime and do not require a complicated and relatively expensive (even if you make your own) battery holder.

357mag1 said:

Other than reduced runtime you are correct.
If you already have rechargeable AAs and don't want to get into Ds it is definitely a viable solution. One of the reasons I have the adapters, I love having options.

These are the adapters I use:
http://www.candlepowerforums.com/vb...M6-rechargeable-solutions-Dummy-cells-Customs!

Not cheap but worth the money. You would have to contact mdocod and have him build you a 4D adapter that only totaled 4.8volts with Nimh batteries. This link contains series adapters that would have too high a voltage for your use.

Click to expand...

Emphasis mine.

Wait a minute. Where are the numbers that support the claim that AA cells will run longer than D cells in a light made for D cells?

WoodMan said:

My point was not that the Imedion cells are the only ones to go with, but rather that C NiMH LSDs are a better alternative than AAs (if you have the charger) in a 3D or 4D Mag since they offer better runtime and do not require a complicated and relatively expensive (even if you make your own) battery holder.

Click to expand...

Woodman,

I agree the battery holders are expensive though fairly priced. Only an option if you want to stick with AAs or just like to experiment.

You did state in your post that the Imedion C cells were "far cheaper than the D size LSD cells" and I was addressing that point.

357mag1 said:

Woodman,

I agree the battery holders are expensive though fairly priced. Only an option if you want to stick with AAs or just like to experiment.

You did state in your post that the Imedion C cells were "far cheaper than the D size LSD cells" and I was addressing that point.

Click to expand...

If you are comparing apples to apples then my statement is absolutely true. If you want to compare the costs of the Tenergy C and D LSD cells that you prefer then go ahead. In my experience Imedion cells are of premium quality (and worthy of a price premium over Tenergy), with performance equivalent to eneloops which of course are not available in the larger sizes. The Tenergy cells I've used are of low quality, although I admit that my experience with the brand is limited to Li-ion cells and thus not a good comparison. The Imedion C cells are about two-thirds the cost of the Imedion D cells and 4 C cells give about two-thirds the runtime (still excellent) of 3 D cells in a 3D Mag. However, since the cells are sold only in packs of two, you must purchase 4 D cells even though you only need three. This swings the cost advantage even more toward the C size cell. But again, my point was only that the performance of the C cells is superior to the AAs. Additionally, I have edited post #8 to clarify my meaning.