D size eneloops - to buy or not to buy

I have the opportunity to get some D size eneloops directly from Japan - someone from my family lives there and will come to my country soon. The NiMHs cost about $20 each, I don't know anything about their capacity yet.

I will be using them for 4D Mag with 3xSSC P7 Elektrolumens drop in.

Does anyone have D eneloops to recommend me the purchase or advice against it?

Yavox said:

I have the opportunity to get some D size eneloops directly from Japan - someone from my family lives there and will come to my country soon. The NiMHs cost about $20 each, I don't know anything about their capacity yet.

I will be using them for 4D Mag with 3xSSC P7 Elektrolumens drop in.

Does anyone have D eneloops to recommend me the purchase or advice against it?

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5.7Ah D, 3.0Ah C minimum, as per JIS method. The C and D eneloops have a PTC much like lithium ion to protect against short circuit. This may work against you in high drain applications.

http://sanyo.com/news/2008/08/08-2.html

Bright+ said:

5.7Ah D, 3.0Ah C minimum, as per JIS method. The C and D eneloops have a PTC much like lithium ion to protect against short circuit. This may work against you in high drain applications.

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This is what worries me. This Electrolumens drop in is supposed to give about 2000 lumens and draw up to 6A. The only batteries I currently have are D alkalines - and according to Wayne the alkalines should give only about 50% brightness due to their internal resistance. So now I am looking for good D NiMHs and I become more and more impatient to get them, because I want to see the drop in in its full glory as soon as possible :devil:

The NiMHs that are fastest to get for me are the eneloops from Japan. But if they do not work well, they are just a waste of money for me, because the only device I need them for is this modded Mag

I tried to run the drop in on 4xAA NiMHs just to see how bright it eventually will be and to be mentally able to wait longer for CTA D cells I could order from USA, but the AAs gave me the same brightness as D alkalines (God, why?)

What AA NiMH are you using? Not all NiMH are created equal.

Some AA can not produce 6A such as the Energizer.


Others like the Eneloop can.

LEDninja said:

What AA NiMH are you using? Not all NiMH are created equal.

Some AA can not produce 6A such as the Energizer.

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Thank you for the info - I was using 2500mAH Energizers A moment ago I have put 2700 Power Accu Vartas into the charger and another 4 Duracells 2650 into another. I can also give a try to 1000mAH AAA GPs - maybe at last one of the NiMH sets will power this direct drive drop in for a moment and I will be able to learn what 2000 lumens are before the batteries recommended by Wayne (12000mAH D CTAs) arrive.

This unfortunately does not help to decide whether to buy D eneloops (just for the purpose of having 4 spare cells for the Mag) or not. I can of course do it in a CPF way - buy them and then buy one more flashlight just for the cells, if they don't work with the drop in correctly.

For 6A, you're going to want a low resistance cell.

If you have a 2Ah cell and you run 4A, you're running 2C, but when you parallel the two, the relative rate becomes 1C. 6Ah isn't impressive for a D cell and for the cost, 3xAA or size permitting, 4xAA to D adapter should provide 6 to 8Ah capacity with impedance comparable or better than a single D cell.

Bright+ said:

For 6A, you're going to want a low resistance cell.

If you have a 2Ah cell and you run 4A, you're running 2C, but when you parallel the two, the relative rate becomes 1C. 6Ah isn't impressive for a D cell and for the cost, 3xAA or size permitting, 4xAA to D adapter should provide 6 to 8Ah capacity with impedance comparable or better than a single D cell.

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Does that mean that I should be fine with 12AA>4D converter, even if single NiMH AA has greater resistance than D cell?

Yavox said:

Does that mean that I should be fine with 12AA>4D converter, even if single NiMH AA has greater resistance than D cell?

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Yes, if you can get the whole thing to fit. Four cells in parallel will have a lower resistance than one cell, but not necessarily 1/4th because of adapter contact resistance.

A lot of people like the AccuEvolution LSD (AccuLoops?), D cells. If you can find them in Poland, or a shop that will ship them to you, they are an alternative to the eneloops.

Dave

Yavox said:

I have the opportunity to get some D size eneloops directly from Japan... ...or advice against it?

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My advice is to buy cells with a Capacity that you will fully use on on regular basis.

If you think that you'll be recharging those D cells weekly, then it looks like your application is ideal; 520 recharges in 10 years. But, if the 'device' / light is going to sit idle for the majority of the time, go with alkaline or lithium primaries. Or, if you use AAs in other applications and already have cells and a good charger, go with the adapters. Finally, if your 'device' / light NEEDS the current capability of the D cells but it will be sitting idle for long periods, you probably bought the wrong 'device'.

45/70 said:

A lot of people like the AccuEvolution LSD (AccuLoops?), D cells. If you can find them in Poland, or a shop that will ship them to you, they are an alternative to the eneloops.
Dave

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I had a look at the datasheet for AccuEvolution 11500mAH. It says "Discharge to 1.0V - Standard 0.2C, High rate - continuous 2.0C, momentary (less than 1 second) 2.5C". As far as I understand, this limitation does not make them friendly to a drop in that can pull 4-6A.

TakeTheActive said:

Finally, if your 'device' / light NEEDS the current capability of the D cells but it will be sitting idle for long periods, you probably bought the wrong 'device'.

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That is exactly the case. I would have to be a Lighthouse Operator to NEED 2000+ lumens and use it on a regular basis!

Yavox said:

I had a look at the datasheet for AccuEvolution 11500mAH. It says "Discharge to 1.0V - Standard 0.2C, High rate - continuous 2.0C, momentary (less than 1 second) 2.5C". As far as I understand, this limitation does not make them friendly to a drop in that can pull 4-6A.

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It is important to note, that the data sheet you read is not for the 10000mAh LSD cell. The 11500mAh is their standard D NiMH cell. Now, I do not know where to find a data sheet for the LSD version, but in general, LSD cells have been known to hold up to higher current better than standard NiMH cells. In other words, no guarantee, but I'd guess that the LSD version would work in your M@g.

Dave

45/70 said:

It is important to note, that the data sheet you read is not for the 10000mAh LSD cell. The 11500mAh is their standard D NiMH cell. Now, I do not know where to find a data sheet for the LSD version, but in general, LSD cells have been known to hold up to higher current better than standard NiMH cells. In other words, no guarantee, but I'd guess that the LSD version would work in your M@g.

Dave

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Thanks for pointing the difference - I thought I have found the right datasheet. As for the datasheets - what is "low" and what is "high" internal resistance of a D cell? Some people say that alkalines have high resistance and NiMHs have low, but without knowing the numbers, this is not informative for me. For example the datasheet for those 11500mAh cells says them to be 8 Ohms - which tells me nothing...

Er, if they can take 2C discharge and they hold 11Ah, why would they not be ok for 6 amps? 11Ah at 2C = 22 Amps

Any decent D size cell should be capable of delivering the 5 A your looking for.

T0RN4D0 said:

Er, if they can take 2C discharge and they hold 11Ah, why would they not be ok for 6 amps? 11Ah at 2C = 22 Amps

Any decent D size cell should be capable of delivering the 5 A your looking for.

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Errr... it seems I have to learn more about electronics. What does "2C" mean and what does this "C" stand for? I thought that "2C" means that the battery is able to deliver 2 Ampers current, but it was just a fast guess... It seems I was wrong...

Yavox said:

Errr... it seems I have to learn more about electronics. What does "2C" mean and what does this "C" stand for? I thought that "2C" means that the battery is able to deliver 2 Ampers current, but it was just a fast guess... It seems I was wrong...

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C stand for the (m)Ah rating, i.e. for a battery with 2000mAh (2Ah) 2C is 4A and for a battery with 11Ah, 2C is 22A

Yavox said:

Does that mean that I should be fine with 12AA>4D converter, even if single NiMH AA has greater resistance than D cell?

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Be very careful with AA to D converters. Most 12AA to 4D are in series and will give you 14.4V more than enough to fry the DD drop in.

Yavox said:

Thanks for pointing the difference - I thought I have found the right datasheet. As for the datasheets - what is "low" and what is "high" internal resistance of a D cell? Some people say that alkalines have high resistance and NiMHs have low, but without knowing the numbers, this is not informative for me. For example the datasheet for those 11500mAh cells says them to be 8 Ohms - which tells me nothing...

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Here is the data sheet for the LSD Accupower d cell.
http://lib.store.yahoo.net/lib/theshorelinemarket/d-specs.pdf

Yavox said:

Thanks for pointing the difference - I thought I have found the right datasheet. As for the datasheets - what is "low" and what is "high" internal resistance of a D cell? Some people say that alkalines have high resistance and NiMHs have low, but without knowing the numbers, this is not informative for me. For example the datasheet for those 11500mAh cells says them to be 8 Ohms - which tells me nothing...

Click to expand...

The internal resistance of cells is measured in milliohms (thousandths of an ohm). A good AA cell like an Eneloop might have an internal resistance of 100 milliohms. A D size NiMH or NiCd cell can have a much smaller internal resistance of 10 milliohms or less. An AA size alkaline cell would be rather higher, at about 300 milliohms.

The internal resistance roughly correlates to the maximum current the cell can supply. An internal resistance of 10 milliohms is really very small, meaning that such cells can supply many amps of current without a sweat. (If you accidentally short such cells you are going to get fireworks.)

45/70 said:

A lot of people like the AccuEvolution LSD (AccuLoops?), D cells. If you can find them in Poland, or a shop that will ship them to you, they are an alternative to the eneloops.

Dave

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Here you can get them in Europe KLICK