How about these (NiMH) D-Cells?

  • Thread starter Thread starter **DONOTDELETE**
  • Start date Start date
LEDBE
D

**DONOTDELETE**

Guest
I saw these on eBay. 9,000 mA NiMh D-cells sounds like a nice proposition for my 4 D Maglite plus it comes with a charger for NiCd or NiMh batteris. $53.00 isn't bad for those batteries and a charger. Hell, buying 4 new D-cells all the time would easily equal that.

Now, not being an expert on batteries... Is 9000mA a lot for a D Battery? It would seem to me that 9 amps is a WHOLE LOT unless I am interpreting something wrong here?
 
I bought some no-name Chineses 9000's from an EBAY vendor w/o the charger about 3 months ago and am happy with them. I can't either veryify or disclaim the run time, though. I had a hobby shop build 12 of them into a battery pack that has two 6.2 V connectors for charging and a 14.4 V connector to drive various 12 V high current light sources. The cells successfully handle a 4.7 A load without much voltage drop.

I negotiated the vendor into selling me 16 of them for $116 plus shipping -- that's $7.25 @.
 
Originally posted by FireRanger:
Is 9000mA a lot for a D Battery?
Click to expand...
<font size="2" face="Verdana, Arial">You did good. Some NiMh D's are only 2200mA
shocked.gif
 
BTW, that's mAh (milliamp hours, i.e. its capacity)

The cells most likely can't deliver 9A. But they can probably deliver 1A for around 9 hours. (at higher currents, the capacity rating is reduced. So it may only be 6-7 hours)

As to why some are only 2200 mAh - If you were to open them up you'd find that a good portion of the cell is hollow? 75% or more of rechargeable Ds are C cells plus a spacer, or worse. You can tell the difference by comparing the weight.
 
Just to make sure I am not having a brain malfunction here...

A Battery that is for example rated to a capacity of 10 amp hours means it can hold a 10 amp draw for 1 hour, right?

Or is it the other way around... 1 amp for 10 hours? Or are they equally proportional, in theory.
 
Fireranger:

The capacity of any cell is specified at a specific current. The higher the current, the less the effective capacity.

Some cells are specifically designed for very high currents, and their rated capacity appears unimpressive. Nonetheless, they typically will deliver more capacity with lesser voltage drop at that higher current than a nominally higher capacity cell optimized for lower currents.

This is why, for example, that the Powerstream 1/2 D NiCAD cells that are rated at 2500 mAh and 98 Amp currents are specced as being able to deliver > 1.2V at 2 amps for > 90 % of their rated capacity.
 
Cell capacity is generally rated in two different, but similar parameters: Ah capacity and Wh capacity.

Both are generally specified at a particular current or power rate. Depending on cell chemestry this draw rate can have a large effect on the capacity values or very little. Alkaline cells have a high internal resistance and are quite effected by drain rate. NiCd and NiMH cells have very small internal resistances and generally don't suffer much effect from drain rate--for reasonable rates (generally less than 2C, but higher for certain specially designed cells). So 9A for 1h form a 9Ah NiMH wouldn't be unreasonable. The same form an alkaline would not be true.

Here's a general rule of thumb for battery capacity measurements. Normally capacities for a particular chemestry will be done at a rate which gives N hours of use. These typical N values are:
Alkaline: 10 hours
NiCd, NiMH: Doesn't much matter, but normally > 1 hour
Li-ion: 3 hours
Lead-Acid: 10 to 24 hours
Some specialized cells are rated very strangely--in particular the 'AA' sized Taridan cells that some people have been trying to use to mod flashlights are rated at a 1mAh rate which is some 1800 hours or so.

Short summary: You're better off trying to draw 9A for a 9Ah NiMH cell than 9A form a 17Ah (typical D sized value) alkaline cell.
 
9000mah IS a lot for a battery, and a D sized NiMh is a lot for a flashlight. To put it in perspective, the Tigerlight uses 6 slightly-sub-AA NiMH's, so that would be somewhere around 1500-1800 mah, probably.

As the guys above have pointed out, while 9A is a lot for a flashlight, it shouldn't be a big deal for that battery. (I believe a lot of the "D cell" NiMH's that are rated around 2200mah are really C's in a big case.)

Keep in mind that the short circuit current capacity of the battery is probably somewhere in the neighborhood of 100+A. If you connect about 10 of them in series, you could probabaly start your car...or burn out your starter motor.
smile.gif


Good luck on the project!
 
Originally posted by FireRanger:
Just to make sure I am not having a brain malfunction here...

A Battery that is for example rated to a capacity of 10 amp hours means it can hold a 10 amp draw for 1 hour, right?

Or is it the other way around... 1 amp for 10 hours? Or are they equally proportional, in theory.
Click to expand...
<font size="2" face="Verdana, Arial">Most cells are rated at either a 10 or 20 hour draw - aka a 10 Ah cell can deliver 1 amp for 10 hours (if it's rated for 10 hours) or .5 amps for 20 hours

As you increase the rate of draw, you have to derate the battery
 
OK, so let me ask this in another way. Would these cells "kick ***" in my 4 D cell maglite? Would they either

A. Make it somewhat brighter
B. Last a long time
C. All of the above
D. None of the above
E. This is like flashback to the SAT's?
 
Fireranger:

A. It depends upon your bulb. If you had Carley ceramically pot a 4.7 v 3.85A W/A #01183 bulb it would put out 411 lumen and probably run for > 2 hours. A high current 5000 mAh NiCad might have lower voltage drop and drive it marginally more brightly fopr a shorter run time.

B. It should last proportionately longer lower capacity batteries.

I have 2 * 6 of these cells ganged as a 14.4 V battery pack that I use in an antique battery Big Beam case designed for 2 @ 6V lantern batteries. I drive a 12 v 55 W PIA Running light on it. the batteries handle the 4.7 Amp current with no complaints, so the cells should handle the 3.85 Amp bulb I discuss above.
 
I have a INRETECH Super 6 on order and stated run time for D Alkalines is 2 hours. I have been looking at the 8000 mAh batteries from cheapbatteries, but am not sure if this is a good way to go.

Does anyone use re-charageable batteries in a Super 6?

Tom
 
What do you guys use to charge these 8-9Ah cells?

The CCrane will do it, but takes a very long time for 4 of them. The Maha pack charger does them in series, and still takes 14+ hours.

Anything do 'em in 8 or less?
 
I use a Vanson and Radio Shack's charger, and they both still need 10+ hours to charge 8Ah-9Ah Ds...

Unless you're workin' with RC chargers or make your own, and you have batts with insanely high Cs (C5-C10), you're not going to charge these guys anwhere less than 10 hours (without risking explosion or leakage).
 
You must log in or register to reply here.

Latest posts

Top