NiMH or NiCd D's @ 4A Load?

[jayflash]

NiMH or NiCd D\'s @ 4A Load?

UK's Vectra Lantern comes with 5.8 watt lamps but will accept the 18 watter made for a different model. I already have 4500mAh NiCd D cells. 9 & 11 Ah NiMH D cells are available, but would 4 amps be too much drain for them? I'd rather go with the shorter run time of the NiCd's rather than ruining the NiMH cells. Thanks for any help.

Oops, I thought I was in the battery forum - please move.

 

[bwaites]

Re: NiMH or NiCd D\'s @ 4A Load?

jayflash,

The NiMh cells should be fine at 4A draw unless they are some special, low amperage cell, I run my 1/2D's at 8-9 with no problems.

Bill

 

[jayflash]

Re: NiMH or NiCd D\'s @ 4A Load?

Holy cow, 8 Amps for a 1/2 D?! I had no idea - thanks for the good news.

 

[bwaites]

Re: NiMH or NiCd D\'s @ 4A Load?

jayflash,

The remote control guys run A's at 10-15 amp discharge rates. Sub C's and 1/2 sub C's at more! I run a 250 Watt spotlight putting out 10,000 lumens off of 20 1/2 D's.

Bill

 

[udaman]

Re: NiMH or NiCd D\'s @ 4A Load?

[ QUOTE ]
jayflash said:
UK's Vectra Lantern comes with 5.8 watt lamps but will accept the 18 watter made for a different model. I already have 4500mAh NiCd D cells. 9 & 11 Ah NiMH D cells are available, but would 4 amps be too much drain for them? I'd rather go with the shorter run time of the NiCd's rather than ruining the NiMH cells. Thanks for any help.

Oops, I thought I was in the battery forum - please move.

[/ QUOTE ]

I am not familiar with the UK Vectra, if the reflector or bulb mount is made of plastic, an 18watt bulb may melt the plastic.

Careful jayflash, you may be getting misleading information from bwaites (unintentional of course). 18w at what voltage, do you have more information on how you are determining that you will see a 4a load be placed on the cells? 18w/4a = 4.5v ? Would that be the 5v WA1160?

I am making a guess the 1/2D NiMH bwaites is referring to are the special high-current capable AeroNiMH. What I am assuming from your post above, you are talking about consumer D-cell NiMH, like the 11Ah Maha D-cells? Maha tends to get fairly good performing Chinese made cells, so 4a loads might work well on these. With other less expensive Chinese made D-cell NiMH, that could be a gamble. Most NiMH D-cells of 8000ma capacity should be capable of C/2 discharge currents, without too much voltage sag or capacity loss.

This is not the case with D-cell alkalines, just incase you find yourself without rechargables and try to use alkaline in their place; alkaline might be useless-see SilverFox's test on D-cell alkaline at 3aAlkaline Battery Shoot Out

S4MadMan was working on a 'mini-Aurora' style project light using the Maha 11ah D-cells, using I believe an Osram 5a/6v projector bulb. Perhaps you can PM him and ask his opinion, if no one else can answer your question adequately.

 

[RussH]

Re: NiMH or NiCd D\'s @ 4A Load?

I plan to try my Chinese 9000mah D cells (Nexcell?) at 4 amps as soon as my Pelican BigD 24w, 6v bulbs get here. I really intend to use the 4 amp bulbs on gelcells, but there will be some testing of other arrangements, especially while I melt a few reflectors. I have a couple of $5 lanterns which aren't worth keeping in repair but will do for some testing. And a couple of 4Dto4F(6v lantern) adaptors.

Udaman makes a number of good points. I'm assuming a 4 cell 6V (nominal) size lantern, so 18w implies a 3 amp load. But this one apparently comes as NiCad so it is probably 4.8v @ 4amp, or around 4.5amp under load as Udaman figured. I'd expect a 9000mah NiMH to have slightly more voltage drop at 4 amps than 4500mah NiCads would, but it would probably still work well enough.

Is this one of those lanterns with an adaptor from 6v lantern size (originally 4F) to 4 D batteries? If so, a 6v gell cell will work, and you may be able to find them in a lantern battery configuration. If you want to know how well alkalines would work, try finding pictures of some that have experienced a dead short. It's not going to be pretty...

 

[Ginseng]

Re: NiMH or NiCd D\'s @ 4A Load?

Ahhh,

This sounds like fun. I've got a great little 6V lantern mod coming in January and it'll be pretty bright. Going right for 100W+ /ubbthreads/images/graemlins/wink.gif

4A should not be a problem for either chemistry in D size.

Wilkey

 

[jayflash]

Re: NiMH or NiCd D\'s @ 4A Load?

Thank you, everybody, for your help.

UK claims the 18 watt T-4 lamp will not be too hot for the innards and BrightGuy says the Vectra is almost like the diving light that lamp is normally used in.

At 4.8 volts from four full size D cells, I rounded the 3.75 amps to four, just to be conservative. I know NiCds will handle a continuous 4A but, based on what I know, thought that might be close to the limit for consumer grade NiMH.

As NiCd comes in high drain cells I'll look for the same in NiMH to be on the safe side. Hopefully the NiMH cells will be cost effective, otherwise I'll stick with the NiCds which I can beat up without worrying so much about their health.