Dive lights and NiCad batteries

Dive lights and NiCad batteries

Post by Shane Jens » Sat, 20 Aug 1994 11:19:45


I have a question about battery types in dive lights.  I looked through
the FAQ and didn't find my question answered (doesn't mean it's not in
there 8-).  I was wondering if it was OK to use nicads or the rechargable
alkaline batteries in dive lights.  What are the pitfalls of using
rechargables?  

I'm new to SCUBA (waiting for my permanent c-card) and in my
limited experience I have only seen people use alkalines and I
currently don't own a light so I have no personal experience with them,
but I am looking at buying a light in the near future.

It seems like a rechargable battery would be financially better in the
long run.

Just curious,

shane

 
 
 

Dive lights and NiCad batteries

Post by Gary Jace » Sat, 20 Aug 1994 17:26:22

Reply:

Quote:
> I have a question about battery types in dive lights.  I looked through
> the FAQ and didn't find my question answered (doesn't mean it's not in
> there 8-).  I was wondering if it was OK to use nicads or the rechargable
> alkaline batteries in dive lights.  What are the pitfalls of using
> rechargables?  

<stuff deleted>

I have a couple of Underwater Kinetics Model 1200 lights.
One Halogen, one not.  Went out and bought rechargeable batteries
for them and they both work great.  Only two problems:

 - when a ni-cad starts to fade, it fades fast.
   Usually in less than a minute you're in the dark.
   So carry a second light, especially at night.

 - ni-cads are much lighter than alkalines, so you will
   have a buoyancy problem if you use them in a light
   that's not designed for them.  The solution for my
   UK1200's was to go to Goodyear (yep, the tire people)
   and beg for some used lead wheel weights.  Straighten
   them out in a vise and remove the steel claw component
   and they will fit neatly between the batteries in a
   UK1200 to make it neutrally buoyant.

Welcome to the sport. :-)

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Dive lights and NiCad batteries

Post by Tom Furuka » Sun, 21 Aug 1994 05:05:28

Quote:

>I have a question about battery types in dive lights.  I looked through
>the FAQ and didn't find my question answered (doesn't mean it's not in
>there 8-).  I was wondering if it was OK to use nicads or the rechargable
>alkaline batteries in dive lights.  What are the pitfalls of using
>rechargables?  

>I'm new to SCUBA (waiting for my permanent c-card) and in my
>limited experience I have only seen people use alkalines and I
>currently don't own a light so I have no personal experience with them,
>but I am looking at buying a light in the near future.

>It seems like a rechargable battery would be financially better in the
>long run.

>Just curious,

>shane


Well in good dive lights with working seals, the battery should not get wet.
With that said, there is a definite disadvantage to using Nicad batteries.
The underwater flashlights are much brighter than dry flashlights on the general.
Thus they use more battery power.

When an alkaline battery starts to lose it's power, you will notice the
brightness of the buld decreasing.  However you still have about 10 - 15 or more
minutes of light left.  If you are using a Nicad battery and it starts to
lose power, you will be out of light in a matter of seconds. Nicad batteries
do not last as long and when their charge begins to fade, it fades really
fast.

I would strongly recommend using alkaline batteries in a dive light.
If you are diving where it is very dark and you lose your light, might as
well end your dive.

Tom

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Dive lights and NiCad batteries

Post by Becky Brenn » Sun, 21 Aug 1994 06:28:37

I've used rechargeable NiCads in our dive lights in good viz,
Carribean night dives.  A few things to consider:

1.  When they start to die, they go _fast_!  One second you're saying
    "these are a bit dim" and much less than a minute later, you're in
    the dark.  Carry backups (OK, you always carry backups, but since
    they go so FAST, it's especially important).
2.  You really need to drain them completely and recharge after each use,
    to ensure you have enough juice to last an entire dive.  They don't
    seem to last 2 night dives without a recharge.
3.  You have to carry a recharger with you on dive trips.  Make sure you
    have a converter for the local electric current.  Sometimes a power
    surge can melt down your recharger...  The islands have rather
    variable power.  This also means it takes longer to recharge than
    you're used to at home.

 
 
 

Dive lights and NiCad batteries

Post by -Knudsen,M. » Sun, 21 Aug 1994 06:43:17


Quote:

>I have a question about battery types in dive lights.  I looked through
>the FAQ and didn't find my question answered (doesn't mean it's not in
>there 8-).  I was wondering if it was OK to use nicads or the rechargable
>alkaline batteries in dive lights.  What are the pitfalls of using
>rechargables?  

Well, nicads are rechargeable (many times) and lightweight.
Disadvantages are that they don't hold nearly as much juice as
alkalines (or maybe even as much as zinc-carbon plain batteries),
and they put out lower voltage (1.2V per cell instead of 1.5).
So your light won't be quite as bright, and the batteries won't
last long at all per charge.

Even their light weight may be a problem -- other than Coz wall
dives, I'd rather a dropped light sank than floated up to the
surface.

The new "Renewal" rechargeable alkies from Ray-o-Vac seem pretyy
good -- all the weight and power of regular alkies, but
renewable.  I've heard that each charge cycle gives less and less
charge, but haven't tested my own yet.

Quote:
>It seems like a rechargable battery would be financially better in the
>long run.

Funny, I hate buying batteries and throwing them away, but for a
dive, when you consider all the time and energy and money you put
into each dive (must be at least $40 per tankfull when you
consider everything), buying 4 or 6 brand new batteries before
each dive doesn't seem so expensive anymore.  You probably tip the
boat crew more than the cells would cost.

And consider that batteries that survive one dive can be swapped
out and used in your radio, etc where you don't mind when they run
down.  You want fresh cells on every dive.
--

It's not how many friends come to your funeral;
It's how many collectors come to your estate sale that counts!

 
 
 

Dive lights and NiCad batteries

Post by CC015.. » Sun, 21 Aug 1994 03:52:43

We discussed divelights and Nicads some time back.

4Ah Nicad D cells (Radio Shack HiCap f.ex) are no lighter than
alkaline.

In a UK1200 (1.3A discharge current) they last 3 hours.

In a UK1200  (8 D cells) the internal resistance of the alkaline
are so high and the loss of voltage so big that it is the NiCad
that gives you the brightest light over a significant portion of the
discharge cycle.

Any part of your lamp can fail at any time anyhow - always carry
a backup or two if your safety depends on light.

More issues were brought up last time but I feel the above
issues were misrepresented this time around.

john

 
 
 

Dive lights and NiCad batteries

Post by Ron Fo » Sun, 21 Aug 1994 13:18:43


Quote:
(Shane Jensen) writes:
>Posted: 19 Aug 1994 02:19:45 GMT

>I have a question about battery types in dive lights.  I looked through
>the FAQ and didn't find my question answered (doesn't mean it's not in
>there 8-).  I was wondering if it was OK to use nicads or the rechargable
>alkaline batteries in dive lights.  What are the pitfalls of using
>rechargables?

>I'm new to SCUBA (waiting for my permanent c-card) and in my
>limited experience I have only seen people use alkalines and I
>currently don't own a light so I have no personal experience with them,
>but I am looking at buying a light in the near future.

I've got a Pelican BriteLite and it leaked.  One dive shop told me he had
similar problems with that brand.  So if you are buying a light, you may
want to steer clear of this one.
Also, I was using brand new rechargeables, so there goes $20 right there!!!
I got the light replaced by the manufacturer but batteries ...
I still have that brand, so I don't know how common leaky lights are (I'm
talking manufacturing defect or design flaw; not O-ring problems).
Good Luck.
 
 
 

Dive lights and NiCad batteries

Post by Bill Sche » Wed, 24 Aug 1994 06:26:04

On the other hand, the lower internal resistance of nicads allows you
to pull more current from them (of course for a shorter amount of
time).  I have a UK (Underwater Kinetics) 800 dive light and my buddy
has a UK 1200. They are same light, except the 800 has nicads and a
higher wattage bulb. The UK 1200 is rated at about 12 watts, the UK
800 at 30 watts.  Obviously, the 800 is MUCH brighter (it's a very
nice light, although somewhat expensive).

Of course, my light only gets about one hour on a charge, while my
buddy's light is rated at (this is from memory) 8 hours on a set of
eight alkaline D cells.  I don't believe you could get away with
putting the higher wattage bulb in the D-cell based light, without
over heating the batteries.  It's a good idea to carry a small
backup light though, since when the nicads start to go, they
go REAL fast.

Bill Schell

 
 
 

Dive lights and NiCad batteries

Post by Anthony DeBo » Wed, 24 Aug 1994 10:04:46

Quote:

> - when a ni-cad starts to fade, it fades fast.
>   Usually in less than a minute you're in the dark.
>   So carry a second light, especially at night.

Just as a theory, perhaps it might be best to use ni-cads in your main
light that you use, thereby discharge, and then recharge all the time,
but keep alkalines (long shelf life, gradual fadeout as they die) in
your backup light(s) that you seldom use except for checking before dives
(replacing them, though, at regular intervals as needed).
--
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Dive lights and NiCad batteries

Post by CC015.. » Wed, 24 Aug 1994 08:12:41


Schell) said:

Quote:
>.......UK 1200 vs. UK800
>They are the same light, except the 800 has nicads and a
>higher wattage bulb. The UK 1200 is rated at about 12 watts, the UK
>800 at 30 watts.  Obviously, the 800 is MUCH brighter (it's a very
>nice light, although somewhat expensive).
>Of course, my light only gets about one hour on a charge, while my
>buddy's light is rated at (this is from memory) 8 hours on a set of
>eight alkaline D cells.  I don't believe you could get away with
>putting the higher wattage bulb in the D-cell based light, without
>over heating the batteries.  It's a good idea to carry a small
>backup light though, since when the nicads start to go, they
>go REAL fast.

Most interesting.

Two questions:
a) The UK800 generates about 30W of heat. Are the reflector and
lens specially made to deal with the high temperature ?

b) What is the rated life (if specified) of the UK800 bulb ?

Some numbers.  The UK1200 w/ 4Ah Nicads (which incidentally
weight 146 grams/cell as opposed to 143 grams for the Duracell
Copper Top D cell) draws 1.3 Amps.  A guess for the UK800
would be closer to 3.6 Amps.

The internal resistance goes up as alkaline batteries discharge.
I have measured the internal resistance of alkalines to be 1.2
Ohms for 8 D cells at a current of 1.28 Amps.  Assuming the ESR
remains about the same, the voltage loss in the UK800 would be
12V -3.5 * 1.2  or about 7.8 Volts over the bulb. From this I
suspect that the UK800 would actually go somewhat dim if loaded
with alkalines.  With alkalines the discharge
current might drop way below 3.5 Amps.  The heat generated
in the alkaline batteries is given by  RII and that's less
than 4W (1/2 W per cell) so battery heating should *not* be a
problem.

Radio Shack sells a 12V, 20W halogen bulb that could be a middle
ground for the UK1200/800. I have hesitated trying this bulb in
the UK1200 because I feared it would melt the reflector.
At $2 I have now decided to give it a try.

john

 
 
 

Dive lights and NiCad batteries

Post by Brian Gran » Mon, 29 Aug 1994 11:49:23

: > Two questions:
: > a) The UK800 generates about 30W of heat. Are the reflector and
: > lens specially made to deal with the high temperature ?

: > b) What is the rated life (if specified) of the UK800 bulb ?

: Hi John.

: I don't know if the UK800 and UK1200 have different reflectors and
: lenses.  At the moment, the lights are stored in different towns,
: so it's hard to check.  However, if they are different, it's not
: obvious upon cursory examination.  I do know that the instructions
: the go with the UK800 say not to run it above water for more than
: a few minutes. Perhaps they are relying on water cooling to compensate
: for using the same lens/reflector in each light.

: I'll check my light when I get home and see if they give a number
: for the life of the UK800 bulb.  Let me know how your experiment with
: the Radio Snack 20W halogen bulb goes.  I believe UK puts a xenon/halogen
: bulb in both the 800 and 1200.  It will be interesting to know how
: the straight halogen compares at 20W.

: Bill Schell

I get about 20 dives per bulb from my UK 800.  The bulbs cost me around
$10 I seem to remember, (though I work for a dive store so this may be
less than what the retail cost is) so I guess this must work out to
around about 15-20 hours per bulb.  

Still it is by far the brighest light I have ever seen U/W :)

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Dive lights and NiCad batteries

Post by Brian Gran » Wed, 31 Aug 1994 02:15:03

: Well, nicads are rechargeable (many times) and lightweight.
: Disadvantages are that they don't hold nearly as much juice as
: alkalines (or maybe even as much as zinc-carbon plain batteries),
: and they put out lower voltage (1.2V per cell instead of 1.5).
: So your light won't be quite as bright, and the batteries won't
: last long at all per charge.

This is not correct.  A Nicad light will be much brigher than a alkaline
of the same size.  To use an example, my UK 800 which has 8 D size nicads
(albeit in one "UK matched pack") is MORE than twice as bright as the UK
1200 which has either 8 or 12 D size alkaline battries.  The comparable
wattage output is 30 watts for the 800 to 15 for the 1200.

: Even their light weight may be a problem -- other than Coz wall
: dives, I'd rather a dropped light sank than floated up to the
: surface.

Well I am not sure what sort of light you are using but the UK 800 is
negitively bouyant.

: >It seems like a rechargable battery would be financially better in the
: >long run.

Make no mistake about it, it is.  It seems silly to me to pay for
battries when you can get brighter light for nothing.

For sure a nicad will not last as long as an alkline will,  but again to
use my UK 800 as an example I get about 1.5 hours per charge with the 30W
bulb and 3 hours with the 15W bulb.  As the avg time that most of our
passangers seem to spend in the water on a night dive is around 45
minutes I can get 2 dives in with the 30W bulb.  The light does not
suddenly go out when the battery gets low, though when the light does
start to dim it is time to either switch to your backup light or think
about ending the dive.

Having said all this there is ONLY one reason to choose a Alkaline over
Nicad and that is price.  A UK800 is around twice as expensive as a
UK1200!!!

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Dive lights and NiCad batteries

Post by CC015.. » Wed, 31 Aug 1994 05:27:30


Quote:

>: Even their light weight may be a problem -- other than Coz wall
>: dives, I'd rather a dropped light sank than floated up to the
>: surface.
>Well I am not sure what sort of light you are using but the UK 800 is
>negitively bouyant.

Many rechargeable D cells actually are C cells in disguise.
4Ah D cells of the NiCad kind weight 147 grams as opposed to
143 grams for the alkaline Copper Top.

john

 
 
 

Dive lights and NiCad batteries

Post by Brian Rober » Wed, 31 Aug 1994 18:59:19



Quote:
>This is not correct.  A Nicad light will be much brigher than a alkaline
>of the same size.  To use an example, my UK 800 which has 8 D size nicads
>(albeit in one "UK matched pack") is MORE than twice as bright as the UK
>1200 which has either 8 or 12 D size alkaline battries.  The comparable
>wattage output is 30 watts for the 800 to 15 for the 1200.

huh? the 15watt from the 1200 should be less bright than the 30 watt from
the 800, what kind of example is that.  Or are you saying you knew the
15watt was less bright than the 30watt and you got out a light meter and
measured the output from a set distance for both of them and
somehow came up with a factor greater than 2x when comparing the difference?
 
 
 

Dive lights and NiCad batteries

Post by Doug Ste » Sat, 03 Sep 1994 02:39:35

Good point about many D cells being C cells in disguise.  Almost all the
consumer, over-the-counter types are C cells in a D cell shell.  The way to
tell is to look at the ampHr rating.  Real D cells are up around 4.5 ampHr,
plus or minus depending on whether they are rapid-charge, high-energy, etc.
C cells are down around 1.2 ampHr.

I've used many battery types in commercial applications and very much prefer
the Lead-Acid technology, Gates brand in particular.  Unlike NiCads that
tend to last five years, a good lead-acid will last many years.  i have
some that are 25 and still going.  I have D cells, which are 2.2 volts,
2.5 ampHr and E cells that are 5 amphr.  The only problem with a lead-acid
of quality is that it can refuse to charge if totally discharged, due to
ion depletion.  it takes time and special charging to bring them back.

Radio-Shack sells a 3-cell pack in both D and E cell sizes.  However, I have
had very poor experience with these.  I need to charge them constantly.
Then again, they are intended for stand-by power in alarms, where quality
doesn't matter much.

doug