D4 Lamp modification

[ifukuda]

I've checked with both Underwater Kinetics and onlybatteries.com and have gotten confirmation that there would be no problem powering an 18-watt bulb with 4 x 4.5Ah C-cells (drawing 3.75Ah).

I've just ordered the 18-watt bulb, 4.5Ah NiMH C-cells, and a high end recharger... for a little under $100.

Power of a D4R in the size of a C4. (I'm guessing the beam will narrower because of the smaller reflector).

 

[fmerkel]

Did the UK folks _specifically_ indicate the NiMh were OK? Last I checked with the local rep. he stated the UK position was that the NiMh batteries gave off too much hydrogen for use in a dive light. NiCads are less of a problem and OK.

An experiment (crude but easy) was to put 6 NiMh in an Ikelite PCa with the O-ring seal removed. Put that in a new ziplock and suck excess air out before sealing. Turn it on, put it in a bowl of water, and run it until the batteries were dead (not good for the batteries for the reasons already discussed). (I contacted Ikelite and they are they gave the OK for NiMh).

There was NO additional air (hydrogen) in the bag that I could tell at all. I ran them until dead because some research indicated that the hydrogen was made at the end of the discharge cycle. I've also listened carefully while opening a Light Canon run with 8 C-NiMh's. No hissing that I could tell indicating excess pressure.

There are some strobe manufacturers that are strongly discouraging NiMh batteries. They claim an explosion hazard.

Personally I believe the issue is the low internal resistance (the pipe I made analogy to) if a flooding happens. With the shorting associated with a saltwater flooding the battery can (and will) discarge like crazy. Things get quite hot. I don't know if this causes the hydrogen release or some actual steam pressure may be created causing potential explosion. The only NiMh device I've ever flooded was a camrera with 2-AAA batteries. I was amazed on how hot those tiny little things got.

At any rate I've been running my modified UK400's for about 6 months now and they work fine with either kind of battery. The NiMh's seem to be a tad better but that may be a result of an inferior charger I started with on the NiCads and was not charging them properly. I get a solid hour+ out of them and then need to recharge. I don't push them farther. If the beam gets weaker I use this as a signal to turn them off.

Fritz Merkel

 

[Aquamaniac]

Have a guess at what gas we use to cool the rotor windings in Large Turnine Alternators?

 

[ifukuda]

I'd put a 18W bulb on my C4 (powered by four 4.5Ah NiMh C cells).

The light worked flawlessly during the dive. But, after the dive, when I turned off my light, the bulb had melted and fused itself onto the relfector.

What do you think went wrong?

1) Are the UK D light relectors any different than the C's? The C-4 and C-8 seem to have identical reflector assemblies, and the C-8R comes with a 20W bulb...

2) Could this have occured without the bulb coming in contact with
the reflector? I tried to be careful when I installed the bulb, but I difficult to be sure that the bulb and reflector weren't touching. (I'm guessing this was the most likely cause).

3) Are the UK D and C bulbs any different? There is a visual difference between the stock 6.6W bulb and the 18W bulb. The bottoms of the stock 6.6W bulbs are partially filled with "blue stuff", but the 18W bulb is completely clear. I'd assumed that the blue stuff was just some type of bonding agent. Could it be something else?

 

[Scubaroo]

ifukuda once bubbled...
I'd put a 18W bulb on my C4 (powered by four 4.5Ah NiMh C cells).

The light worked flawlessly during the dive. But, after the dive, when I turned off my light, the bulb had melted and fused itself onto the relfector.

What do you think went wrong?

1) Are the UK D light relectors any different than the C's? The C-4 and C-8 seem to have identical reflector assemblies, and the C-8R comes with a 20W bulb...

2) Could this have occured without the bulb coming in contact with
the reflector? I tried to be careful when I installed the bulb, but I difficult to be sure that the bulb and reflector weren't touching. (I'm guessing this was the most likely cause).

3) Are the UK D and C bulbs any different? There is a visual difference between the stock 6.6W bulb and the 18W bulb. The bottoms of the stock 6.6W bulbs are partially filled with "blue stuff", but the 18W bulb is completely clear. I'd assumed that the blue stuff was just some type of bonding agent. Could it be something else?

My answer would be "C". About 11.4W of heat output to be exact.

I asked a similar question of Princeton Tec about a year ago - my plan was to put the 20W bulb from the rechargeable Shockwave into my 12W Shockwave - but was strongly advised not to, because the higher heat output of the 20W bulb would melt the reflector - the lower wattage lights come with a cheaper plastic reflector. The Princeton Tec rep said that they sell a rechargeable upgrade kit with the 20W bulb, but that it came with a new reflector capable of handling the higher heat.

To put it simply, you flew too close to the sun Although your observation about the C8-R's reflector could mean it was something else...

 

[ifukuda]

Thanks Scubaroo,

I think you are right on about the reflector.

I just checked with UK, and they confirmed that the rechargeable lights come with a different reflector than their alkaline powered counterparts ... I only wished someone at UK would have warned me about the reflector when I contacted them originally to discuss installation of the 18W bulb into my light...