To NiCad or NiMH?

After reading the rechargable battery thread, i was about to order some 2000mA/h NiMH batteries and charger for my new Epoque ES 150 strobe.

However in the manual it does not recommend these - only alkaline and NiCad.

The responce from the supplier was:

"It is best to use alkaline or ni-cad batteries as NIMH batteries

have a more violent reaction should they come into contact with salt

water."

Is this an issue - surely the whole idea is that the batteries never come into contact with water...

Thanks

Steve

It only takes moisture, not really even water. They discharge a lot more gas and have the ability to pop off the back of the strobe. It would probably void your warranty.

The new nicads work very well. I've been using the high capacity ones from Radio Shack with very good results. They are much cheaper. They recycle faster than nimh also, almost instantly on my YS120. The issue of them having a memory is much improved, and usually not an issue on strobe batteries as you usually are discharging them pretty deeply. The new chargers have a discharge/recharge ability also.

I know there's 18 guys here that will say that the nimh work great, but having had a couple of flashlights go pop I'm wary of them.

Jack

What is considered high capacity on nicads? NiMH are going up to 2200 mah (that's a lotta juice).

I have used AA NiMH batts from thomas distributing for several years now, never a problem.

Now I got something else to worry about down there. THANKS!

I think the NiCads are only around 1200MaH. The Nimh work, but just be very sure that they are dry, it's easy to have damp hands, etc.

I've gotten 3+ rolls off my YS120. I guesss that's one dive with digital

Jack

I've been using rechargeable NIMH batteries for two years. I keep them in marked sets of 4, and use and charge like sets together. In over 300 dives I've had only one instance where my strobe leaked and the salt water/battery combo corroded the interior of the housing. After rinsing it out and replacing a spring it still works fine.

In considering which type of battery to use I considered not only function (I use NIMH 1600 through NIMH 1800's) but their affect on the environment. NIMH batteries are considered non toxic whereras NICADs contain cadmium (toxic heavy metal). Eventually these will end up in a landfill somewhere.

A word of caution worth sharing: In opening ANYTHING like a flashlight housing or strobe housing, one should always do so in a way to protect their person and surroundings in case it is flooded. In opening my flooded housing the gas pressure buildup was released as I loosened the strobe cover. The acidic battery/salt water misted out and onto the bedspread I was working on. I noticed a few minutes latter that there were tiny holes in the bedspread. Luckily none of this got on me. Now I always cover my strobe with a towel before I open it...just in case. B)

FYI, my Greenforce HID dive light is NiMH powered, as are many new rechargeable dive lights. I wouldn't worry too much it the seals are trustworthy.

Martyn

FYI, my Greenforce HID dive light is NiMH powered, as are many new rechargeable dive lights. I wouldn't worry too much it the seals are trustworthy.

The dive lights have a special gas filter/absorbent in them.

Jack

FYI, my Greenforce HID dive light is NiMH powered, as are many new rechargeable dive lights. I wouldn't worry too much it the seals are trustworthy.

 

The dive lights have a special gas filter/absorbent in them.

 

Jack

That's because the Greenforce battery compartment is sealed. It is not advised to charge batteries in a sealed compartment. Greenforce needs to take extra care because they do so. I suspect their charger is carefully designed as well.

I once dove with 500 watt-hours of NiMH batteries in a single cannister mounted to my tank. I nicked a switch boot and slowly flooded the cannister when the batteries had a full charge. There was a massive outgassing that forced the endcap off but no actual explosion. The capacity of my battery was 50 times greater than 4 AA's.

The lessons I learned were: (1) always use an aluminum cannister for large NiMH batteries. The plastic cannister people like Halcyon are crazy. (2) Make sure that the endcaps are well attached. Mine are now threaded. Once again, the two-clip design of the Halcyon is nuts. (3) Minimize or eliminate penatrations. My switches are now in a separate housing. Halcyon still uses the switchboot that caused my failure.

Battery experts tell me that the risk of explosion with NiMH is remote (unlike LiIon). The greater concern with NiMH AA's is simply overexpansion damaging your strobe or light. If you want big batteries be very careful who you choose. Look at the European companies. American cave diving companies don't know how to make big lights. A failure of an Extreme Exposure or AUL light with a big NiMH pack could cause serious injury.

Yes, the Greenforce battery tube has a pressure release valve at one end, mostly to relieve outgassing during charging while the tube is closed, but obviously a great safety feature in the case of water ingress.

If people haven't seen these lights, they're of a tubular design, where each joint, from tube to umbilical to handle to head are all triple o-ring sealed. Boy, do they mean it!

Anyway back onto topic Steve, any rechargeable battery is going to heat up, outgas and generally get upset if flooded. It would appear that the Epoque ES-150 is listed by vendors as accepting NiMH, so you should not be stepping outside the design specs by using the cells you are considering.

It does pay to think about the worst case scenario and then make up your own mind as to how likely it is and how bad the likely consequences are. In general, over pressure in a plastic housing is safer than over pressure in a metal one, largely due to plastic failing at a lower pressure.

Regards to all

Martyn

Thanks for the replies

Where have you seen information regarding the Epoque system accepting NiMH batteries - just for my own satisfaction...

Off to Cornwall next week to try it out. Should be more manageable than using my Kowalski 1250 after the strobe went back under warrenty within 12 hours of delivery

If NiMH batteries are on, then the final question is which capacity?

My inclination is to get the largest i can - 2300mAh is very tempting compared to the 800 mAh of the NiCad, but is 1600 or 1800 a safer middle ground if the larger capacity will create more of a pressure buildup?

Steve