8 hours ago, Chris Ross said:

Sorry, you actually do need liquid water to setup an electrochemical reaction, a thin film of salt is enough to do it as salt is hygroscopic and will pull water out of the air. But unless the humidity reaches 100% you won't get any condensation and even pure water needs a little in the way of salts to become conductive enough to facilitate dis-similar metal corrosion. I'm quite familiar with corrosion mechanisms in my line of work. It won't happen if the contacts are dry. Leaking batteries of course can cause it as they leak electrolyte. Regarding copper, it is quite resistant to sea water corrosion, but tarnishes quite readily which can reduce conduction.

Here is a collection of cotton tip swaps sprayed with a bit of contact cleaner and 30 seconds of rubbing. None of these ever flooded or got even a little bit wet. My camera room humidity is typically about 40-45%.

Inon 330:

Backscatter HF-1:

OrcaTorch v710v and Backscatter MF-1 (Rub/spin the battery housing contact surface on a towel):

My suggestion it to do some preventative maintenance on all of your strobe and light electrical contact surfaces to avoid problem. Don't forget to clean the contact surface of the batteries too. I rub the batteries contacts on a scrap towel on occasion, when I happen to about it.

Edited December 23, 2025Dec 23 by Dave_Hicks

Good points.

Several years ago I ordered a set of "scratch brush" electrical contact cleaners and carry a couple of those with me on dive trips. I only had to use them once on another person's strobe, but they can clean contacts that suffer some corrosion or other issues. They are cheap, light and small and can be purchased on Amazon and at other places. May be worth sticking in your gear somewhere, in case Coke or contact cleaner or alcohol isn't available after a leak?

As far as preventative maintenance goes, I know Sealife warns that:

1. IMPORTANT UPDATE – Clean battery contacts every time before charging

Applies to all Sea Dragon lights with 1200+ lumens and Fluoro-Dual Beam models.

Clean the gold-plated contacts on battery and inside battery compartment EVERY TIME before charging the battery.  Use a clean cotton cloth moistened with isopropyl alcohol to thoroughly clean contacts.  Not cleaning the contacts will permanently damage the gold plating and result in the device not powering on.

DO NOT store the device with battery installed.  Remove battery before storage.

Left contact shows black spots resulting from not cleaning the contacts.

Kind of boosts my appreciation of my old Inon lights with their AA batteries. But I know Lithium and massive lumens are the future.

Just to compare my strobes here's my Z240 cap contacts and a swab that just wiped them over, this is the first time I've cleaned them:

I can only see the slightest trace of residue being picked up. I agree though if you are getting corrosion on contacts regular cleaning will help. My routine with these strobes is that every time I pull the batteries the o-rings are removed shaken dry checked and greased and the water left in the o-ring groove dried out and cleaned, then replaced and sealed up. Because I'm diving regularly, the batteries normally go back in the strobe. The strobe is 10 years old.

Even after soaking the strobes for 2 hours the water trapped in the cap between the edge of the cap and the o-ring in still salty (I've checked by taste). If I don't pull the batteries I end up with salt crystals in there as the water slowly evaporates. The O-ring on these strobes is not a super tight fit in the groove and it seems to me there is a risk of traces of salt water making its way inside the strobe unless I dry out the o-ring as described.

In the more than two decades I have owned a set of Inon D2000 strobes I have never cleaned them, flooded them or seen any sort of corrosion on them. My new S220 strobes are clean as can be, maybe in another twenty years I will give them a good cleaning. If I am still around to do so.

This was not a common problem with AA powered devices. It does appear to be an issue with higher powered lithium devices.

16 hours ago, Nemrod said:

I am not clear here. Did Backscatter state the specific reason the strobes quit working was "stained" contacts and that there is no other malfunction involved?

I was in contact with the service department before sending in the strobes and have send photos of the contacts (after cleaning with a Dremel tool and with alcohol). I was told the reason are the contacts, some "stain" from corrosion (there were still remains of this stain to see on the photos). According to Backscatter, this can happen even without direct contact with water (and there has never been a contact with water)...

At present the strobes are at Backscatter for repair and they will tell me the details after the repair. I will report here then...

Edited December 24, 2025Dec 24 by Architeuthis

11 hours ago, JohnD said:

Good points.

Several years ago I ordered a set of "scratch brush" electrical contact cleaners and carry a couple of those with me on dive trips. I only had to use them once on another person's strobe, but they can clean contacts that suffer some corrosion or other issues. They are cheap, light and small and can be purchased on Amazon and at other places. May be worth sticking in your gear somewhere, in case Coke or contact cleaner or alcohol isn't available after a leak?

As far as preventative maintenance goes, I know Sealife warns that:

1. IMPORTANT UPDATE – Clean battery contacts every time before charging

Applies to all Sea Dragon lights with 1200+ lumens and Fluoro-Dual Beam models.

Clean the gold-plated contacts on battery and inside battery compartment EVERY TIME before charging the battery.  Use a clean cotton cloth moistened with isopropyl alcohol to thoroughly clean contacts.  Not cleaning the contacts will permanently damage the gold plating and result in the device not powering on.

DO NOT store the device with battery installed.  Remove battery before storage.

Left contact shows black spots resulting from not cleaning the contacts.

Kind of boosts my appreciation of my old Inon lights with their AA batteries. But I know Lithium and massive lumens are the future.

The contact marked as "Corosion..." is exactly how my contacts looked (but the corrosion was much less intense in my case).

Here the photos of the contacts after cleaning, rests of the stain can still be seen (unfortunately I did not make photos before). One strobe was working after cleaning (upper photo), the other not (lower). Backscatter said better send in both since the problem will reappear soon...

Edited December 24, 2025Dec 24 by Architeuthis

This has been an educational discussion. I guess Sealife is ahead of the curve and if using high power strobes and lights with lithium batteries, take q-tips and isopropyl alcohol and wipe the contacts with every battery change. Luckily, isopropyl alcohol can be carried on planes (under 3.4 oz). and is readily available.

Wondering what Oskar from Retra thinks about this, now that the maxi strobes have gone over to the dark side (Lithium).

By the way, when I comment on lithiums, it is in large part because one of my sons is an engineer working in forensics, and travels within the U.S. and internationally investigating fires, explosions, train wrecks, boat fires, etc. Earlier in his career he was employed as an engineer by Panasonic, working primarily on battery technology and testing, and has set fire to, exploded, crushed and otherwise abused a large number of lithium batteries. I have numerous lithium battery devices and will undoubtedly have more, but am aware of their downsides including significant fire risk. Take a look at what Backscatter warns about their lithium battery devices:

Never do the following:

Never charge batteries in unattended areas.

Never charge while sleeping.

Never charge below decks of a boat.

Never store batteries below decks of a boat.

Never store batteries in the light below decks of a boat.

Never use batteries without protection circuitry.

Never dispose of batteries in the garbage or trash.

Never put batteries in checked baggage when traveling.

Never walk around with bare batteries in your pocket, especially with other metal

objects than can easily bridge battery contacts.

Always do the following:

Only charge batteries in common areas where and when others are around.

Always remove the battery from the Macro Wide 4300 light when not in use.

Only use batteries designed for end use by consumers with safety protection circuitry.

Only store batteries in a battery box designed for 21700 batteries.

Always travel with batteries in cabin baggage.

Edited December 24, 2025Dec 24 by JohnD

And what about my RGBlue light? 🤣🤣🤣

I bought it used in this condition and has been working flawlessly for 5 years. probably, prior owner didn't respect all the guidelines.

28 minutes ago, Davide DB said:

And what about my RGBlue light? 🤣🤣🤣

I bought it used in this condition and has been working flawlessly for 5 years. probably, prior owner didn't respect all the guidelines.

Perhaps it because uses a battery module instead of bare batteries and that makes a difference?

Perhaps better quality contacts? Maybe luck?

I have lithium-powered lights on which I have never cleaned the contacts and the manufacturers don't say anything about that, but they are expensive lights and other items intended for hard use and not used underwater and mostly made in the USA, Germany or Japan.

Maybe manufacturing quality matters? I believe the RGBlue stuff is/was well made, no?

Maybe the relatively low power of the light and the absence of strobe functions?

Just speculating

Edited December 24, 2025Dec 24 by JohnD

7 minutes ago, JohnD said:

Perhaps it because uses a battery module instead of bare batteries and that makes a difference?

Perhaps better quality contacts? Maybe luck?

I have lithium-powered lights on which I have never cleaned the contacts and the manufacturers don't say anything about that, but they are expensive lights and other items not used underwater and mostly made in the USA, Germany or Japan. I think RGBlue are/were made in Japan?Maybe manufacturing quality matters? I believe the RGBlue stuff is/was well made, no?

Maybe the relatively low power of the light and the absence of strobe?

RGBlue manufacturing quality is very high. The contact tracks on the head are gold-plated. The head doesn't need to be rotated to make contact, so I have no idea what could have happened to damage them like this. Perhaps a partial flood ruined the contacts, and then the owner must have used something too abrasive to clean them. Regardless, I have two of them—one is perfect—and there's absolutely no difference in how they perform. Also, I took a photo five years ago when I first got it, and the damaged area hasn't changed since then.

Fingers crossed!!!

9 hours ago, Davide DB said:

RGBlue manufacturing quality is very high. The contact tracks on the head are gold-plated. The head doesn't need to be rotated to make contact, so I have no idea what could have happened to damage them like this. Perhaps a partial flood ruined the contacts, and then the owner must have used something too abrasive to clean them. Regardless, I have two of them—one is perfect—and there's absolutely no difference in how they perform. Also, I took a photo five years ago when I first got it, and the damaged area hasn't changed since then.

Fingers crossed!!!

I think the lights have lower current, a 100 W-hr battery if it lasts 1 hour at full power it's running at 100W and I believe they are 14.4V, so running 7 amps. Some newer ones have higher power of course, but typically aren't run at full power for long periods. The backscatter flashes talk about 20Amp current drain. The contact area on the RG Blue battery is also a lot bigger. As the video light is constant draw, it probably needs the bigger contact area to minimise resistance and heat build up.

I think it could be related to the higher voltage of the individual cells compared to NiMH.

6 hours ago, Grantmac said:

I think it could be related to the higher voltage of the individual cells compared to NiMH.

Voltages are not that different, nominal 3.6V per cell, so 7.2V total with two cells, four 1.2V cells gives 4.8V, if using a Retra with 8 cells it's 9.6V nominal. What counts is the voltage of all of the batteries in series. The voltage in isolation doesn't give the whole story as it is the current produced which is related to circuit resistance and voltage that sets the energy being transmitted.

I don't know exactly what is going on here, 20A is a high current load for a battery , but for example a normal 220-240V power point can handle 15 amps of AC current without any problem. I know DC is different, but for contacts the main issue is arcing when disconnecting. You don't get power plugs being destroyed and they are handling a lot more power and video lights with bigger contacts don't seem to have the issue.

Information from Deoxit Gold product sheet. Very interesting and relevant to this discussion.

https://acct113328.app.netsuite.com/core/media/media.nl?id=793&c=ACCT113328&h=cf9f74b54878595f50b4&_xt=.pdf

Also, some Copilot AI research of the topic. TLDR; Even a little oxidation/resistance can make a big drop of voltage at these power levels.

---

When a 3.7 V battery capable of 20 A current is used in high-powered electronic devices (e.g., advanced LED arrays, portable amplifiers, or hobbyist drones), battery contact degradation due to oxidation or corrosion is a significant concern. The mechanisms and implications for performance in such devices can be analyzed systematically.

---

1. Electrochemical Basis

1. Metal Oxidation at Contacts

   • Contacts are often made of copper, brass, nickel, or tin-plated alloys.

   • Exposure to moisture, oxygen, and trace electrolyte can initiate the formation of oxides:

   Cu+12O2→CuOorNi+O2→NiOCu+21O2→CuOorNi+O2→NiO

   • In high-current scenarios, oxidation is accelerated due to local potential differences generated at microscopic imperfections.

2. Localized Electrolytic Effects

   • Even in dry conditions, leakage currents or minute electrolyte residues create micro-electrochemical cells, further catalyzing oxidation.

   • High amperage increases the rate of these redox reactions proportionally (Faraday’s law of electrolysis).

---

2. Thermal and Electrical Factors

1. Joule Heating

   • Power dissipated at a contact: P=I2RP=I2R, where I=20 AI=20 A and RR is the contact resistance (~milliohms).

   • Even low voltage (3.7 V) produces:

     P=(20)2×R≈400R WP=(20)2×R≈400RW

   • Local temperature rises accelerate oxidation and plating degradation, creating microcracks that exacerbate corrosion.

2. Voltage Drop and Contact Resistance

   • Oxidation increases resistance at the interface.

   • Voltage drop across contacts: Vdrop=I⋅RoxideVdrop=I⋅Roxide

   • In high-power devices, even 0.01 Ω can cause noticeable voltage loss:

     Vdrop=20 A×0.01 Ω=0.2 V(∼5% of 3.7 V)Vdrop=20A×0.01Ω=0.2V(∼5% of 3.7 V)

I've looked on and off for websites covering contact degradation, but really can't find anything like the AI output above and I really can't find anything definitive about this. There are a great many Li-ion based items, around, I'm thinking of things like power tools, ultra bright spotlight torches etc and if this was common there would be something out there. These strobes draw a lot of power but they are really not pushing the envelope, things like Li-ion power tools - I looked up specs for a small saw from De walt, it uses and a 6 A-hr 18V battery rated to provide up to 800W of power, this is 44 amps at 18V. If the issues with terminal contacts is related to amps, you would expect to see it on something like this. and I couldn't find anything like this on power tools - and these are used in rather dirty environments.

The fact of the matter is for electrochemical corrosion to occur you need moisture, you can get this if there are salts of some type on the contacts, fingerprints have a little salt, or you might be pushing traces of salt water in from water droplets on the o-ring if you don't dry it off. Certainly high currents can accelerate this type of corrosion but unless the contact is that bad you get arcing, clean terminals should not corrode. If they are corroding poor quality materials cant be ruled out, it is hard to judge quality just by looking, the quality and materials used in plating can vary significantly for example and choice of base metal can have an impact. Springs can also be too light and fatigue over time so contact pressure is reduced. A question was asked on the Retra maxi post and Oskar replied that Retra uses a multi layer plating on their contacts and claim not to have had issues unless they have flooded.

As an aside, my company is in an "AI will be the key to success" phase and are busy exploring ways to use it. Talking to some people who have tried, they say it's great for writing reports, organizing facts, all sorts of language tasks, but it tends to suck at technical topics. They are language models working what words should be placed in what sequence based on all of the content they have ingested and the starter phrase provided. Very easy to mix things from different fields to write a load of rubbish, the Joule heating equation for example is rather garbled. The correct answer is that 0.01 ohms at 20A produces 4W of heat.

Just a thought/question...

Granted, we are always concerned about corrosion caused by salt water but when talking about the type of corrosion or damage caused to contacts as addressed by Sealife in their instructions or as shown in some of the photos earlier in this thread, I got to thinking about it and wondered if any moisture in a battery compartment, combined with high electrical current and/or heat could cause the type of damage we have been discussing.

Some brief research suggests that is so. Overall it was dry and technical reading, but the AI summary (I know, but still) is this:

High humidity can lead to condensation on electrical contacts, causing corrosion and rust, which can damage the connections. Additionally, heat combined with humidity can exacerbate these issues, leading to electrical failures and reduced performance of devices.

putnammechanical.com cable-world.co.uk

When diving we are generally in high humidity environments, or at least I am. Perhaps as we increase the power demands of lights and strobes and the energy provided by more powerful batteries, the increased heat and current combined the moisture in the air alone can cause damage?