12 minutes ago, insomniac said:

For the Sony, I bought a GoPro 3 housing many many years ago that had an external battery holder for 1x 18650 battery (at the time it was like over $500, and it came with a custom aluminum gopro case that I didn't even need). Anyways, I cut the wire on the battery holder and then soldered a USB cable to the other side. Before connecting the wires I ran it through a Nauticam Socket Extension and then I just made sure my wires were split up pretty good and fully inside the socket extension and epoxied it inside. This worked amazing for about 6 years, and then I started getting an insanely small vacuum leak (only on land, stayed sealed when testing with some toilet paper and a 5 gallon bucket). I ended up just using a Dremel to remove about 2cm of epoxy and epoxied it and hasn't been a problem since.

It's a super simple cable that could have any tip (Micro USB, USB-C, etc), and because it's magnetic it makes it super easy to install in the housing (there's a million on Amazon, here's an example), mine has a little light that comes on so you know it's connected. The battery has an on / off switch which can be annoying but it's been so nice. You get an entire day without having to open the housing and swap batteries.

Here's some pics of that...

Wow - this is amazing. An external battery pack would really, really change my life.

Since we're derailling the thread (maybe these posts can be moved to the DIY forum), I'd love to have your opinion - My NALX10 housing has a single M14 port, which I use for vaccum.so really not sure what can be done.

I seem to remember that there was some option to have dual output bulkhead (vaccum + one cable) but can't seem to find that.
A dummy battery does exist for the cameras - battery requires 8.4 V .


main issues for me would be solving the bulkhead issue, best battery for UW use and cannister...

I'd given up but your post is giving me hope!

thanks

ben

24 minutes ago, bghazzal said:

Wow - this is amazing. An external battery pack would really, really change my life.

Since we're derailling the thread (maybe these posts can be moved to the DIY forum), I'd love to have your opinion - My NALX10 housing has a single M14 port, which I use for vaccum.so really not sure what can be done.

I seem to remember that there was some option to have dual output bulkhead (vaccum + one cable) but can't seem to find that.
A dummy battery does exist for the cameras - battery requires 8.4 V .


main issues for me would be solving the bulkhead issue, best battery for UW use and cannister...

I'd given up but your post is giving me hope!

thanks

ben

If you want to take the risk and forgo the vacuum (scary), you could for sure do it. I would recommend keeping your battery; and just charging it through the USB port. The RX100 can charge and be powered on at the same time. Some camera's only charge when off (but still, just turn off the camera between dives and it will charge up). The Canon actually runs off my custom battery pack (when turned on, and my pack has juice); and when the camera is off it charges the camera battery. You really don't want to use a dummy battery unless you have no other choice; as you are giving up additional capacity and redundancy.

The issue I'm having is that battery life is very limited. I shoot 1 minute clips tops, to edit, and turn off the camera to save battery as recommended by Panasonic, but still don't have enough for one dive. I did a two hour dive this morning, and the battery died out on me. I haven't opened the camera yet, but I probably have around 20 minutes of footage.

I've never tried filming continuously, but based on the footage length I'm getting I think I have enough juice for about 20 to 30 minutes of filming or so before the battery is empty, and this is being very very careful with battery life, fully charged, new batteries.

Charging is not an option unfortunately. I desperately need more runtime underwater. It would completely change my life if I could have say one full hour of shooting or even a little more.

The point of the dummy battery is to power the camera from it, either from DC or a battery pack.

Edited August 22, 2025Aug 22 by bghazzal

6 minutes ago, bghazzal said:

Wow - this is amazing. An external battery pack would really, really change my life.

Since we're derailling the thread (maybe these posts can be moved to the DIY forum), I'd love to have your opinion - My NALX10 housing has a single M14 port, which I use for vaccum.so really not sure what can be done.

I seem to remember that there was some option to have dual output bulkhead (vaccum + one cable) but can't seem to find that.
A dummy battery does exist for the cameras - battery requires 8.4 V .


main issues for me would be solving the bulkhead issue, best battery for UW use and cannister...

I'd given up but your post is giving me hope!

thanks

ben

Hi Ben, perhaps you could hop over to this thread, it has some of the missing details.

Unfortunately many of these types of solutions require some skills in electronic assembly, not sure how you are with this and selecting proper components for battery packs like charge monitors etc.

For your case there are probably a few solutions - the simplest would be some sort of USB-C bulkhead. I believe you can charge the LX10 via the USB port which seem to be a mini USB. If you had this you could recharge the battery between dives without any sort of UW housing for the battery.

If you go for an UW housed battery - The first thing to consider for an UW battery housing is if you can charge the battery while the camera is running via USB, many cameras cannot. In this case this is where the dummy battery would come into play.

You might be able to find a second hand monitor housing to hold batteries, you could install something like some 18650 or 21700 batteries in a holder and just cut off the HDMI cable plug and use that cable for getting the power down to the camera housing. Something like this:

battery holder

This way you could use a land based 18650 charger to recharge the batteries and not need to build in a charging circuit. It would probably be fiddly using the fine wires in the HDMI cable for power and terminating them so they don't break and you would need to have some means to plug the USB cable in - inside the housing. The biggest barrier might be the M14 thread, many bulkheads for this sort of service are at least M16.

I see Backscatter has a used Ninja housing on sale currently: used housing

There's probably a few other items about you could utilise, for example subtronic have external batteries built into strobe arms which might be adaptable, but likely expensive.

Thanks Chris, I'd forgotten about this thread, and sorry for derailing this one - in my case the LX10 cannot be charged by USB, it's data-transfer only, so dummy battery / DC coupler is the only way.
I don't think there really any vaccum-safe practical option with my camera + M14 bulkhead housing combo, though this thread had given me hope!

1 hour ago, bghazzal said:

Thanks Chris, I'd forgotten about this thread, and sorry for derailing this one - in my case the LX10 cannot be charged by USB, it's data-transfer only, so dummy battery / DC coupler is the only way.
I don't think there really any vaccum-safe practical option with my camera + M14 bulkhead housing combo, though this thread had given me hope!

If you could find a Nauticam 26526 m14 offset vacuum valve you might have a chance but I think they are discontinued. With enough money Dive and see might be able to do something custom??

We really should move this thread to a new forum regarding custom battery solutions, but oh well here we are... This might work (as the 16mm isn't discontinued yet). And actually they still might be able to make the M14 one as the description says they are manufactured on demand.

It would be "clunkly-ish" but you could maybe do this:

Nauticam

M16 to M14 Step-Down Adapter ~for Electrical Bulkhead

Allows for the use of M14 electrical bulkheads in M16 housing sockets.

and this

Nauticam

M16 Offset Connector with Dual Activation Vacuum Valve ~C...

This dual-activation offset vacuum valve supports creating a vacuum with either the hand pump or via a low pressure inflator. The offset allows the bulkhead to be used for another purpose such as an e

Edited August 22, 2025Aug 22 by insomniac

29 minutes ago, insomniac said:

We really should move this thread to a new forum regarding custom battery solutions, but oh well here we are... This might work (as the 16mm isn't discontinued yet):

It would be "clunkly-ish" but you could do a this

Nauticam

M16 to M14 Step-Down Adapter ~for Electrical Bulkhead

Allows for the use of M14 electrical bulkheads in M16 housing sockets.

and this

Nauticam

M16 Offset Connector with Dual Activation Vacuum Valve ~C...

This dual-activation offset vacuum valve supports creating a vacuum with either the hand pump or via a low pressure inflator. The offset allows the bulkhead to be used for another purpose such as an e

I thought the same but he would need the other way around. He has an M14 threaded hole on the housing.
Anyway, as Chris suggested, this should be ok:

https://www.backscatter.com/Nauticam-M14-Offset-Connector-w-Vacuum-Valve-II-Pu

Once we have an M16 thread hole, what kind of connector do we need on the cable?

P.S.

I'll try to move part of this thread to DIY forum. Bear with me!

On 5/1/2024 at 8:43 AM, boduoguo said:

If your housing has a space reserved for flash trigger. It can be used to install a lithium polymer battery. It's a rudimentary method, but it works and will last for a day's diving. No need to open the housing.
battery are cheap and can be recharged over and over again .

Old post but... From your photos I see you are using a 3,7V Lipo battery pack. 3,7V are enough to power your A7? camera?
I shot video only so I'm thinking for a similar out of the box solution for my GH5M2 that can be powered via USB-C...

9 hours ago, Davide DB said:

Old post but... From your photos I see you are using a 3,7V Lipo battery pack. 3,7V are enough to power your A7? camera?
I shot video only so I'm thinking for a similar out of the box solution for my GH5M2 that can be powered via USB-C...

I think many camera batteries are 7.2V or around that voltage, a few small compacts use 3.6V cells

16 hours ago, Chris Ross said:

If you could find a Nauticam 26526 m14 offset vacuum valve you might have a chance but I think they are discontinued. With enough money Dive and see might be able to do something custom??

I'm giving up. It's too much of an investement for an old camera. It doesn't power through USB, just charge, and even the dummy battery is problematic because housing space is so restricted:



One solution would be to connect a battery bank which could charge the battery when the camera is off, but there's not enough space inside, even if we remove the flash trigger, and the USB port isn't accessible.

I guess I'll just have to make the most of my 20/30 minutes of shooting until I can upgrade the camera 🙂

7 minutes ago, bghazzal said:

I'm giving up. It's too much of an investement for an old camera. It doesn't power through USB, just charge, and even the dummy battery is problematic because housing space is so restricted:



One solution would be to connect a battery bank which could charge the battery when the camera is off, but there's not enough space inside, even if we remove the flash trigger, and the USB port isn't accessible.

I guess I'll just have to make the most of my 20/30 minutes of shooting until I can upgrade the camera 🙂

It's certainly tight in there, one question is if your battery might be getting a little tired?

2 hours ago, Chris Ross said:

It's certainly tight in there, one question is if your battery might be getting a little tired?

Yes, I try to rotate them but bought a cheap USB tester today which should - if it works - give me a clearer view of where they all are.
I'm also going to power off stabilisation for macro, could give a few extra minutes.

Edited August 23, 2025Aug 23 by bghazzal

I'm super happy; while building the custom battery for my wives housing I starting thinking if I could do something similar in my Nauticam Sony A1 housing. My solution is exponentially easier, and anyone with a similar housing can do this with no electronic knowledge required!

A bit of background, I noticed you can buy 21700 batteries with bi-directional USB-C circuit charging built into the battery itself; I was wondering if something might exist for 18650's as well; and it took some digging but I found some (and I was order #1001 AKA#1) so I don't think anyone else knows about them:

LBF Battery

Button Top Protected 18650 3500mAh Flashlight Battery Typ...

【Battery Specification】Battery type: 18650 Button Top PCB Proctected, Capacity: 3500mAh, Wh Rating: 12.95Wh, Voltage: 3.7V, Size: 18.5*70.5mm(0.72*2.77 inches), Feature: Type-C Input/Output, Quantity:

That combined with this from Amazon:

https://www.amazon.com/dp/B0F8HW858S

And it fits perfect in the housing. Just put a little electrical tape over the positive/negative ends for safety; plug it in and you are good to go. If my math is right this should add about 70% capacity to an existing Sony battery (aka 1-2 more dives).

Here it is installed:

Edited August 25, 2025Aug 25 by insomniac

14 minutes ago, insomniac said:

I'm super happy; while building the custom battery for my wives housing I starting thinking if I could do something similar in my Nauticam Sony A1 housing. My solution is exponentially easier, and anyone with a similar housing can do this with no electronic knowledge required!

A bit of background, I noticed you can buy 21700 batteries with bi-directional USB-C circuit charging built into the battery itself; I was wondering if something might exist for 18650's as well; and it took some digging but I found some (and I was order #1001 AKA#1) so I don't think anyone else knows about them:

LBF Battery

Button Top Protected 18650 3500mAh Flashlight Battery Typ...

【Battery Specification】Battery type: 18650 Button Top PCB Proctected, Capacity: 3500mAh, Wh Rating: 12.95Wh, Voltage: 3.7V, Size: 18.5*70.5mm(0.72*2.77 inches), Feature: Type-C Input/Output, Quantity:

That combined with this from Amazon:

https://www.amazon.com/dp/B0F8HW858S

And it fits perfect in the housing. Just put a little electrical tape over the positive/negative ends for safety; plug it in and you are good to go. If my math is right this should add about 70% capacity to an existing Sony battery (aka 1-2 more dives).

Here it is installed:

I don't understand, do those batteries provide output voltage even through the USB charging port? Can you take a photo of what you've assembled? 1 or 2 batteries? A 18650 doesn't fit in my housing. The only free space is the space for the strobe trigger, but even there there are only 5 cm.

10 minutes ago, Davide DB said:

I don't understand, do those batteries provide output voltage even through the USB charging port? Can you take a photo of what you've assembled? 1 or 2 batteries? A 18650 doesn't fit in my housing. The only free space is the space for the strobe trigger, but even there there are only 5 cm.

The last photo shows the 1x 18650 battery in the housing (green thing on left) with it plugged into camera and the camera charging. This battery has a built in bi-directional USB-C port (most batteries this size only have support for charging the battery, not charging a device - but this one does).

As you can see in the upper right screen shot, it's charging my battery via USB-C.

If you have 5cm that is enough; you could fit in an 18500 battery (the 500 part representing 50.0mm or 5cm). Scroll back to see my custom 18500 battery pack for that solution.

Edited August 25, 2025Aug 25 by insomniac

I thought that 3,7V were not enough to charge the camera.

Thanks, I'll check the dimensions.

P.S.

Googling for that battery I came across a lot of extreme solutions 😄

1 minute ago, Davide DB said:

I thought that 3,7V were not enough to charge the camera.

Thanks, I'll check the dimensions.

P.S.

Googling for that battery I came across a lot of extreme solutions 😄

USB-C delivers 5V, I believe it just ups the V and drops the amperage using a micro boost converter.

Update: Just confirmed (see below)

**I'll keep this thread updated in case my camera starts on fire; you never really know with some of this stuff....

Edited August 25, 2025Aug 25 by insomniac

Not sure if I love this solution so far, the battery is getting pretty hot during the charging process. It would probably be ideal to run two batteries at 7.2V for this solution; but that requires "work." I'll keep an eye on the max temp of the battery with a thermal camera and report back.

Edited August 25, 2025Aug 25 by insomniac

18 minutes ago, insomniac said:

USB-C delivers 5V, I believe it just ups the V and drops the amperage using a micro boost converter.

Update: Just confirmed (see below)

**I'll keep this thread updated in case my camera starts on fire; you never really know with some of this stuff....

Wow nearly 4A, really too much

1 minute ago, Davide DB said:

Wow nearly 4A, really too much

Yeah, the charging circuit on this battery is not safe at all... My custom solution earlier in this thread is exponentially safer. Can't say I'm surprised #china.

So let this be a warning of what not to do or you could start a fire.

AKA: Only buy batteries from reputable sources; and if it's hard to find something there's likely a good reason for that.

These batteries are immediately getting disposed of. But the "silver lining" is these things did start "rebooting" on their own when max temp was achieved.

Edited August 26, 2025Aug 26 by insomniac

7 hours ago, Davide DB said:

I don't understand, do those batteries provide output voltage even through the USB charging port? Can you take a photo of what you've assembled? 1 or 2 batteries? A 18650 doesn't fit in my housing. The only free space is the space for the strobe trigger, but even there there are only 5 cm.

There's three issues to deal with and the voltage delivered is just one of them. First can you get a battery to fit and is what you can fit a decent enough capacity. Second How does the camera react when plugged in. Some cameras only accept charge when the camera is turned off, newer ones will draw from both USB-c plug and the onboard battery.

On getting batteries to fit, the 18650 is 18mm dia x 65mm long which is probably a Squeeze. You can get 18500 batteries which in the high capacity version might fit. For your GH5 a twin 18500 battery holder might fit like this one:

Battery holder

The 18500 is 18mm dia x 50mm long.

If you sourced two 18500 cells and wired the box so it was in series maybe you could use that and they seem to have a 2040 mA-hr version available. and that would have 15.1 W-hr available which is just a little more than the standard GH5 battery at about 13.4 W-hr. You could remove them from the holder and charge them in a Li-ion battery charger. The advantage of the battery holder is you can pull the batteries out and charge them in a regular charger.

Whether that is worth doing depends on how the GH5 behaves when plugged in via the USB port, the GH5-II it seems will power up through the USB-port but needs a battery installed, but it seems the GH5 only allows charging of the battery when camera is off. It is said to need at least 9V though and the two 18650 will deliver 7.4V. Using a dummy battery could also be an option, but to be worthwhile you would need more capacity in your extra battery, so probably 4 18500 cells but voltage is a little low at 7.4V.

Apparently the GH5 batteries are chipped and if the voltage is too low it assumes you are using an unchipped battery and won't power up, but if it's 8,4V or higher it will assume you are using an AC adapter with dummy battery, but much higher than 9 and it will maybe fry the camera. You could use a regulated step up converter, but that is starting to complicate things and you would be running out of space. The step up converter needs to supply 9V at 3Amps to keeps things stable.

I would also add I found this video talking about using an external battery to power a camera. Basically the issue is the voltage step up keeps the voltage stable at the 8.4-9V so the battery charge indicator always shows 100%. As the battery depletes eventually the battery protection circuit cuts in (assuming you have protected batteries) and shuts the camera off. There is no low battery warning!

The battery voltage can then recover after the camera powers down and the camera can re-start and it can cycle like this for a while apparently. The video says that this destroyed the circuit board in the camera after a few cycles. So you need to be extra aware of the power level in the auxiliary battery with type of system.

I see though he is using a very compact little step-up box to get the right voltage.

1 hour ago, Chris Ross said:

I would also add I found this video talking about using an external battery to power a camera. Basically the issue is the voltage step up keeps the voltage stable at the 8.4-9V so the battery charge indicator always shows 100%. As the battery depletes eventually the battery protection circuit cuts in (assuming you have protected batteries) and shuts the camera off. There is no low battery warning!

The battery voltage can then recover after the camera powers down and the camera can re-start and it can cycle like this for a while apparently. The video says that this destroyed the circuit board in the camera after a few cycles. So you need to be extra aware of the power level in the auxiliary battery with type of system.

I see though he is using a very compact little step-up box to get the right voltage.

Yes I knew that video and it's absolutely true for the O.G. GH5.

Normally UW I use the GH5II that has a different charger. With the MK2 they introduced an USB-C port with PD (Power Delivery) and it works in two ways:

• If you connect a normal 5V source (classic phone charger or power bank) it will be able to power on the camera but not charging the battery at the same time. IIRC when you power off the camera, then the battery is charged.

• If you connect a P.D. source (9V 3A) it will power the camera and charge the battery at the same time.

I've used the first method several times doing time lapses at home just connecting the camera to a phone charger and wall socket.

In an UW scenario, maybe even the first option would work: The camera start using the external battery and when it's depleted (the BMS cut out the voltage) the camera switch to the internal battery. I should try on my desk with a small power bank.

The second method requires a more specific circuit board (P.D.) and IDK if two 18350 are enough to power everything.

Regardless of the method, I'm agree with you: I would never, never power my camera simply connecting directly one or two battery. Maybe it works (previous posts shows that it works with Sony cameras. probably different camera brand implemented different logics. I would use a step-up converte with all the protections.

Here a video that shows the different options on latest Lumix cameras:

6 hours ago, Davide DB said:

If you connect a normal 5V source (classic phone charger or power bank) it will be able to power on the camera but not charging the battery at the same time. IIRC when you power off the camera, then the battery is charged.

I did a quick test of the first option, connecting the camera with a full battery to a normal USB charger.

Upon connection, the camera warns you that the connected power source is weak and can only charge the battery when the camera is off.

I started recording in FHD (otherwise I would have filled the card) and after 50 minutes the recording was still going and the battery was still at 100%.

When the USB charger was disconnected, the recording continued without issues, using the battery.

So I would feel confident in confirming that a couple of small batteries in parallel with a step-up converter with the proper protections would be enough.

In my housing, the main problem is space.