MK 15.5 battery

Niels Doorduijn

List,

I am looking into making batteries for the MK 15.5. I understand that the way to do it is called spotwelding. Looking at marketplaats.nl and other second hand places in the net, I found several spotwelding-machines.

Does anyone know enough about spotwelding and batteries to tell me what type of spotwelding machine I would need (obviously, I will need to figure out how to use them, but that is step 2).

Alternatively, does anyone know of a company which sells mk 15.5 battery packs in northern Europe? I asked an electro shop locally and they asked about 30 euro's for it, when ordering 10 to 20. Not too bad a price, but as spotwelding equipment costs about 250 euro second hand .....

Rgs,
Niels Doorduijn

decoweenie

FWIW, I used to make my own battery for the MK-15 (which is essentially the same unit except for the scrubber size)...

The method that I use was:

• line up the battery in a bundle
• tape around to keep them together
• break small sections of metal paper clip to lengths needed between terminals
• solder the clips directly to the battery terminals, then the connector
• let everything cool
• wrap everything tightly with electrical tape

I am sure there are much better ways, but that method provided enough working batteries for a few years of diving the unit...

If there was a source to make them professionally back then, I would have bought them without hesitation since my soldering skill is non-existent.

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Steve

It is easy to spot weld them, more reliable than soldering and much easier than soldering. It is even quite easy to build your own spot welder perfect for making battery packs. I use lithium batteries for their excellent energy density but they are a pig to solder as a lithium battery fire isn't much fun and neither is over heating them and reducing their performance.

When I built my welder I bought a pack of el cheapo batteries that I had no intention of using, I just wanted to practice and to get the input voltage for my capacitor sorted out. You want it to happen quickly but not get to hot. I just used a single 1 Farrad cap

Ebay is your friend but the strip nickel is hard to track down and if anyone has a source I'd appreciate it.

Here are some links to start you off. Have a read and get back to me if you have any questions.

Hobby Spot Welders
philpem.me.uk :: electronics :: welder

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jvos

I wanted my batteries to be easily replaceable, so I went to Radio Shack and bought 2 - 4 cell holders and 2 - 9 volt terminals for about $10. total. Now I can replace the cells anytime with no soldering. Hopefully the picture will help.

Jeff

Attached Images

DSC00807.jpg (72.6 KB, 189 views)

decoweenie

Have some green!

Sometimes you see something and just want to smack yourself in the head for not thinking of it. This was one of those moments...

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schford

superb.... coudl this be the easy solution for Meg BAttery packs too

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Skipbreather

Hi Stuart-

Not sure if what is pictured above will fit, but I found an even easier Meg solution. It is simply a 9v connector hooked up to the appropriate Molex connector for the Meg. I’ve had an alkaline 9v (advertised at 400 mah capacity) still going strong at 4 ½ hours of use. Lithium 9v cells as used in smoke detectors & medical gear are advertised to have 3 times that capacity (1200 mah). Although I’m a fan of the C cell lithium battery packs, I keep a sealed 9v lithium and the appropriate connector in my save a dive kit.

Important disclaimer: I have the APECS 2.xx electronics, and I know you have the Shearwater. I’d contact either Leon or Bruce before trying a 9v. Smoke tests can be SO expensive……

Best,
Ken

koputai

Not sure which rebreather you're using there Jeff, but that won't power a 15 or 15.5. The electronics need +/-12VDC, that set up gives +/-6VDC which will NOT open the solenoid, and probably won't even light the LED's in the primary.

Jason.

Steve

There are 8 batteries in that pic Jas

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koputai

Try the maths again Steve.
8 x 1.5v = 12v. Yes, eight cells gives 12v.
But, the 15/15.5 requires +/-12v, which is 24v all up, so requires 16 cells.
The standard 15/15.5 battery consists of 18 cells, giving +/- 13.5 volts for a total of 27 volts. No matter how you wire up eight cells, you're never going to run a 15/15.5 on them.

Jason.