DIY Hid light batteries

[Kwbyron]

yeah, mine will be a perm. battery pack...although I might re-do it later. all the parts for it was less than $10, and I am thinking of getting 10 more c-cells and putting them parallel to my first set to double the burn time.... I bought these 10 for $40 on ebay though... I'm not doing extensivly long dives yet, so I think an hour will be sufficient....

 

[SmileMon]

Check out CTA batteries for D size and 6000 (model name) for C size.

I think you can find both on bhphoto.com

 

[ultravinnie]

do not use lithium ion cells.
the charging electronic is a precision circuit. evven beeing off a tenth of a volt leads to exploding cells.

another problem is what happens when the thing chould flood.
lithium reacts violently when in contact with wather. should the cell casing be eaten away by the initial contact with saltwater ( remeber what a happens to a normal cell when dunked in saltwater : the brown muck and corrosion eating away the cell casing ... )
the lithium will be exposed and come in contact with water.
lithium strips the electrons from the oxygen atom in h2o effectively breaking it apart in hydrogen and oxygen. during that process a lot of heat is generated. enoughto make the generated oxygen self combust. with the generated hydrogen in the vicinity ... you get the picture.

this from someone who worked on the silicon (chips) for battery chargers in cell phones... DON'T MESS with LiIon ! i have seen batteries attempt to reach 'orbit' in the lab. those were the real tiny cellphone packs. they blast holes a foot in diameter in a lab bench that is an inch thick...

if you can get a standard liion battery pack ( like a camcorder battery ) AND the charger that is built for that pack then you may give it a try. but please do not attempt to build you own pack and charger from parts. you are playing with your life. For safety reasons almost all the commercial cells these days have the actual charger electronics built in the cell. ( while charging every individual cell in the pack needs to be monitored and the temperature measured as well as the voltage across each cell and the current throught it. charging is done under supervision of a cpu )


make sure that your housing is waterproof.
the few commercial systems out there that use the LiIon cells have a precision milled housing that leaves virtually no room between the housing and the cell. the entire cell is then immersed in 'potting compound' making the cell waterproof. the only two things that stick out are the two wires. the rest is 'potted' in there and cannot be removed.


commercial battery packs include protection circtuiry ( thermal control circuit , over discharge protection ( a sort of electronic fuse ) and overvoltage protection for charging. the connection strips in the cells are also a special contruction. they will 'fuse' ( actually 'open') when a hazardous condition occurs, effectively disconnecting the cell forever.

 

[ultravinnie]

if you are looking for NiMh cells check out www.digikey.com , www.mouser.com and www.jameco.com

they sell the bulk cells. ( no frills cell used to make battery packs ) you can get the tabbed flat-top versions ( tabs are spot welded and there is not 'top' like with a standard cell at the + pole )

they can even pre assemble the pack and overmold it with heat schrink for you.

they hace true C eand D cells ( 4500 and 9000mA capacities ) , not an aa cell packaged in a D can ( 2500 maH )