"C" battery modification

[Anthony P]

I have an Aries 100, 532 dpss that I purchased over a decade ago. It runs on 2 "C" batteries. Full strength battery life is only a few minutes. It draws about 0.7A. I am thinking of building an adapter to use a single 18650 battery instead.
Questions:
Does such an adapter exist I could just buy?
What about 1 or 2 ,1N5402 diodes to drop voltage a bit?
Any better ideas?

 

[brendon7358]

You have tried different batteries right? It should last longer than that. Would a 26650 fit? Those come in pretty high capacities.

I know some cheap rechargeable C batteries are just a shell with a AA inside.

 

[paul1598419]

I believe they still make a NiCd battery in a C size cell that is close enough to 1.5 volts to work. It has been many years since I bought any of these batteries. I bought ten NiCd D cells for $120.00 back in the 70s for a Tektronix scope I had back then.

 

[CDBEAM777]

Hmmmm….MAYBE !!! Go with a single 26650 LiPo…...4.2 VDC nominal....higher than the 3.0 VDC of the C cells,,,,THAT may blow the pump diode !!!!!...
Check with the manufacture !!!!! Who made this unit ???? Laserglow ???? Check with them !!!

Size is NO problem !!! Get a short section of Black Tubing....3/4 Sprinkler Irrigation tubing....sand out the ID a bit...THAT works perfect !!...For diameter adapter....Length is another issue....Maybe an Aluminum bar....on the negative side only !!!!

Like I said...check with Laserglow…...Do not use ANY LiPo ...unless they say the cell @ 4.2 VDC will NOT damage the driver or Pump Diode !!!!

How to drop the 4.2 VDC to 3.0 VDC...NO IDEA !!

CDBEAM

 

[RedCowboy]

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=rechargable+C+cells&_sacat=0

 

[Anthony P]

Thank you, gentlemen, for your advice. Just received response from LaserGlow. Max input voltage is 3.6V. Also the coherence length is only 1-2mm... no holography from this one. I will start with C NiMH and see how it goes. I may still end up building an adapter for 18650 or 26650. The voltage would be a concern. I could probably find a LDO voltage regulator or just series a couple diode droppers. As with any experimental science, at this point, all I can do is try and see what works best.

 

[Cyparagon]

You may also wish to consider the "4/5 sub C" NIMH. This is one of the standard sizes used in battery packs that is conveniently 2/3 the length of a standard C cell. This means 3 cells will fit where the 2 C cells sat previously, at 3.6V instead of 2.4V. That may or may not be necessary for full power, depending on how well the driver was designed.

The 3.6V max spec they quoted you isn't based on an actual overvoltage condition, but rather a driver overtemp condition, since this is a linear driver. This also means 4.2V for a few seconds would be harmless. Lithium cells are NOT nominally 4.2V devices, they quickly fall to somewhere closer to 3.6 or 3.7V under load.

2 alkaline, 2 NiMH, 3 NiMH, or 1 lithium would all be close enough, unless the driver was designed poorly.

 

[Benm]

There are some options here - apparently this laser needs a battery voltage close to 1.5 volt per cell to operate, though may not be the only problem: 0.7 amps on a good alkaline C cell is not that big of a load, so it really shouldn't lose much power in a few minutes on fresh cells.

I suspect the problem might be thermal.

One thing to attempt would be to run this laser off a 3.0 volt lab supply and see if the power still drops off. If it does you can be sure the issue is thermal and no solution in using different batteries will make a difference.

 

[Lifetime17]

Hi, A 26500 is equivalent to a c size battery I use them in aa few builds . Thats if your laser can handle 3.7v's sort about being late to the party.

Rich

 

[Anthony P]

Contacted LaserGlow. Battery end-cap is usually the problem. I polished all connections and wire brushed the black anodizing off of the threads. It seems to work much better now. I am still going to experiment with 18650 battery adapter as I have all the parts laying around and that is what hobbyists do.
BTW while researching 4/5 C cells I found premade 3 cell sticks NiMh.
To clarify, battery drain persists though everything else works much better since cleaning.

 

[Anthony P]

Battery adapter is up and running. It uses 1- 18650 battery to replace 2- C cells. I used a single 1n5402 diode to drop voltage a bit. Fresh charge output is 3.9V. It fits nicely into host. Optical output is stable and back to original specs. It took a bit more tooling than anticipated, as all of the parts almost fit. Total cost, including battery, was about 10 bucks. I will try to get some photos up within the next few days.

 

[Seoul_lasers]

Very nice modification, it makes me wonder if once could make a 26650 out of smaller Li-ion cells. 26650 cells in Canada are virtually non-exsistant due to the amount of lithium present and Hazmat fees.

 

[BowtieGuy]

Hey Seoul, are you just looking for a sleeve type adapter to convert something like an 18650 cell to a 26650?

Something like one of these ?

 

[Seoul_lasers]

Something that would take multiple smaller li-ion cells for upping the current.

 

[paul1598419]

If you are planning on paralleling cells that is not easy to do. You need to match them to keep one cell from being dominant and taking on much of the load.

 

[BowtieGuy]

There's also these type adapters for multiple cells. -Link-