My version of js's m6r LVR rechargable battery pack

The Surefire M6 is without a doubt my favorite incandecent light. However I think many of us cringe at the thought of 6 cr123s being done in less then 20 minutes with the wonderful MN21 bulb.
With that in mind I know I'm not the only one that was totally thrilled with the m6r battery pack when Jim announced it.
When I first saw it I decided it would be a fun project to build it myself, well its been close to a year but its finally done!
The biggest challenge was getting the darned LVR3i regulator. I contacted Willie Hunt directly but he really had no interest in selling me a small quantity(I totally understand from his point of view, but talk about frustrating!) I also let Jim know I was interested but he had none to sell at the time. Well around two weeks ago he decided to sell some spare lvrs he had so I jumped on a pair of them.

I had already built the battery portion of the pack six months ago. I used the same cells as Jim - GP1100s. I left the original shrink on them though and was quite please at how the end to end soldering turned out(some technique is required for this step!!!) I tested my soldering by snapping two soldered cells apart, if you get it right it is extremely strong and very very tough to break.

Being I've been waiting so long for the LVR3i's I've had lots of time to ponder what to use for end caps and how to integrate a charging jack.
I decided to use PC board for the end caps, using a small CNC machine I cut two round discs the right diameter. I also cut two more discs the same diameter but with center holes cut out.
For battery contacts I soldered brass washers to the center of each of the first two discs using silver solder. I took the copper off the second set of discs and they became washers to put on the ends of the pack that allowed the brass contacts to be slightly recessed - same as the contacts on the original M6 battery pack.
I then attached the LVR3i pretty much the same as Jim does, I did however add a 25 volt 470uf super low ESR capacitor to the input of the LVR - it was what I had on hand and just fit. Having a super low ESR capacitor on the input should give a little more runtime as the batteries will see a more constant load as the PWM supply switches which in turn keeps the batteries and FET cooler.
The last step was to integrate a charging jack into one of the end caps. I used a JST connector(widely used in the RC hobby industry) which was glued to the negative end cap using CA, I then used ShoeGoo to attach the rest of the connector to the batteries themselves which should give it plenty of strength. The entire connector is recessed so there is no chance of anything shorting out.
The final step was to finish the pack with black shrinkwrap, polish the contacts and build a charging cable to connect to my Schulze 330D.

I'm very pleased with the results, the pack is working great!

My hat is off to Jim who spent countless hours building m6r packs for people. At the price he sold them for he certainly had no plans to make any money. These things just do not go together quickly, and several steps, such as the soldering of the cells together requires technique and experience.

I believe Jim still has lvr's left, so maybe this will inspire someone else to also build one!
If anyone has any questions fire away!

Edit - here are some links:
Original project by js:
https://www.candlepowerforums.com/threads/64008
Forsale thread for the LVR3i's
https://www.candlepowerforums.com/threads/116544

Here are several pictures of the end result:

The pack built, lvr side:

The pack built, charging jack:

Negative end with charging jack:

Positive end:

Pack with shrinkwrap:

Pack charging:

Fantastic - great job !!!

Will

outstanding , makes me now ponder a m-6 which i would not do unless rechargeable, i don't like rechargeables in general but for a m6 i feel it a must , can you preform some tests , will you make more ?

TENMMIKE said:

outstanding , makes me now ponder a m-6 which i would not do unless rechargeable, i don't like rechargeables in general but for a m6 i feel it a must , can you preform some tests , will you make more ?

Click to expand...

I plan to make one more with my other LVR3i, but its going to be a little different - still cooking up the plans to that one, if/when it happens I'll post about it.
There is currently another rechargable option in works for the M6 using lithium ion cells, maybe that would work for you:
https://www.candlepowerforums.com/threads/114948

Very well done. How long does it run?

Curtis

sweet job!

nice recessed connect design.

Nice job

Good charger too.


Tim.

TheSteve,

Congratulations! Very nice job! Few people probably REALLY understand how much work and ingenuity is required to build your own first M6-R pack, but I am certainly one of them, and my hat is off to you.

I really like the way you did the charging connection. That is one of the things about my own M6-R packs that I feel is less than ideal, because the charging connector is not securely connected to the pack and can in extreme cases get bent outwards. And while this does not cause any problems, and can be just bent back in again, it just doesn't feel as solid as I would ideally prefer.

The way you did it solves this problem. Of course, in my case, I would have had to put holes in the copper end caps to do this, and that would have meant more work--and more work is definitely NOT the way I wanted to go with a re-design! LOL!

One quibble--

I actually don't think that the runtime will be extended with a capacitor across the inputs.

But, I could be wrong. Might be interesting to do the test and see if the cap does in fact increase rutime to dimming.

Probably, for higher capacity, lower draw rate cells, an input capacitor would make a runtime difference--and I would DEFINITELY recommend a cap for use with Li-ion or Li-poly cells and an LVR--but for medium or high draw rate cells I would very much doubt that it would extend runtime.

That said, it's certainly a nice thing to add, and can only help matters. I didn't want to deal with anymore space issues than I already had to, so I left out the input cap. But that was the only reason.

Anyway, congratulations again! Very nice work. Quite an accomplishment!

Thanks for the kind words Jim! I haven't done a runtime test yet but will after there are a few cycles on the batteries.
How much difference the power capacitor makes remains to be seen,
I haven't yet scoped the output to see what frequency the PWM operates at.
I am very into the RC car hobby where the controllers and batteries depend on the power capacitor - so I had to do it!(they do use higher amperage though)

a second on the nice solution to the charging jack! really nice job on the top n bottom plates too.. I hope people can carbon copy your solution and use the WH LVR that JS is selling hate to see them not be used.. great regulators.

-awr

Very nice setup. I wonder how long it will be until people ask you to build more ?

Well if you ever want more practice I would be happy to finance and test it. Brilliant work.

Great Job! Whats holding everything together?? Is there a center rod?


Mac

andrewwynn said:

a second on the nice solution to the charging jack! really nice job on the top n bottom plates too.. I hope people can carbon copy your solution and use the WH LVR that JS is selling hate to see them not be used.. great regulators.

-awr

Click to expand...

Haven't used mine yet though. I want to try to lose the undervoltage blinks but I haven't posed the question to JS yet if the sense resistor controls it or the MC.

cmacclel said:

Great Job! Whats holding everything together?? Is there a center rod?


Mac

Click to expand...

The cells are directly soldered to each other and then the three sticks are glued together using shoegoo. The positive connection from the batteries is soldered directly to the top contact PCB. The negative contact is held in place by the connection wire and a very small amount of glue. It was actually strong enough to use before the shrink wrap was added. With the shrink wrap applied its very solid.

I would have loved to use a rod down the center but there really isn't the space required. It would have to be insulated somewhere as the ends are the contacts.


I've yet to see any low battery warning flashes, when my battery dies it dies fast(as a good NiMH pack should)

have always like solution using multiple nmh cells VS multiple li-ion cells. unless newer saphion technologies is used. always more hazards using multi-cell li-ion packs VS multi NMH cell packs.

nmh has drawback to not holding charge near as well as li-ion. but has huge advantage of safety margin during charging. both versions will sustain current loads needed to drive NM21.

if you own a shultz or triton, charging either version is no problem. IMHO charging a large capacity multiple cell li-ion pack requires a high end charging solution like triton or shultz for safety. VS a low end charger can be used safely for multi-cell NMH packs.

correct me if I'm wrong, a while back there was a post that covered, NMH packs will outperform li-ion packs in extreme cold conditions.

JS's design has the further advantage of not requiring an extension to surefire M6. totally elegant solution!

again wonderful job building your pack! if you decide to put this into production. folks will be lining up....