FM Li-Ion Battery Holder With Balance Charging Taps (Pictures)

[LuxLuthor]

I decided to make a 5 tap wire balance charging setup with the 2P-4S FiveMega battery holder that Litho sold in this thread. It works great, and the only thing I am looking for now is a 5-pin round plug fitting that I could put on the tailcap, but it needs to have a ring that would be attached to the tailcap that allows the center 5-pin plug to rotate so the wires don't get twisted when replacing the cap.

For now, I left the pigtail of wires ending in a 5 pin JST connector that plugs into the Tenergy charger. Because this is 2P-4S using protected 14500 cells @ 750 mAh each, I charged it with the Tenergy at 1.2A

One of the reasons this light was failing so much was the bottom contact shown in this picture was two separated pieces which I soldered together, giving reliable contact to the center post. Otherwise it was very easy for them to not touch reliably to make contact.

I used some very thin copper strips that could be cut to shape for the contact points with scissors.

 

[VidPro]

wow, i was wondering how you were going to pull that off, that is awesome.

 

[LuxLuthor]

I'm on the hunt now for a 5 pin round plug (like a DIN plug) that I can have swivel in the cap while tightening it down. Then just make an external plug match up with it. Something like these types of connectors.

This is gonna be like a search for the Holy Grail.

 

[AlgaeEater]

God speed good man.

 

[LuxLuthor]

You can imagine how much fun it is to search through all these esoteric electronics websites....like watching paint dry.

 

[Lips]

Nice work! These will be standard issue at some point and you may have pushed up the time frame :thumbsup:

 

[LuxLuthor]

I am still looking for a good 5 pin connector that I can have in the tailcap, but that won't rotate as the tailcap is tightened so the wires don't twist, then I could easily make a connecting cable with various charger connections. I'm looking at some things like this page shows which is the type XeVision uses in the XeRay spotlights, and is the best option I have found so far.

In the meantime, to get more accurate balancing with my Hyperion LBA-10 balancer, I made this other adapter cable that works great. The Hyperion balances the cells to within 0.005 V (5 mV) of each other, and can even work without a charger, by bleeding off voltage from the highest cells.

Click for hi-res image

 

[VidPro]

i have used those types of "microphone" din connectors for 12v power before they are much capable of powers exceeding mic line levels. we ran 1-2Amps through them with no problem, i would bet they are good for more like 5-10amps. we chose that method, because it could be Locked down, unlike your average cig lighter connect.

people are using "USB" type connections to get very small connections. of course that would be a disaster the first time somone shoved it on a USB itself USB conncections come in the tiny 4 or 5 pin, and the larger 6 pin, and will not rotate as you have here. the really small ones are only good for a max of 1-2amps, and only when fully pushed in.

 

[LuxLuthor]

Thanks for the feedback. I will probably order a variety of 5 pin connectors and mate plugs just to play around and get it working. Given that many of these Li-Ion lights go up to 4S reaching charging peaks of 16.8V (4 x 4.2V cutoff), but likely not more than 1.5-2.0A per cell tap, I'm thinking the DIN are probably the safest.

I'm trying to picture getting the USB to work. My goal is to have something on the light that would be FLUSH with the tailcap which needs to rotate around it. I don't want the pigtail coming out like it is now.

I guess I could have the rectangular end of USB or Micro-USB BELOW the inside of the tailcap...or make the tailcap hole large enough so it goes around the longest side of the USB plug. Not sure of the current/voltage parameters of USB connectors...since most of those devices are very low power.

 

[petrev]

Nice . . .


The mic plug/socket conn. system looks good.

Keep up the good work
Pete

 

[LuxLuthor]

I finally found the parts at Mouser, and I ordered a bunch of variations of the 5 pin connectors like this one. Man I need those calipers I ordered from harbor freight....like....yesterday!

 

[Aircraft800]

Doesn't your battery pack tail portrude threw the cap? Can't you attach the connector dierctly to the tail portion of the battery pack, and adjust it so it is flush with the cap? You would just have to drill the cap to fit the connector and there would be no twisting issue.

I must be missing something here.

 

[LuxLuthor]

Doesn't your battery pack tail portrude threw the cap? Can't you attach the connector dierctly to the tail portion of the battery pack, and adjust it so it is flush with the cap? You would just have to drill the cap to fit the connector and there would be no twisting issue.

I must be missing something here.

If you look at my pictures, normally the end of the aluminum charging post goes inside of the tailcap spring and as the tailcap is screwed down the aluminum charging post end of the battery holder becomes flush with the outside.

Now you need to find a 5 pin connector that can attach to the balance tap wires from inside. That 5 pin plug will partly be outside the cap, but the wires are soldered underneath it (and will be inside of the spring & cap).

If you have the 5-pin plug outside the tail cap, and wires going inside into the battery holder, you need to be able to screw the tailcap back down without having it rotate the 5-pin plug (with wires soldered underneath)....without twisting the wires all to hell and shorting one out, or breaking a soldered contact. The consequences of shorting out a Li-Ion is no small matter.

There are no 5 pin connectors that are made that I have ever been able to find that are small enough to set this up SAFELY in the space below the tailcap....so that if it were all attached to the existing aluminum charging post like it is with FM's center pin arangement, that would be ideal....but there are no connectors made that small for 5 pins