Can Dead B90s Be Resurrected?

[nein166]

I've been using an 8AX for 3 years now at work on a daily basis. I bought it after the charger was redesigned to not kill the batteries, the indicator blinks(my good fortune). My original B90 lasted a year after being recharged about every other day, so I bought another, it wasn't so long lived. Number 2 started dying after 6 months so did I call in a warranty with SF? Heck no I got some Sub C NiMH 3300 cells and rebuilt both sticks.

I also opened up my charger and noticed the letters "NiMH" on the pcb next to "NiCd". I'm OCD about opening everything to see how it works even if I have no clue about what I am looking at. Well in between NiCd and NiMH it says "SW1". I removed the trace bridge and added a switch hey guess what theres a rectangular hole under the instruction sticker right on the back plate. I moved the sticker and now with a screw driver I can switch between both charging modes. Its almost like SureFire was planning on upgrading its batteries and included this option in early planning but forgot to remove it after figuring out what Stride Gum found out. Longer lasting is bad for business! Well its good for me and my charger doesn't blink in the NiMH mode. I think I'm getting a full charge after 1 1/2 hours on my NiMH 3300maH stick. I took a pic before adding the switch. Its all at work so I never test it for voltage off the charger or runtime I just know I can charge it once every 2 weeks. It helps to run a X80 LA modded to SSC on a GD750 (sigline link #1)

I recently snagged some dead B90s and 8NXs on CPFMP for cheap, and decided to upgrade these B90s as well.
Got these button top cells from all-battery, not sure if I believe the 4500maH claim but the price is right, and I got free shipping at the time.

I'm getting heatshrink tube and kapton tape, to isolate the negative return ribbon from the first 2 cells in series. Now I don't have a tack welder and I've heard soldering to the battery case is a bad thing for the cells so....
My Question to you the community is will the heatshrink be enough to hold the cells in contact with each other and the ribbon to the last cell? Or is there a conductive epoxy out there that will hold it all together better under the heatshrink.
ASEpoxy is not conductive enough.
I considered a conductive sheath heatshrink tube and kapton taping the first 2 cells but the tube is too expensive at 1 1/2" dia.
Thanks,
Brian

 

[nein166]

Any body have experience with heatshrinking their own battery sticks

Or using epoxy to hold batteries together?

 

[65535]

You need THIN solderable metal strips long enough to go from the middle of one cell to the middle of another cell when stacked next to each other, go + to - except on the first and last cell. Tin the bottom of the ribbon with solder, and tin THINLY the top and bottom of the cells then solder the ribbon on both cells. Requires a 50+ watt iron. Then heat shrink them together tightly.

LuxLuther could also do this quickly for you with tack welding, or someone with a high powered soldering iron could do it.

 

[SilverFox]

Hello Nein,

My original charger actually had the switch in it. When I did the run of NiMh B90 battery packs, I was unable to find any difference in charger performance when switching between NiCd and NiMh. Have you done any testing and been able to uncover any differences between the two settings?

At any rate, my goal was to find an improved battery pack that would work with the stock charger. I didn't spend a lot of time testing the charger.

Making the - connection using heat shrink to hold it in place will work, but it is not durable. Spot welding is best, but soldering is also very good. To get the highest voltage from the pack you need to minimize any resistance.

A problem that comes up is that the larger capacity cells are physically larger. The 4200 cells won't quite fit into the charger. You can jam them in, but it is a very tight fit. The other problem comes with the diameter. The higher capacity cells are also larger in diameter and won't fit all of the lights that use this battery pack.

Interesting choice of cells... I was also thinking about using those cells and putting together a more reasonably priced pack. I ended up rejecting them because of cell to cell variations.

Grepow makes some very good cells for power tools. Tenergy gets some of these cells, but it seems they also throw some junk cells in as well. The price is right, but after I sort through the cells and find matching ones, I am ahead getting cells that cost twice the price and work properly right out of the box.

Tom

 

[nein166]

You need THIN solderable metal strips long enough to go from the middle of one cell to the middle of another cell when stacked next to each other, go + to - except on the first and last cell. Tin the bottom of the ribbon with solder, and tin THINLY the top and bottom of the cells then solder the ribbon on both cells. Requires a 50+ watt iron. Then heat shrink them together tightly.

LuxLuther could also do this quickly for you with tack welding, or someone with a high powered soldering iron could do it.

I'll try tinning the strips and cell. I think I can reuse the strips from the original B90s.

 

[nein166]

Hello Nein,

My original charger actually had the switch in it. When I did the run of NiMh B90 battery packs, I was unable to find any difference in charger performance when switching between NiCd and NiMh. Have you done any testing and been able to uncover any differences between the two settings?

At any rate, my goal was to find an improved battery pack that would work with the stock charger. I didn't spend a lot of time testing the charger.

Making the - connection using heat shrink to hold it in place will work, but it is not durable. Spot welding is best, but soldering is also very good. To get the highest voltage from the pack you need to minimize any resistance.

A problem that comes up is that the larger capacity cells are physically larger. The 4200 cells won't quite fit into the charger. You can jam them in, but it is a very tight fit. The other problem comes with the diameter. The higher capacity cells are also larger in diameter and won't fit all of the lights that use this battery pack.

Interesting choice of cells... I was also thinking about using those cells and putting together a more reasonably priced pack. I ended up rejecting them because of cell to cell variations.

Grepow makes some very good cells for power tools. Tenergy gets some of these cells, but it seems they also throw some junk cells in as well. The price is right, but after I sort through the cells and find matching ones, I am ahead getting cells that cost twice the price and work properly right out of the box.

Tom

Thanks for the info I will take my DMM and take some readings on the 2 different settings. I can do a runtime test till the light starts dimming. But I don't have the tools to be accurate (light meter, smart charger)

These cells stripped of wrapping are the same dia. and .5mm longer than SF's Sub-C cells so the new stick should fit. If ~1.5mm is too long I'll sand down the back of the charger.

I don't have the tools or skills to test and match these Tenergy cells.
Best I could do is charge each up let cool for set time, and discharge each for a set time and match by end voltage. Would that be a good test?

 

[SilverFox]

Hello Nein,

If you can figure out a way to apply a load to your cells, you can match them by keeping track of runtime down to a cell voltage of 1.0 volts. Run each cell individually and match the cells with similar runtimes.

Tom

 

[dano]

When I made the first hi-cap three cell sticks for SL Stingers and B90 replacements, I used R/C car packs. The three sub-c cells are already connected and I added a nipple from a 9volt battery to the positive tip (for the B90) and re-shrink wrapped the stick.

For Stinger sticks, I was fortunate to have a bunch of dead stinger battery sticks and scavenged the parts needed to place both ends of the battery on the positive side (the metal ring and flat ribbon that connects to the negative terminal of the stick).

My first sticks were using NiMH 3300MAH cells, but the newest cells are rated at 4500MAH in capacity. BUT some of these cells are too thick to get into a SF 8X (at least my vintage 8X. The newer 8AX's may be different). The thick cells fit in a Stinger.

Charging is an issue. Using a dummy slow charger, the hi-cap cells charge fine.

Using a peak charger with the stick in the light (Stinger) caused some issues as there's a diode in the light, and most chargers will not detect the voltage drop needed to stop the fast charge cycle. I used a gutted Stinger cradle plugged into an Integy brand charger that charged via capacity: I can enter the capacity I want and the charger will shut off when that capacity is reached. This isn't an issue with a dead/used pack, as the charger will shut off o.k. Charging a partially discharged pack using this method may cause the pack to vent or overheat as the charger doesn't know when to turn off.

Charging outside of the light is easy with any peak detection charger. You just have to make an appropriate fixture to hold the stick.

-dan

 

[SilverFox]

Hello Dan,

The question was brought up if you could simply use heat shrink to attach the negative ribbon to the bottom cell. Have you ever tried that?

I have always spot welded or soldered the connection, but don't know if a "shrink" connection would work, or hold up over time.

Tom