Question about battery testing

[robo]

Hi there,
I would like to change the B90 rechargeable Ni-Cd Batteries for my Surefire 8NX when they are nearly empty, but before the light starts to get yellow, because from that point it only runs for about 10 seconds, and when on duty I sometimes don´t realize it at once when I´m concentrated on dealing with people and I don´t want to deep-discharge them. So I tried to find a battery tester to check
the batteries, but all the battery-testers one can buy seem to have just 2 settings, one for 1,5 Volt batteries and one for 9 Volt batteries. I tried some other settings with a thing like a combined voltmeter/Amperemeter (Please forgive me, I really aren´t an electrician). It showed something like 3.5 Volts on my fully charged B90 and around 1600 or 1.6 in "DC A" mode.
Can I test the battery with that one or is something different required????
((I also posted this on the electronics-forum, hope this is ok))
Thanks for your help

 

[lemlux]

Better yet, is there a reasonably priced conditioning smart charger that will discharge the B90 NiCad and shut off when charged?

I have an older MAHA charger with and alligator clip cable that sometimes says it recognizes my B90 and sometimes doesn't.

I would love it if I knew someone who was competent to make up some aftermarket B90 packs with the 3000 mah Sub C Nimh's that are designed for racing cars and rated for drains of up to 20 Amps.

I've seen "matched sets" of 6 separate cells (enough for 2 "super B90's) selling for $55.

I don't know if any hobby shops could easily duplicate the SF connector hardware that goes in each pack.

I gather that SF hasn't sold any of the 3000 mah Nimh batteries in packs because they aren't as forgiving to overcharging. My basic 300 Ma SF charger is a dumb "put an empty battery on the charger and take it off in 12 hours or you'll damage the battery" charger. I suppose I could monitor heat with my hand if I knew how hot was too hot.

Then, when I buy my 8X Hola on the 12th of Never I'll be able to run it for a while.

 

[robo]

The Charger which comes with 8X/9N series Surefires is a "smart" charger, according to the manual. There it sais that you can charge the battery in every condition and the charger will charge it and keep a small flow to keep the battery fully charged - no overcharging. Don´t know if that is true in reality.

 

[lemlux]

Robo

Maybe the new chargers and fast chargers are more sophisticated than mine. For your sake, I hope so.

 

[Chris M.]

I bought my 9N from CPF member Dennis Wong, and he had made an extra capacity NiCd battery pack for it. 2400mAh and it works in the CN800 charger, not sure how well higher capacity NiMH would do as it`s not really designed for them. Seems to give just over an hour of light, but I havn`t runtested it yet, all my runtests are suspended till I get my new PC. The last thing I want is for the system to fail halfway through a test and lose all the results.

Anyway, from what I can tell, it`s one half of a 6 cell sub-c racing car pack, or maybe from some other configuration. I`ve seen ones for RC boats which are 2 side by side packs of 3, joined by an interconnecting wire. The three batts are joined by flat metal strips, spot-welded. He`d just removed the tabs from the bottom of the first cell, and soldered on the positive terminal from a defunct 9v battery to the top of the 3rd one, then shrink wrapped it all together in a tube. It`s mildly longer than the original B92, but works fine in the light.


Assuming you can solder to large metal surfaces (ie, got a big-*** soldering gun), and don` mind hacking a racing battery pack in half, try it. When I get the time, I`ll have a go myself- those stock B90s are fairly underperforming by todays standards and I could do with some packs to keep charged seperately as backups. And if the SF chargers don`t like the cells, a different one (like those Mahas) would be OK.


But I must admit I do like the charge-in-place option of the 9N/CN800, seems better than having to remove the batts to charge them seperately. I`d not be too keen to lose that ability.

 

[Brock]

moving over to the battery section.