Mag85 instaflash, switch to 8 cells?

[VegasF6]

Well I finally got my new pack charger and promptly instaflashed my 1185 with about 30 mins max runtime on it. The 9 eneloops came hot off the charger at 13.04 volts and like a big dummy I popped it right in. After looking at the destructive bulb test data I guess I realize my error

Just how much can I expect voltage to drop after say a couple hours resting time? Or is this a myth? Should I switch to 8 cells and a dummy? If so I may as well just get a 2d bored to accept 8AA.

Thanks.

 

[mdocod]

A few hours of resting will definitely help a LOT with NIMH, which comes off the charger ~1.45V per cell (13.04V that you measured correlates to this accordingly)... A few hours and they will settle down to below 1.4V per cell. Which makes all the difference in these applications.

Also, when cells are fresh off the charger, they are above room temp by a fair bit usually. Higher cell temperature results in a more "excited" electrolyte, which has the effect of increasing voltage under a load.

Rest your pack and your bulbs will thank you

Eric

 

[VegasF6]

Well, after about 4 hours sleep (which is entirely not enough by the way) AND 4 hours rest for the pack, voltage is at 12.81.

I figures within a second or two that should drop .1~.2 volts at the approx 3.5 amp load. Still somewhat dangerously close to flash voltage.

Is there something inherently wrong with my complaining that my low self discharge batteries are (*edit* I meant are NOT)self discharging fast enough for me? What a whiner

I do have a modified tailspring, but never did get around to the switch fixes yet.

Well it is one more testament to your battery carriers, Eric. Thanks bud.

 

[mdocod]

You know, I had never really looked at how slow/fast the eneloops "settled" down off that high voltage from the charger... I'm surprised to hear they only dropped 0.025V per cell in 4 hours off the charger... Maybe wait another few hours, hehe.... I think if it were me, I'd wait till the pack was reading ~12.6V or less if possible... I'd say leave your switch alone, you need the resistance at this point

Eric

 

[Illum]

hmmm...9 cells off the eneloop charger doesn't appear to instaflash any of my mag85s...but then again my old clunker mag probably have alot of hidden resistance compared to yours.

I'm not sure what the 1185 looks like with 8 cells, but there shouldn't be any considerable difference. I'll need to try that tonight:twothumbs

 

[fugleebeast]

I did the same thing a couple weeks ago. I was all excited to play with my Mag85 again and thought, "bah, all that 'hot off the charger' nonsense."




I slapped myself and then ordered more 1185 bulbs. Two weeks later, after the bulbs came, I let the Eneloops rest for a few hours and had no problems. I've done a few resistance fixes to the mag but not all of them so I was quite surprised when it flashed.



I'm not sure about the 1185 but I tried the 1331 on 8 cells and was really unimpressed. I'd definitely stick with 9 cells.

 

[rjr104]

Someone here talked about a bleeder lamp which consists of a 12v 50w halogen lamp and a M16 ? socket. I nuse that and in about three minutes my 9 eneloops are discharged to a safe level (about 11.2). The bulbs are easily found at the home center. About 8 or 9 bucks for a two pack. I just used aligator clips initially before a got the socket off eBay for little of nothing. If you can't wait this works very well.

 

[VegasF6]

18 hours, down to 12.67
Funny how I hadn't had this problem before, this cheap pack charger must either really be bringing out the full potential of the batteries, or it is giving them a quick death! 1.9amp charge rate, terminated charge just fine and they barely got warm though, so I am hoping for the best. In the next couple days I am going to dis-assemble the pack and check each cells voltage, even though I know that isn't a very good indicator of "charged-ness" for ni-mh.

Don't tell my wife, BUT a little birdy told me to expect the LaCrosse BC-900 for Christmas :thumbsup: then I can properly analyze the pack. These particular cells have never been used in anything else, and have only a few cycles through them, and they were short cycles.

I wonder if I can design a voltage regulator based on the LM338 and fit it alongside the Kiu socket. It appears it can also function as a soft start device as well as a voltage regulator with a few more components...hmm.

 

[mdocod]

You should be fine after 18 hours. close enough.

The 1.9A charge rate will result in higher final termination voltages than a slower charge rate would, really fast charge rates can bring cells to ~1.5V per cell at termination... just thought I would throw that out

Eric

 

[wacbzz]

As much as I hate to say it, it's thread's like this one that makes many wish that AWR hadn't been such an A-hole...

 

[VegasF6]

Charged up my ROP pack even though it wasn't very low, I wanted to test this charger at .9 amps this time. Hot off the charger at 8.83V/6=1.47V gave it a 7 hour rest, 8.41/6=1.401.

Checked the 1185 pack again this afternoon also, it had about 36 hours rest, settled at 12.61/9=1.401 also. Same within a thousandth of a volt! I am not really sure what this tells me, but I have to guess it speaks for the quality of the batteries, huh?

 

[ANDREAS FERRARI]

As much as I hate to say it, it's thread's like this one that makes many wish that AWR hadn't been such an A-hole...

I only wish I had been around when AWR was offering his Hotdrivers.My only hope is if AW offers a regulated C or D Mag switch.Then we won't have to have a discussion like this.BTW,try sticking your batteries in the freezer for 2 hours after charging,I do and I have never instaflashed a '85 yet.

 

[LuxLuthor]

Yeah, it has been wonderful to have a bunch of AWR Hotdrivers, both to avoid flashing, but mainly to keep optimal regulated output. If you are going to use a mostly stock Mag setup with 9 x Eneloops, I would just add a tiny bit of resistance and/or use AW's soft starting multi-level driver. The soft starter should help a lot.

 

[SafetyBob]

I don't know about you guys, but I am waiting for JimmyM's version of a regulated driver.......problem solved!!!

Thats no matter how many batteries you have. OK, actually Jimmy's driver will solve one big problem for us, runtime. As long as the heat doesn't start melting crap, we should be able to slam a whole bunch of batteries into something and have alot of light for a long time. Gotta love regulation.

I can't wait!!

Bob E.