Which NiMHs to run in my Mag85?

[ScottW]

Hi all. As my first real build, I'm putting together a Mag85. I've got all the parts in my posession or on order, except for the batteries. I'll be using a fivemega 9AA to 3D adapter.

I've read a little bit, including the NiMH shootout thread. I'm intrigued by the Eneloops ability to hold a charge longer, but it seems they're down a bit on capacity (2000 mAh vs 2500 & up). I can give up a few minutes of runtime for their lower self-discharge rate, but will the Eneloops still deliver decent performance under the load of the 1185?

Besides the Eneloops, it seems that Sanyos and Titaniums are towards the top of the list. Any pros or cons between them, or are traditional NiMHs pretty similar for a given capacity rating? I'm trying to keep the cost around $2.50 per battery.

I guess my decision is low self-discharge with shorter runtime, versus normal self-discharge with longer runtime. Is there a consensus recommendation? What do y'all run in your Mag85s?

 

[oregon]

What do y'all run in your Mag85s?

http://www.batteryjunction.com/12po20aaba.html

Tenergy 2600 mAh NIMHs. No complaints.

I am very satisfied with Batteryjunctions products and service.

Also, fivemega's MOP cammed reflector sure took the "skull and cross bones" artifacts out of the beam.

oregon

 

[Gunslinger1LA]

Hi Scott, I built my 85 on a 4C host . I use 3x LG chem 2600 MaH 18650 Li-ion. in a 3/4 inch ID pvc holder. No tail cap mods needed. Fires every time with no instaflash. I use a fivemega PR to bi pin adapter for the bulb. FM reflector and borofloat lens.

Good Luck with yours !

 

[VWTim]

I had good luck with my Mag85 on Sanyo 2500's until 3 of them started to self discharge. rather quickly. I am using Rayovac Hybrids in my Mag74 with great results. Might be worth a try, especially if you can come up with some of the discount coupons.

 

[nzgunnie]

I had a Sanyo 2700 pack that self discharged in a week to begin with, and after about 6 weeks was only lasting about 4 days before being too low to use.

Made the light useless, since the batteries were always flat when I needed it, and if I recharged them I had to wait a few more hours....

I've got a pack on the way made from CBP 1650s, which although lower capacity and shorter runtime at least are supposed to hold their charge well.

If I had the $$$ I'd get a fivemega 9x14500 holder and use Li-ions, but at $9 a battery and $39 for the holder I'll have to pass for now, but it's something to think about.

 

[glockboy]

Go with CBP 1650s, it can handle the 1185 bulb.

 

[Alin10123]

Go with CBP 1650s, it can handle the 1185 bulb.

I've heard there was a bad batch of 1650's floating around out there. Of course, it's probably been fixed by now. I personally use sanyo 2700 cells. I just top them off every couple of weeks.

 

[ScottW]

Does anybody have the CBP 1650s available right now? At cheapbatterypacks.com they're listed as out of stock. They list a "replacement" right below the CBP 1650s, the IB2000. Has anybody tried these to see how they stack up? I noticed the IB2000 are button top but the 1650s aren't.

I already dropped $39 on the 9AA to 3D adapter so I'm pretty darn set on using AAs. I briefly thought about running 9 x 14500, but dropping $80 on batteries just ain't in the cards right now.

VWTim, I think you might be the same guy who sold me the HBE holster for my Mak (?) If so, small world! I found some Rayovac hybrid coupons on slickdeals.net so I'll see if I can find them in stock near me.

 

[VWTim]

Does anybody have the CBP 1650s available right now? At cheapbatterypacks.com they're listed as out of stock. They list a "replacement" right below the CBP 1650s, the IB2000. Has anybody tried these to see how they stack up? I noticed the IB2000 are button top but the 1650s aren't.

I already dropped $39 on the 9AA to 3D adapter so I'm pretty darn set on using AAs. I briefly thought about running 9 x 14500, but dropping $80 on batteries just ain't in the cards right now.

VWTim, I think you might be the same guy who sold me the HBE holster for my Mak (?) If so, small world! I found some Rayovac hybrid coupons on slickdeals.net so I'll see if I can find them in stock near me.

Yup, that's me. Still likeing it?

 

[Alin10123]

Does anybody have the CBP 1650s available right now? At cheapbatterypacks.com they're listed as out of stock. They list a "replacement" right below the CBP 1650s, the IB2000. Has anybody tried these to see how they stack up? I noticed the IB2000 are button top but the 1650s aren't.

I already dropped $39 on the 9AA to 3D adapter so I'm pretty darn set on using AAs. I briefly thought about running 9 x 14500, but dropping $80 on batteries just ain't in the cards right now.

VWTim, I think you might be the same guy who sold me the HBE holster for my Mak (?) If so, small world! I found some Rayovac hybrid coupons on slickdeals.net so I'll see if I can find them in stock near me.

In terms of the battery being able to hold up to the discharge rate, the sanyo's will definately do the trick for you. Just top them off every couple of weeks and you should be ok. I've heard the "enloops" are supposed to be good capacity, have a good discharge rate without voltage sag, and have a very slow self discharge. You can't avoid self discharge with nimh batteries. It's going to be there no matter what.

 

[speederino]

I've been running Eneloops in my M/\g85 with good results. I think they come in #3 behind the CBP1650 and the Amondotech 1800's as far as holding their voltage under load in Silverfox's tests. They seem to hold up better than other NiMHs in cold weather too. Can't beat the low self discharge, and no forming charge is needed with the Eneloops. These things are hard to beat.

 

[Alin10123]

Just keep in mind that when it comes to nimh, typically the higher the capacity, the higher the self discharge rates.

 

[mdocod]

I agree with the tenergy solution if you are trying to keep the budget reasonable- I've been using those cells in various lights, and have run various tests of my own, they seem to hold up just fine. Here's some tests a ran on them a long time ago.... The
voltage is probably not reporting correctly because of the setup I was using to test it...

here's an energizer 2500AA in my testing setup into a heavy load:
time/volts/amps/watts
00/0.988/10.06/9.94
01/0.902/9.22/8.32
02/0.887/9.05/8.03
03/0.873/8.91/7.78
04/0.865/8.81/7.62
05/0.860/8.76/7.53
06/0.854/8.69/7.42
07/0.844/8.58/7.24
08/0.843/8.57/7.22
09/0.836/8.51/7.11
10/0.829/8.43/6.99
11/0.822/8.34/6.86
12/0.813/8.24/6.70
13/0.798/8.09/6.46
14/0.779/7.90/6.15
15/0.741/7.51/5.56

here's a Tenergy 2600AA in the same test setup:
time/volts/amps/watts
00/0.989/10.5/10.38
01/0.897/9.28/8.32
02/0.899/9.28/8.34
03/0.900/9.28/8.35
04/0.895/9.22/8.26
05/0.889/9.15/8.13
06/0.883/9.07/8.01
07/0.875/8.99/7.87
08/0.865/8.88/7.68
09/0.856/8.79/7.52
10/0.848/8.70/7.38
11/0.829/8.52/7.06
12/0.801/8.27/6.62
13/0.775/7.98/6.18
14/0.731/7.51/5.49
15/0.656/6.74/4.42


the voltage results here may not be accurate- however... since I have results for a very WELL KNOWN cell compared in the same test to the tenergy- it is easy to see that they both perform very similarly. So if a energizer 2500 is ok with you, then spending less on the tenergy will give similar results in a hotwire... I've also found that the tenergy cells do not suffer from self-discharge anywhere near as bad as the energizers do.

 

[lexina]

I have pretty much given up running my Mag85 on NiMhs - the self-discharge was just too much PITA. What was worse was that frequently, 1 or 2 cells would run down before the others and (other than becoming useless) this would result in the light dimming after sitting for less than a week. I guess NiMhs would be allright if you intend to use the light frequently and are willing to take the effort to remove and charge each cell individually (rather than pack-charging as I did). Right now, I am using 3 X 18650s in my 3D. Eventually, I hope to run it on 3 X 'C' LiIons from Aw's GB in a Mag3C.

 

[SilverFox]

Hello Lexina,

The secret to running NiMh cells in a multi cell application is to start with a forming charge on the cells. Next you need to match your cells on capacity and mid point discharge voltage, and finally try to also match them on internal resistance.

When using your light, you need to make sure that you don't over discharge it, and you have to re-balance the battery pack after charging it.

The matching also applies to your Li-Ion cells. Li-Ion chemistry does not need to be formed, but does benefit from a few cycles of 0.5C discharges to "break them in." This does not seem to help in low drain applications, but when you are pulling over 1C, it helps.

I have 2 Mag85 lights. In one of them I am running Eneloop 2000 mAh cells. In the other Titanium 2600 mAh cells. The Titanium 2600 mAh cells give me almost as bright a beam as the Eneloop 2000 mAh cells do, and I get a few extra minutes of runtime.

Now let's look at the dreaded self discharge issue.

I charged both lights up last September and have not had a chance to use them since them. I just ran a test to see if they would light up at all. I knew the Eneloop cells would be good, but what about the Titanium cells?

The Eneloop pack measured at roughly 12 volts, and the Titanium pack came in at around 11.6 volts. I fired both lights up and, as expected, the Eneloop powered light was a little brighter, but the Titanium powered light was holding its own.

The runtime results were 26 minutes for the Titanium powered light and 34 minutes for the Eneloop powered pack.

Yes, the Titanium 2600 mAh cells do suffer from self discharge, but I would hardly call it a PITA.

With healthy cells and some care in assembling the battery pack, NiMh cells can provide very good performance in the Mag85.

While I enjoy the extra runtime that the Titanium 2600 mAh cells give, I must admit that I enjoy a brighter light more. I will be changing these cells out with the Titanium "Power Max" 1800 mAh cells. The 1800 cells at room temperature work almost as well as the CBP 1650 cells did hot off the charger. They stomp all over the 1650 cells at room temperature.

Tom

 

[ScottW]

Thanks for all the info guys. I'll probably get a set of the Titanium 1800s since they keep up with the CBP 1650s as far as brightness goes. I might also pick up some higher mAh Sanyo cells for comparison, and I'll look for the Rayovac hybrids next time I'm at wally world since the coupon makes them real cheap. So in the end I suppose I'll try a couple different cells but try not to let batteries become a whole separate hobby in itself!

And yes, VWTim, I'm still liking it. Although I must admit that I've taken to carrying a j-frame more often now that I've gotten spoiled with how easy they conceal. But the Mak still goes for a spin every now and then.

 

[Timson]

I have some IB2000's on order.

I'll be doing a forming charge and a couple of cycles on each to get them upto speed - then I'll be taking em out for a test drive in the Mag85.

I'm expecting great things - if the blurb on CBP's website is anything to go by.

Hope it doesn't go


Tim

 

[David1]

I just got some IB2000's today and am doing a forming charge as we speak. These will be used in a regulated M*g138. Hoping they do better than CBP1650's with large currents. Time will tell, I'll let you know in a couple day's how they work.

 

[lexina]

Hello Lexina,

The secret to running NiMh cells in a multi cell application is to start with a forming charge on the cells. Next you need to match your cells on capacity and mid point discharge voltage, and finally try to also match them on internal resistance.

When using your light, you need to make sure that you don't over discharge it, and you have to re-balance the battery pack after charging it.

Tom

Thanks for the helpful advice, Tom. I guess NiMh would serve well for those able/willing to do all the matching, balancing and re-balancing required.