I thought I'd share this. So I found a mystery power pack while rummaging through the bins at my local Goodwill outlet store. I love to find them because they are a good source of rechargeable batteries, like lithium ion or NiMH. I tore it open and got excited because I thought there were 7 18650 2400 mah cells in there, but after some closer inspection I couldn't find any information or identification on them...

Looks like some generic no-name li-ions, right?

Upon closer inspection...

Surprise! These are 18650-size NiMH. 2400 mah and all of 1.45 fully charged volts. I put them in my Zanflare to see how healthy they were and sadly, they're too far gone. Less than 700 mah for the two healthiest ones and less than 100-300 for the others and most would only charge to 0.78 volts. The date code is 2006, so they're pretty old.

Anyway, I thought I'd share this.

Anyone ever see 18650-size NiMH before?

That’s odd. But are you sure they’re 18x65mm? I’m not seeing that size listed on the wiki list of cylindrical battery’s

Yes, those are the old standard size for computer battery pack NiMHs — the li-ions when they came into use were specified for the same size. I’ve bought them new for use in flashlights but unfortunately there are no low-self-discharge NiMHs in that size.
I was hoping to rebuild last year’s li-ion lights as NiMH lights to make them safer to give away to muggle friends who I wouldn’t challenge to practice li-ion safe use.

I compared them to my real 18650 li-ions and the dimensions were within 1mm.

True. I think the era these came from was right around the time the transition from nimh to li-ion for computer batteries. Maybe they were cheaper, or maybe li-ions weren’t in that capacity yet? A lot of older high capacity laptop batteries used 9 cells 1500-2100 mah li-ions to get the high capacity. Plus, high self discharge, easier to charge, and safer. What do you think?

7/5 A

I thought I knew about fractional sizes but even I’d never heard of 7/5A, good job Chad!

That’s gotta be it, 17.5x67mm.

Thanks, Was just a guess, the look skinnier then the 4/3 AF.

Interesting. I never heard of that size battery. I’ll measure them with my digital calipers tonight and update.

So I put the NiMH cells on my calipers and did a real Moli Energy 18650 to compare. Turns out my eyeballs aren't as accurate as my calipers! Here's the real dimensions... Blue cell NiMH is 16.21mm x 66.11. The li-ions are 18.47mm x 64.65mm.

  • They're probably off .1mm or so on the blue ones becauase the wrapper is pretty thick, but they're not 18650 sized. 16660? :P