Looks like an 18650, but isn't?

I received my Rayfoss unit today sans all accessories, which they ship separately via slow boat from wherever, so I can't test it yet. Looking around for a source of 18650 batteries, I ripped open the laptop battery from my non-working Ferarri Acer laptop. It's even got "18650UR" in the battery pack part number.

The nine batteries inside are not labelled, but they are physically the right size to go in the laser, which needs an 18650. But they didn't work in it. So I measured them, and they're producing 1.59v.

Looking a little further, the pack has nine of them and is labelled as 11.6V. But nine times 1.6 would be 14.4, so unless it had an internal regulator, I'm totally lost.

Anyone care to guess what these batteries actually are, if not 18650s?

Thanks!
Dave

PS: If Amazon carried them, I'd just overnight some, but I could not find any Prime-elligible 18650s on Amazon either.

If the individual cells are reading sub 2v, they're dead. They won't hold much of, if any of a charge, as 3.2v is the normal safe drop off for Li-ion batteries.

those are 18650 and should work , but you need to charge them first, If they still hold a charge.

davepl said:

Looking a little further, the pack has nine of them and is labelled as 11.6V. But nine times 1.6 would be 14.4, so unless it had an internal regulator, I'm totally lost.

Click to expand...

The pack could be three parallel sets of three batteries in series?

davepl said:

. . . Looking around for a source of 18650 batteries, I ripped open the laptop battery from my non-working Ferarri Acer laptop. It's even got "18650UR" in the battery pack part number.

The nine batteries inside are not labelled, but they are physically the right size to go in the laser, which needs an 18650. But they didn't work in it. So I measured them, and they're producing 1.59v.

Anyone care to guess what these batteries actually are, if not 18650s?

Thanks!
Dave

Click to expand...

Dave;

They are #18650 cells (3 in parallel).

At 1.59 VDC, they have been left discharged for a long time.

One factor with typical lithium-ion cells, is that they have a ~5 year life from the time of manufacture.
(top brand cells last longer)

Do you know how old the battery pack is ?

With the numerous cycles of charging in a notebook,
they can also lose capacity, in addition to the aging issue.

You can check the internal resistance to get a better idea of their condition.

LarryDFW

I had the same thing happen with my batteries. I made a dummy battery with wires coming off of it, I soldered a magnet in the middle of each wire, then 1 on each end. Then I took a battery I knew would charge and put the end magnets on it, n the "dead" battery at the half way point. My battery charger took twice as long because of the "dead" battery but once it was done my batteries both had a 4.2V charge. It worked for most of my (50 out of 52 18650s and 17670) batteries I got from old laptops.

DTR said:

The pack could be three parallel sets of three batteries in series?

Click to expand...

Indeed, this is a very common arrangement for laptop batteries.

Manufacturers usually rate lithium cells as 3.7 volts each, and with series strands of 3 this equates to 11.1 volts. Strands of 3 in series are still common at 11.1 volts, although you see strands of 2 or 4 cells (7.2 or 14.8 volts) more and more on the market nowadays.

The individual cells in a laptop battery are very likely to be 3.7 volt cells, regardless of their size and shape. The 18650 form factor is losing market share as it makes laptops too thick, but the cells that replace them are still the same chemistry and hence voltage.

Also notice that spent notebook battery cells aren't very useful - if they fail to power your notebook, chances are they will also fail at powering any serious laser.

I've taken about 10 old packs apart. It's only a few of the individual cells that have failed while the rest are fine, although the capacity is reduced either from the stress of over-current, normal wear, or age. They'll still supply an amp or so fine.

Thats true, a single celll failing can cause the entire battery to read as malfuncional. I'd still caution against using rescycled cells from such packs though. Some cells may still be fine, but its sure they have a good deal of wear on them.

Thats what happens inside those laptop battery packs. The "magic circuit board" (protector) disables the battery to protect the $500+ laptop its hooked up to if one of the cells fail.

Some laptops even come with software that will tell you this.

Hidden inside some battery packs there is also a time bomb. After a certain number of charge-discharge cycles, the chip disables the battery, by preventing it charging. This forces you to buy a new one. Clever, if not cheeky business practice.

With 18650's, if it's under 2V like Proto said, you should avoid using it. Lithiums are damaged by undervoltage, and could possible turn into a pipebomb on your charger or while in use due to high internal resistance.