BATTERY GODS: help identifying cells pulled from Dell Battery Pack

While I am waiting for my flashlights to come in, I was cleaning out the old electronics bin and pulled out two Dell Type 75UYF battery packs. I've read that some BLF'ers recycle batteries from inside laptop packs, so I decided to open one up.

I carefully pried the pack apart to unveil an 8-cell cluster. I was expecting to easily read the battery type right off the cell but none of the numbers matched up. I tried to Google the pack model number and any of the numbers off the cell itself but could not find anything. I was hoping that one of the BLF battery gods could help me identify what I have. I was hoping to recover some 18650's.


Rechargeable Li-ion Battery
Rating 14.8V 3800mAh
Type 75UYF
Charging Current: 3.5A


Color: RED
Size: 6.5cm x 1.75cm


Thanks in advance!

They are probably Sanyo "red" 18650's. Do a google image search and see if they match.

Hey! Thanks kbark!

Being new to lights and batteries I didn't want to assume that they were 18650's. Comparing them to the pics on the web, they look like they are Sanyo Red 18650's.

Per instructions here on BLF, I separated the cells and took off the thin metal straps located on the positive and negative ends of the battery. However, it looked like they were "stapled" onto the ends. Now the leads have remnants of "staples" on them. How should I "knock down" those pointy ends or should I just leave them?

I usually just hit them with a file or a dremel works too.

Thanks again kbark for the heads up. Here are the eight batteries from the first battery pack all cleaned up. I used a dremel to knock down the "staples"

Got another pack to open and harvest! Woot!

I think they are low mah but okay if run time isn't an issue.

look the same as the ones I got out of an old IBM notebook.
(they are clearly a fair bit smaller than my 18650 Flames.. )

They were all about 4.1x Volt after charging them in the laptop.

This I could check of course after I opened the battery pack!

Recharged them on my TR001 charger.. then they had all between 4.15-4.18V

when that laptop still worked, it could work on the battery for about 10 minutes.....
(now maybe thinking about putting the batteries in my other old laptop, that has only 3 cells, which are probably dead.. no charge at all)

I just got in my 4Sevens Quark 123^2 and fighting the urge to charge and put in one of these 18650's I pulled from my Dell pack. Should I really wait for a multimeter to test the batteries BEFORE putting them in or do you think the Quark is robust enough to give it a try?

Wait for your DMM please. Better safe than sorry.

Hate to break it to you, but 18650s don't fit in the Quark 123x2. You would need a 18650 tube which has long since been discontinued.

Can anyone explain why it is so dangerous to try the batteries from a battery pack..

why not just charging them in your Li-ion charger, and then put them in your flashlight..

Where can it go wrong? whats the difference between these batteries, and non-protected you buy elsewhere?

Yep they don't, and the 18650 Tube is not produced anymore. You can fit a 16650 from Sanyo with is 2100 Mah.

Inner tube diameter is 17.10mm. Some use a 17670 battery. But capacity is only 1600mAh.

Well, these cells are actually used. At the end of their life cycle, sometimes a cell may be in better condition than others. If you use them in a 2S or 3S configuration, problems may arise especially without PCB protection.

Other unprotected cells that you buy elsewhere are new.

@2100 ;) yes, the ones you buy elsewhere are new.. but as long as you only use them in a 1battery configuration... it must be safe enough?! right?

Yeah, 1 cell should be safe enough. But you need to see if it can give out enough current esp for those full current XM-Ls.

DOH! In my excitement about recovering these 18650's I realized that I misspoke about about the 18650's going into the Quark X 1232 (thanks mitro for pointing it out). What I'll be looking at for my new Quark will be the 17670.

I opened the other Dell battery pack and pulled out 8 Sony Greens. Now I'm on the search for a single 18650 setup. Anyone got suggestions? I heard the Solarforce L2i is a relatively good form factor to build on.

Check them with a meter before attempting to charge them ..obviously the pack is bad for a reason ..Right ? something in there is bad or it wouldn't be an old laptop bad battery pack . You need to know which cells are bad and toss those ..i keep only batteries that aren't discharged lower than 3 volts ..i charge them as high as they will go.. 4.2 volts .. and then check voltage again and write it on the cell and date it .. Then let it sit for about 3 days or so checking voltages once a day .. if a cell won't even charge up to 4.2 volts that's not a good sign and any cell that starts to freefall just by sitting is talking to you .. you need to listen if it drops to under 4.volts by its self it's bad .. tape it up and recycle it Imho this is the minimum safeguards to be taken with regards to l-ion cells

Be safe rather than sorry ... obviously if they get hot while charging at all they are bad .. pull the plug asap some good info at cpf at the end of this thread

You MUST have a meter before charging cells ...

Boaz -

Thanks for the heads up. The packs in question weren't bad. The laptop that went with them went bad. That's not to say the batteries aren't bad until I test them.

I ordered the Equus 3320 DMM from Walmart to go with the Ultrafire WF-139 I got in. Thanks for the great advice.

Discharging them in series with balance leads connected is a good way to see if any cells lag behind and if they will be good for multi cell use, but you need a hobby charger.

Great info Boaz! Woukd you mind starting a general purpose 18650 info thread with this info and anything else you could share? We could all benefit fro. Your knowledge. Thanks.