A Li-ion powered [pistol grip] spotlight? Dremel-out the peaks in a SRK battery tube and put a coupleafew of those in? A test-bench for driver and LED tuning?
I have bee tossing around that idea for a couple days now. When I get a chance I will switch them around. I wish I could add another editor to the spreadsheet post.
The change could better for some. When I open a thread it is only the new posts and in reverse order (except for the original post (post zero). So it is better if the original post is an intro or is packed with info/links and not packed with large images. This also reduces the download streaming requirement at my end - and on the website.
One cell was slightly scraped during removal and the metal beneath the casing is exposed. If I wrap it in packing tape would that render it safe for use?
I would totally hop on his sale again, but I already have TOO MANY batteries! :P However I do suggest you to get packs from him if you're looking for a pack to pull from.
After 30 minutes shuffling through the battery packs at our local used PC shop, I only found two packs that seemed new enough to be interesting, so I paid $1 each and took them home to tear open.
Inside I found pretty much what I was expecting. 2,800 mAh cells, specifically, LGDC118650s in ugly greenish brown wrappers.
Next up, an HP TD06 pack. Most of the TD06 packs in the bin had a 10.8v nominal voltage. This one had a 11.1v nominal voltage, and so I assumed it was newer.
The pack was made in china with Korean batteries, but which kind? Inside, I found 2,800mAh cells, as expected. Specifically, they were lavender-wrapped Samsung ICR18650-28As, which have a 4.3v termination voltage.
I’m leaving the circuits intact for now, because I want to see if I can read out some information from the battery management boards and see how that relates to the voltages, capacities, internal resistance and self-discharge rates of the individual cells.
I’ll update the blog posts (linked to above) once I’ve got that info.
Pack Summaries:
Asus, AL32-1005; 11.25v, 5600mAh, 63Wh 3s2p; LG, LGDC118650, 2800 mAh
HP, HP TD06; 11.1v, unspecified mAh, 62 Wh, 3s2p; Samsung, ICR18650-28A, 2800 mAh
This pack is a bit unusual. Its an internal pack, but unlike most internal packs, its made with 18650s, rather than pouch cells.
One benefit is that its really easy to get in to. I just had to peel some tape off the thin shell.
Inside, I found eight Panasonic NCR18650A 3,100 mAh cells. Not bad for a $22 new-old-stock pack!
Or perhaps it wasn’t such a deal after all. The pack voltage was ~7.7v, which wouldn’t be bad if this were a 3S pack. On an 4S pack though, that works out to less than 2v a cell. In retrospect, I can now see why the seller wasn’t asking more for the pack, and now that I’ve gone back to check, I see that they have other NOS packs of the same type for almost 2x the price. No mention though that it was marginal
I decided to give it a slow charge to 12V at 200 mA, which didn’t take long. Overnight, the voltage settled to ~11.6v. I am taking it up to 14.8v now at 660mA, which is probably where I’ll leave it until I manage to read out the pack info over SMBus. Then I’ll separate the cells and do a couple rounds of tests.
Not to drag this too far off topic, but I’ve made some progress. I was able to get this info out of one of the $12 acer packs:
I need to figure out how to interpret the manufacture date. I also want to figure out if I can get the individual voltages for each parallel bank, and also how to deal with string data, like the manufacturer and serial number.
Once I do, I’ll clean up the code a bit and share it.