New memberhere from the Houston area. Caught the electric bike bug a few years back and have expanded my fleet to an ATV and scooter. A Software guy by trade, I also dabble in electronics (my minor)and a big LED fan. SO, I might be new to the powerwall group, I have some background.
Been wanting to do some audio and illumination (LED)related work on the scooter and needed some juice. I have been frequenting slibuy.com, which is a store returns/surplus auction site. I have picked up some nice Ryobi tools plus a few other things from them. I noticed they had what appeared to be auctions forNOS (new old stock) laptop batteries as well as some batteries made fora Roomba. The laptop batteries were all aftermarket packs containing mostly 1800-2000mAH 18650s plus a few LiPo soft pack batteries. Nothing first tier name brand. Only thing found in this forum's cell DB is someASO/SZN batts. The Roomba 18650 were a different story. Each pack had 8 (4S2P)nice green Sony US18650V3 which are rated slightly more than 2000mAH, but not the high current that the newer cells have. The Roomba cells also had a nice hard BMSboard with aNeotec NT1775 chip with AO4407A8 pin DIP FETs (30V/12A) on the board. Also nice big tabs for the cells (see picture below). I might keep and repurpose these.
Downside, is the Sony's have adate code which Batt Bro's site told mewere from 2013. Some of thelaptop cells had2013 dates. I also noticed some rust looking corrosion on either the cells themselves, but mostly at the terminals and/or on the nickel strips. See enclosed picture. (This was the odd ball Roomba pack with older LG cells in it (again, not made for high C). Next to it is one of the worst of the laptop cells I cut open since it looked like a bad case of acne (bumps) on the outside, and the inside was even worse. I hate to throw out the other cells which have minor rust on them. But you know the old saying: "rust never sleeps". Which makes me wonder where the heck these packs were stored (since 2013). I would assume some warehouse or shelf with some climate control. Makes me worry about the condition of the chemistry of the cells themselves.
Have you guys run across this kind of rust before? Are the slightly rusty ones worth saving? Granted this would require unwrapping, cleaning, and a fresh wrapper.
Because I ended up with something on the order of 300+ cells, I obtained what I thought was a decent charger, theMiboxer C8 which does 8 cells. I like that it givesinternal resistance and total mAH it charged with, but no discharge test
About 10% of the cells measured too low to charge (without using the special slot the Miboxer has) so I set those aside. Most of the off brand cells once charged have around 75 mOhms internal. The Sony have been slightly better in the 50s range. I've concluded that these are not high C cells. Using my old RC iMax B6 charger, which does have a discharge test, I'm seeing numbers in the high teens (1500-2000 mAH) at 1/2Afor the few cells I've sampled. At this point I'm waiting to see which cells are going to naughty (self discharge) or nice (keep their charge).
FYI: I figured with shipping I'm around 60 to 75 cents a cell and I'm sticking with the Roomba pack auctions and limit my bids plus shipping to 0.75/cell. Considering what I know know about buying sorted/tested cells (aka from battery hookup) in the $1 range, I'm not saving much money as a DIY. But there is something I find relaxing, almostcathartic about breaking open and harvesting cells. I've got some country property I'd like to do solar with, so I'm planning on doing a power wall in the future. And some DIY solar powered lights using some of the weaker cells.
What are you US guys buying local savage cells paying? I guess I'm asking what's a good price for untested, unknown (but probablyNOS) cells? I figure in big H-town, there has to be some places to get cells/packs locally. There is a guy selling panels in the area for less than $0.65/W, with no shipping to worry about (local pickup). (i.e. 355W/$225)
Been wanting to do some audio and illumination (LED)related work on the scooter and needed some juice. I have been frequenting slibuy.com, which is a store returns/surplus auction site. I have picked up some nice Ryobi tools plus a few other things from them. I noticed they had what appeared to be auctions forNOS (new old stock) laptop batteries as well as some batteries made fora Roomba. The laptop batteries were all aftermarket packs containing mostly 1800-2000mAH 18650s plus a few LiPo soft pack batteries. Nothing first tier name brand. Only thing found in this forum's cell DB is someASO/SZN batts. The Roomba 18650 were a different story. Each pack had 8 (4S2P)nice green Sony US18650V3 which are rated slightly more than 2000mAH, but not the high current that the newer cells have. The Roomba cells also had a nice hard BMSboard with aNeotec NT1775 chip with AO4407A8 pin DIP FETs (30V/12A) on the board. Also nice big tabs for the cells (see picture below). I might keep and repurpose these.
Downside, is the Sony's have adate code which Batt Bro's site told mewere from 2013. Some of thelaptop cells had2013 dates. I also noticed some rust looking corrosion on either the cells themselves, but mostly at the terminals and/or on the nickel strips. See enclosed picture. (This was the odd ball Roomba pack with older LG cells in it (again, not made for high C). Next to it is one of the worst of the laptop cells I cut open since it looked like a bad case of acne (bumps) on the outside, and the inside was even worse. I hate to throw out the other cells which have minor rust on them. But you know the old saying: "rust never sleeps". Which makes me wonder where the heck these packs were stored (since 2013). I would assume some warehouse or shelf with some climate control. Makes me worry about the condition of the chemistry of the cells themselves.
Have you guys run across this kind of rust before? Are the slightly rusty ones worth saving? Granted this would require unwrapping, cleaning, and a fresh wrapper.
Because I ended up with something on the order of 300+ cells, I obtained what I thought was a decent charger, theMiboxer C8 which does 8 cells. I like that it givesinternal resistance and total mAH it charged with, but no discharge test
About 10% of the cells measured too low to charge (without using the special slot the Miboxer has) so I set those aside. Most of the off brand cells once charged have around 75 mOhms internal. The Sony have been slightly better in the 50s range. I've concluded that these are not high C cells. Using my old RC iMax B6 charger, which does have a discharge test, I'm seeing numbers in the high teens (1500-2000 mAH) at 1/2Afor the few cells I've sampled. At this point I'm waiting to see which cells are going to naughty (self discharge) or nice (keep their charge).FYI: I figured with shipping I'm around 60 to 75 cents a cell and I'm sticking with the Roomba pack auctions and limit my bids plus shipping to 0.75/cell. Considering what I know know about buying sorted/tested cells (aka from battery hookup) in the $1 range, I'm not saving much money as a DIY. But there is something I find relaxing, almostcathartic about breaking open and harvesting cells. I've got some country property I'd like to do solar with, so I'm planning on doing a power wall in the future. And some DIY solar powered lights using some of the weaker cells.
What are you US guys buying local savage cells paying? I guess I'm asking what's a good price for untested, unknown (but probablyNOS) cells? I figure in big H-town, there has to be some places to get cells/packs locally. There is a guy selling panels in the area for less than $0.65/W, with no shipping to worry about (local pickup). (i.e. 355W/$225)
