I have 7 MagicShine batteries...yikes! They've generally worked fine for me. No fires, etc. However, on my 24 Hour solo race in September, I had 2 batteries that flaked out on me way before I would have expected. One was a friend's that I borrowed and one was mine. I had charged all of the batteries to the green light stage prior to the race.
Fast forward to this week when I received an RC battery hobby charger (much more complex and feature laden than the standard MS charger). Due to the recent battery issues, I also started reading more about li ion batteries and realized they shouldn't be stored in full state for long periods of time.
So, after testing the new hobby charger for charging, I decided I'd use the "storage" feature and discharge most of my packs to the recommended state. Well, one of the packs kept coming up with "connection broken" when I attached it to the hobby charger.
Plug it into the MS charger, green light. Plug it into the light head, functional. Strange. I figure with 7 batteries (not all purchased from Geoman), I'll sacrifice this one and dissect it to see what's up.
Surprisingly, the plasti-dip just peels off (once you get it started enough to grab onto). I slit open the shrink wrap and the insides look just as I'd expect: 4 2200mah 18650 cells wired 2s2p, with a protection circuit.
The sketchiness reveals itself when I put the voltmeter on the cells. The whole pack tests to 8.14V, which would seem ok. However, testing the individual cells reveals some issues: 4.27V, 4.27V, 3.86V, 3.86V. Completely unbalanced, with two cells significantly overcharged and two significantly undercharged. Yikes!
I actually have 20 RC car balance leads on their way to me in the mail and will install them into this pack (and maybe all the rest that don't get covered under the recall). The balance leads in conjunction with the RC hobby charger should provide a much safer method of charging these batteries. I may need to replace the protection board on this one too. Not sure what's up with the connection broken message...
Fast forward to this week when I received an RC battery hobby charger (much more complex and feature laden than the standard MS charger). Due to the recent battery issues, I also started reading more about li ion batteries and realized they shouldn't be stored in full state for long periods of time.
So, after testing the new hobby charger for charging, I decided I'd use the "storage" feature and discharge most of my packs to the recommended state. Well, one of the packs kept coming up with "connection broken" when I attached it to the hobby charger.
Plug it into the MS charger, green light. Plug it into the light head, functional. Strange. I figure with 7 batteries (not all purchased from Geoman), I'll sacrifice this one and dissect it to see what's up.
Surprisingly, the plasti-dip just peels off (once you get it started enough to grab onto). I slit open the shrink wrap and the insides look just as I'd expect: 4 2200mah 18650 cells wired 2s2p, with a protection circuit.
The sketchiness reveals itself when I put the voltmeter on the cells. The whole pack tests to 8.14V, which would seem ok. However, testing the individual cells reveals some issues: 4.27V, 4.27V, 3.86V, 3.86V. Completely unbalanced, with two cells significantly overcharged and two significantly undercharged. Yikes!
I actually have 20 RC car balance leads on their way to me in the mail and will install them into this pack (and maybe all the rest that don't get covered under the recall). The balance leads in conjunction with the RC hobby charger should provide a much safer method of charging these batteries. I may need to replace the protection board on this one too. Not sure what's up with the connection broken message...