How to charge 3.6VDC battery with DC Power Supply
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From: jg on 2 Mar 2010 02:59 I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to charge. These were originally charged with a camcorder that I do not have. However, I have the next best thing. I have a DC Power Supply (BK Precision 1660A) with both voltage control and current control. Basically I can set this bad boy to output any volt and current combination. I have tried charging the batteries at 4.0v and 100mA and let them charge for about 3 hours. Batteries never got hot (which to me would indicate that they were never really charged.) When I first unplug them, they register about 3.6v. However after a day or so, their voltage drops to 2.6v or so. So... I am either not charging them up completely or they are no longer functional. However, these batteries were never put in production. They are old, but they were still in original packaging as of a few days ago. Any help greatly appreciated. jg
From: Tom Biasi on 2 Mar 2010 06:24 "jg" <juangarcia(a)sacbeemail.com> wrote in message news:a0bea318-05c8-47bb-8dc0-a61815ecf97e(a)z10g2000prh.googlegroups.com... > > I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to > charge. These were originally charged with a camcorder that I do not > have. However, I have the next best thing. I have a DC Power Supply > (BK Precision 1660A) with both voltage control and current control. > Basically I can set this bad boy to output any volt and current > combination. I have tried charging the batteries at 4.0v and 100mA > and let them charge for about 3 hours. Batteries never got hot (which > to me would indicate that they were never really charged.) When I > first unplug them, they register about 3.6v. However after a day or > so, their voltage drops to 2.6v or so. > > So... I am either not charging them up completely or they are no > longer functional. However, these batteries were never put in > production. They are old, but they were still in original packaging > as of a few days ago. > > Any help greatly appreciated. > > jg It would help to know what type of batteries you have. Tom
From: Robert Roland on 2 Mar 2010 07:19 On Mon, 1 Mar 2010 23:59:19 -0800 (PST), jg <juangarcia(a)sacbeemail.com> wrote: >I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to >charge. That'll be a Li-Ion battery, judging by the voltage. >I have tried charging the batteries at 4.0v and 100mA >and let them charge for about 3 hours. Batteries never got hot (which >to me would indicate that they were never really charged.) Li-Ion batteries don't get very hot during normal use. At such a gentle charge current, you'd not be able to detect a temperature rise at all with bare hands. To get the correct charge voltage, you'd have to check the data sheet, but 4.1V or 4.2V are the normal voltages for Li-Ion batteries. Be very careful to avoid overcharging them, or they'll catch fire. >When I >first unplug them, they register about 3.6v. However after a day or >so, their voltage drops to 2.6v or so. A certain amount of self-discharge is normal. That looks bit too much, though. >So... I am either not charging them up completely or they are no >longer functional. At 4.0V you are probably not charging them completely, and 100mA for 3 hours is only 300mAh, so that is definitely not enough to completely charge them. >They are old, but they were still in original packaging >as of a few days ago. Li-Ion batteries die of old age. High temperatures or incorrect charge level shortens life. Ideal storage charge is normally specified at about 50-60%. If your batteries are more than 3 years old, they're probably pretty much dead. -- RoRo
From: Tim Wescott on 2 Mar 2010 11:52 Robert Roland wrote: > On Mon, 1 Mar 2010 23:59:19 -0800 (PST), jg > <juangarcia(a)sacbeemail.com> wrote: > >> I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to >> charge. > > That'll be a Li-Ion battery, judging by the voltage. > -- snip -- Could be three Ni-Cd in series, though. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: Tim Wescott on 2 Mar 2010 11:55
jg wrote: > I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to > charge. These were originally charged with a camcorder that I do not > have. However, I have the next best thing. I have a DC Power Supply > (BK Precision 1660A) with both voltage control and current control. > Basically I can set this bad boy to output any volt and current > combination. I have tried charging the batteries at 4.0v and 100mA > and let them charge for about 3 hours. Batteries never got hot (which > to me would indicate that they were never really charged.) When I > first unplug them, they register about 3.6v. However after a day or > so, their voltage drops to 2.6v or so. > > So... I am either not charging them up completely or they are no > longer functional. However, these batteries were never put in > production. They are old, but they were still in original packaging > as of a few days ago. > > Any help greatly appreciated. The correct charge cycle depends heavily on the battery type. Chances are you've either got three NiCd (or NiMH) cells in series, or one LiPo cell. The charge profile for NiCd and NiMH are quite similar -- with care you can use the same charging algorithm for both. The correct charge profile for a LiPo cell is completely different (and completely wrong) for NiCd/NiMH, and visa versa. So, your first step is to figure out your battery chemistry. Without that first step, there is no second step. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com |