Lithium suicide. - Page 1
Forum section: electronics / general

author: G7PSK
author_rank: Super Contributor
timestamp: April 12, 2012, 09:15:53 pm
content: Just over a year ago I purchased a replacement power cell for my Nikon camera. It recently stopped holding its charge for more than a few hours, and would go flat over night. I took the battery apart and found that just after charging the cell gave a bit over 4.6 volts each. I looked at the battery control board and found that it was putting a resistance of 412 ohms across the cells at all times. I removed the board and re-assembled the battery which has now held its charge for several days and still works the camera. The replacement battery carries the Duracell brand name which is supposed to be reputable. I was wondering what the real risks of running this battery is without the suicide chip in place. Is just an unfortunate chip failure or dose the chip contain a timer or charge counter to disable the battery after a preset time. The original Nikon battery is still going strong after about five years of use.

author: bilko
author_rank: Frequent Contributor
timestamp: April 12, 2012, 09:46:21 pm
content: It sounds like a controller board failure. How old is the battery ? Is it still under warranty?I used to swear by Duracell, now I swear at them!Search this forum or Google for Duracell battery leak, they were once a good company but not any more.

author: T4P
author_rank: Super Contributor
timestamp: April 12, 2012, 09:50:02 pm
content: Duracell was a good company ... years agoNow it's just bullshit .

author: IanB
author_rank: Super Contributor
timestamp: April 12, 2012, 11:19:52 pm
content: Quote from: G7PSK on April 12, 2012, 09:15:53 pmThere's something a bit wrong there. A lithium ion battery should not be higher than 4.20 V when charging is complete. Over 4.6 V is getting close to "this battery is about to explode" territory. Are you certain of the voltage measurement?If you measure the Nikon battery when fully charged, what voltage does that have?

author: slateraptor
author_rank: Frequent Contributor
timestamp: April 13, 2012, 01:15:19 am
content: Quote from: G7PSK on April 12, 2012, 09:15:53 pmQuestionable is a rechargeable battery sold by a company whose profits revolve primarily around disposable replacements.Quote from: G7PSK on April 12, 2012, 09:15:53 pmIf by "suicide chip" you mean charge controller, then the risks are very, very real. Do not attempt to charge a Li battery without an appropriate controller. Although it's purely speculative (professional validation please), I suspect these charge controllers are purposely designed with a failure mode that prevents overcharge, and thus violent explosions.

author: T4P
author_rank: Super Contributor
timestamp: April 13, 2012, 05:34:07 am
content: Quote from: IanB on April 12, 2012, 11:19:52 pmI have a nikon and normally the voltage should be 7.4VAs with most cameras their battery voltage is nominally 7.4V

author: Psi
author_rank: Super Contributor
timestamp: April 13, 2012, 05:49:54 am
content: Quote from: Dave.S on April 13, 2012, 05:34:07 am7.4v is just a two cell lithium pack (3.7 x 2)

author: G7PSK
author_rank: Super Contributor
timestamp: April 13, 2012, 07:19:18 am
content: Both the battery packs read over 8 volts the Nikon one is 8.3 volts and the Duracell is 8.27 volts today neither one has been on charge since last Sunday both state &. volts on the label and both were charged in the Nikon charger I checked my meter which is fairly new on a CR2032 cell and got a reading of 3.2 volts which is what I would expect I will check it against another meter later today but I dont think its the meter.Could the charger be at fault or is the stated voltage an on load voltage.

author: amyk
author_rank: Super Contributor
timestamp: April 13, 2012, 07:58:52 am
content: 3.2v on a CR2032 sounds a bit high.Lion batteries are 3.7v nominal and 4.2v fully charged.

author: IanB
author_rank: Super Contributor
timestamp: April 13, 2012, 08:10:52 am
content: Quote from: G7PSK on April 13, 2012, 07:19:18 amThat's OK. At 4.2 V per cell a two cell battery should charge up to a bit under 8.4 V. When drained you should be seeing something like 7.2 V.

author: G7PSK
author_rank: Super Contributor
timestamp: April 13, 2012, 08:34:47 am
content: Checked against my other meter (an AVO) and get the same sort of reading, just over 8.25 volts on the Lithium packs and just over 3 volts on the CR2032 which when you consider that it is a coil meter with the increased loading is much what one would expect. Surely the main charge regulation is done by the charger and the onboard chip is just a precautionary measure in case of shorting of the cell etc, there is no temperature sense with these cell packs.

author: Psi
author_rank: Super Contributor
timestamp: April 13, 2012, 01:07:21 pm
content: Quote from: amyk on April 13, 2012, 07:58:52 amNa that's completely normal for a CR2032.They're always ~3.2V when bran-new (unless they're a crap brand or have been sitting around for years)

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2012, 02:57:12 pm
content: With lithium cells most of the charge intelligence is built into the battery itself, especially if it is removable. The device holding it generally only provides power and sometimes a switch to terminate charge under instruction from the battery pack. Only if the battery is permanent will there be a charge controller in the equipment, with at least a thermal sensor on the battery, and a current measuring method ( low value resistor) in series with the battery to control charge current and detect discharge.That is why you will find almost all lithium secondary battery packs have 3 or more connections to the equipment, 2 are power, and the others are either a data channel to communicate charge state ( most simple is a logic level to stop charging) and battery condition and status on more complex packs.thus, if your controller board is dead, you need either a new one, or to buy a new battery pack. Those cells have an energy density equal to dynamite, and can release all of it in a few seconds if they are grossly abused, or develop a fault due to overcharging because there is no charge controller. They then burn, and this fire cannot be put out easily, as the battery contains both a combustible metal ( metallic lithium in the sandwich) and an oxidiser in the electrolyte and the manganese dioxide and carbon electrodes. The working fluid is also flammable.

author: G7PSK
author_rank: Super Contributor
timestamp: April 13, 2012, 03:09:00 pm
content: The Nikon battery pack only has two connections on it there is no thermal sensor on the board inside the pack which means there must be one inside the external charger pack. The battery is charged out of the camera. All the other bits of equipment I have that use Lithium ion cells have three or more terminals on the battery packs.Does any one know how high a current is required to explode these types of cells, I had wondered about conducting an experiment to find out but that will have to wait until it stops raining as I it is something that will have to be done out side in the open well away from the house, the most I will be able to push through will be 180 amps at 24 volts, if I do the experiment I will video it for all to see.

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2012, 03:16:53 pm
content: You do not need a high current, just charge the cells with 6V per cell, at around 2A. They will take off as soon as they are fully charged and start to make metallic Lithium metal inside. Attach a thermocouple to a cell ( with a long lead to a meter) and you will see a temperature spike just before the fireworks start.

author: ejeffrey
author_rank: Super Contributor
timestamp: April 13, 2012, 04:00:48 pm
content: Quote from: SeanB on April 13, 2012, 02:57:12 pmThis is completely untrue and dangerous misinformation. Lithium ion packs rarely have the charge circuit built in, and should only ever be charged from a charge controller designed for lithium ion batteries and with a current limit appropriate to the battery pack in question. Your confusion probably results because Lithium ion/lipo battery packs and individual cells often have protection circuits built in, especially when the are designed to be removable. These provide overvoltage protection, undervoltage lockout, and short circuit protection. However, these are additional failsafes designed to avoid catastrophic failure (i.e., fire or explosion) if the battery is accidentally short circuited or connected to the wrong charger. They are not a substitute for a proper Li-ion charge controller!The protection PCB (which is probably what the OP found inside his battery) is not optional, and should not be removed or defeated. It should have a FET switch that only activates in case of overvoltage. It sounds from the description like the protection circuit has failed with the switch shorted, leaving only a current limiting resistor. That could be either due to a low quality battery or that it was connected to an incorrect or defective charging circuit. The battery should be disposed of and the charger should be inspected or replaced.

author: G7PSK
author_rank: Super Contributor
timestamp: April 13, 2012, 04:15:43 pm
content: Quote from: ejeffrey on April 13, 2012, 04:00:48 pmI would think the charger is OK as the original Nikon battery is fine. I think that the extra battery I bought is of inferior build as seems to be the norm with all replacement batteries whatever the type, ever noticed how the battery supplied in a new car lasts for five or six years and the replacement is dead in three.