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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Wireless Battery for Electric Drill failure Ryobi
I purchased this unit less then a year ago that comes with two set of
batteries. One of the batteries failed (short circuit) .I open the unit that consists of 10 Panasonic batteries and all of them are in short circuit. I wonder what makes ALL of them to short circuit. Vlad |
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Vlad wrote:
I purchased this unit less then a year ago that comes with two set of batteries. One of the batteries failed (short circuit) .I open the unit that consists of 10 Panasonic batteries and all of them are in short circuit. I wonder what makes ALL of them to short circuit. Although rare in a 1 year old battery, this is usually a sign of dendrites... whiskers of nickel that grow within the cell as the cell ages. The dendrites can grow long enough to make a short circuit between the poles of the cell. |
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Vlad wrote:
I purchased this unit less then a year ago that comes with two set of batteries. One of the batteries failed (short circuit) .I open the unit that consists of 10 Panasonic batteries and all of them are in short circuit. I wonder what makes ALL of them to short circuit. Vlad Does seem unlikely. Are you sure they're all shorted and not merely at zero volts? Problem is user misuse plus dumb fast charger. You're drilling a hole. The drill starts to slow down. You finish the hole. Maybe you're in a hurry and drill the last two holes too. Result, one battery reversed. Next time the weakened cell reverses sooner, but the others are still good and you keep drilling until it slows down markedly. Result, one cell seriously damaged and damage started on the next one. Eventually, one shorts. The charger is dumb and charges the crap out of the others trying to get the n-1 pack up to n volts. Cells overheat and vent. Viscous cycle destroys the pack. It is unusual for ALL to go shorted at the same time. It is not unusual for overheated cells to self-discharge and all end up at zero volts rather quickly. The premeptive solution is to make sure the battery is fully charged before you start and stop before it's fully discharged. This is difficult. If you sense any sudden weakening in torque, stop immediately and recharge the pack. If you start drilling with a battery that's been fully charged then set on the self for two weeks, you're asking for trouble. mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/ |
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On Thu, 03 Mar 2005 10:48:10 -0800, mike wrote:
Vlad wrote: I purchased this unit less then a year ago that comes with two set of batteries. One of the batteries failed (short circuit) .I open the unit that consists of 10 Panasonic batteries and all of them are in short circuit. I wonder what makes ALL of them to short circuit. Vlad Does seem unlikely. Are you sure they're all shorted and not merely at zero volts? Problem is user misuse plus dumb fast charger. You're drilling a hole. The drill starts to slow down. You finish the hole. Maybe you're in a hurry and drill the last two holes too. Result, one battery reversed. Next time the weakened cell reverses sooner, but the others are still good and you keep drilling until it slows down markedly. Result, one cell seriously damaged and damage started on the next one. Eventually, one shorts. The charger is dumb and charges the crap out of the others trying to get the n-1 pack up to n volts. Cells overheat and vent. Viscous cycle destroys the pack. It is unusual for ALL to go shorted at the same time. It is not unusual for overheated cells to self-discharge and all end up at zero volts rather quickly. The premeptive solution is to make sure the battery is fully charged before you start and stop before it's fully discharged. This is difficult. If you sense any sudden weakening in torque, stop immediately and recharge the pack. If you start drilling with a battery that's been fully charged then set on the self for two weeks, you're asking for trouble. mike Mike I didn't realized they were so difficult to please . Worse then my mother in law. Thanks Vlad |
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