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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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#1
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
Trying to find a replacement for a 1F/2.5V supercap.
Original: http://www.newark.com/cooper-bussman...super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave |
#2
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote:
Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...5-r/capacitor- super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave Logic would dictate it would discharge quicker but my logic is usually flawed. -- Live Fast, Die Young and Leave a Pretty Corpse |
#3
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
On 2/22/2011 2:52 PM, Meat Plow wrote:
On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote: My question: what's the impact of replacing a supercap with one with a higher ESR? Logic would dictate it would discharge quicker but my logic is usually flawed. Considering that the draw on these caps is usually measured in microamps, I doubt the higher ESR is going to effect how well it works. Maybe might make a bit of difference in how long it takes to fully charge though. Jeff |
#5
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
Meat Plow Inscribed thus:
On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote: Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...5-r/capacitor- super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave Logic would dictate it would discharge quicker but my logic is usually flawed. I would have thought that the cap, same value, wouldn't be able to provide the same peak current because of the higher ESR. Other than that, physical size might be an issue ! -- Best Regards: Baron. |
#6
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
On Tue, 22 Feb 2011 21:07:04 +0000, Baron wrote:
Meat Plow Inscribed thus: On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote: Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...5-r/capacitor- super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave Logic would dictate it would discharge quicker but my logic is usually flawed. I would have thought that the cap, same value, wouldn't be able to provide the same peak current because of the higher ESR. Other than that, physical size might be an issue ! I don't think peak current is an issue however size might be. In such a device I would look for a taper off of charge as long as possible in order to sustain programmed memory until the bitter end. Otherwise with proper charge the device is pretty much transparent. -- Live Fast, Die Young and Leave a Pretty Corpse |
#7
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote:
Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...5-r/capacitor- super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave Supercaps are also used as batteries in those quick charging micro rc cars where they supply current for about a minute to a small motor and the steering servo. Those models could probably have a lower internal resistance. |
#8
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
"DaveC" schreef in bericht ... Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Thanks, Dave Well, As its says itself it's a Equivalent Series Resistor so it can be considered a resistor in series with the capacitor. As such it dissipates some energy during charging and charging takes some more time. On discharging the resistor will also dissipate some of the energy and lowers the on the cap available voltage by the voltage drop over the resistor. So a high ESR gives a less power efficiency and will earlier be "empty". petrus bitbyter |
#9
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
asdf wrote:
Supercaps are also used as batteries in those quick charging micro rc cars where they supply current for about a minute to a small motor and the steering servo. Those models could probably have a lower internal resistance. I once bought two of those little toy RC cars for about two bucks apiece from the clearance bin. It was fun, for a little while, but frustrating because there was no throttle or proportional steering. It was either stop or go-as-fast-as-you-can, and straight or lock left or lock right, so it was almost impossible to actually steer it, especially over anything but a totally bare hard smooth floor. The tires were about 1/4" diameter. Some months later, they hired some new kid in the shop, and he bought one of them for ten bucks. :- Cheers! Rich |
#10
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
In article ,
DaveC writes: Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...super-1f-2-5v- 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? Depends on the application. Some are designed to provide backup power at low currents for long periods. Some are designed to provide high power at high currents for short periods. The latter type won't like an increase in ESR. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
#11
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
"Jeffrey Angus" wrote in message . .. On 2/22/2011 2:52 PM, Meat Plow wrote: On Tue, 22 Feb 2011 12:21:55 -0800, DaveC wrote: My question: what's the impact of replacing a supercap with one with a higher ESR? Logic would dictate it would discharge quicker but my logic is usually flawed. Huh! The higher the ESR the lower the peak current you can draw from it and the longer it will take to fully charge with a given source. Considering that the draw on these caps is usually measured in microamps, I doubt the higher ESR is going to effect how well it works. Huh? (Again!) The draws are usually measured in the 10s of Amperes. In some applications, the 100s of Amperes (such as when a super cap is used to help start something.) Maybe might make a bit of difference in how long it takes to fully charge though. That but also how much the cap heats when both charging the discharging. If it's being used in a power supply filtering function, a high ESR will both reduce the filtering effect and increase the heating of the cap. |
#12
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.repair
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Supercaps and ESR
On Feb 22, 3:21*pm, DaveC wrote:
Trying to find a replacement for a 1F/2.5V supercap. Original: http://www.newark.com/cooper-bussman...pacitor-super-... 0-4ohm/dp/78K7800?Ntt=B0810-2R5105-R I can find local replacements rated 1F/5V but the ESR is ~30 ohms instead of 0.4. I presume that supercaps aren't applied to filter applications -- their specialty being an alternative to batteries to power memory or such -- so ripple current shouldn't be an issue. My question: what's the impact of replacing a supercap with one with a higher ESR? I think it depends on application. I haven't done detailed measurement but I would postulate that the low-ESR supercaps have more surface area and higher leakage, and the higher-ESR supercaps have less surface area and less leakage. Tim. |
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