Supercaps and ESR

[DaveC]

Trying to find a replacement for a 1F/2.5V supercap.

Original:

<http://www.newark.com/cooper-bussmann/b0810-2r5105-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

 

[Meat Plow]

Trying to find a replacement for a 1F/2.5V supercap.

Original:

<http://www.newark.com/cooper-bussmann/b0810-2r5105-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.

 

[Jeffrey Angus]

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

 

[Baron]

Meat Plow Inscribed thus:

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 !

 

[Meat Plow]

Meat Plow Inscribed thus:

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.

 

[asdf]

Trying to find a replacement for a 1F/2.5V supercap.

Original:

<http://www.newark.com/cooper-bussmann/b0810-2r5105-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.

 

[petrus bitbyter]

Trying to find a replacement for a 1F/2.5V supercap.

Original:

<http://www.newark.com/cooper-bussmann/b0810-2r5105-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

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

 

[Rich Grise]

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

 

[Andrew Gabriel]

Trying to find a replacement for a 1F/2.5V supercap.

Original:

<http://www.newark.com/cooper-bussmann/b0810-2r5105-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?

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.