DC UPS with Capacitor circuit

In the past I had posted a similar circuit for a DC UPS that would also charge a SLA battery. I would now like to replace the SLA battery with a 52F Ultracapacitor.

The capacitor will look like a short when first being charged (0 V across cap) so I adjusted the resistor in series to be 15hm: to limit current draw to 1 AMP max while charging. Using 5x the RC time constant I believe the charging time should be arond 65 minutes.

Assuming a load of 15hm: I calculate (VL=VC*e^(-t/RC) a run time (without the DC source present) of a little over 5 minutes until voltage drops to 10V.

Does anyone see any issues with my assumptions and this circuit.

Does it work? - I would have thought it's probably got a much shorter life than an SLA, and may not be able to supply enough current? - their internal resistance is usually fairly high?.

Have not tried it yet . The Ultracapacitor used is made by Maxwell (PN: BMOD0052-P015-B1). The spec sheet claims it has an ESR of 14.5mohms and an Ic of 1mA (not sure what Ic is though).

Shmedly said:

Have not tried it yet . The Ultracapacitor used is made by Maxwell (PN: BMOD0052-P015-B1). The spec sheet claims it has an ESR of 14.5mohms and an Ic of 1mA (not sure what Ic is though).

Click to expand...

Presumably Ic is the current the ESR was measured at?.

Well going on his charge RC curve a 52F cap should be good for 1A for 12minutes, with a 15R load. So 15W for 10-12 minutes?

It is a capacitor, not a battery so its voltage begins to drop immediately it is loaded.

Its datasheet lists its max current at 1500A!