SX500IS external power with battery Vs AC adapter?

[ju1234]

I am not an engineer and have minimal understanding of electronics other than common sense. I was trying to rig SX500IS with external power and ran into couple of issues. The camera uses the thin flat 3.7V battery and works fine on batteries. However I am trying to get longer duration of uninterrupted use. I got the ACK-DC40 equivalent. It comes with the DC coupler (Dummy battery) and AC converter of 4.3 Volt output (the original battery is 3.7V). This external power works fine with the camera. However I am wanting to use a high MAH battery instead of the AC converter, since there is no AC power available in the field. I have connected a battery through a step down buck regulator to reduce the voltage down to 4-4.5 volt. I have tried several different power sources 12 volt 7AH alarm system battery, 6 volt 5AH Lead acid battery, older NiCD / NiMh camcorder battery rated at 6 Volt 3000MAH which works fine on my camcorder. I run into same problem with all of them. The camera turns on but turns off immediately as if there is not enough power. I assume there is not enough "driving amps", if my terminology is correct? The same set up works fine with my other camera SX400IS which also uses 3.7 volt battery. Any suggestions on how I can make it work? Thanks for the help.

[kvbarkley]

The NB-6L battery is 3.7 V, but it is unclear how much current it can supply. It is rated for 1000 mA hours, which implies that it can supply 1 Amp for 1 hour. That says to me that your D-DC converter must be able to supply at least 1 A. Batteries can supply very high peak currents, so that might be too conservative, you might need up to 3 A.

[ju1234]

Thank you for the answer. The maximum amps of the Buck regulator I am using is 2.5A. I don't think the buck regulator is the problem. With the A/C adpater 4.3V rated at only 1.5A works fine. I took several spare A/C adpaters and put them through the same step down regulator. I tried a regular 9V 1A, laptop 19V, 2.5A, 2A and 3.5A, they all work fine. But when it comes to battery it does not work. I have already listed the batteries I have tried. Even the laptop battery which is 14.4V 4.5A did not work (I am sure a laptop draws lot more current than this camera). So, there must be some other factor.

[newsense52]

" The camera turns on but turns off immediately as if there is not enough power". 

This is a camera protective procedure not to further damage the camera. No way to exceed the ampacity of the battery except only until its allowable tolerances. Use only its true charger. The best way is to have spare batteries and not explore how to prolong battery life.

Do not frequently off/on the camera because its RLC circuit use a maximum current in the first three milliseconds after power is on. Yes the flash use too much current, Only way not to use it is lighting the room/area of concern.

[ju1234]

Thank you very much.

[newsense52]

You are very welcome.