Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
BFL:
I believe (course your future use may prove me wrong, but I'll say it anyway) that if you use the part proposed by powermax and "change" your use scenerio to the following that your failures will go away.
a) Have the converter off for 3 minutes minimum
b) connect the battery(s) to the converter
c) power on the converter
and your failure will go away.
With a battery connected at power on, the input caps charge, the output circuit starts a ramp up towards 12V. At some point in time the output voltage is above the battery voltage and it starts to supply charging current, but it won't supply 100A instantly, it will ramp current up as the control loop keeps the output voltage rising. How long? don't know. Depends on how it was designed, may take fractions of a second, may take a few seconds till it can supply the full 100A. But the control circuit determines that. And thats likely how it was tested.
As a result input current stays in check and rises predictably till it supplies the needed current to sustain output.
In your previous case as I understand it,
The discharged battery connected to the converter that had no load on it and a voltage in the 15 range with a battery voltage in the low 12V range that looks almost like short circuit. This likely caused a very rapid discharge to the input caps, the ouput voltage drops way down, feedback circuit goes into fits trying to keep the output voltage up, may even oscillate or go in and out of current limit for a while and it takes a sustained high current draw, maybe well in excess of the nominal 15A for a while (seconds?) till the output recovers.
I believe (course your future use may prove me wrong, but I'll say it anyway) that if you use the part proposed by powermax and "change" your use scenerio to the following that your failures will go away.
a) Have the converter off for 3 minutes minimum
b) connect the battery(s) to the converter
c) power on the converter
and your failure will go away.
With a battery connected at power on, the input caps charge, the output circuit starts a ramp up towards 12V. At some point in time the output voltage is above the battery voltage and it starts to supply charging current, but it won't supply 100A instantly, it will ramp current up as the control loop keeps the output voltage rising. How long? don't know. Depends on how it was designed, may take fractions of a second, may take a few seconds till it can supply the full 100A. But the control circuit determines that. And thats likely how it was tested.
As a result input current stays in check and rises predictably till it supplies the needed current to sustain output.
In your previous case as I understand it,
The discharged battery connected to the converter that had no load on it and a voltage in the 15 range with a battery voltage in the low 12V range that looks almost like short circuit. This likely caused a very rapid discharge to the input caps, the ouput voltage drops way down, feedback circuit goes into fits trying to keep the output voltage up, may even oscillate or go in and out of current limit for a while and it takes a sustained high current draw, maybe well in excess of the nominal 15A for a while (seconds?) till the output recovers.
