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
The ratings on the bridge rectifiers are the maximum usable amperage of the rectifier. Running more amps than the rating through them is not a good thing.
Your transformer will draw a lot of amps, so much that it will saturate the transformer. While it is drawing this large amount of current that can be harmful to the windings, we also don't want it to exceed the ratings of the diodes. This is the role of the thermistor, it limits the excessive draw asked for by the transformer and also protects the diodes.
So, if we offer an unlimited amount of current with our AC power, we have to assess the amount of current, initially (the inrush current), through the device that is going to be friendly and also size the thermistor to be able to endure the steady current needed to power the device, continually.
I know the Powermax spec is a steady current rating of 13A but I question that, especially if the charger is asked to put out 100A to the batteries. The mfg also suggests using an AC circuit that is rated to 20 amps.
In the manner of thermistor sizing it may be prudent to have a thermistor that will endure current to higher than the spec current of 13A, perhaps as much as double or 25A. I'm offering this as intuitive knowledge, rather than working through the equations. Your sizing program should be more specific as to the type and size of thermistor needed.
Your transformer will draw a lot of amps, so much that it will saturate the transformer. While it is drawing this large amount of current that can be harmful to the windings, we also don't want it to exceed the ratings of the diodes. This is the role of the thermistor, it limits the excessive draw asked for by the transformer and also protects the diodes.
So, if we offer an unlimited amount of current with our AC power, we have to assess the amount of current, initially (the inrush current), through the device that is going to be friendly and also size the thermistor to be able to endure the steady current needed to power the device, continually.
I know the Powermax spec is a steady current rating of 13A but I question that, especially if the charger is asked to put out 100A to the batteries. The mfg also suggests using an AC circuit that is rated to 20 amps.
In the manner of thermistor sizing it may be prudent to have a thermistor that will endure current to higher than the spec current of 13A, perhaps as much as double or 25A. I'm offering this as intuitive knowledge, rather than working through the equations. Your sizing program should be more specific as to the type and size of thermistor needed.
