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
I don't think you can make the judgment call that the thermistor was still OK after the first charge was completed. We know the part is under a tremendous heat stress. It's stressed to the point the material surrounding the actual wire within the thermistor becomes very brittle. You touch it and it falls apart. You don't know if this occurred during the initial connection to the battery. Poking the device with a penile during various times could give you a better idea when the body breaks down due to heat stress.
Regarding the thermistor resistance value. Everybody else thought more is better. If 2.5 ohm is good then 6 ohms is even better. They thought the higher resistance is better during the initial surge, giving proof that initial surge power is less when resistance is greater. They ignored the fact that a 2.5 ohm thermistor already has enough resistance to safely charge a 6000 uF capacitor bank. The OP's bank is only 2400 uF. 2.5 ohms is already more than enough. The 6 ohm part has a very negative characteristic. After the initial surge is over, it will always run hotter than the lower resistance part. And heat is killing the part.
Sal
Regarding the thermistor resistance value. Everybody else thought more is better. If 2.5 ohm is good then 6 ohms is even better. They thought the higher resistance is better during the initial surge, giving proof that initial surge power is less when resistance is greater. They ignored the fact that a 2.5 ohm thermistor already has enough resistance to safely charge a 6000 uF capacitor bank. The OP's bank is only 2400 uF. 2.5 ohms is already more than enough. The 6 ohm part has a very negative characteristic. After the initial surge is over, it will always run hotter than the lower resistance part. And heat is killing the part.
Sal
BFL13 wrote:Salvo wrote:
As I see it, the thermistor blew because it had too high resistance. You turned on the converter, waited a while and then connected converter leads to battery. And then, POW! During the delay, the thermistor cooled and its resistance increased........
No it did not go POW. That's the whole thing. It only went POW on a restart from starting just fine the first time. So it might even support your theory that it would be better to have low R when the current hits, as it has done with my clamp on last method, which works no problem on the first start.
When I try the clamp on first method and if it goes POW then, that would show having more R at start up is bad, if it is. Only one way to find out.... :)
