Need a high power, Cheap soft starter.

[Juggernaut]

Ok what is the cheapest soft starter I can buy, it needs to handle up to 21 volts and 61 amps, it's size is really not important, obviously it's not going into a Maglite……

 

[lctorana]

Parallel several 1-ohm NTCs

 

[ANDREAS FERRARI]

it needs to handle....61 amps....obviously it's not going into a Maglite……

OK,I give up,what are you building-a lighthouse???LOL

 

[Juggernaut]

I know little about electronic resistance, so a little walk through would be appreciated:thanks:. How do I set up these 1-ohm NTCs? Do I run them in series, parallel, 2, 3, 4+ of them? Not to get to specific with the details, but I'll be using 15 A123 batteries, 5 in series and then 3 of these series in parallel. I'll have 18 volts from 5x3.6 volts but the resting voltage is 20.5 or something close to that and I'm afraid I'll instaflashs the lamp assembly which flashes around 19.1 with a soft starter, so once the battery sag to their rated voltage or a little less it should be fine. I want as little resistance while running as possible since the 18 rated volts of the battery pack is what I'm going for if it ends up closer to 17.5 or something I can live with that but not much less. From this 18 volts I be pulling somewhere around 61 amps.

OK,I give up,what are you building-a lighthouse???LOL

 

[325addict]

Use some monster-MOSFETs in parallel, and switch them on by using an RC-network to drive the gates... simple and cheap, and it works, GUARANTEED. No more

Remember not to go beyond about 20V for the Ugs otherwise not the bulb, but the MOSFETs go

Timmo.

 

[kosPap]

I know little about electronic resistance, so a little walk through would be appreciated. How do I set up these 1-ohm NTCs? Do I run them in series, parallel, 2, 3, 4+ of them? .....I want as little resistance while running as possible since the 18 rated volts of the battery pack is what I'm going for if it ends up closer to 17.5 or something I can live with that but not much less. From this 18 volts I be pulling somewhere around 61 amps.

despite my limited lelecronincs knowledgeI can answer that...

paralleling resistors drops their combined value...see wikipedia for more specifics.

Now a NTC is a special kind or resistor that resists current flow till it gets hot...AKA teh delay/soft-start feature....

So when you parallel 1Ohm ones you make a very low value resistor yet retain their thermal performance....

all the best, kostas