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I am building out the precharge circuit for my EV conversion and i am going down the route of using a software controlled relay bank to trigger the other elements.

Here is what i have so far
https://youtu.be/RcIAnKZcI3I

I am currently using an Arduino Nano clone to trigger this. Before I go too far down the path of writing code for this, I wantes to see if there were any better alternatives.

Thanks

Shane
 

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In my Think EV they have used PTC's controlled by a MOSfet as a pre-charge circuit. Works pretty wel and very simple. By parallelling less or more PTC's you can set the pre-charge time.
 

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Did you ask your Youtube buddy for the code he used? The code's pretty simple, but it's always nice to have a skeleton to put the meat onto.
 

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I used a 555 IC with a few resistors and capacitors to get a time delay in relay turn on in a couple of places in my 1991 Geo Metro EV. Only costs a couple of dollars in parts to implement. Google "555" timer circuits" for more info.
 

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I took a bit of a different approach. If this is a car you plan to use with some frequency, my method was to actually permanently wire in the resistors into the electrical system with a manual disconnect via a switch.

So basically I have both of my resistors connected to both sides of the terminal with one of the wires going up near the cabin to a toggle switch.

When the switch is off, there's no full circuit, so the resistors are disabled and don't kill the battery, which is used for long term storage.

Then when I plan to use the car for a bit, I can turn the switch on and leave it so the system is always charged, all I have to do is give the controller voltage and connect the contactors at startup and I am ready to go.

I cover my initial setup and installation of my contactor/resistor system in this video here if that helps, I'll be showing that toggle switch addition in a later video (https://youtu.be/V86oAZzfwRE)
 
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