How a high voltage Precharge circuits works on a DIY Tesla drive project

[@Chawaonga]

The precharge circuit explanation was helpful, thanks!

[@hotrodsandgolfcarts8247]

Very nice explanation. I too purchased a Stealth EV kit with Tesla LDU and 14 model S modules, going in a 911. Got the batteries and motor mounted, now at stage of bench testing and learning how it all comes together. While the Stealth kit came with every component, it lacked any instructions. I'm learning form youtubers like yourself, but wish Matt would answer his phone! Anyways, keep up the great content and please post more I'll be watching.

[@ev-swap]

Yeah, I got ghosted by Stealth after I purchased my drive. It was a real disappointment. Had to decline the charge on my card to get Matt to respond at all. Search their name on the DIY forum and you will find lots of similar stories. Do you have a website or a build page so I can follow your progress?

[@xudongwang8137]

Thank you for precharge circuit demonstration, very clear!

[@ev-swap]

Glad it was helpful!

[@MryoutubeOYB]

Perfect explanation, thanks a lot

[@g-mech1244]

So your start button is a click on, click off button? Not a momentary push button. Also, does this setup need an economizer circuit to stop overheating the contactor?

[@vilasith88]

Can't wait for the next video

[@cliv3-88]

Hi, im new to this, just in case my question is dump 😅 ,,.what voltage did you drop using the precharge circuit? Is there a rule of what voltage you need to drop to be safe?

[@donaldtaylorjr9878]

Nice! This was a clear demonstration! Thank you! I was wondering, with your setup was it your estimated range and top speed. I am thinking of getting a Model S, using the Damien Maguier board and pairing with Chevy Volt Batteries. I was actually looking at the Orion BMS for my build too. Just doing a lot of research and planning at the moment.

[@ev-swap]

A good rule of thumb is 100 miles of range for every 30 KWh of battery. So this 16 KWH Volt Pack should be good for 50 miles. Which is what the Chevy Volt was rated for. But that range depends heavily on the weight of the car, its aero dynamics and how you drive it!

[@donaldtaylorjr9878]

@@ev-swap Thank you!

[@samnile2]

I like your test bench setup,, sorry.. what is brand of your motor speed controller and inverter

[@ev-swap]

I am using a ZeroEV controller board for the Tesla drive. It is based on the Open Inverter board. The inverter is the stock Tesla inverter that comes with the Sport version of the Large Drive Unit (LDU)

[@mattevans7352]

Thanks for the video! For the pre-charge circuit, why the relay and not a 2nd contactor with the load resistor?

[@ev-swap]

Hi Matt, that is a good question. Really, a relay and contactor are the same thing, its just a contactor is designed to handle high current. There is a fascinating video here on KZbin by gigavac showing how the contactor works and deals with the arcflash that is created every time it closes its circuit. So to answer your question, I used a low current relay because it is less expensive than another contactor ($25 vs $200). The relay works fine since the resistor prevents a lot of current from crossing its circuit.

[@leenaz6237]

great work! just wondering how to connect a pre-charge circuit to orion bms? what pins do you use?

[@ev-swap]

The Orion BMS does not control the precharge circuit, it is normally handled by the motor controller, since the controller can measure the voltage on the high voltage invertor's bus. So in my case, the logic board (aka motor controller) that is embedded inside of the Tesla drive will activate the precharge relay and eventually the contactor once it detects enough voltage internally. I believe most motor controllers are in charge of the precharge circuit, even if they are external to the drive (like a Curtis controller)

[@ronriley2907]

Is the resister in the pre charge circuit sometimes part of the controller/inverter? Also, is the main contactor you are using a 48v economized contactor from Gigavac? I heard they went out of business and if so do you know where they can be sourced?

[@ev-swap]

The resistor is a stand alone component. It's gold colored in the video, with fins.

[@ev-swap]

I imagine in some oem setups, it's integrated with the contactor, but most DIY setups I have seen, the are separate components, but the main relay and contactors are controlled by a logic board on the invertor because it needs to monitor the incoming current

[@ev-swap]

Yes to the gigavac.

[@ev-swap]

Gigavac merged with Sensata. There contacts still seem to be available on the interwebs

[@JoseCampos-ux6vo]

Thank you 👍👍👍👍

[@mervedelibas2504]

Hello, I would like to ask you a question. What might be as a possible causes for delay in precharge time. The expected 1 cycle is between 400-800 mS but the circuit that I have complete the cycle in 1.5second. Also how dcdc converter ıs working in precharge?

[@ev-swap]

I guess it depends on the pre charge controller you are using. In my video, the control board inside of the Tesla invertor controls the pre-charge circuit. And it watches the voltage levels in the MOSFETS and once they reach a particular voltage, it engages the high voltage circuit. Maybe other pre-charge circuits just use a timer, but it seems like watching the voltage is better. What pre-charge circuit are you using?

[@moperez10]

Which cooling pump did you use for your battery pack?

[@ev-swap]

The Tesla cooling pump. There are lots of them on ebay for less than $100.

[@vilasith88]

Good work 👏

[@ev-swap]

Thanks ✌️

[@andreyl2705]

awesome))

[@hamzahammadi1277]

Hi Mark how can u help me... I have question.. And thank u??

[@ev-swap]

About what?

[@hamzahammadi1277]

I need to mesure height voltage in range 240 to 450....with microcontroller aurix tc3... Input analog support _0.7 to 6.75 Do u think voltage divider circuits is correct?

[@nikhilkanitkar695]

How much did you cost for this EV project

[@ev-swap]

So some of the electronics you see in the video are not too expensive. The resistor is $10, the small relay is about the same. The high voltage gigavac contactors are about $200. But the batteries can be very expensive (about $3000 for my Volt battery) and its only 18 KW. The Tesla drive you see in the video is even more expensive, I bought a refurbished unit for $11,000 (including the aftermarket control board). For drives, you can get a Tesla small drive for much less on ebay (around $3,000) but you would need a control solution that is going to be around $3,000 as well

[@softspot5269]

What's the resistor value?

[@ev-swap]

Its a ARCOL HS100-100RF rated at 100 ohms www.tme.com/us/en-us/details/hs100-100rf/100w-resistors/arcol/?brutto=1

[@buckithed]

how bad was the shock?

[@ev-swap]

Enough to make me say a bad word! All kidding aside, I'm much more careful now and invested in a good set of HV gloves and covers.

[@jamesvandamme7786]

@@ev-swap Always keep one hand in your pocket. Or at least don't touch a different part of the circuit so you don't get a current patch through your arms, with your heart in between them.

[@kwapin7]

@@ev-swap How did You survive 300V DC ? Everything above 50V is fatal. Unless it is not DC?

[@winfactor]

@@kwapin7 Im not sure it is accurate to say that everything above 50V is fatal. I believe it depends on the time of contact along with the path the current is taking through your body.

[@cyumadbrosummit3534]

More videos.

[@samirkhanduri]

Good work 👍

[@ev-swap]

Thank you so much 😀