FSAE Electric: Precharge | Intro & voltage-feedback design 

Warning! I drew the discharge circuit incorrectly. Of course, the negative side should remain on the TS side of the AIR-

Thanks a lot Michael!! I understood this very well

Hey Michael! just wanted to leave another comment since i've now successfully implemented my own modified version of your design. i removed the resistor overtemp circuitry, moved the resistor off-board, and swapped various parts like the optos, HV relay, and so on. cheers!

You are very clever. thank you for you for making this video. Parts were over my head but it was still interesting. :)

Really awesome video! Thank you

thanks for the info! really helpful mate!

Excellent explanation 👌

Yes, if you infer the Inverter voltage from signals inside the accumulator housing then there are open-circuit failure modes that can trip you up. Therefore detecting a pre-charge that is too fast takes care of those. Good idea. The messier solution is to wire the actual inverter voltage back into the accumulator housing, to the pre-charge controller, and perform a direct comparison between accumulator and inverter voltages. Thanks for sharing.

sweet vid dude, and iirc the rules(at least for american comp) now require actual monitoring of the precharge voltage rather than just charging for a conservative amount of time

Very nice video! Could you do another about cell stackup methods?

What if I use two accumulators with two pairs of main contactors, do I need two precharge circuits. If so how to sync them.

Hi Michael, would this approach work as well? Instead of using a V-F converter, why not have a microcontroller on the HV side which measures the voltage at the divider. Then it can communicate over Serial through the optocouplers to the mcu on the low voltage side. Thoughts? And thank you for the advice!

Thank you for the video, I need this for my HV storage. Just a question - wouldn't it be enough to simply connect the optocouplers to both sides of the charging resistor via the divider and compare the voltage differential? Either it's within the allowed range and it turns on the relay, or it's not within the allowed range and nothing turns on. Absolute voltage values are irrelevant I think. Sorry, I'm not an expert :) One more question, can this board be bought?

Im refering to the schematic that you have uploaded on github....i saw that that there are two high voltage grounds, Gnds and TS- ....Both these grounds have been connected using a 0 ohm resistor...is there and specific reason to do this? Also do they refer to the same ground?

Really good explanation of the precharge circuit! It really cleared my concepts and now have a very clear understanding of precharge. I had some doubts regarding precharge in general 1) is resistor divider a good measure of the voltages? Because a small error in the resistor value will cause a very big change in the corresponding high voltage measurement... especially if its around 500V 2) can we use an isolated adc directly instead of converting to voltage and then frequency? 3) are there any other possible approaches for precharge?

Hey Michael, thanks for the video - fantastic explanation of the system. Quick question that I'm hoping you could answer. What's the advantage of measuring the voltage across the precharge resistor? Would it not make more sense to measure the voltage across the capacitor, since you can then detect a few more failure methods? I was thinking that the TSAL and precharge circuits could make use of the same voltage divider to perform their respective duties.

Hey Michael i want to implement your design, but im having a difficult time understanding function of all the components. could you assist me with right documentation and information?

How do you power That voltage frequency converter, Do connect it to GLV Battery? if that's the case, does it break the galvanic isolation rules??

Is programmable logic allowed for precharge circuit as per FSAE rules ?

Hey Michael, Fantastic explanation for me to look at and understand very easily with year 11 knowledge. I just have a few questions? 1 - What does it take to get into FSAE? 2 - What kind of hours and training is put into building and creating the Formula Students Cars? 3 - What kind of knowledge do I need to understand the basics of FSAE I have been practising on Assetto Corsa (Im pretty serious about join, as its what I have been working towards to drive and make a Formula Car) Thanks

Can I get some help designing a precharge circuit for My off grid system?

Hey! Can u also add schematic files for precharge and AIL in pdf format? I couldn't see them through your GitHub account :c

Hi Michael I need some help to build a pre-charger and a dis-charger how do I get in contact with you

What about the provisions of Galvanic isolation between the the potential divider u used and voltage to frequency converter ,I believe According to fsae rules we do need to provide galvanic isolation between high voltage system and low voltage component ,even though if we drop down the voltage of the accumulator still it is from high voltage side . If the v tof conevertor is galvanically isolated ,can u share the ic number

can share the schematic digram of the precharge circuit which u have designed

can we charge Capacitor using constant current ?

Which team are you with Michael?

hey michael, i am trying to access the github files, but none of them seem to open, nor could i download the raw files. Could you help. Great video, helped alot.

can share the schematic digram of the precharge circuit which u have designed