5Kw charging basic wiring

[phillipschip]

Hi, I am new to all this and just starting out with my project. I will be using a Tesla SDU with openinverter board in a small car with a very modest battery pack. 1/2 the pack will be in front, and the other in the middle by the motor. I am trying to keep this as light and simple/inexpensive as possible. I have a very basic knowledge of electronics-I didn't build and electric go kart recently though, so the wiring of the motor to controller and battery pack I think I got. I don't understand the wiring diagram for wiring up the boost mode charging however. Could someone point me in the right direction? What exactly do the two incoming wires go to from the charge port? Do I need a bridge rectifier? If so, what kind? I assume I will be using a 240v outlet? My pack voltage is 400v (120s8p A123 lifepo4 cells, (10 x 36v modules).

[johu]

With those integrated drive units inverter boost charging is a bit more challenging as you somehow need to access motor terminal 1 or 3.
Yes you need a 240V bridge rectifier. The "-" of the rectifier goes directly to your battery "-" and the "+" goes to phase 1 or 3. An additional common mode choke before the rectifier and a 10u capacitor across the AC inputs will stop your fuses from singing.

The remaining relay logic is to prevent short circuits when plugging in when the car is in ready to drive, it immobilizes the car and also wakes up components needed for charging.

[phillipschip]

Thanks for the response! Does the system basically just need to turn on when plugged in to charge and off when unplugged? Is there anywhere to check out a basic wiring diagram of a simple setup that involves relays needed. I know there is one on this site but I would need an electrical engineer to translate it for me :0

[tom91]

If you are asking these levels of questions there is no way of you implementing this safely. So please reconsider your approach.

[phillipschip]

Wow, discouraging response. Is this typical of this forum? Everyone needs to start somewhere right? I haven’t even started my build yet. I figure I’d start out by asking questions first to insure that I can accomplish what I want in the safest way. I thought I’d start here. Maybe not a good idea….

[johu]

Get to know people here before coming over all insulted.
Non-isolated inverter charging has more risks than just throwing a purpose built, isolated charger in there. If you don't understand what you're doing and need spoon-feeding it is a risky undertaking. So Tom has a point in "pointing you away" from this in his unique way.

I'm terribly liberal in letting people electrocute themselves and have put people off with that attitude.

The wiki page https://openinverter.org/wiki/Battery_Charging is all the documentation there is. You need a solid EE background to understand it. If you don't, leave it for now or make some tests with non-lethal voltages to get your head around it. The videos that are provided also feature low voltage testing.

[phillipschip]

Thanks for the response! I have a good attitude and am extremely excited to start this project. I will definitely be running tests with low voltages for all steps of this project. I just want to make sure I am absolutely safe before I even begin. I have built an 70mph electric go kart with a brushless sinusodial DC motor at this point, and built batteries. The motor controller/battery management part seems similar. I just wanted to find out a bit more about the onboard charging capabilities of the inverter board. My build will be very short range, with a modest battery pack, in a very light 1600lb mid engine car-Tesla SDU+openinverter board already installed. Onboard charging sounds appealing because of weight reduction and it sounded like when wired up correctly it could be very convenient and safe. Sounds like I need to go another route though-I'm not an electrical engineer by any means and if it's super complicated and risky-something not possible for someone like me to learn over the course of a year or so by the time I start the wiring process, I'll seek some other charging system.

[Daveturpin]

I had considered using the onboard charging capability in the openInverter card, but here is why I decided against it:

1) You still need a BMS, and there are fairly inexpensive solutions for BMS and charging on the same hardware.
2) What EVSE are you using? If you are using a J1772 (CCS A/C) charger, Tesla charger, etc., you still need to figure out the interface.
3) Having the charging NOT ISOLATED from the motor increases risk.
4) You need to choose whether to buck or boost (unless I am not understanding the schematics). In my case, since I want to charge a 90-cell battery pack (288-378v), with a 220VAC charger, I would not be able to fully discharge because my voltage range spans the rectified voltage of level-2 J1772 charger.

Basically, it seems like this capability is there for ADVANCED users who are charging with their own protocol.

So:
-What EVSE are you going to use?
-What battery modules are you using?
-What are you going to use for displays?